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<h3>Building Stock Quoter system in PICML</h3><br />
<p>This section describes modeling the Quoter application using PICML. If you have trouble producing a functioning model from this tutorial, please see the, <a href="Model/Quoter.xme">pre-built Quoter model</a> which is provided for your reference. This model contains all elements created as part of this tutorial.</p>
<div class="important">
<strong>Note:</strong> To import an XML file in GME, select <em>File->Import XML..</em> from GME and choose your XML model<br />
</div>
<p>The PICML paradigm is designed for the <a href="http://www.omg.org/cgi-bin/doc?ptc/2003-07-08">OMG Deployment & Configuration (D&C) specification (ptc/2003-07-08)</a>, so the modeling process is straightforward if you are familiar with the specification. Please see the <a href="http://www.cs.wustl.edu/%7Eschmidt/ACE_wrappers/TAO/CIAO/docs/releasenotes/dance.html">DAnCE project</a> for more information.</p>
<hr />
<h3>Table of Contents</h3>
<ul>
<li><a href="#1">ImplementationArtifacts</a></li>
<li><a href="#2">ComponentImplementations</a></li>
<li><a href="#3">ComponentPackages</a></li>
<li><a href="#4">PackageConfiguration</a></li>
<li><a href="#5">TopLevelPackage</a></li>
<li><a href="#6">Targets</a></li>
<li><a href="#7">DeploymentPlan</a></li>
</ul>
<hr />
<p>The complete PICML Quoter model consists of modeling elements distributed across various folders. If you used <em>idl_to_picml</em> to generate the initial model, you will see that it has created all these folders and some of the tedious boilerplate modeling for us. The rest of the section will explain the purpose of each folder as well as the modeling entities contained in these folders. We will also show how to model some of the folders that have to be done by hand.</p>
<div class="important">
<strong>Important:</strong> The interpreters that generate deployment artifacts expect very strict constraints in the model. When you finish your model, and any time you wish to generate anything, it is a good idea to check constraints by clicking on <em>File->Check->Check All</em> in GME. This will help you find many logic errors in your model.
</div>
<h3><a name="1">ImplementationArtifacts</a></h3>
<p>This folder contains implementation artifacts associated with components. <em>idl_to_picml</em> has created these artifacts for us, with their dependency relationships correctly captured. Figure 4 shows the Implementation Artifacts for <em>Broker</em>.</p>
<div style="text-align: center;">
<img alt="" src="Images/fig4.jpg" style="border: 1px solid ; width: 891px; height: 552px;" /><a name="1"><br />
Figure 4.<br /></a><br />
</div><a name="1"></a>
<hr />
<h3><a name="2">ComponentImplementation</a></h3>
<p>This folder contains models that describe the implementations of component interfaces. In the Quoter example, we will have two monolithic component implementations - named <em>StockDistributorImplementation</em> and <em>StockBrokerImplementation</em> - and an assembly component implementation named <em>StockQuoter</em>, which is an assembly of <em>StockDistributorImplementation</em> and <em>StockBrokerImplementaion</em>. <em>idl_to_picml</em> has created the monolithic component implementations for us, as shown in figure 5 for example, but we have to specify the connections between them in order to construct a Quoter system.</p>
<div style="text-align: center;">
<img alt="" src="Images/fig5.jpg" style="border: 1px solid ; width: 922px; height: 639px;" /><br />
Figure 5<br />
</div>
<p>Assembly components provide a boundary for the composition of monolithic components and even other assemblies. Assembly components do not provide actual implementations for their interface, it is a virtual component that delegates its ports and attributes to one or more of the entities it contains. There are slight differences between modeling an assembly and modeling a monolithic component. Since the assembly is a virtual component, it is not necessary to model a <code>MonolithicImplementation</code>. Instead, <em>instances</em> of other components are placed within the assembly and connected. Let's try to assemble the <em>StockQuoter</em>.</p>
<ol>
<li>Right click the <em>ComponentImplementations</em> folder, choose <strong>Insert Model->ComponentImplementationContainer</strong>, rename it as "StockQuoterImplementation" in the Attribute Panel. Double click to open it.</li>
<li>From the Part Browser, drag a <<ComponentAssembly>> to the modeling window, name it "StockQuoter". Double click to open it.</li>
