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diff --git a/docs/tutorials/008/combine.shar b/docs/tutorials/008/combine.shar deleted file mode 100644 index f12ae4c4ee3..00000000000 --- a/docs/tutorials/008/combine.shar +++ /dev/null @@ -1,465 +0,0 @@ -#!/bin/sh -# This is a shell archive (produced by GNU sharutils 4.2). -# To extract the files from this archive, save it to some FILE, remove -# everything before the `!/bin/sh' line above, then type `sh FILE'. -# -# Made on 1999-01-26 19:48 EST by <jcej@chiroptera.tragus.org>. -# Source directory was `/var/home/jcej/projects/ACE_wrappers/docs/tutorials/008'. -# -# Existing files will *not* be overwritten unless `-c' is specified. -# -# This shar contains: -# length mode name -# ------ ---------- ------------------------------------------ -# 515 -rw-rw-r-- hdr -# 59 -rw-rw-r-- bodies -# 2769 -rw-rw-r-- page01.pre -# 416 -rw-rw-r-- page02.pre -# 345 -rw-rw-r-- page03.pre -# 481 -rw-rw-r-- page04.pre -# 578 -rw-rw-r-- page05.pre -# 952 -rw-rw-r-- page02.pst -# 367 -rw-rw-r-- page03.pst -# 1173 -rw-rw-r-- page04.pst -# -save_IFS="${IFS}" -IFS="${IFS}:" -gettext_dir=FAILED -locale_dir=FAILED -first_param="$1" -for dir in $PATH -do - if test "$gettext_dir" = FAILED && test -f $dir/gettext \ - && ($dir/gettext --version >/dev/null 2>&1) - then - set `$dir/gettext --version 2>&1` - if test "$3" = GNU - then - gettext_dir=$dir - fi - fi - if test "$locale_dir" = FAILED && test -f $dir/shar \ - && ($dir/shar --print-text-domain-dir >/dev/null 2>&1) - then - locale_dir=`$dir/shar --print-text-domain-dir` - fi -done -IFS="$save_IFS" -if test "$locale_dir" = FAILED || test "$gettext_dir" = FAILED -then - echo=echo -else - TEXTDOMAINDIR=$locale_dir - export TEXTDOMAINDIR - TEXTDOMAIN=sharutils - export TEXTDOMAIN - echo="$gettext_dir/gettext -s" -fi -touch -am 1231235999 $$.touch >/dev/null 2>&1 -if test ! -f 1231235999 && test -f $$.touch; then - shar_touch=touch -else - shar_touch=: - echo - $echo 'WARNING: not restoring timestamps. Consider getting and' - $echo "installing GNU \`touch', distributed in GNU File Utilities..." - echo -fi -rm -f 1231235999 $$.touch -# -if mkdir _sh30434; then - $echo 'x -' 'creating lock directory' -else - $echo 'failed to create lock directory' - exit 1 -fi -# ============= hdr ============== -if test -f 'hdr' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'hdr' '(file already exists)' -else - $echo 'x -' extracting 'hdr' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'hdr' && -<HTML> -<HEAD> -X <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> -X <META NAME="GENERATOR" CONTENT="Mozilla/4.04 [en] (X11; I; Linux 2.0.32 i486) [Netscape]"> -X <META NAME="Author" CONTENT="James CE Johnson"> -X <TITLE>ACE Tutorial 008</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> -X -<CENTER><B><FONT SIZE=+2>ACE Tutorial 008</FONT></B></CENTER> -X -<CENTER><B><FONT SIZE=+2>Sending and receiving datagrams</FONT></B></CENTER> -X -X -<P> -<HR WIDTH="100%"> -X -SHAR_EOF - $shar_touch -am 0121153899 'hdr' && - chmod 0664 'hdr' || - $echo 'restore of' 'hdr' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'hdr:' 'MD5 check failed' -e74ecd3335da844c263f961a8ba5f867 hdr -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'hdr'`" - test 515 -eq "$shar_count" || - $echo 'hdr:' 'original size' '515,' 'current size' "$shar_count!" - fi -fi -# ============= bodies ============== -if test -f 'bodies' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'bodies' '(file already exists)' -else - $echo 'x -' extracting 'bodies' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'bodies' && -PAGE=2 -server.cpp -directed_client.cpp -broadcast_client.cpp -SHAR_EOF - $shar_touch -am 0121153799 'bodies' && - chmod 0664 'bodies' || - $echo 'restore of' 'bodies' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'bodies:' 'MD5 check failed' -707d1735ca25694e2b5fddc1f6e7e124 bodies -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'bodies'`" - test 59 -eq "$shar_count" || - $echo 'bodies:' 'original size' '59,' 'current size' "$shar_count!" - fi -fi -# ============= page01.pre ============== -if test -f 'page01.