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|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<!-- -->
<title>Options for TAO Components</title>
</head>
<body bgcolor="#ffffff" link="#000fff" vlink="#ff0f0f" text="#000000">
<hr>
<p></p>
<h2 align="center">Options for TAO Components</h2>
<h3>Table of Contents</h3>
<ul>
<li><a href="#MOT">Introduction</a> </li>
<li><a href="#choose">Choosing the Right Approach</a> </li>
<li><a href="#EXP">TAO's ORB Configuration Options</a>
<ul>
<li><a href="#EV">Environment Variables</a> </li>
<li><a href="#CLO">Command-line Options</a>
<ol>
<li><a href="#CSCB">Controlling Service Configurator Behavior </a>
</li>
<li><a href="#CDI">Controlling Debugging Information </a> </li>
<li><a href="#ORP">Optimizing Request Processing </a> </li>
<li><a href="#CMPS">Connection Management and Protocol
Selection </a> </li>
<li><a href="#IRO">Multiple Invocation Retry Options</a></li>
<li><a href="#MO">Miscellaneous Options </a></li>
</ol>
</li>
<li><a href="#SVC">Service Configuration File </a>
<ol>
<li><a href="#TRF">Simple and Advanced Resource Factories </a>
<ol>
<li><a href="#TDRF">TAO_Default_Resource_Factory </a> </li>
<li><a href="#TARF">TAO_Advanced_Resource_Factory </a></li>
</ol>
</li>
<li><a href="#TSSF">Server_Strategy_Factory </a> </li>
<li><a href="#TCSF">Client_Strategy_Factory </a></li>
<li><a href="#TUPF">TAO_UIPMC_Protocol_Factory </a></li>
<li><a href="#TMSF">MIOP_Strategy_Factory </a></li>
<li><a href="#TTSM">Time_Policy_Manager</a></li>
</ol>
</li>
</ul>
</li>
</ul>
<hr>
<h3><b><a name="MOT">Introduction</a></b></h3>
TAO is a highly flexible ORB that contains a wide range of ORB
configuration options. One or more of these options can be combined
to meet various application requirements, such as low-latency,
predictable real-time behavior, or small memory footprint. TAO's ORB
configuration options are managed by an object-oriented framework
within the ORB Core that contains the following types of entities:
<ul>
<li><b>Settings</b>, which are options that can be assigned values
differing from their default settings. Examples include setting the
size of a Portable Object Adapter (POA)'s active object map or
configuring the ORB to print debugging information as it processes
requests. A few of these are run-time options, while a majority of
them are compile-time options.
<p></p>
</li>
<li><b>Resources</b>, which are objects used internally by TAO, such
as a <em>reactor</em> framework that demultiplexes new connection and
data requests from a client or <em>synchronization mechanisms</em>
used to regulate access to certain parts of the ORB.
<p></p>
</li>
<li><b>Strategies</b>, which are objects that use the <b>Resource</b>
entities to perform various ORB tasks, such as connection management,
concurrency, and demultiplexing.
<p></p>
</li>
<li><b>Factories</b>, which TAO uses to create and consolidate its
many resources and strategies into a manageable number of factories
that can be (re)configured into the ORB conveniently and consistently
by ORB and application developers.
<p></p>
</li>
</ul>
The set of TAO ORB configuration options that are represented by the
settings, resources, strategies, and factories can be specified via
<b>environment variables</b>, <b>service configuration files</b>, and
<b>command-line arguments</b>, as outlined below:
<ul>
<li> <b>Environment variables</b> are limited to specifying the
interoperable object reference (IOR) and port number of TAO's Naming
Service, Trading Service and Implementation Repository. They are
limited in flexibility and don't provide the most important
configuration hooks necessary to configure TAO for real-time and
high-performance applications.
<p></p>
</li>
<li> <b>Command-line options</b> are passed to the ORB
initialization
factory method, <code>CORBA::ORB_init()</code>, by an application
using the standard <i>argc/argv</i> tuple passed to the application's
<code>main()</code>. Most of the options that can be exercised
through
environment variables can also be manipulated through command-line
options. Command-line options override the environment variable
settings if both are enabled.
<p></p>
</li>
<li> The <b>Service Configurator</b> is a framework that can be used
to statically and dynamically configure components into middleware and
applications. The information comprising the names of these
components and their corresponding options are specified in a service
configurator file, whose default file name is
<code>svc.conf</code>. The service configurator is opened and
processed by the ORB in <code>CORBA::ORB_init()</code>. The service
configurator processing is done after all the command-line options
have been parsed.
</li>
</ul>
<p></p>
<hr width="25%" align="left">
<p></p>
<h3><a name="choose">Choosing the Right Approach</a></h3>
TAO's command-line options are useful when there's a fixed set of
configuration options, each of which has a predefined list of
alternative values. Conversely, TAO's service configurator file is
useful for configuring a broader range of resources, strategies, and
factories. Generally speaking, the service configurator file allows
the user to <br>
<ul>
<li>configure the existing components (<em>i.e.</em>, resources,
strategies and factories) based on the predefined list of alternatives
that TAO provides or
<p> </p>
</li>
<li>extend the existing factories by providing user-defined
components and dynamically load them through the service configurator
mechanism. </li>
</ul>
Additionally, the service configurator mechanism allows an
application to control the behavior of the ORB using extensible
configuration information. In general, the command-line configuration
options are provided in TAO
in order to leverage preexisting configuration settings that are
compiled within the TAO ORB. Users are not allowed to change these
settings. In contrast, those options that require more flexible
manipulation of resources, strategies, and factories must be
configured via <a href="#SVC">service configuration files</a>. As a
result, the command-line options and the service configurator options
cannot be used interchangeably.
<p></p>
<hr>
<h3><b><a name="EXP">TAO's ORB Configuration Options</a></b></h3>
This section provides a detailed overview of how to configure TAO's
options using environment variables, command-line options, and service
configuration files.
<p></p>
<hr width="25%" align="left">
<h3><a name="EV">Environment Variables</a></h3>
As mentioned earlier, environment variables have a limited use in TAO
ORB configuration. The currently supported environment variables are
listed below. They are used to specify the IOR and port numbers for
three of TAO's ORB services.
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Environment Variable</th>
<th>Description</th>
</tr>
<tr>
<td><code>NameServicePort</code> <em>which</em></td>
<td>Specifies which port the Naming Service is listening on for
multicast requests. </td>
</tr>
<tr>
<td><code>TradingServicePort</code> <em>which</em></td>
<td>Specifies which port the Trading Service is listening on
for multicast requests. </td>
</tr>
<tr>
<td><code>ImplRepoServicePort</code> <em>which</em></td>
<td>Specifies which port the Implementation Repository is
listening on for multicast requests. </td>
</tr>
</tbody>
</table>
</p>
</blockquote>
In addition to being able to define the port where these known services
are listening for multicast requests, as above, it is possible to set
an environment variable that specifies the IOR of any named service.
For example <code>NameServiceIOR=<which,TradingServiceIOR=<which>,
ImplRepoServiceIOR=<which>, MyServiceIOR=<which></code>. This
will have a similar effect to defining an -ORBInitRef value on the
command line (see below). Any value set as a command line -ORBInitRef
option will override any value set as an environment variable for the
same service name.<br>
<br>
In general, setting environment variables is not particularly portable
or convenient, which is why users can also set these options via
command-line options. The example shown below demonstrates a
deployment scenario where the client and Naming Service run on the
same host:
<p><code>
% NameService.exe -ORBEndpoint iiop://localhost:12345
</code></p>
<p><code>
% client.exe -ORBInitRef NameService=corbaloc:iiop:localhost:12345/NameService
</code></p>
<p>An explanation of these command-line options appears below. </p>
<p></p>
<hr width="25%" align="left">
<h3><a name="CLO">Command-line Options</a></h3>
TAO's run-time behavior can also be controlled by passing options via
the CORBA initialization method <code>CORBA::ORB_init()</code>. ORB
initialization options are commonly passed into the program from the
command-line, using the <code>argc</code> and <code>argv</code>
parameters available to the <code>main()</code> function.
<p>Command-line options can be classified into the following groups
according to their purposes:</p>
<ol>
<li><a href="#CSCB">Controlling Service Configurator Behavior</a> </li>
<li><a href="#CDI">Controlling Debugging Information</a> </li>
<li><a href="#ORP">Optimizing Request Processing</a> </li>
<li><a href="#CMPS">Connection Management and Protocol Selection</a> </li>
<li><a href="#MO">Miscellaneous Options</a>
</li>
</ol>
We describe each of these five groups of options below.
<p></p>
<h4><a name="CSCB">1. Controlling Service Configurator Behavior</a></h4>
The options described below influence the behavior of the ORB's <a
href="#SVC">service configurator, which is opened and processed <em>after</em>
the command-line options
have been parsed. </a>
<p></p>
<blockquote><a href="#SVC"> </a>
<p><a href="#SVC"> </a>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBSvcConf</code> <em>config filename</em></td>
<td>Specifies the name of the file used to read service
configuration directives via the Service Configurator framework. By
default, a service configurator-based application will look for a file
named <code>"svc.conf"</code> in the current directory. </td>
</tr>
<tr>
<td><code>-ORBSvcConfDirective</code> <em>directivestring</em></td>
<td>Specifies a service configuration directive, which is
passed to the Service Configurator. You can pass multiple of these
options on the same command-line. </td>
</tr>
<tr>
<td><code>-ORBServiceConfigLoggerKey</CODE> <em>logger key</em></td>
<TD>Set the logger key in the <code>ACE_Service_Config</code>
framework. Equivalent to the <code>-k</code> option on the ACE
service configurator class.
</td>
</tr>
<tr>
<td><code>-ORBSkipServiceConfigOpen</CODE> </td>
<TD>Do not process any <code>svc.conf</code> files, which has the
side-effect of not initializing the ACE Service Configurator
framework or registering the SIGHUP signal.
</td>
</tr>
<tr>
<td><code>-ORBIgnoreDefaultSvcConfFile</CODE> </td>
<TD>Do not process default <code>svc.conf</code> file. This does not
prohibit processing of explicitly provided <code>-ORBSvcConf</code> and/or
<code>-ORBSvcConfDirective</code> options.
</td>
</tr>
<tr>
<td><code>-ORBGestalt Local|ORB:<i>orbid</i></CODE> </td>
<TD>Instruct the ORB to create a local configuration "gestalt" or
context. By default, all ORBs share a common configuration context. This
is defined by a Service Repository that contains service objects, such
as the resource factory. In some cases multiple ORBs may be dynamically
loaded and as such may wish to have distinct configurations. Passing the
<code>Local</code> argument achieves this. Service objects loaded by an
ORB with a local configuration context will be used by that ORB in place
of any default service object. The final variation is that of shared
contexts. Passing the argument <code>ORB:<i>orbid</i></code> will cause
the ORB to share the local configuration of another ORB as identified with
the supplied id. <i>The shared context feature is not yet implemented.</i>
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="CDI">2. Controlling Debugging Information</a></h4>
During application development and testing, it is often necessary to
control the amount and type of debugging information output by the
ORB. The following options enable TAO to provide debugging
information at several levels of granularity.
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBDebug</code></td>
<td>Instructs the ORB to print debugging messages from the
service configurator framework. This option does not have a value but
is used as a toggle to enable or disable debugging messages.</td>
</tr>
<tr>
<td><code>-ORBDebugLevel </code><em>level</em></td>
<td>Control the level of debugging in the ORB. Higher numbers
generate more output (try 10). The default value of this option is 0.</td>
</tr>
<tr>
<td><code>-ORBVerboseLogging</code> <em>level (0|1|2)</em></td>
<td>Controls the amount of status data printed on each line of
the debug log. Higher numbers generate more output.