<li>Now we will create two instances for interfaces <em>StockBroker</em> and <em>StockDistributor</em>. To do that, expand the folder <code><em>InterfaceDefinitions</em></code>, then expand the <code><em>InterfaceDefinitions/</em></code> <em>Broker</em>, then <code><em>InterfaceDefinitions/</em></code> <em>Broker/ Stock</em> until the interface definition of <em>StockBroker</em> shows. While expanding the tree, always keep the "StockQuoter" <<ComponentAssembly>> window open. Then drag <code>MyQuoter/InterfaceDefinitions/Broker/Stock/StockBroker</code> in the browser to the "StockQuoter" <<ComponentAssembly>> window while pressing ALT key. Repeat the same steps for <code>MyQuoter/InterfaceDefinitions/Distributor/Stock/StockDistributor</code>, and you will see two instances of component interfaces have been created as shown in Figure 6 (the black line in the figure only indicates .mapping)<br /></li>
</ol><br />
<div style="text-align: center;">
<img alt="" src="Images/fig6.jpg" style="width: 972px; height: 714px;" /><br />
<br />
Figure 6<br />
</div>
<ol>
<li value="4">Create an <<PublishConnector>>.<br /></li>
<li>Now assemble the components together according to <a href="Images/fig1.jpg">Figure 1</a>(make sure you change to connect mode <img alt="" src="Icons/AddConnMode.gif" style="width: 20px; height: 17px;" /> ) and the resulting assembly model should look like Figure 7. Note that to create connections between StockDistributor.notify_out and StockBroker.notify_in, you will need the intermediate connector <<PublishConnector>>.<br /></li>
</ol><img alt="" src="Images/fig7.jpg" style="width: 724px; height: 402px;" /><br />
<br />
Figure 7<br />
<hr />
<a name="3"></a>
<h3>ComponentPackage<br /></h3>This folder contains deployable component packages. Every instance in an assembly should have a corresponding monolithic implementation and packaged in a ComponentPackagebe To create a package for <em>StockBroker</em>.instance<br />
<ol>
<li>Right click folder <em>ComponentPackage</em>s , insert a <<PackageContainer>>, name it "Broker"; Double click to open it.<br /></li>
<li>From the PartBrowser, add the following:<br />
<ul>
<li>a <<ComponentPackage>> named "Broker";</li>
<li>a <<ComponentImplementationReference>> named "Broker";</li>
<li>a <<ComponentRef>> named "Broker";</li>
</ul>
</li>
<li>Refer the <<ComponentImplementationReference>> <em>Broker</em> to <code>MyQuoter/ComponentImplementations/StockBroker</code>Implementation/StockBrokerMonolithicImpl. Refer the <<ComponentRef>> <em>Broker</em> to <code>MyQuoter/InterfaceDefinitions/Broker/Stock/StockBroker</code>. To create a reference in GME, simply drag the tree node in the Browser "into" the reference model. For example, you should drag the tree node <code>MyQuoter/ComponentImplementations/StockBroker</code>Implementation/StockBrokerMonolithicImpl into <<ComponentImplementationReference>> <em>Broker.</em> Check GME manual(tutorials) for more information.</li>
<li>Switch to Connect Mode and create two connections according to the following relationship.<br />
<ul>
<li><<ComponentImplementationReference>> <em>Broker</em> implements <<ComponentPackage>> <em>Broker</em>;</li>
<li><<ComponentPackage>> <em>Broker</em> realizes <<ComponentRef>> <em>Broker</em>.</li>
</ul><br />
<br />
The model you built should resemble Figure 8.<br />
<br />
<div style="text-align: center;">
<img alt="" src="Images/fig8.jpg" style="width: 675px; height: 497px;" /><br />
<br />
Figure 8<br />
<br />
</div>Now create a ComponentPackage/StockDistributor following the same steps.
</li>
<li style="list-style: none">
<br />
We will also need to create a package for the assembly component StockQuoter. Remember assembly component is a virtual component, it does not "realize" a certain interface, so different from the Broker and Distributor packages, the StockQuoter does not need a <<ComponentRef>>. To create this model:
<ol>
<li>Insert a <<ComponentPackage>> named "StockQuoter"<br /></li>
<li>Add a <<ComponentImplementationReference>> named "StockQuoter", refer it to MyQuoter<code>/ComponentImplementations/StockQuoter/StockQuoter</code></li>
<li>Switch to connect mode and connect <<ComponentImplementationReference>> StockQuoter with <<ComponentPackage>> StockQuoter, as in Figure 9.<br /></li>
</ol>
</li>
</ol>
<div style="text-align: center;">
<img alt="" src="Images/fig9.jpg" style="width: 549px; height: 354px;" /><br />
<br />
Figure 9<br />
<br />
</div>
<hr />
<a name="4"></a>
<h3>PackageConfiguration<br /></h3>This folder contains just one model capturing specific configuration of Component packages.<br />
<ol>
<li>In the folder <em>PackageConfiguratio</em>n, and create a <<PackageConfigurationContainer>>, name it "Default", click to open it.<br /></li>
<li>Add a <<PackageConfiguration>> named "default" and a <<ComponentPackageReference>>, name it "StockQuoter", connect "Default" to "StockQuoter"<br /></li>
<li>Refer <<ComponentPackageReference>> StockQuoter to <<ComponentPackage>> <code>MyQuoter/ComponentPackage/StockQuoter/StockQuoter<br />
(Not <<ComponentImplementationReference>></code> <code>MyQuoter/ComponentPackage/StockQuoter/StockQuoter!) </code></li>