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page01.pre' '(file already exists)' -else - $echo 'x -' extracting 'page01.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page01.pre' && -<P>In a lot of IPC programming, the clients know where the servers -are. A mail client, for instance, has a configuration file that says -where the mail host is. Your web browser has a "location" field that -you type into to give it a destination. -X -<P>What if you have written a server application and then you execute it -on several systems in your network? All of the instances are probably -more or less equal to the client's point of view, so you don't want to -"configure" the clients to a single server each. Likewise, you -want the ability to add and remove servers at any time so you can't just -give the clients a list to choose from. -X -<P>So... how do the clients know where the servers are? -X -<P>Let 'em ask! -X -<P>Datagrams are great for this. You can toss a datagram out onto -the network and any servers listening at the correct port will* hear it. -Like ACE_SOCK_Stream that we've seen before, you can get the peer address -from a datagram. With that, the server can send a response -back to the client. The client, in turn, can pull the peer address -out and know exactly where the server lives. -X -<P>In this tutorial we'll develop three applications: a server listening -for datagrams, a client that can send to a known host and a client that -can send to the entire (sub)network. In the next tutorial, we'll -expand on this to make the server a bit more prudish. -<P> -Kirthika's abstract: -<UL> -Here, we play with datagram sockets and use it for server discovery by -the client. Datagrams are used by UDP, which is an unreliable and -connectionless protocol. Datagrams packets are generally very small in -size and aren't designed to be used to handle serious communication -between the server and the client. -<P> -The server waits for datagrams to arrive at a fixed port. -The client either sends to a datagram to the server at a known host, -which is not really the case generally, as the client needs to discover -the server and so it needs to broadcast its datagram request in its -subnet. Then, all servers listening at that interface receive it. The -appropriate server will then handle the request. Remember that -no solid connection is made. On the recv() itself the server obtains the -address of the remote client and then communicates with it. -<P> -Thus, we get a fair glimpse of using another means of communication via -datagrams. -</UL> -<P><FONT SIZE=-1>* Actually, the servers <I>might</I> hear the datagram. -Datagrams are rather unreliable. (Sort of like some operating systems -I know.) Still, if the network traffic isn't too bad, they generally -get through. Your clients can always send out more queries if there -aren't any responses in a timely fashion.</FONT> -X -SHAR_EOF - $shar_touch -am 0121155099 'page01.pre' && - chmod 0664 'page01.pre' || - $echo 'restore of' 'page01.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page01.pre:' 'MD5 check failed' -829e35e4a7b8e8c75e38abf492033395 page01.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page01.pre'`" - test 2769 -eq "$shar_count" || - $echo 'page01.pre:' 'original size' '2769,' 'current size' "$shar_count!" - fi -fi -# ============= page02.pre ============== -if test -f 'page02.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page02.pre' '(file already exists)' -else - $echo 'x -' extracting 'page02.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page02.pre' && -X -<P>The first thing we want to look at is <A HREF="server.cpp">server.cpp</A>. -This is a pretty simple application that listens for datagrams at a known -port and sends back a response. In order to implement a true "discovery" -mechanism, the server will have to be a little bit more picky about who -it responds to. We'll tackle that issue in the next tutorial though... -X -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 0121153899 'page02.pre' && - chmod 0664 'page02.pre' || - $echo 'restore of' 'page02.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page02.pre:' 'MD5 check failed' -6b27ef52d53a13d2d9e5a5ad16e9be4d page02.