The default value of this option is 0. </td>
</tr>
<tr>
<td><code>-ORBLogFile</code> <em>Logfilename</em></td>
<td>Causes all <code>ACE_DEBUG</code> and <code>ACE_ERROR</code>
output to be redirected to the designated <code>Logfilename</code>. </td>
</tr>
<tr>
<td><code>-ORBHandleLoggingStrategyEvents</code>
<em>LoggingStrategyServiceName</em></td>
<td>Causes use of ORB reactor for dispatching timer events to
ACE_Logging_Strategy configured as a dynamic service with name
<code>LoggingStrategyServiceName</code>. This allows to implement log file
rotation. </td>
</tr>
<tr>
<td><code>-ORBObjRefStyle</code> <em>IOR/URL</em></td>
<td>Specifies the user-visible style of object references. The <code>IOR</code>
style (default) is the conventional CORBA object reference, whereas the
<code>URL</code> style looks more like a URL.
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="ORP">3. Optimizing Request Processing</a></h4>
It is often possible to <a href="performance.html">increase TAO's
throughput and reduce latency</a> by optimizing certain stages of
request processing in the ORB. The following command-line options
control various optimizations during request processing.
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBCDRTradeoff</code> <em>maxsize</em></td>
<td><a name="-ORBCDRTradeoff"></a>Control the strategy to
tradeoff between copy vs. no copy marshaling of octet sequences. If an
octet sequence is smaller than <code>maxsize</code> (which defaults to
<code>ACE_DEFAULT_CDR_MEMORY_TRADEOFF</code>) -- and the
current message block contains enough space for it -- the octet
sequence is copied instead of appended to the CDR stream. </td>
</tr>
<tr>
<td><code>-ORBMaxMessageSize</code> <em>maxsize</em></td>
<td><a name="-ORBMaxMessageSize"></a>Set maximum size of
outgoing GIOP request/reply. The request or reply
being sent will be fragmented, if necessary.</td>
</tr>
<tr>
<td><code>-ORBCollocation</code> <em>global/per-orb/no</em></td>
<td><a name="-ORBCollocation"></a>Specifies the use of
collocation object optimization. If <code>global</code> is specified
(default), objects in the same process will be treated as collocated.
If <code>per-orb</code> is specified, only objects in the same ORB are
treated as collocated. When <em>no</em> is specified, no objects are
treated as collocated. </td>
</tr>
<tr>
<td><code>-ORBCollocationStrategy</code> <em>thru_poa/direct/best</em>
</td>
<td>Specifies what type of collocated object to use. If not specified
the TAO_DEFAULT_COLLOCATION_STRATEGY default (default on thru_poa) is used.
If the <code>thru_poa</code> strategy is used, TAO uses the collocation object
implementation that respects POA's current state and policies. When
using the <code>direct</code> strategy, method invocations on
collocated objects become direct calls to servant without checking
POA's status, which can increase performance. If you use the <code>direct</code>
strategy, your interfaces must be compiled with the <code><a
href="compiler.html#collocation-stubs">-Gd</a></code> IDL <a
href="compiler.html">compiler option</a>. If you choose for the <code>best</code> strategy,
TAO tries to perform the best possible collocation, first <code>direct</code> collocation if possible,
else <code>thru_poa</code> collocation if possible and otherwise no collocation. </td>
</tr>
<tr>
<td><code>-ORBAMICollocation</code> <em>1|0</em>
</td>
<td>Specifies what happens when making collocated AMI invocations.
When 1 (default) an AMI call will be done on a collocated
servant and the client thread will be used to invoke the
servant, when 0 the collocated call will be converted
to a remote call so that a different thread could be used
to execute the servant.</td>
</tr>
<tr>
<td><code>-ORBNodelay</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBNodelay"></a>Enable or disable the <code>TCP_NODELAY</code>
option (Nagle's algorithm). By default, <code>TCP_NODELAY</code> is
enabled.</td>
</tr>
<tr>
<td><code>-ORBRcvSock</code> <em>receive buffer size</em></td>
<td><a name="-ORBRcvSock"></a>Specify the size of the socket
receive buffer as a positive, non-zero integer. If not specified, the <code>ACE_DEFAULT_MAX_SOCKET_BUFSIZ</code>
default is used.</td>
</tr>
<tr>
<td><code>-ORBSndSock</code> <em>send buffer size</em></td>
<td><a name="-ORBSndSock"></a>Specify the size of the socket
send buffer as a positive, non-zero integer. If not specified, the <code>ACE_DEFAULT_MAX_SOCKET_BUFSIZ</code>
default is used.</td>
</tr>
<tr>
<td><code>-ORBStdProfileComponents</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBStdProfileComponents"></a>If <em>0</em> then
the ORB does not generate the OMG standardized profile components, such
as the ORB type and code sets. Notice that the presence of this
components is optional in GIOP 1.1 The default value is controlled by a
compile-time flag defined in <CODE>orbconf.h</CODE>.</td>
</tr>
<tr>
<td><code>-ORBNegotiateCodesets</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBNegotiateCodesets"></a>If <em>0</em> then the ORB
does not include the codeset negotiation subsystem, TAO_Codeset. This yields
a somewhat smaller runtime footprint as well as a smaller IOR. However this
also removes the ability to interoperate with ORBs on systems using
alternative character or wide charater encodings. The default value may be set
at compile time by defining <CODE>TAO_NEGOTIATE_CODESETS 0</CODE> in
<CODE>orbconf.h</CODE>. Codeset negotiation support is enabled by default in
TAO as shipped.<br> <b>Note to static lib users</b> In order to build
TAO statically and get the codeset negotiation feature, two additional steps
are needed to ensure the TAO_Codeset library is linked in and initalized. Add the MPC feature "negotiate_codesets=1" to the default.features file and regenerate your makefiles, and add <CODE>#include "tao/Codeset/Codeset.h"</CODE> somewhere in your application source, such as the cpp file containing your main.</td>
</tr>
<tr>
<td><code>-ORBSingleReadOptimization</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBSingleReadOptimization"></a>This option
controls whether TAO's ``single read optimization'' is used when
receiving requests. If this option is disabled (<code>0</code>), the
ORB will do two reads to read a request: one reads the request header
and the other reads the request payload. If this option is enabled (<code>1</code>),
the ORB will do a read of size <code>TAO_MAXBUFSIZE</code>, hoping to
read the entire request. If more than one request is read they will be
queued up for processing later.
<p> This option defaults to <code>1</code> because it can
provide better performance. In the case of Real-time CORBA, however, this
option should be set to <code>0</code>. Consider the following
scenario: (1) two requests are read from one socket, (2) the additional
request is queued, and (3) the ORB uses its Reactor's notification
mechanism to wake up the follower threads. If at the same time,
however, new requests arrive on others sockets of higher priority the
lower priority queued message will be processed before the newly
arrived higher priority request since Reactor notifications are given
preferences over normal I/O, thereby causing priority inversion.</p>
</td>
</tr>
<tr>
<td><code>-ORBDisableRTCollocation</code> <em>boolean (0|1)</em></td> <td><a name="-ORBDisableRTCollocation"></a>This
option controls whether the application wants to use or discard
RT collocation decisions made by the RT ORB. A value of
<CODE>1</CODE> (true) disables RT collocation decisions and falls back on the default
collocation decisions implemented in the default ORB, which is
useful for applications using the RT ORB and doesn't want
to use the RT collocation decisions but fallback on the default
decisions for better performance. The default value is
<code>0</code> (false). </td>
</tr>
<tr>
<td><code>-ORBUseLocalMemoryPool</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBUseLocalMemoryPool"></a>TAO can use a local memory pool
to satisfy some of its needs for heap storage, as it is often more
efficient than using the platform's default memory allocator. The local
pool will always grow as large as necessary to satisfy memory allocations,
but it will never shrink. This means that sometimes a process can retain
memory that it no longer needs. If the default allocator is used then
TAO gives memory back as soon as it is not needed which allows for better
resource sharing at the expense of memory deallocation time.
<p>If this option is disabled (<code>0</code>), the ORB will use the
default allocator for the platform.</p>
<p>If this option is enabled (<code>1</code>), the orb will use the
local memory pool.</p>
<p> This option defaults to the compile-time option specified by
<code>TAO_USES_LOCAL_MEMORY_POOL</code>.</p>
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="CMPS">4. Connection Management and Protocol Selection</a></h4>
TAO can send and receive requests and replies using various <a
href="pluggable_protocols">transport protocols</a>. Each protocol has
its own concept of an <a href="ORBEndpoint.html">endpoint</a>.
The following options manage connections and control protocol
selection within a TAO application.
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBAcceptErrorDelay</code> <em>seconds</em></td>
<td><a name="-ORBAcceptErrorDelay"></a>This argument controls the
amount of time to wait before attempting to accept new
connections in the event that a transient error occurs (such as
running out of file handles). A delay of zero indicates that
accepting should not be attempted again after the transient error
and the handler will be removed from the reactor.
</td>
</tr>
<tr>
<td><code>-ORBDefaultInitRef</code> <em>IOR prefix</em></td>
<td><a name="-ORBDefaultInitRef"></a>This argument allows
resolution of initial references not explicitly specified with
<CODE>-ORBInitRef</CODE>. It requires a URL prefix that, after appending a slash '/'
('|' for the UIOP pluggable protocol) and a simple object key, forms a
new URL to identify an initial object reference. The URL prefix format
currently supported is based on the standard <code><A href="INS.html#corbaloc">corbaloc</A></code>
mechanism in the CORBA <a href="INS.html">Interoperable Naming
Service. </a></td>
</tr>
<tr>
<td><code>-ORBDottedDecimalAddresses</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBDottedDecimalAddresses"></a>Use the dotted
decimal notation for addresses. This option can be used to workaround
broken DNS implementations and may also reduce the time spent resolving
IP addresses. This option is enabled (<code>1</code>) by default on
Windows since DNS is often misconfigured there. On other platforms
this option is disabled (<code>0</code>) since domain names are
more flexible address notations for IORs.</td>
</tr>
<tr>
<td><code>-ORBIIOPClientPortBase</code> <em>base</em></td>
<td><a name="-ORBIIOPClientPortBase"></a>Clients using IIOP can be
constrained to connect <em>from</em> a range of ports. The range is set using
this base value then supplying a span to make it from <code>base</code> to
<code>base + span</code>. The default base port value is 0, meaning a system
selected port is used. If there are no available ports in the range, the ORB
will throw a TRANSIENT exception. </td>
</tr>
<tr>
<td><code>-ORBIIOPClientPortSpan</code> <em>span</em></td>
<td><a name="-ORBIIOPClientPortSpan"></a>Clients using IIOP can be
constrained to connect <em>from</em> a range of ports. The range is set using
a base port value along with this span to make a range from <code>base</code> to
<code>base + span</code>. The default span is 0, meaning a client may connect from
only the base port. The span is ignored if the base port number is 0.</td>
</tr>
<tr>
<td><code>-ORBNoServerSideNameLookups</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBNoServerSideNameLookups"></a>Setting this to 1 will
prevent the ORB from looking up the peer's hostname when accepting an incoming
connection from a client when the above value (<code>ORBDottedDecimalAddresses</code>)
is <code>0</code>. This option is disabled (<code>0</code>) by default.</td>
</tr>
<tr>
<td><code>-ORBEndpoint</code> <em>endpoint</em></td>
<td><a name="-ORBEndpoint"></a>This option is same as the <a
href="#-ORBListenEndpoints"><code>-ORBListenEndPoints</code></a>
option described below. <font color="red">This option will be
deprecated in later versions on TAO since the CORBA
specification now defines the <code>-ORBListenEndpoints</code>
option instead. </font> </td>
</tr>
<tr>
<td><code>‑ORBPreferredInterfaces</code>
<em>targetNetwork=localNetwork[,...]</em></td>
<td><a name="-ORBPreferredInterfaces"></a> This option allows
clients running on a multihomed host to pick a local
network/interface to communicate with a remote target.
