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<td width="60%" align="left"><font class="indextop">jst j2ee</font>
<br>
<font class="indexsub">modulecore api overview</font></td><td width="40%"><img width="207" hspace="50" height="129" align="middle" src="../../../../../webtools/images/wtplogosmall.jpg"></td>
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<td valign="top" bgcolor="#0080c0" align="left" colspan="2"><b><font face="Arial,Helvetica" color="#ffffff">Overview</font></b></td>
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<BR>
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<P>
The purpose of the following document is to highlight the API exposed as
part of the Web Tools Platform Project for the creation and access of
flexible project structures using the new ModuleCore API.
</P>
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<td valign="top" bgcolor="#0080c0" align="left" colspan="2"><b><font face="Arial,Helvetica" color="#ffffff">Module Structural Model (MSM) Metamodel</font></b></td>
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<p>
The Module Structural Model (MSM) is an EMF model that allows the tooling
to understand most project structures. Each project has a single (MSM)
which is stored under the project root named
<I>.wtpmodules</I>
. The XML format is defined by the Module Core namespace (
<a href="http://www.eclipse.org/webtools/moduleCore.xsd">
http://www.eclipse.org/webtools/moduleCore
</a>
). The following diagram is a UML representation of the metamodel.
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<p>
<img src="./diagrams/module_structural_model.jpg">
</p>
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<p>
<i>Figure 1: The Module Structural Model API</i>
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<p>
Each logical module contained in the project is represented by a
WorkbenchModule element. The WorkbenchModule defines information about
the type of module, the resources consumed by the module from the
project, and the dependent modules. The WorkbenchModule is very generic,
and as modeled, does not necessarily correspond to only J2EE artifacts.
</p>
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<p>
The WorkbenchModule has a
<i>deployedName</i>
, which is the name that will be used when the deployable form of the
module is constructed. For a web application, the
<i>deployedName</i>
might be "MyWebApplication.war".
</p>
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<p>
The WorkbenchModule may be uniquely referenced by a URI (stored on the
WorkbenchModule as the
<i>handle</i>
). The fully qualified URI to any module must begin with the module
protocol ("module:"), specify a subprotocol ("resource|classpath") and
then a path to the referenced module. A WorkbenchModule with the
deplyedName "MyWebApplication.war" defined in a project named
"MyWebModulesProject" would be referenced by the following URI:
"module:/resource/MyWebModulesProject/MyWebApplication.war".
</p>
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<p>
The WorkbenchModule has a ModuleType. The ModuleType defines a
<i>moduleTypeId</i>
, which indicates the specific kind of module. The Web Tools Platform
uses the
<i>moduleTypeId</i>
to determine how to work with the content module of the WorkbenchModule
and prepare the module for deployment. The ModuleType may also define the
runtime-paths of special metadata resources which are important to the
WorkbenchModule. "Metadata" refers to resources which explain the content
details of the specific modules. An example of such a file would be the
"WEB-INF/web.xml" deployment descriptor for Web Applications.
</p>
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<p>
The WorkbenchModule contains a list of WorkbenchModuleResources. Each
WorkbenchModuleResource has "sourcePath" and a corresponding
"deployedPath". The "sourcePath" can reference either a file or folder,
but the referenced resource must be contained in the same project as the
WorkbenchModule definition. The "deployedPath" specifies a location
relative to the deployed structure of the WorbenchModule where the
contents of the referenced resource will be placed when the module is
prepared for deployment.
</p>
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<p>
The WorkbenchModule contains a list of DependentModules. Each
DependentModule provides a handle that must resolve to a WorkbenchModule,
a deployedPath that defines where the constructed module will be placed
within the context of the deployed WorkbenchModule, and a DependencyType
that can be either "consume" or "use" to indicate how the contents of
that DependentModule should be absorbed by the WorkbenchModule.
DependentModules may reference WorkbenchModules in other projects and on
the classpath. The DependencyType will determine whether the contents of
the DependentModule are absorbed as-is or archived into a *.{w|j|e}ar
file.
</p>
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<p>
The ProjectModules object provides a root container for all
WorkbenchModules defined in a given project.
</p>
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<p>
ModuleCore provides an instance facade to manage the underlying model for
clients. Static methods
<code>ModuleCore.getModuleCoreForRead()</code>
and
<code>ModuleCore.getModuleCoreForWrite()</code>
may be used to acquire an ModuleCore adapter, and clients are responsible
for invoking
<code>dispose()</code>
whenever they are finished using the model.
</p>
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<td valign="top" bgcolor="#0080c0" align="left" colspan="2"><b><font face="Arial,Helvetica" color="#ffffff">Constraints enforced by the MSM</font></b></td>
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<p>
The following constraints are enforced by the model or by components in
the Web Tools Platform that use the model.
<ol>
<li>
<p>
The solution will not check dependencies for modules that are
contained in the same project. To get the full benefits of
inter-module dependency checking, modules must be separated
into different projects. We do not have the necessary
flexibility in constructing and scoping classpaths on a level
more granular than the project level, which would be needed
to support this functionality.
</p>
</li>
<li>
<p>
The solution will not allow a single module to span more than
one project. Within that project, we will have fairly broad
flexibility to specify which resources map to which modules.