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page02.pre'`" - test 416 -eq "$shar_count" || - $echo 'page02.pre:' 'original size' '416,' 'current size' "$shar_count!" - fi -fi -# ============= page03.pre ============== -if test -f 'page03.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page03.pre' '(file already exists)' -else - $echo 'x -' extracting 'page03.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page03.pre' && -X -<P>In <A HREF="directed_client.cpp">directed_client.cpp</A> we create a -client that knows how to send a datagram to a server on a known host. -This is a good thing if you know where the server lives and want to have -a conversation. The Unix <I>talk</I> utilitiy, for instance, -could be written this way. -X -<P> -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 0121153899 'page03.pre' && - chmod 0664 'page03.pre' || - $echo 'restore of' 'page03.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page03.pre:' 'MD5 check failed' -aa0724ca0a09f5b5e6c7e3f355646111 page03.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page03.pre'`" - test 345 -eq "$shar_count" || - $echo 'page03.pre:' 'original size' '345,' 'current size' "$shar_count!" - fi -fi -# ============= page04.pre ============== -if test -f 'page04.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page04.pre' '(file already exists)' -else - $echo 'x -' extracting 'page04.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page04.pre' && -In <A HREF="broadcast_client.cpp">broadcast_client.cpp</A> we -find out how to send a single datagram to every host on our (sub)network. -I have to say <I>(sub)network</I> because broadcast datagrams typically -are not passed through routers. So, if your network admin has divided -up your network into subnets, your broadcasts will likey stay on the -subnet you're a part of. -X -<P>I've only commented the parts that are different from the directed_client. -<HR WIDTH="100%"> -SHAR_EOF - $shar_touch -am 0124144899 'page04.pre' && - chmod 0664 'page04.pre' || - $echo 'restore of' 'page04.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page04.pre:' 'MD5 check failed' -8811bded669a7a7be85a4878d5076190 page04.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page04.pre'`" - test 481 -eq "$shar_count" || - $echo 'page04.pre:' 'original size' '481,' 'current size' "$shar_count!" - fi -fi -# ============= page05.pre ============== -if test -f 'page05.pre' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page05.pre' '(file already exists)' -else - $echo 'x -' extracting 'page05.pre' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page05.pre' && -<BR>That's it for this tutorial. In the next one we'll add some intelligence -to the data put into the datagrams. By doing so, we'll be able to -classify our clients and servers into groups. By combining the data -content and the server's port we can get fairly fine-grained control over -who talks to who. -X -<P>For you convenience: -<UL> -<LI> -<A HREF="server.cpp">server.cpp</A></LI> -X -<LI> -<A HREF="directed_client.cpp">directed_client.cpp</A></LI> -X -<LI> -<A HREF="broadcast_client.cpp">broadcast_client.cpp</A></LI> -X -<LI> -<A HREF="Makefile">Makefile</A></LI> -</UL> -SHAR_EOF - $shar_touch -am 0121153799 'page05.pre' && - chmod 0664 'page05.pre' || - $echo 'restore of' 'page05.pre' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page05.pre:' 'MD5 check failed' -b05fdac8c7eb81813c74eb99525cf601 page05.pre -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page05.pre'`" - test 578 -eq "$shar_count" || - $echo 'page05.pre:' 'original size' '578,' 'current size' "$shar_count!" - fi -fi -# ============= page02.pst ============== -if test -f 'page02.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page02.pst' '(file already exists)' -else - $echo 'x -' extracting 'page02.