When TAO attempts to establish a connection with a host
matching targetNetwork, then it will use the local ip address
matching localNetwork. Simple wildcards can be used for both
parameters, and multiple preferred interfaces can be specified
using comma separators (no embedded spaces allowed) or additional ‑ORBPreferredInterfaces directives.
For example, for a machine with two network cards
identified by the ip addresses 192.168.1.10 and 192.168.1.20, you can
use -ORBPreferredInterfaces *=*10,*=*20 (or the two directives
‑ORBPreferredInterfaces *=*10 ‑ORBPreferredInterfaces *=*20).
Or to force all communication to first try to
use the loopback address, use <code>‑ORBPreferredInterfaces *=127.0.0.1</code> .
<em>targetNetwork</em> can use any string, and must typically match
with the value read from an IOR.
<em>localNetwork</em> must use a dotted decimal address, because it
will be matched with the local ip interfaces.
</tr>
<tr>
<td><code>-ORBEnforcePreferredInterfaces</code>
<em>boolean (0|1)</em></td>
<td><a name="-ORBEnforcePreferredInterfaces"></a> If this
option is set to <CODE>1</CODE> (true), then TAO will only try to use the
interfaces specified by the <CODE>-ORBPreferredInterfaces</CODE> option.
The default is <CODE>0</CODE> (false), in which case if a connection
cannot be made using a preferred interface, TAO will
attempt to use the default interface (<CODE>INADDR_ANY</CODE>).
Note: If none of the preferred interfaces apply to an outgoing connection
then they will not be enforced. For this option to have
any effect, therefore, the connection through a legal preferred interface must fail.
</tr>
<tr>
<td><code>-ORBKeepalive</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBKeepalive"></a>This option allows users to specify
that the SO_KEEPALIVE option is set on TCP sockets used by IIOP.
The default is <code>0</code> (false).
</td>
</tr>
<tr>
<td><code>-ORBDontRoute</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBDontRoute"></a>This option allows users to specify
that the SO_DONTROUTE option is set on TCP sockets used by IIOP.
The default is <code>0</code> (false).
</td>
</tr>
<tr>
<td><code>-ORBLingerTimeout</code> <em>timeout</em></td>
<td><a name="-ORBLingerTimeout"></a> This option allows users to
set the linger timeout on a TCP socket before closing it. Hence,
this option is only useful when using IIOP. The
<code>timeout</code> value can be in the range of zero to the
maximum signed integer value for the particular platform on which
TAO is running.
</td>
</tr>
<tr>
<td><code>-ORBIPHopLimit</code> <em>hops</em></td>
<td><a name="-ORBIPHopLimit"></a>This option allows users to
specify the TTL (IPv4) or hop limit (IPv6) value used when datagrams are
sent over a socket. The default is the one selected by the Operating System.
The <code>hops</code> value can be in the range of zero to the
maximum signed integer value for the particular platform on which
TAO is running. Currently this feature works in IIOP, DIOP, SCIOP, and MIOP.
</td>
</tr>
<tr>
<td><code>-ORBIPMulticastLoop</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBIPMulticastLoop"></a>This option allows users to
specify that the IP_MULTICAST_LOOP / IPV6_MULTICAST_LOOP option is set on
multicast sockets. The default is <code>1</code> (true).
</td>
</tr>
<tr>
<td><code>-ORBListenEndpoints</code> <em>endpoint</em></td>
<td><a name="-ORBListenEndpoints"></a> This option was
introduced with the CORBA <a
href="https://www.omg.org/cgi-bin/doc?orbos/01-01-04">Object
Reference Template</A> (ORT) specification. It instructs a
server ORB to listen for requests on the interface specified
by <code>endpoint</code>. When used with Real-time CORBA, the option
specifies the endpoints that the default thread pool listens
to. TAO endpoints are specified using a URL style format. An
endpoint has the form:
<blockquote><code>protocol://V.v@addr1,...,W.w@addrN
</code></blockquote> where <code>V.v</code> and
<code>W.w</code> are optional protocol versions for each
address. An example of an IIOP endpoint is:
<blockquote><code>iiop://<i><em>hostname</em></i>:<i><em>port</em></i>
</code></blockquote>
Sets of endpoints may be specified using multiple
<code>-ORBListenEndpoints</code> options or by delimiting
endpoints with a semi-colon (;). For example,
<blockquote><code>-ORBListenEndpoints iiop://localhost:9999
-ORBListenEndpoints uiop:///tmp/mylocalsock
-ORBListenEndpoints shmiop://10002 </code></blockquote> is
equivalent to: <blockquote><code>-ORBListenEndpoints
'iiop://localhost:9999;uiop:///tmp/mylocalsock;shmiop://10002'
</code></blockquote> Notice the single quotes (') in the
latter option specification. Single quotes are needed to
prevent the shell from interpreting text after the semi-colon
as another command to run. <p>If an endpoint is specified
without an <code>addr</code> such as the following: </p>
<blockquote><code>-ORBListenEndpoints uiop://
-ORBListenEndpoints shmiop:// </code></blockquote> then a
default endpoint will be created for the specified
protocol. <p>
Click <a href="ORBEndpoint.html"> here</a> for much more on
how to specify endpoints.
</td>
</tr>
<tr>
<td><code>-ORBLaneEndpoint</code> <em>endpoint</em></td>
<td><a name="-ORBLaneEndpoint"></a>This option is same as the
<a
href="#-ORBLaneListenEndpoints"><code>-ORBLaneListenEndPoints</code></a>
option described below. <font color="red">This option will be
deprecated in later versions on TAO.</font>
</td>
</tr>
<tr>
<td><code>-ORBLaneListenEndpoints</code>
<em>thread-pool-id:thread-lane-id endpoint</em></td> <td><a
name="-ORBLaneListenEndpoints"></a> This option allows the
user to specify endpoints for thread pools and lanes. This
option is only meaningful when used with Real-time CORBA and
only makes sense when the thread pools and lanes are created in the
same order across server incarnations. See <a
href="#-ORBListenEndpoints"><code>-ORBListenEndPoints</code></a>
option on how to specify endpoints. An example is:
<blockquote><code>2:3 iiop://localhost:2345
</code></blockquote> where <code>2</code> specifies the second
thread pool created by the process and <code>3</code>
specifies the third lane of that thread pool. Note that
<code>0</code> should be used for the lane when specifying
endpoints for thread pools without lanes. <code>*:*</code>
can be used to specify all pools and lanes, <code>1:*</code> means
all lanes from pool <code>1</code>, and <code>*:1</code>
means lane <code>1</code> from all pools.
<p>Sets of endpoints may be specified using multiple
<code>-ORBLaneListenEndpoints</code> options or by delimiting
endpoints with a semi-colon (;). For example,
<blockquote><code>-ORBLaneListenEndpoints 1:4
iiop://localhost:9999 -ORBLaneListenEndpoints 1:4
uiop:///tmp/mylocalsock -ORBLaneListenEndpoints 1:4
shmiop://10002 </code></blockquote> is equivalent to:
<blockquote><code>-ORBLaneListenEndpoints 1:4
'iiop://localhost:9999;uiop:///tmp/mylocalsock;shmiop://10002'
</code></blockquote> Notice the single quotes (') in the
latter option specification. Single quotes are needed to
prevent the shell from interpreting text after the semi-colon
as another command to run. <p>If an endpoint is specified
without an <code>addr</code> such as the following: </p>
<blockquote><code>-ORBLaneListenEndpoints 2:3 uiop://
-ORBLaneListenEndpoints 2:3 shmiop:// </code></blockquote>
then a default endpoint will be created for the specified
protocol.
</td>
</tr>
<tr>
<td><code>-ORBImplRepoServicePort</code> <em>portspec</em></td>
<td>Specifies which port the Implementation Repository is
listening on for multicast requests. By default, the <code>TAO_DEFAULT_IMPLREPO_SERVER_REQUEST_PORT</code>
(10018) is used.</td>
</tr>
<tr>
<td><code>-ORBInitRef</code> <em>ObjectId=IOR</em></td>
<td><a name="-ORBInitRef"></a>Allows specification of an
arbitrary object reference for an initial service. The IOR could be in
any one of the following formats: OMG <code>IOR</code>, <code>URL</code>,
<code>corbaloc</code> (including <code>uioploc</code>) or <code>file</code>.
<code><A href="INS.html#corbaloc">corbaloc</A></code> is a multiple end-point IOR understood by
<code>ORB::string_to_object()</code> and used as a
boot-strapping mechanism by the <code>ORB::resolve_initial_references()</code>.
The mappings specified through this argument override the ORB
install-time defaults. The <code>file://pathname</code> interprets the
contents of the <code>pathname</code> file as an object reference in
any of the above formats. </td>
</tr>
<tr>
<td><code>-ORBMulticastDiscoveryEndpoint</code> <em>endpoint</em></td>
<td>Specifies the <code>endpoint</code> that should be used
for locating the Naming Service through multicast. <em>endpoint</em>
is of the form <code>ip-number:port-number</code> (<em>e.g.</em>, <code>"tango.cs.wustl.edu:1234"</code>
or <code>"128.252.166.57:1234"</code>). If there is no <code>':'</code>
in the end_point it is assumed to be a port number, with the IP address
being <code>INADDR_ANY</code>. </td>
</tr>
<tr>
<td><code>-ORBNameServicePort</code> <em>portspec</em></td>
<td>Specifies which port the Naming Service is listening on for
multicast requests. By default, the <code>TAO_DEFAULT_NAME_SERVICE_REQUEST_PORT</code>
(10013) value is used.</td>
</tr>
<tr>
<td> <code>-ORBTradingServicePort</code>
<em>portspec</em></a></td>
<td> Specifies
to which port the Trading Service is listening on for multicast
requests. By default, the <code>TAO_DEFAULT_TRADING_SERVICE_REQUEST_PORT</code>
(10016) value is used.</td>
</tr>
<tr>
<td> <code>-ORBUseIMR</code> <em>boolean (0|1)</em></td>
<td>This argument specifies that for POAs with the <code>PERSISTENT</code>
policy, that the TAO <a href="implrepo/">Implementation Repository</a>
should be used for notification of startup and shutdown and object
references should be changed to use the Implementation Repository also (N.B.
although see <code>-ORBIMREndpointsInIOR</code> below). </td>
</tr>
<tr>
<td> <code>-ORBIMREndpointsInIOR</code> <em>boolean (0|1)</em></td>
<td>This argument specifies whether, for POAs with the <code>PERSISTENT</code>
policy, the TAO <a href="implrepo/">Implementation Repository</a>
listen endpoints should be encoded into IORs when <code>-ORBUseIMR</code>
is set. The default is true. </td>
</tr>
<tr>
<td><code>-ORBUseParallelConnects</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBUseParallelConnects"></a>This option allows users to
specify the ORB attempt to connect simultaneously to all endpoints
listed in profiles, rather than stepping through individual endpoints,
trying and possibly failing, before moving on to the next. For this
feature to work, the server must be using shared profiles.
The default is <code>0</code> (false).
</td>
</tr>
<tr>
<td><code>-ORBUseSharedProfile</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBUseSharedProfile"></a>
This option allows multiple implicit or explicit endpoints to be
combined into a single profile for a given protocol rather than using
multiple profiles. For IIOP in non RTCORBA environments, the CORBA
specified tagged component <code>TAG_ALTERNATE_IIOP_ADDRESS</code> is
used to encode the combined endpoints. Processses using RTCORBA and
priority banded connections will continue to generate Profiles with
<code>TAO_TAG_IIOP_ENDPOINT</code> components.
This options is disabled by default.
</td>
</tr>
<tr>
<td><code>-ORBParallelConnectDelay</code> <em>unsigned long msec</em></td>
<td><a name="-ORBParallelConnectDelay"></a>When using parallel
connection attempts, this option defines the number of milliseconds to
delay when polling previously started connection attempts. If a server
is likely to be busy, this client side option will help avoid creating
redundant connections that must be accepted, only to be closed a moment
later. However, if the first reachable endpoint is far down the list,
this option will increase the delay before that endpoint is reached.