</ol><br />
<hr />
<a name="5"></a>
<h3>ToplevelPackage<br /></h3>This folder contains one model capturing information about the top-level element that will be fed to the application.<br />
<ol>
<li>In the folder <em>ToplevelPackage</em>, and create a <<ToplevelPackageContainer>>, name it "Default", double click to open it.<br /></li>
<li>Add a <<ToplevelPackage>> named "ToplevelPackage" and a <<PackageConfigurationReference>>, name it "Default", connect "ToplevelPackage" to "Default"<br /></li>
<li>Refer "Default" to My<code>Quoter/PackageConfiguration/Default/Default</code><br /></li>
</ol><br />
<hr />
<a name="6"></a>
<h3>Targets<br /></h3>This folder contains domain-specific models capturing information about the target environment in which component-based application will be deployed. In this Quoter example, we can either deploy the two components into ONE host, or into TWO different host. We will deploy the Quoter into two different host.<br />
<ol>
<li>In the folder <span style="font-style: italic;">Targets</span>, insert a new <<Domain>> named "Domain"; double click to open it.<br /></li>
<li>From the Part Browser, add two <<Node>> named "Broker" and "Distributor" respectively.<br /></li>
</ol><br />
Now we are ready to deploy our Components to the actual physical environment.<br />
<hr />
<a name="7"></a>
<h3>DeploymentPlan<br /></h3>This folder contains a plan model that captures information about the assignment of component to nodes.<br />
<ol>
<li>In the folder <em>DeploymentPlan</em>, insert a model <<DeploymentPlan>>; name it "Plan", click to open it<br /></li>
<li>From the PartBrowser, add the following:<br />
<ul>
<li>Two <<CollocationGroup>></li>
<li>Two <<NodeReference>> named "Node_Broker" and "Node_Distributor" respectively, refering to <code>MyQuoter/Targets/Domain/Broker</code> and <code>MyQuoter/Targets/Domain/Distributor</code> respectively</li>
<li>Two <<ComponentRef>> named "StockBroker" and "StockDistributor" respectively, refering to <code>MyQuoter/ComponentImplementations/StockQuoterImplementation/StockQuoter/StockBroker</code> and <code>MyQuoter/ComponentImplementations/StockQuoterImplementation/StockQuoter/StockDistributor</code> respectively. Note that the <<ComponentRef>> in DeploymentPlan is not referring to the interface, but rather the actual instance of the implementation.</li>
</ul>
</li>
<li>Switch to Connect Mode, connect one <<CollocationGroup>> to <<NodeReference>> <em>Node_Broker</em>, connect another <<CollocationGroup>> to <<NodeReference>> <em>Node_</em><em>Distributor</em>. Now the model looks like the following.<br />
<br />
<div style="text-align: center;">
<img alt="" src="Images/fig10.jpg" style="width: 752px; height: 530px;" /><br />
<br />
Figure 10.<br />
<br />
</div>
</li>
<li>Now we need to associate <<ComponentRef>> StockBroker to the <<CollocationGroup>> running on the <<NodeReference>> Broker, and <<ComponentRef>> StockDistributor to the <<CollocationGroup>> running on the <<NodeReference>> Distributor. To do that, switch the Edit Mode Bar to Set Mode (<img alt="" src="Icons/SetMode.gif" style="width: 20px; height: 17px;" />), and move the cursor to the <<CollocationGroup>> running on <<NodeReference>> Distributor, right-click on it. You will find the cursor is changed to set mode cursor, and only the <<CollocationGroup>> you clicked in is highlighted, as shown in Figure 11.<br />
<br /></li>
</ol>
<div style="text-align: center;">
<img alt="" src="Images/fig11.jpg" style="width: 672px; height: 505px;" /><br />
<br />
Figure 11<br />
<br />
</div>
<p>Now move your cursor to <<ComponentRef>> StockDistributor, and left-click it, so that it looks like Figure 12.<br /></p>
<div style="text-align: center;">
<img alt="" src="Images/fig12.jpg" style="width: 672px; height: 505px;" /><br />
<br />
Figure 12<br />
<br />
</div>
<p>This operation associates <em>StockDistributor</em> component to the <<CollocationGroup>> running on <em>Distributor</em> node. To do the same with Broker, just right-click on another <<CollocationGroup>>, and left-click on StockBroker <<CollocationGroup>> which is highlighted.<br />
<br /></p>
<hr />
<a name="8"></a>
<p>Up to this point, we are basically done with the modeling part. Before we generate anything from this model though, please <span style="font-weight: bold;">DO</span> remember to check the constraints of the model as we mentioned earlier.</p>
<p>After we are done with the modeling, the flattened_deploymentplan interpreter that comes along with PICML will help us to generate a flattened_deploymentplan.cdp file. Please make sure you generate this file to MyQuoter/descriptors.</p>
<address>
<br />
<br />
<br />
<a href="mailto:ming.xiong@vanderbilt.edu">Ming Xiong<br /></a>
</address><!-- Created: Sat Nov 27 15:25:06 CST 1999 -->
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