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page02.pst' && -<HR WIDTH="100%"> -X -<P>And that's really all there is to it. Obviously there is some -room for improvement. The most blatant is the somewhat small buffer -size for receiving the datagram. I've never been able to get a solid -answer on datagram sizes. The theoretical limit is just under 64k -but you have to deal with fragmentation. Some readings indicate that -8k is a reasonable size, others go much smaller. My general rule -of thumb is to keep datagrams relatively small (eg -- under 8k or so) and -test a lot. If you find that your routers are fragmenting your larger -datagrams, back off to something smaller. Of course, if you must -send 100k and can only do so 1k at a time, you'll have to worry about retransmissions -& reordering. At that point, you might consider going to TCP. -Remember: datagrams are unreliable! Don't try to make 'em do -something they werent' designed for! -SHAR_EOF - $shar_touch -am 0121153899 'page02.pst' && - chmod 0664 'page02.pst' || - $echo 'restore of' 'page02.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page02.pst:' 'MD5 check failed' -3cb7da5f75a40616f6cc498a731f4a16 page02.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page02.pst'`" - test 952 -eq "$shar_count" || - $echo 'page02.pst:' 'original size' '952,' 'current size' "$shar_count!" - fi -fi -# ============= page03.pst ============== -if test -f 'page03.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page03.pst' '(file already exists)' -else - $echo 'x -' extracting 'page03.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page03.pst' && -<HR WIDTH="100%"> -X -<P>That's all neat and good but the point of what we're doing here is not -to talk to a server we know about but to discover servers we don't know -about. Now, you could send a directed datagram to every possible -host address on your network but that's not a very nice thing to do. -On the next page, we'll find out the right approach... -X -SHAR_EOF - $shar_touch -am 0121153899 'page03.pst' && - chmod 0664 'page03.pst' || - $echo 'restore of' 'page03.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page03.pst:' 'MD5 check failed' -0fcbc10be47175a0d42590fb4adab43b page03.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page03.pst'`" - test 367 -eq "$shar_count" || - $echo 'page03.pst:' 'original size' '367,' 'current size' "$shar_count!" - fi -fi -# ============= page04.pst ============== -if test -f 'page04.pst' && test "$first_param" != -c; then - $echo 'x -' SKIPPING 'page04.pst' '(file already exists)' -else - $echo 'x -' extracting 'page04.pst' '(text)' - sed 's/^X//' << 'SHAR_EOF' > 'page04.pst' && -<HR WIDTH="100%"> -X -<P> About that subnet thing: -<BLOCKQUOTE>If you run this client on a host that has multiple network -interfaces, the broadcast will go to all of those (sub)networks. -What do you do, though, if you need to get past a router? My advice -is to write a server that will run on hosts on both sides of your router. -When a server on one side of the router receives a broadcast, it would -send a directed datagram to it's counterpart on the other side of the router. -The counterpart would then re-broadcast the original datagram on that sub-net. -Cheap, simple and effective.</BLOCKQUOTE> -One final word of warning: -<BLOCKQUOTE>When creating your broadcast datagrams you may see something -like this: <I>ACE_SOCK_Dgram_Bcast::mk_broadcast: Broadcast is not -enable for this interface.: Unknown error</I>. There are some interfaces -(ppp, slip) that don't support broadcast datagrams. That's what you're -seeing here.</BLOCKQUOTE> -Ok, one more warning: -<blockquote>If you happen to have multiple servers running on your -network when you invoke this client, the response could come from any -one of them. -</blockquote> -X -SHAR_EOF - $shar_touch -am 0126194899 'page04.pst' && - chmod 0664 'page04.pst' || - $echo 'restore of' 'page04.pst' 'failed' - if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ - && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then - md5sum -c << SHAR_EOF >/dev/null 2>&1 \ - || $echo 'page04.pst:' 'MD5 check failed' -2e01fc6b6638dfa77ed629c0e3e77e21 page04.pst -SHAR_EOF - else - shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page04.pst'`" - test 1173 -eq "$shar_count" || - $echo 'page04.pst:' 'original size' '1173,' 'current size' "$shar_count!" - fi -fi -rm -fr _sh30434 -exit 0 |