The default is <code>0</code>.
</td>
</tr>
<tr>
<td><code>-ORBPreferIPV6Interfaces</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBPreferIPV6Interfaces"></a>
If option is <CODE>1</CODE> (true) it directs the default
endpoint selector for client connections to first attempt to
connect any IIOP endpoints from a provided IOR specifying
IPv6 interfaces. Only when none of these can be found or sucessfully connected IPv4
interfaces will be tried. The default is <CODE>0</CODE> (false).
<p>
This option is only available for IPv6 enabled builds of TAO (<CODE>ACE_HAS_IPV6</CODE>).
</td>
</tr>
<tr>
<td><code>-ORBConnectIPV6Only</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBConnectIPV6Only"></a>
If this option is <CODE>1</CODE> (true) it directs a server ORB to:<br><p>
<li>allow only IPv6 interfaces as listening endpoints</li>
<li>encode only IPv6 interfaces in the IOR profile</li>
<li>prevent (depending on availability of IPV6_V6ONLY socket option)
or block IPv6 to IPv4 connections</li>
<p>
This option directs the default endpoint selector for client connections
to only attempt to connect any IIOP endpoints from a provided IOR specifying
IPv6 interfaces. Any available IPv4 interfaces will be
ignored. The default setting is <CODE>0</CODE> (false).
<p>
This option is only available for IPv6 enabled builds of TAO (ACE_HAS_IPV6).
</td>
</tr>
<tr>
<td><code>-ORBUseIPV6LinkLocal</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBUseIPV6LinkLocal"></a>
If this option is <CODE>1</CODE> (true) it directs a server ORB to allow
connections on IPv6 link local addresses.
The default setting is <CODE>0</CODE> (false).
<p>
This option is only available for IPv6 enabled builds of TAO (ACE_HAS_IPV6).
</td>
</tr>
<tr>
<td><code>-ORBAllowZiopNoServerPolicies</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBAllowZiopNoServerPolicies"></a> If this option is <CODE>1</CODE>
(true) it directs a client ORB to use any client-side (sender) configured ZIOP compression
without having seen any server-side (listener) ZIOP available compressor's list policies.
The CORBA Compressed GIOP (ZIOP) V1.0 specification states that the Server publishes
its available (i.e. allowable) compressors in the IOR of each server object. This
option allows ZIOP to be used with MIOP and/or CORBALOCs that have no such
compression list policies embedded. The client simply has to trust that the server is
configured to allow its highest priority compressor to be used. Any servers
that cannot decompress the client's used ZIOP compressor will reject the
request as they simply cannot decode or handle it (client-side (sender) comms will simply
timeout or lock-up for any such incorrect two-way requests, or be oblivious
to the failure for any such incorrect one-way requests). The default
setting is <CODE>0</CODE> (false) i.e. to disallow compression in such cases
and conform to the ZIOP specification; but this can be changed by adding
<CODE>#define TAO_ALLOW_ZIOP_NO_SERVER_POLICIES_DEFAULT true</CODE> to TAO's <CODE>config.h</CODE>
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="IRO">5. Multiple Invocation Retry Options</a></h4>
In cases such as connection timing issues or a load balancing server
is temporarily not able to handle requests, it may be desirable to have
the ORB transparently retry an invocation a maximum number of times
until a successful invocation is made. To support this, a set of
parameters can be used to cycle over base and location forwarded
profiles until an invocation is successful. When cycling over
profiles and the first base profile is to be used, a user-defined
delay is made before retrying.
<p></p>
These parameters are used in the following situations:
<p></p>
<ul>
<li>Initial connection: If the connection to a server would result
in a TRANSIENT exception being thrown, cycle over profiles no more than the value of
the -ORBForwardOnTransientLimit option before throwing the exception.
<p></p>
</li>
<li>Waiting for a reply from the server: When using the IIOP protocol,
on many platforms if zero bytes is read as the server's reply, this could
indicate that the server may have had a disorderly shutdown or the
connection to the server was abruptly terminated. In this case
cycling through the profiles to retry the request will not exceeding the
value of -ORBForwardOnReplyClosedLimit. If for example the Implementation
Repository and Activator are used to start the server then this cycling could be
used to give the server enough time to re-launch. When this option is
used the -ORBForwardOnTransientLimit option should also be used to
avoid exceptions being thrown when trying to reestablish a connection.
<b>Note that because it is not known if the request was sent, this
could result in the request being processed more than one by the
server. Therefore this option should be used with care.</b>
This is why, although a COMM_FAILURE exception is normally thrown in this case,
this option is kept distinct from -ORBForwardOnCommFailureLimit
discussed below.
<p></p>
<li>Server sends an exception as a reply: A reply is received
and it is checked if it is an exception. If the exception is
of type COMM_FAILURE with completion status of COMPLETED_NO, then
the profiles will be cycled no more than the value of option
-ORBForwardOnCommFailureLimit until a successful reply is
received. Similar retries can be applied to TRANSIENT exceptions
(-ORBForwardOnTransientLimit), OBJECT_NOT_EXIST exceptions
(-ORBForwardOnObjectNotExistLimit), and INV_OBJREF exceptions
(-ORBForwardOnInvObjrefLimit).
<p></p>
</li>
</ul>
The retry options are given in the table below. Note that for
backward compatibility, the -ORBForward* options described in the
<a href="#MO">Miscellaneous Options </a> section are retained.
However, if any option in this section is used, then any
-ORBForward* option given in the Miscellaneous Options
section is ignored.
<p></p>
These options can also be used in the list of
<a href="#TCSF">Client_Strategy_Factory</a> options
in the service configurator file.
Using the service configurator file can help insure these
options are uniformly applied across multiple clients by
having them use the same configurator file.
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBForwardOnTransientLimit</code> <em>limit</em></td>
<td>Use this option to cycle through profiles when
establishing a connection with a server or when a
server replies to a request with a TRANSIENT
exception.
The number of retries will not exceed <em>limit</em>.</td>
</tr>
<tr>
<td><code>-ORBForwardOnCommFailureLimit</code> <em>limit</em></td>
<td>Use this option to cycle through profiles when a
server replies to a request with a COMM_FAILURE
exception.
The number of retries will not exceed <em>limit</em>.</td>
</tr>
<tr>
<td><code>-ORBForwardOnObjectNotExistLimit</code> <em>limit</em></td>
<td>Use this option to cycle through profiles when a
server replies to a request with a OBJECT_NOT_EXIST
exception.
The number of retries will not exceed <em>limit</em>.</td>
</tr>
<tr>
<td><code>-ORBForwardOnInvObjrefLimit</code> <em>limit</em></td>
<td>Use this option to cycle through profiles when a
server replies to a request with a INV_OBJREF
exception.
The number of retries will not exceed <em>limit</em>.</td>
</tr>
<tr>
<td><code>-ORBForwardOnReplyClosedLimit</code> <em>limit</em></td>
<td>Use this option to cycle through profiles when it has
been detected that a connection is closed when reading a server reply
and having the server possibly process the reqest more than once
is acceptable. This option currently does not work under FreeBSD,
OpenVMS, AIX, and Solaris.
The number of retries will not exceed <em>limit</em>.
If this option is used then -ORBForwardOnTransientLimit should
also be used to avoid a TRANSIENT exception being thrown.
</td>
</tr>
<tr>
<td><code>-ORBForwardDelay</code> <em>int msecs</em></td>
<td>Defines the number of milliseconds to delay while
cycling through profiles when the first base profile
is to be tried. The default is 100,000 milliseconds
(0.1 seconds).</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="MO">6. Miscellaneous Options</a></h4>
Options in this category don't control the behavior of the ORB in
terms of resouces or strategies. Instead, they are helper options
provided for specific application requirements.
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBId</code> <em>orb_name</em></td>
<td><a name="-ORBId"></a>This option allows the name of an ORB
to be set to <code>orb_name</code>. The <CODE>ORBId</CODE> will be
passed to the <CODE>CORBA::ORB_init()</CODE> method to differentiate
coexisting ORBs (when there is more than one ORB).</td>
</tr>
<tr>
<td><code>-ORBServerId</code> <em>server_id</em></td>
<td><a name="-ORBServerId"></a>This option allows setting a name/id
to a server to uniquely identify a server to TAO's <a href="implrepo">Implementation
Repository</a>. </td>
</tr>
<tr>
<td><code>-ORBDaemon</code></td>
<td>Specifies that the ORB should <em>daemonize</em> itself, <em>i.e.</em>,
run as a background process. Note, that this changes the working directory to
be the root directory "/". This especially affects relative paths specified at the command line.
This option is only meaningful on OS platforms that support daemonization.</td>
</tr>
<tr>
<td><code>-ORBForwardInvocationOnObjectNotExist</code> <em>boolean (0|1)</em></td>
<td>If this option is 1, the ORB forwards the request to next available profile when
receiving OBJECT_NOT_EXIST exception reply. The default value is <CODE>0</CODE>
which means the request is not forwarded upon OBJECT_NOT_EXIST exception.
</td>
</tr>
<tr>
<td><code>-ORBForwardOnceOnObjectNotExist</code> <em>boolean (0|1)</em></td>
<td>If this option is 1, the ORB forwards the request if it
receives OBJECT_NOT_EXIST exception reply. If it receives one of the exceptions
(OBJECT_NOT_EXIST, COMM_FAILURE, TRANSIENT, INV_OBJREF) during forwarding,
the request is not forwarded again and exception is propagated to the client
code. The default value is <CODE>0</CODE> which means the request
is not forwarded upon OBJECT_NOT_EXIST exception.
</td>
</tr>
<tr>
<td><code>-ORBForwardOnceOnCommFailure</code> <em>boolean (0|1)</em></td>
<td>If this option is 1, the ORB forwards the request if it
receives COMM_FAILURE exception reply. If it receives one of the exceptions
(OBJECT_NOT_EXIST, COMM_FAILURE, TRANSIENT, INV_OBJREF) during forwarding,
the request is not forwarded again and exception is propagated to the client
code. The default value is <CODE>0</CODE> which means the request is not forwarded upon
COMM_FAILURE exception.
</td>
</tr>
<tr>
<td><code>-ORBForwardOnceOnTransient</code> <em>boolean (0|1)</em></td>
<td>If this option is 1, the ORB forwards the request if it
receives TRANSIENT exception reply. If it receives one of the exceptions
(OBJECT_NOT_EXIST, COMM_FAILURE, TRANSIENT, INV_OBJREF) during forwarding,
the request is not forwarded again and exception is propagated to the client
code. The default value is <CODE>0</CODE> which means the request
is not forwarded upon TRANSIENT exception.
</td>
</tr>
<tr>
<td><code>-ORBForwardOnceOnInvObjref</code> <em>boolean (0|1)</em></td>
<td>If this option is 1, the ORB forwards the request if it
receives INV_OBJREF exception reply. If it receives one of the exceptions
(OBJECT_NOT_EXIST, COMM_FAILURE, TRANSIENT, INV_OBJREF) during forwarding,
the request is not forwarded again and exception is propagated to the client
code. The default value is <CODE>0</CODE> which means the request
is not forwarded upon INV_OBJREF exception.
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<p></p>
<hr width="25%" align="left">
<h3><a name="SVC">The Service Configurator File</a></h3>
Internally, TAO uses the <a
href="http://www.dre.vanderbilt.edu/~schmidt/PDF/Svc-Conf.pdf">ACE Service
Configurator framework</a> to allow applications to configure the ORB
at run-time. Applications provide a file named <code>svc.conf</code>
with options that configure appropriate strategies in to the ORB. The
options enable developers to control the behavior of the factories,
strategies, and resources that the ORB uses. By default, TAO provides
the following set of factories:
<p></p>
<ol>
<li><a href="#TRF">Default Resource and Advanced Resource Factories.</a>
This factory controls the creation of configurable resources used by
TAO's ORB core. The resource factory is responsible for constructing
and providing access to various resources used by the ORB irrespective
of whether they perform client or server roles. ORB resources include
reactors, protocol factories, message flushing strategies, connection
purging strategies and different IOR parsers.
<p> </p>
</li>
<li> <a href="#TSSF">Server Strategy Factory.</a> This factory
creates various strategies of special utility to the ORB that is useful
for controlling the behavior of servers. This factory is responsible
for creating strategies useful for server objects like the concurrency
strategy and the request demultiplexing strategies used by the POA.
<p> </p>
</li>
<li> <a href="#TCSF">Client Strategy Factory.</a> This factory
creates various strategies of special utility to the ORB, useful for
controlling the behavior of clients. This factory is responsible for
creating strategies useful for clients such as request multiplexing
strategies, wait strategies, connect strategies etc.
<p></p>
</li>
<li> <a href="#TUPF">TAO UIPMC Protocol Factory </a> This factory is
responsible for controlling the behavior of clients and servers that
use UDP sockets.
<p></p>
</li>
<li> <a href="#TMSF">MIOP Strategy Factory.</a> This factory is
responsible for controlling the behavior of clients and servers that
use MIOP protocol.
<p></p>
</li>
<li> <a href="#TTSM">Time Policy Strategy Manager.</a> This factory
manages the TIME_POLICY strategy used by the ORB for timers and
countdowns.
<p></p>
</li>
</ol>
Options specified via a <code>svc.conf</code> file can represent
either the components provided by TAO (including the
<code>Resource_Factory</code>, and the
<code>Server_Strategy_Factory</code> and
<code>Client_Strategy_Factory</code>) or customized components
developed by the users. The service configurator file
(<code>svc.conf</code>) provided by the user identifies the components
to be loaded with the required strategies for each component.
<p>A <code>svc.conf</code> file is <em><b>not</b></em> required to
run
TAO applications since TAO provides a set of default values for
strategies useful for the most common use cases, <em>i.e.</em>, the
default values are set for all options. When a TAO application calls
<code>CORBA::ORB_init()</code> it will try to find the
<code>svc.conf</code> file. If found, TAO will parse and process the
directives in the file; if not found, the default value for the
default components will be used.</p>
<hr width="25%" align="left">
<h4><a name="TRF">1. Default and Advanced Resource Factories</a></h4>
Many of TAO's ORB Core resources are fixed, including the allocators
for
the incoming and outgoing data paths, and data structures for the
various
maps and lists maintained by the ORB. There is some flexibility,
however, in the choice of a reactor, the selection of transport
protocols, choice of data flushing strategy, various forms of
connection resource management strategies and possibility of using
different IOR parsers. The resource factories supported by TAO
include the <code>Resource_Factory</code> and
<code>Advanced_Resource_Factory</code>. TAO provides defaults of these
factories, as well as the specialized resource factories described
below:
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Resource Factory</th>
<th>Description</th>
</tr>
<tr>
<td><code><a href="#TDRF">Resource Factory</a></code></td>
<td>Unless configured otherwise, this is the default resource
factory used by the ORB.The resource factory is responsible for
creating and providing access to various resources used by the server
and client ORBs. The resources managed by this factory include creation
of acceptor and connector registries, choice of data flushing strategy,
limits for connection resource management, types of CDR buffers used
for marshalling and demarshalling data, and different IOR parsers. </td>
</tr>
<tr>
<td><code><a href="#TARF">Advanced Resource Factory</a></code></td>
<td>This factory provides more advanced configuration options
in the addition to all the features of the default resource factory.<br>
<br>
The advanced resource factory gives more control than the default
resource factory over the type of resources used and how those
resources are accessed. In addition to the options provided by the
default resource factory, the advanced resource factory provides
options that allow selecting different reactors, choosing different
transport mechanisms and selecting the right connection purging
strategy to maintain limits on resources used. The advanced resource
factory was created to allow more advanced options while keeping the
footprint of the default resource factory small.<br>
<br>
The advanced resource factory inherits from the default resource
factory and accepts all of its options in addition to its own. </td>
</tr>
<tr>
<td><code>Qt Resource Factory</code></td>
<td>This is a specialized resource factory providing the means
for integrating with the Qt GUI toolkit from Trolltech. </td>
</tr>
<tr>
<td><code>Xt Resource Factory</code></td>
<td>This is a specialized resource factory providing the means
for integrating with the X Window System's Xt Intrinsics toolkit. </td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<p></p>
<h4><a name="TDRF">1.1. Resource_Factory</a></h4>
Typically, the above options are exercised via the service
configurator (svc.conf) file. The following line in the
<code>svc.conf</code> file (all in one line)
<p> <code>static
Resource_Factory "[list of options]"</code></p>
<p>will load the default
resource factory with the options listed within the double quotes. The
following table shows the list of possible options that can be
specified within the double quotes in the above directive. There is an <a
href="../tests/LongUpcalls/svc.conf">
example</a> of how this is used in TAO.</p>
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBConnectionCacheLock</code> <em>locktype</em></td>
<td><a name="-ORBConnectionCacheLock"></a>Specify the type of
lock to be used by the Connection Cache. Possible values for lock type
are <code>thread</code>, which specifies that an inter-thread mutex is
used to guarantee exclusive access, and <code>null</code>, which
specifies that no locking be performed. The default is thread. </td>
</tr>
<tr>
<td><code>-ORBConnectionCacheMax</code> <em>limit</em></td>
<td><a name="-ORBConnectionCacheMax"></a>The transport cache
will grow to a maximum of the specified limit. The default is system
dependent, but can be overridden at compile-time by defining the
preprocessor macro <CODE>TAO_CONNECTION_CACHE_MAXIMUM</CODE>. </td>
</tr>
<tr>
<td><code>-ORBConnectionCachePurgePercentage</code> <em>percent</em></td>
<td><a name="-ORBConnectionCachePurgePercentage"></a>If the
transport cache is purged, the specified percentage (20 by default) of
the total number of connections cached will be closed. </td>
</tr>
<tr>
<td><code>-ORBConnectionPurgingStrategy</code> <em>type</em></td>
<td><a name="-ORBConnectionPurgingStrategy"></a>Opened
connections are added to the transport cache so they can be reused.
If a process continues to run and these connections are not reused,
however, the cache will continue to grow. Before each new connection,
therefore, the cache is checked and purged if it has reached the limit
specified by the <CODE>-ORBConnectionCacheMax</CODE> option or the
system default if that option was not used. The possible values for
type are <CODE>lru</CODE>, <CODE>lfu</CODE>, <CODE>fifo</CODE>, and
<CODE>null</CODE>. The default is <CODE>lru</CODE> (least recently
used). The other options are <CODE>lfu</CODE> (least frequently used),
<CODE>fifo</CODE> (first in first out), and <CODE>null</CODE> (no
connections are purged) and are contained within the TAO Strategies
library. </td>
</tr>
<tr>
<td><code>-ORBDropRepliesDuringShutdown</code> <em>boolean (0|1)</em></td>
<td><a name="-ORBDropRepliesDuringShutdown"></a> Strategy to
make the ORB wait for replies to show up even if the ORB is
shutdown. The default is to drop replies. For example, clients
comunicating with misbehaved servers will continue to hang if
replies don't show up and even if the client ORB is shutdown
from another thread. This strategy helps the ORB decide to
wait for the replies or drop replies. Some clients may not
want to drop replies, and may want all their requests to be
processed until ORB::destroy () is called. Setting the value
of this option to 0 would help with that. </td>
</tr>
<tr>
<td><code>-ORBFlushingStrategy</code> <em>type</em></td>
<td><a name="-ORBFlushingStrategy"></a>By default TAO provides
three strategies to flush queued messages. The <code>leader_follower</code>
strategy uses the Reactor and non-blocking I/O to send the outgoing
messages, this strategy participates in the Leader/Followers protocol
to synchronize access to the Reactor. The <code>reactive</code>
strategy uses the Reactor but does not take part in the
Leader/Followers protocol, thus it is better used only in single
threaded applications. Finally, the <code>blocking</code> strategy
flushes the queue as soon as it becomes "full", and blocks the thread
until all the data is sent.
</td>
</tr>
<tr>
<td><code>-ORBIORParser</code> <em>parser</em></td>
<td><a name="-ORBIORParser"></a>Name an IOR Parser to load. IOR
Parsers are used to interpret strings passed to <code>ORB::string_to_object()</code>.
By default the ORB can handle multiple string formats, including <code>IOR:</code>,
<code>corbaloc:</code>, <code>corbaname:</code>, and <code>file:</code>.
The application developer can <a href="ior_parsing.html">add
new IOR formats </a>using this option. </td>
</tr>
<tr>
<td><code>-ORBMuxedConnectionMax</code> <em>number</em></td>
<td><a name="-ORBMuxedConnectionMax"></a>The transport cache
allows only specified number of connections-per-QoS property to be
added to connection cache. Threads not getting the connections will
wait for the connections to be released. This option is more useful for
transports using a muxed connection strategy and want control over the
number of connections that are created by the active threads. </td>
</tr>
<tr>
<td><code>-ORBOutputCDRAllocator</code> <em>mmap|local_memory_pool</em></td>
<td><a name="-ORBOutputCDRAllocator"></a>When the define
<code>TAO_USE_OUTPUT_CDR_MMAP_MEMORY_POOL</code> is set to 1 then always the mmap pool
will be used.
</td>
</tr>
<tr>
<td><code>-ORBProtocolFactory</code> <em>factory</em></td>
<td><a name="-ORBProtocolFactory"></a>Specify which pluggable
protocol factory to load. By default, only the factory for the IIOP
protocol (<code>IIOP_Factory</code>) is loaded.
<p>For example, if some protocol called <em><code>Foo</code></em>
whose factory was called <em><code>Foo_Factory</code></em> was
available, then it could be loaded into TAO by specifying <code>-ORBProtocolFactory
Foo_Factory</code> in the service configurator file. The <em><code>Foo</code></em>
pluggable protocol would then be available for use. </p>
</td>
</tr>
<tr>
<td><code>-ORBReactorMaskSignals</code> <em>0/1</em></td>
<td>ACE select reactors mask signals during upcalls to the
event handlers. This is only useful if the application is going to trap
those signals and handle them in any special way. Disabling the mask
can improve performance by reducing the number of kernel level locks. </td>
</tr>
<tr>
<td><code>-ORBZeroCopyWrite</code> </td>
<td><a name="-ORBZeroCopyWrite"></a> Use a zero copy write
protocol, which at this moment the only option is sendfile.
If your platform does support sendfile but you don't want
that TAO uses it you can disable
sendfile in TAO by add the define <code>TAO_HAS_SENDFILE 0</code>
to your config.h file.
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="TARF">1.2. Advanced_Resource_Factory</a></h4>
This factory is located in the <code>TAO_Strategies</code> library. It
accepts the options below as well as those described above in the
<code>Resource_Factory</code>. This factory can be loaded dynamically
using a service configurator directive of the form (all on one line):
<p><code>dynamic Advanced_Resource_Factory Service_Object
*</code><br>
<code>TAO_Strategies:_make_TAO_Advanced_Resource_Factory
() "-ORBReactorType select_st" </code></p>
<p>It can also be loaded statically by doing the following:</p>
<p></p>
<ul>
<li>Add <code>#include "tao/Strategies/advanced_resource.h"</code>
to the file containing <code>main()</code>. </li>
<li>Link the TAO_Strategies library into the executable. </li>
<li>Specify a service configurator directive of the form: <code>static
Advanced_Resource_Factory "-ORBReactorType select_st"</code> </li>
</ul>
You can
omit the <code>#include</code> if you always use dynamic libraries.
<p>Loading the <code>Advanced_Resource_Factory</code> disables the
<code>Resource_Factory</code>. Any directives for the
<code>Resource_Factory</code> will have no effect (and generate
warnings telling you so). The following table lists the options that
can be provided in double quotes. An <a
href="../performance-tests/Latency/Single_Threaded/svc.conf"> example</a>
is available that shows how to specify this option in the svc.conf file.</p>
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBAMHResponseHandlerAllocator</code> <em>which</em></td>
<td><a name="-ORBAMHResponseHandlerAllocator"></a>Specify whether the ORB
uses locked (<em>which</em> = <code>thread</code>) or lock-free (<em>which</em>
= <code>null</code>) allocators for the AMH response handlers.</td>
</tr>
<tr>
<td><code>-ORBAMIResponseHandlerAllocator</code> <em>which</em></td>
<td><a name="-ORBAMIResponseHandlerAllocator"></a>Specify whether the ORB
uses locked (<em>which</em> = <code>thread</code>) or lock-free (<em>which</em>
= <code>null</code>) allocators for the AMI response handlers.</td>
</tr>
<tr>
<td><code>-ORBInputCDRAllocator</code> <em>which</em></td>
<td><a name="-ORBInputCDRAllocator"></a>Specify whether the
ORB uses locked (<em>which</em> = <code>thread</code>) or lock-free
(<em>which</em> = <code>null</code>) allocators for the incoming CDR
buffers. Though <code>null</code> should give the optimal performance;
we made the default <code>thread</code>. TAO optimizations for octet
sequences will not work in all cases when the allocator does not have
locks (for example if the octet sequences are part of a return
value). Using locked allocators also allows the users to take
advantage of the TAO octet sequence extensions to preserve the buffer
after the upcall. </td>
</tr>
<tr>
<td><code>-ORBReactorRegistry</code> <em>registry_type</em></td>
<td><a name="-ORBReactorRegistry"></a>This option is no longer
supported. The Advanced Resource Factory will emit an error if you
attempt its use. </td>
</tr>
<tr>
<td><code>-ORBReactorThreadQueue</code> <em>which</em></td>
<td><a name="-ORBReactorThreadQueue"></a>Applies only to the
<CODE>ACE_TP_Reactor</CODE>, i.e., when <code>-ORBReactorType</code> =
<code>tp</code>, and specifies the order, last-in-first-out
(<em>which</em> = <code>LIFO</code>), the default, or
first-in-first-out (<em>which</em> = <code>FIFO</code>), in which
waiting threads are selected to run by the
<CODE>ACE_Select_Reactor_Token</CODE>. </td>
</tr>
<tr>
<td><code>-ORBReactorType</code> <em>which</em></td>
<td><a name="-ORBReactorType"></a>Specify what kind of reactor
the ORB uses. The default reactor is the ACE_TP_Reactor.
<table border="1" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th><em>which</em></th>
<th>Reactor</th>
</tr>
<tr>
<td><code>select_mt</code></td>
<td>Use the multi-thread select-based reactor.</td>
</tr>
<tr>
<td><code>select_st</code></td>
<td>Use the single-thread select-based reactor.</td>
</tr>
<tr>
<td><code>wfmo</code></td>
<td>Use the WFMO reactor (Win32 only).</td>
</tr>
<tr>
<td><code>msg_wfmo</code></td>
<td>Use the MsgWFMO reactor (Win32 only).</td>
</tr>
<tr>
<td><code>tp</code></td>
<td>Use the <code>ACE_TP_Reactor</code>, a select based
thread-pool reactor which is the default.</td>
</tr>
<tr>
<td><code>dev_poll</code></td>
<td>Use the <code>ACE_Dev_Poll_Reactor</code>, a
<code>/dev/poll</code> or Linux <code>sys_epoll()</code>
based thread-pool reactor. It is intended to be a
highly scalable replacement for the
<code>select()</code> based reactors. The
ACE_Dev_Poll_Reactor is currently only supported on
HP-UX, Solaris and Linux. Be aware that dev_poll
support is experimental!</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="TSSF">2. Server_Strategy_Factory</a></h4>
Certain elements of the ORB relate only to a TAO server. In this
context, the server is any application that passively accepts
connection from other processes and receives requests from those other
connections. The server strategy factory is responsible for supporting
features of TAO that are specific to servers. In particular, these
include the following strategies:
<ul>
<li> The <em>concurrency strategies</em> control the thread creation
flags and other concurrency related behaviors.
<p></p>
</li>
<li> The <em>demuliplexing strategies</em> are used
to locate servants inside the POA that are responsible for handling
requests.
<p></p>
</li>
</ul>
TAO provides a default server strategy factory called
<code>Server_Strategy_Factory</code>
<p>Typically, the following options are set via the service
configurator
(svc.conf) file. The following line in the svc.conf file (all in one
line)</p>
<p><code>static Server_Strategy_Factory "[list of
options]"</code></p>
<p>would load all the options listed within "". An
<a href="../performance-tests/Latency/Single_Threaded/svc.conf">example</a>
is available
that shows how to specify this option in the <code>svc.conf</code>
file. </p>
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBActiveHintInIds</code> <em>adds an active hint
in ids</em></td>
<td>Specify whether an active hint should be added to ids. With
active hints, ids can be found quickly. However, they lead to larger
IORs. Note that this option is disregarded <code>if
-ORBAllowReactivationOfSystemids</code> is set to <code>0</code>.
The <em>-ORBActiveHintInIds</em>
can be <code>0</code> or <code>1</code>. This option defaults to <code>1</code>.
</td>
</tr>
<tr>
<td><code>-ORBActiveHintInPOANames</code> <em>adds an active
hint in poa names</em></td>
<td>Specify whether an active hint should be added to POA
names. With active hints, POA names can be found quickly. However, they
lead to larger IORs. The <code>-ORBActiveHintInPOANames</code> can be <code>0</code>
or <code>1</code>. This option defaults to <code>1</code>. </td>
</tr>
<tr>
<td><code>-ORBActiveObjectMapSize</code> <em>active object map
size</em></td>
<td>Specify the size of the active object map. If not
specified, the default value is 64.</td>
</tr>
<tr>
<td><code>-ORBAllowReactivationOfSystemids</code> <em>allows
reactivation of system ids</em></td>
<td>Specify whether system ids can be reactivated, i.e., once
an id that was generated by the system has been deactivated, will the
user reactivate a new servant using the old id. If the user is not
going to use this feature, the IORs can be shortened, an extra
comparison in the critical upcall path removed, and some memory on the
server side can be saved. The <code>ORBAllowReactivationOfSystemids</code>
can be <code>0</code> or <code>1</code>. This option defaults to <code>1</code>.
</td>
</tr>
<tr>
<td><a name="orb_concurrency"><code>-ORBConcurrency</code></a> <em>which</em></td>
<td>Specify which concurrency strategy to use. Range of values
is <code>reactive</code> for a purely Reactor-driven concurrency
strategy or <code>thread-per-connection</code> for creating a new
thread to service each connection. The default is reactive. </td>
</tr>
<tr>
<td><code>-ORBPersistentidPolicyDemuxStrategy</code> <em>persistent
id policy based demultiplexing strategy</em></td>
<td>Specify the demultiplexing lookup strategy to be used with
the persistent id policy. The <em>demultiplexing strategy</em> can be
one of <code>dynamic</code> or <code>linear</code>. This option
defaults to using the <code>dynamic</code> strategy. </td>
</tr>
<tr>
<td><code>-ORBPoaMapSize</code> <em>poa map size</em></td>
<td>Specify the size of the POA map. If not specified, the
default value is 24.</td>
</tr>
<tr>
<td><code>-ORBSystemidPolicyDemuxStrategy</code> <em>system id
policy based demultiplexing strategy</em></td>
<td>Specify the demultiplexing lookup strategy to be used with
the system id policy. The <em>demultiplexing strategy</em> can be one
of <code>dynamic</code>, <code>linear</code>, or <code>active</code>.
This option defaults to use the <code>dynamic</code> strategy when <code>-ORBAllowReactivationOfSystemids</code>
is true, and to <code>active</code> strategy when <code>-ORBAllowReactivationOfSystemids</code>
is false. </td>
</tr>
<tr>
<td><code>-ORBThreadFlags</code> <em>thread flags</em></td>
<td>Specify the flags used for thread creation. Flags can be
any logical-OR combination of <code>THR_DETACHED</code>, <code>THR_BOUND</code>,
<code>THR_NEW_LWP</code>, <code>THE_SUSPENDED</code>. The
default is <code>THR_BOUND | THR_DETACHED</code> . </td>
</tr>
<tr>
<td><a name="server_timeout"><code>-ORBThreadPerConnectionTimeout</code></a>
<em>milliseconds</em></td>
<td>In many platforms it is impossible to interrupt the server
threads created by the <code>thread-per-connection</code> model. This
is because these threads are blocked in <code>read()</code> operations
(and not in <code>select()</code>). As a workaround, the server
threads periodically poll the ORB to find out if they should shutdown.
This option controls the period of the polling, expressed in
milliseconds. Applications that do not shutdown, or that can otherwise
ensure that no server threads will be running at shutdown (for example
if all the clients terminate before the server) can disable the
polling using the magic value <code>INFINITE</code>.
<p>If the option is not provided then the ORB uses the
compile-time flag <code>TAO_DEFAULT_THREAD_PER_CONNECTION_TIMEOUT</code>,
this flag also expresses the time in milliseconds (as a string
constant) and the magic value <code>"INFINITE"</code> can be used to
disable polling entirely. This yields a slight performance improvement
(around 1%). </p>
</td>
</tr>
<tr>
<td><code>-ORBTransientidPolicyDemuxStrategy</code> <em>transient
id policy based demultiplexing strategy</em></td>
<td>Specify the demultiplexing lookup strategy to be used with
the transient id policy. The <em>demultiplexing strategy</em> can be
one of <code>dynamic</code>, <code>linear</code>, or <code>active</code>.
This option defaults to using the <code>active</code> strategy. </td>
</tr>
<tr>
<td><code>-ORBUniqueidPolicyReverseDemuxStrategy</code> <em>unique
id policy based reverse demultiplexing strategy</em></td>
<td>Specify the reverse demultiplexing lookup strategy to be
used with the unique id policy. The <em>reverse demultiplexing strategy</em>
can be one of <code>dynamic</code> or <code>linear</code>. This
option defaults to using the <code>dynamic</code> strategy. </td>
</tr>
<tr>
<td><code>-ORBUseridPolicyDemuxStrategy</code> <em>user id
policy based demultiplexing strategy</em></td>
<td>Specify the demultiplexing lookup strategy to be used with
the user id policy. The <em>demultiplexing strategy</em> can be one of
<code>dynamic</code> or <code>linear</code>. This option
defaults to using the <code>dynamic</code> strategy. </td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="TCSF">3. Client_Strategy_Factory</a></h4>
Similar to the
server strategy factory, the client strategy factory supports those
elements of TAO that are specific to the behavior of clients, which
are any CORBA applications that actively establish connections, submit
requests, and perhap receive responses. The client strategy factory
provides control over several resources used by clients. TAO provides
a default client strategy factory called
<code>Client_Strategy_Factory</code>.
<p>Typically, the following options are set via the service
configurator
(<code>svc.conf</code>) file. The following line in the
<code>svc.conf</code> file (all in one line)</p>
<p><code>static Client_Strategy_Factory "[list of options]"</code></p>
<p> would load all the options listed within "". An <a
href="../performance-tests/Latency/Single_Threaded/svc.conf">example</a>
is available that shows how to specify this option in the <code>svc.conf</code>
file.</p>
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBClientConnectionHandler</code> <em>MT | ST | RW
/ MT_NOUPCALL</em><br>
<code>-ORBWaitStrategy</code> <em>MT / ST / RW / MT_NOUPCALL
</em>
</td>
<td><em>Please note that these two options are synonymous and can be used interchangeably.</em>
<p><a name="-ORBClientConnectionHandler"></a><em>ST</em> means
use the single-threaded client connection handler, i.e., the leader
follower model will not be used. However, <em>ST</em> does support
nested upcalls and handling of new requests while waiting for the reply
from a server.
<p><em>MT</em> means use the multi-threaded client connection
handler which uses the leader follower model. This model allows the use
of multiple threads with a single Reactor. </p>
<p><em>RW</em> selects a strategy that simply blocks in
<code>recv()</code> when waiting for a response from the server
instead of waiting in the Reactor using the Leader/Followers
pattern. The <em>RW</em> strategy only works when the application
does not have to worry about new request showing up when waiting for a
response. Further, this strategy cannot be used with BiDIR GIOP.
Note that applications that require nested upcalls are not compatible
with this strategy. Also note that this strategy will only affect synchronous
two way calls, since there is no waiting for one way calls or AMI requests
(at least not in the same sense as for synchronous two way calls).
This strategy can also be used in an application that
is both a client and a server where the server side is handled by a
separate thread and the client threads are "pure" clients.
Use in single threaded applications with both client and server roles is
also possible but in these cases special care has to be taken to avoid
deadlocks because of nested synchronous calls. Mixing in AMI requests and/or
other asynchronous reactor (timer/notification) events might help solve
such issues.
When this strategy is set to RW, then also the -ORBFlushingStrategy
(which is part of the Resource_Factory) has to be set to <code>blocking</code>.</p>
<p>
<CODE>MT_NOUPCALL</CODE> means use a client connection handler that
participates in the leader-follower model like MT, but, like
RW, does not allow handling of nested CORBA upcalls within the
waiting thread. It does allow handling of other non CORBA (ACE reactor events)
like timers and ACE notification queue events. Note that with
this strategy it is possible
to "run out of threads" in a thread pool, and that TAO doesn't
grow thread pools. Unlike RW, this does not require <a
href="#ORBTransportMuxStrategy">-ORBTransportMuxStrategy <em>EXCLUSIVE</em></a>.
</p>
<p>Default for this option is <em>MT</em>. </p>
</td>
</tr>
<tr>
<td><code>-ORBConnectionHandlerCleanup</code> <em>0 | 1</em><br>
</td>
<td><a name="-ORBConnectionHandlerCleanup"></a>Setting this
option to <em>1</em> lets the ORB know that connection
handlers setup for sending messages need to be cleaned up
when errors occur. This option has an effect only for
<em> -ORBClientConnectionHandler RW </em>. Rest of the
options for <em> -ORBClientConnectionHandler </em> have been
automatically set up for cleaning the connection
handlers. Setting the option to <em> 1 </em> has a side
effect of registering and unregistering the connection
handlers with the Reactor for every invocation, which has a
negative impact on performance. Setting the option to <em> 0
</em> prevents this performance impact but leads to problems
outlined
<A
href="http://bugzilla.dre.vanderbilt.edu/show_bug.cgi?id=2186">
here</A> and <a
href="http://bugzilla.dre.vanderbilt.edu/show_bug.cgi?id=2224">
here</A>
<p>Default for this option is <em>0</em>. </p>
</td>
</tr>
<tr>
<td><code>-ORBConnectStrategy</code> <em>type</em></td>
<td><a name="-ORBConnectStrategy"></a>TAO provides three
strategies to connect to remote servers. The default <em>leader_follower</em>
strategy uses the Reactor and non-blocking connects to connect and this
strategy participates in the Leader/Followers protocol to synchronize
access to the Reactor. The <em>reactive</em> strategy uses the Reactor
for non-blocking connects but does not take part in the
Leader/Followers protocol, thus it is better used only in single
threaded applications. Finally, the <em>blocked</em> strategy as the
name implies, blocks the thread until connection is complete. Some of
the protocols in TAO (such as SHMIOP and SSLIOP) can only use the <em>blocked</em>
strategy.
</td>
</tr>
<tr>
<td><code>-ORBDefaultSyncScope</code> <em>None | Transport | Server | Target</em></td>
<td><a name="-ORBDefaultSyncStrategy"></a>Supply a default sync scope for
the ORB to use when a Messaging Sync Scope policy is not used. When not
supplied, the default sync scope is SYNC_WITH_TRANSPORT.
</td>
</tr>
<tr>
<td><code>-ORBTransportMuxStrategy</code> <em>EXCLUSIVE | MUXED</em></td>
<td><a name="ORBTransportMuxStrategy"></a><em>EXCLUSIVE</em>
means that the Transport does not multiplex requests on a connection.
At a time, there can be only one request pending on a connection.
<p><em>MUXED</em> means that Transport multiplexes more than
one request at the same time on a connection. This option is often used
in conjunction with AMI, because multiple requests can be sent "in
bulk." </p>
<p>Default for this option is <em>MUXED</em>. </p>
</td>
</tr>
<tr>
<td>Invocation Retry options</td>
<td>Options of the same names as the command-line options
described in <a href="#IRO">Multiple Invocation Retry Options</a>
can also be applied client strategy factory service. Any
option provided on the command line will override the
corresponding option in the service configurator
file.
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="TUPF">4. TAO_UIPMC_Protocol_Factory</a></h4>
This factory is located in the <code>TAO_PortableGroup</code> library and
is used with the DIOP and MIOP protocols managing the UDP connectionless
sockets (normally one-way calls only) instead of the standard IIOP TCP/IP
two-way connection based sockets. It accepts the options shown below.
(Any options required should be given
to the TAO_UIPMC_Protocol_Factory between the two double-quotes at the end
of the line as a space separated list; however none are required as all
options take default values if not specified.) This factory can be loaded
dynamically using service configurator directives of the form (all on one line):
<p><code>dynamic UIPMC_Factory Service_Object *
TAO_PortableGroup:_make_TAO_UIPMC_Protocol_Factory() ""</code></p>
<p>Normally however in order to set up the TAO_UIPMC_Protocol_Factory correctly,
the application will have to use other service configurator directives as well;
for example:</p>
<code>dynamic UIPMC_Factory Service_Object *
TAO_PortableGroup:_make_TAO_UIPMC_Protocol_Factory() ""<br>
static Resource_Factory "‑ORBProtocolFactory IIOP_Factory
‑ORBProtocolFactory UIPMC_Factory"<br>
dynamic PortableGroup_Loader Service_Object *
TAO_PortableGroup:_make_TAO_PortableGroup_Loader() ""</code></p>
<blockquote>
<p></p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBListenerInterfaces</code> <em>targetNetwork=localNetwork[,...] | CopyPreferredInterfaces</em></td>
<td ALIGN="left">This is a server-side (listener) option that specifies, on a multihomed host,
which network/interface(s) are to be used to listen for communications from the multicast addressed
remote client(s). If this option is unspecified (or if none of the given
<em>targetNetwork=localNetwork</em> patterns match the current addresses being set-up for
the attempted listener) then the default listener will be set-up as specified or defaulted with the
<code>‑ORBListenOnAll</code> see above.
Otherwise when TAO attempts to establish the listeners for a <em>targetNetwork</em> multicast
address(es), it will use the local ip address(es) matching the <em>localNetwork</em> string. Simple
wildcards can be used for both parameters, and multiple paired <em>targetNetwork=localNetwork</em>
strings can be specified using comma separators (no embedded spaces allowed) or via additional
<code>‑ORBListenerInterfaces</code> directives. It is also possiable to specify loopback
and/or multiple interfaces at the same time for each listener established via such
<code>‑ORBListenerInterfaces</code> directives.
<p>
For example, for a machine with two network cards identified by the ip addresses
<code>192.168.1.10</code> and <code>192.168.1.20</code>, you can use the single directive
<code>‑ORBListenerInterfaces 239.255.*=*10,224.255.*=*20</code> or the pair of directives
<code>‑ORBListenerInterfaces 239.255.*=*10 ‑ORBListenerInterfaces 224.255.*=*20</code>
to establish the link to listen for <em>239.255.*</em> multicast addresses on the first interface, and
<em>224.255.*</em> multicast addresses on the second interface.</p>
<em>targetNetwork</em> can use any string, but must typically match the value writen into the IOR and so
will usually be a dotted decimal multicast address in the administrative "site local" range,
(<em>224.255.0.0</em> to <em>238.255.255.255</em>) or (<em>239.255.0.0</em> to <em>239.255.255.255</em>).
<p><em>localNetwork</em> must use a local dotted decimal address, because it will be matched with
the local ip interfaces.</p>
The same client-side (sender) assignments as specified by the ORB_init supplied command line option(s)
<code>‑ORBPreferredInterfaces</code> can be duplicated by specifying the single special
<em>CopyPreferredInterfaces</em> parameter as in <code>‑ORBListenerInterfaces CopyPreferredInterfaces</code>
(which may be prefixed and/or postfixed by other <code>‑ORBListenerInterfaces <em>targetNetwork=localNetwork</em></code>
options as required).
</tr>
<tr>
<td ALIGN="left"><code>‑ORBListenOnAll</code> <em>0 | 1</em></td>
<td ALIGN="left">This is a server-side (listener) option that by default is disabled; however
this option only takes effect where no <code>‑ORBListenerInterfaces</code>
directives (if any, see below) match the actual multicast address being set-up.
<p>If disabled (<em>0</em>) the multicast address will be listened for only on the default multicast
interface associated with the <CODE>INADDR_ANY</CODE> local address (normally the first such
local interface on the system), the loopback interface is normally excluded.</p>
If enabled (<em>1</em>) the multicast address will be listened for on ALL the local network
interface(s) which are multicast enabled (again the loopback interface is normally excluded).
</td>
</tr>
</tbody>
</table>
</blockquote>
<h4><a name="TMSF">5. MIOP_Strategy_Factory</a></h4>
This factory is located in the <code>TAO_PortableGroup</code> library and
uses the <a href="#TUPF">TAO_UIPMC_Protocol_Factory</a> (see above) to
manage its UDP sockets, you should also look at that factories configuration
options. The MIOP factory accepts it own options detailed below which
should be specified between the two double-quotes shown here as a space
separated list; however none are required as all options take default
values if not specified. This factory can be loaded dynamically using a
service configurator directive of the form (all on one line):
<p><code>dynamic MIOP_Resource_Factory Service_Object *
TAO_PortableGroup:_make_TAO_MIOP_Resource_Factory () ""</code></p>
You would normally have to use other service configurator
directives as well; for example:
<p><code>dynamic UIPMC_Factory Service_Object *
TAO_PortableGroup:_make_TAO_UIPMC_Protocol_Factory() ""<br>
static Resource_Factory "‑ORBProtocolFactory IIOP_Factory
‑ORBProtocolFactory UIPMC_Factory"<br>
dynamic PortableGroup_Loader Service_Object *
TAO_PortableGroup:_make_TAO_PortableGroup_Loader() ""<br>
dynamic MIOP_Resource_Factory Service_Object *
TAO_PortableGroup:_make_TAO_MIOP_Resource_Factory () ""</code></p>
Since MIOP uses UDP sockets (which is not a "reliable" transport unlike tcp/ip)
it is easy to configure MIOP in such a way that messages will not actually
reach the servant. The options below are intended to maximize MIOP reliability
but they must be used with care; users of MIOP must understand that large
messages are sent in fragments and they have to be reassembled by the server in
their entirety to be usable by the servant. If even a single data
fragment/packet is lost, the whole message cannot be reconstructed and will be
unusable. There is no way for the servant to even know it has missed such a
MIOP message, and being a one-way protocol, neither will the client be aware
that the message has been lost. Fragments can be lost due to a variety of
reasons:
<p></p>
<ul>
<li>
The client sends too large a message fragment, or sends messages too fast,
overwhelming the client socket's transmission buffer. (In which case the
client-side (sender) OS simply ignores the excess send requests and some of the
fragments are not actually sent on the wire.)
<li>
The server socket's receive buffer became too full to acquire the fragments off
the wire. (In this case the client is again sending messages too fast, but this
time it is the servant that is too slow to process the messages it has already
received.)
<li>
Something happend to the network or routing and the packet was lost between the
client and the server, or the server OS failed to react to the hardware network
device in a timely manor so that network packets were lost.</li></ul>
<p></p>
<p style="Z-INDEX: 0">In the first two cases above, the loss can be mitigated by
the client adapting/throttling its sending rate so as to not overflow the
capacity of the client's operating system sending buffer and the receiving
buffer of the server socket. If there are multiple clients all sending to the
same server, all of these clients must be configured to slow down their sending
rate (as a software system design descision) as otherwise the server's receive
buffer will become swamped and some messages will be lost.</p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2" ID="Table1">
<tbody>
<tr>
<th>
Option</th>
<th>
Description</th>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBEagerDequeueing</code> <em>0 | 1</em></td>
<td ALIGN="left">This is a server-side (listener) option that is enabled by default;
although this default can be overriden when the TAO libraries are built in the <CODE>
ace/config.h</CODE>, by specifying the new default such as <CODE>#define TAO_DEFAULT_MIOP_EAGER_DEQUEUEING false</CODE>
which in this case would turn this off by default, unless specified in the
service file. If disabled (0) each thread servicing the MIOP listener will only
dequeue enough MIOP message fragments from the socket receive buffer to
complete a single full MIOP message which it will then process. This action
reduces the amount of user memory consumed by the server process, but it also
increases the likelihood of the OS sockets receive buffer overflowing (as
whilst processing each message, the thread cannot dequeue other incomming
message fragments). If enabled (1) it specifies that each server thread will
attempt to dequeue all available MIOP messages from the receiver's socket and
queue these up in a user memory FIFO queue, before attempting to process a
single MIOP message from the head of this FIFO queue. This action attempts to
speed up the dequeueing of MIOP messages from the OS socket receive buffer
(with a corresponding increase in the amount of user memory consumed by the
server process) so as to limit the number of MIOP messages that the server may
miss due to the OS sockets receive buffer becoming full.
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBMaxFragmentRate</code> <em>microseconds</em></td>
<td ALIGN="left">
<P>This client-side (sender) option (if enabled, see <code>‑ORBSendThrottling</code> below)
specifies a non-zero, positive amount of time (in
uSec, i.e. microseconds) that it takes to transmit and process an individual
message fragment of the maximum size; see the <code>‑ORBMaxFragmentSize</code>
option above. (This is the total of the
client‑>server‑>servant processing time not just the average
network transmission delay.) The client attempts to keep the rate at which it
sends messages down to this speed by purposly delaying sending message
fragments, if it would exceeding this capacity (but also see the <code>‑ORBSendHighWaterMark</code>
option below). The default is same value as specified, or is defaulted by, the <code>
‑ORBMaxFragmentSize</code> option above, but this time teated as
microseconds not bytes. (This default delay value is approximatly the time
required to transmit that number of bytes on a 10Base‑T network.) Larger
values will throttle back the clients transmittion rate, smaller values will
speed it up; but note this value is used with the <code>‑ORBMaxFragmentSize</code>
option above to specify a working ratio so this value may need
to be altered if the size is changed.
</P>
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBMaxFragments</code> <em>limit</em></td>
<td ALIGN="left">This is a client-side (sender) option used to limit the maximum number of
fragments that a client can break the outgoing message up into. The limit must
be a positive number or zero (indicating an unlimited number). The default is
normally <em>0 (i.e. unlimited)</em>, but this default can be overriden when
the TAO libraries are built in <code>ace/config.h</code>, by specifying the
new default limit such as <code>#define TAO_DEFAULT_MIOP_MAX_FRAGMENTS 1</code>
which in this case would turn off fragmentation by default (as only a single
fragment would be allowed), unless a new limit is specified in the service
file. Any messages that are too large and require more fragments than allowed
by this setting are simply not transmitted by the client (the message is
effectly lost without any error indication, other than possibly a debug
message). This setting can be used as a safety setting to stop swamping the
network and servants with abnormally large messages, or during testing to
"lose" large messages for whatever reason.
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBFragmentsCleanupStrategy</code> <em>DELAY | NUMBER
| MEMORY</em></td>
<td ALIGN="left">This option is used on the server to specify the incomplete
fragments cleanup strategy. The default is <em>DELAY</em>, indicating that the
fragments that cannot be reassembled after a certain delay should be removed
from the waiting queue (i.e. considered lost messages). The other options are <em>
NUMBER</em> and <em>MEMORY</em>, which respectively mean the number of
messages in the waiting queue will be limited, or the whole memory comsumed by
the incomplete messages in the waiting queue will be limited.
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBFragmentsCleanupBound</code> <em>limit</em></td>
<td ALIGN="left">This option specifies the numerical limit for the server's <code>‑ORBFragmentsCleanupStrategy</code>
option. If the strategy is <em>DELAY</em>, the value indicates the delay in
milliseconds (defaulting to 1000 milliseconds i.e. 1 second). If the strategy
is <em>NUMBER</em>, the limit indicates the number of non-reassembled messages
in the queue (defaulting to 5 messages). If the strategy is <em>MEMORY</em>,
the limit indicates the number of bytes reserved for the whole queue (with the
default being 3000000 bytes).
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBMaxFragmentSize</code> <em>bytes</em></td>
<td ALIGN="left">Another client-side (sender) option used to limit the number of bytes in
each individual MIOP fragment, which must be between <em>272</em> and <em><code>ACE_MAX_UDP_PACKET_SIZE</code>
(normally 65507)</em> bytes inclusive. Smaller values increase (and larger
values decrease) the number of fragments required to send the actual payload
data. Each fragment requires the overhead of a new MIOP header (32 bytes)
prefixing the actual data being sent, with the header reducing the actual
usable payload data inside each fragment. Roughly this value can be considered
as the MTU (Maximum Transmission Unit) set for the specific connection. The
default takes the same value as the <code>ACE_MAX_UDP_PACKET_SIZE</code> for
the system, but this can be overridden in the <code>ace/config.h</code> by
giving a new value for <code>#define TAO_DEFAULT_MIOP_FRAGMENT_SIZE 65507</code>
when the TAO libraries are built. <b>Note: most gateways and routing networks
define an MTU of around <em>1458-1500</em>; it is therefore advisable to
specify the correct <code>‑ORBMaxFragmentSize</code> value otherwise some
fragments may be lost.</b> See also the <code>‑ORBSndSock</code> option
below. Note also if this value is changed (during development) and the <code>‑ORBMaxFragmentRate</code>
option below is also specified, you should change that value by the same
factor, otherwise the speed of transmission will be effected as these two
options specify a working ratio.
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBRcvSock</code> <em>bytes</em></td>
<td ALIGN="left">This server-side (listener) option is the size of the incoming socket's
message buffer, i.e., how much data can be received directly off the wire by the
server and queued for processing by the servant whilst it is busy. If specified
in the service configuration file, this value will override (for MIOP only) the
value specified by the corresponding ORB_init parameter. If NOT specified in
either place, the default value for the system itself will be used. Again for a
Linux type OS, the systems RcvSock is usually about <b>65535</b> bytes, but
whatever value is actually specified it is normally doubled internally to take
account of the control structures required to track the messages themselves and
so it is not a hard limit. Specifying as large a value as possible (i.e.
whatever upper limit the OS will allow) with the MIOP <code>‑ORBRcvSock</code>
option is advisable to maximize the available socket's receive buffer space, but
obviously this is a trade off between available memory and other OS non-paged
memory uses.
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBSendHighWaterMark</code> <em>bytes</em></td>
<td ALIGN="left">This client-side (sender) option (if enabled, see <code>‑ORBSendThrottling</code> below)
is the usable size of the message
buffer, i.e how much data can be sent without introducing delays into the
transmition of individual MIOP fragments (due to the <code>‑ORBMaxFragmentRate</code>
option above). <b>Its default value is the size of the buffer maintained by the
Operating System for the sending socket at the client side (see the <code>‑ORBSndSock</code>
option below) and although it should ideally be based on the server's receive
socket buffer size, that information is not available to the client, and the
two values normally default to the same size anyway.</b> If in doubt specify
this value and set it to a smaller value than the full size of the servers <CODE>
‑ORBRcvSock</CODE> option (especially if multiple clients are all
broadcasting to the same server, when each client should only use a fraction of
the full buffer size based upon the number of clients actually in use).
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBSendThrottling</code> <em>0 | 1</em></td>
<td ALIGN="left">This is a client-side (sender) option that is enabled by default;
although this default can be overriden when the TAO libraries are built in the <CODE>
ace/config.h</CODE>, by specifying the new default such as <CODE>#define TAO_DEFAULT_MIOP_SEND_THROTTLING false</CODE>
which in this case would turn off throttling by default, unless specified in
the service file. If disabled (0) the client will always attempt to transmit
all MIOP message fragments without any delay. If enabled (1) the client will
attempt to automatically restrict the speed of sending individual MIOP messages
to maintain an average of <code>‑ORBMaxFragmentSize</code> bytes per <code>‑ORBMaxFragmentRate</code>
microseconds once the threshold of <code>‑ORBSendHighWaterMark</code> bytes
of data are currently being transmitted or are in progress via each individual transport
(i.e. each individual client-side (sender) connection to the server).
</td>
</tr>
<tr>
<td ALIGN="left"><code>‑ORBSndSock</code> <em>bytes</em></td>
<td ALIGN="left">This client-side (sender) option is the size of the outgoing socket's
message buffer. If specified in the service configuration file, this value will
override (for MIOP only) the value specified by the corresponding ORB_init
parameter. If NOT specified in either place, the default value for the system
itself will be used. NOTE: the <code>‑ORBSndSock</code> size normally
limits the maximum size of an individual message fragment, larger fragments can
be simply ignored (i.e. packet loss) by the client's socket without any error
indication; this value and the <code>‑ORBMaxFragmentSize</code> should be
set with care. For a Linux type OS, the system's SndSock is usually defaulted to
about <b>65535</b> bytes, but whatever value is actually specified it is
normally doubled internally to take account of the control structures required
to track the messages themselves and so it is not a hard limit.
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
<h4><a name="TTSM">6. Time_Policy_Manager</a></h4>
The TIME_POLICY manager controls the actual TIME_POLICY strategy used for
ORB timers and countdowns. TAO provides a default strategy manager called
<code>Time_Policy_Manager</code>.
<p>Typically, the following options is set via the service
configurator
(<code>svc.conf</code>) file. The following line in the
<code>svc.conf</code> file (all in one line)</p>
<p><code>static
Time_Policy_Manager "[option]"</code></p>
<p> would load the option listed within "".
An <a href="../tests/Time_Policy/hr_time.conf">example</a>
is available that shows how to specify this option in the <code>svc.conf</code>
file.</p>
<p></p>
<blockquote>
<p>
<table border="2" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<th>Option</th>
<th>Description</th>
</tr>
<tr>
<td><code>-ORBTimePolicyStrategy</code> <em>strategy</em></td>
<td><p><a name="-ORBTimePolicyStrategy"></a>The <em>strategy</em> argument
defines the TIME_POLICY strategy to load. TAO provides two
standard TIME_POLICY strategies:</p>
<p><em>OS</em> denotes the system time policy strategy which uses the systems
equivalent of <code>gettimeofday</code> to return a current time value. This is the default for
TAO (unless <code>TAO_USE_HR_TIME_POLICY_STRATEGY</code> has been defined).</p>
<p><em>HR</em> denotes the highres time policy strategy which uses the systems
equivalent of a <code>MONOTONIC</code> timer source to return a current time value (when
<code>TAO_USE_HR_TIME_POLICY_STRATEGY</code> has been defined this becomes the default for TAO).</p>
<p>Any other value is assumed to denote the exact name of a dynamically loadable
TIME_POLICY strategy. The <a href="../tests/Time_Policy_Custom">Time_Policy_Custom</a>
test provides an example of this functionality.</p>
</td>
</tr>
</tbody>
</table>
</p>
</blockquote>
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