Each module within a project must have its own source folder,
but a module may contain more than one source folder. Each
source folder may be contained by at most one module. Modules
may reference dependent modules in other projects (so a Web
Application may reference a Web Library outside of the
project that contains the Web Application).
</p>
</li>
<li>
<p>
The solution will not allow more than one server target per
module (and really per-project) at a time. The ability to
switch this server target (via some action or property
setting) will continue to be possible. Users that need the
capability to develop for multiple server targets will need
to manually switch and test as necessary.
</p>
</li>
<li>
<p>
Each module in a project will have its own output folder
structure automatically constructed for it. The output
structure will match the J2EE specification output structure
required for the module type (for J2EE modules). A new
builder will handle this responsibility and work
cooperatively with the Java builder to construct a
deployable, on-disk representation of the module structure.
The necessity for this on-disk structure to match a
J2EE-compliant layout is motivated by the requirement to have
in-workbench testing, so that users will not have to deal
with a deployer actually constructing a deployable module and
shipping it off to a server to test their code. This approach
is consistent with existing Ant-based approaches and
Application Servers which can run in a "debug" mode on disk.
Our value-add will be greater automation and integration with
the workbench -- particularly for incremental based support.
The specialized module builder would not be necessary if the
source was already in the appropriate J2EE specification
compliant structure. The default creation will still
encourage a single module per project, which conforms to the
correct J2EE structure.
</p>
</li>
<li>
<p>
Modules will be described using a simple XML format, and each
project will contain one
<I>.wtpmodules</I>
file that will describe all of the modules for that project.
The level of tooling to help users create these files is yet
to be determined for WTP M4. This would be a great area for
other interested developers to suggest and provide tooling
(e.g. a Wizard or Editor) to create these files from existing
structures. A schema is provided to make it easier for
consumers that want to build their own
<I>.wtpmodules</I>
by hand to take advantage of the content assist in the XML
editor.
</p>
</li>
</ol>
</p>
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<td valign="top" bgcolor="#0080c0" align="left" colspan="2"><b><font face="Arial,Helvetica" color="#ffffff">ModuleCore API: Working with the metamodel</font></b></td>
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<BR>
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<p>
Clients that need to work with the Module Structural Model should use the
ModuleCore API to access the model for each project. ModuleCore uses a
mixed pattern that contains elements of Adapter and Facade. Each
ModuleCore is tied to a specific project, and manages the complexity of
the lifecycle of the underlying model.
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<p>
<img src="./diagrams/modulecore.jpg">
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<p>
<i>Figure 2: The ModuleCore API</i>
</p>
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<p>
Clients should use one of
<code>ModuleCore.getModuleCoreForRead()</code>
or
<code>ModuleCore.getModuleCoreForWrite()</code>
to acquire an instance of ModuleCore.
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<pre>
IProject currentProject = ...
ModuleCore moduleCoreInstance = ModuleCore.getModuleCoreForRead(currentProject);
WorkbenchModule[] modules = moduleCoreInstance.getWorkbenchModules();
... work with modules ...
moduleCoreInstance.dispose();
</pre>
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<p>
<i>
Figure 3: Acquiring an instance of ModuleCore for
read-only access
</i>
</p>
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<p>
For clients that would like to build up their own models for a given
project, or modify the existing metamodel, the ModuleCore instance should
be acquired for write-access.
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<td>
<pre>
...
import org.eclipse.emf.common.util.URI;
...
public static void createWebAppModule(IProject aTargetProject,
IFolder aJavaSourceFolder,
IFolder aWebContentFolder,
IResource aWebAppDeploymentDescriptor,
IProgressMonitor aProgressMonitor)
{
ModuleCore moduleCoreInstance = null;
try {
moduleCoreInstance = ModuleCore.getModuleCoreForWrite(aTargetProject);
/* Create a new module that will be contained by the current ModuleCore */
WorkbenchModule newModule = moduleCoreInstance.createWorkbenchModule("MyWebModule.war");
/* A Java source folder that contains the classes for the current module */
WorkbenchModuleResource javaSource =
moduleCoreInstance.createWorkbenchModuleResource(aJavaSourceFolder);
javaSource.setDeployedPath(URI.createURI("/WEB-INF/classes"));
newModule.getResources().add(javaSource);
/* A resource folder that contains the *.jsp, *.html, .img, ... files */
WorkbenchModuleResource webContent =
moduleCoreInstance.createWorkbenchModuleResource(aWebContentFolder);
webContent.setDeployedPath(URI.createURI("/"));
newModule.getResources().add(webContent);
/*
* A resource that points to a valid web.xml file that follows the J2EE Web Deployment
* Descriptor Specification
*/
WorkbenchModuleResource deploymentDescriptor =
moduleCoreInstance.createWorkbenchModuleResource(aWebAppDeploymentDescriptor);
deploymentDescriptor.setDeployedPath(URI.createURI("/WEB-INF/web.xml"));
newModule.getResources().add(deploymentDescriptor);
moduleCoreInstance.saveIfNecessary(aProgressMonitor);
} finally {
if (moduleCoreInstance != null) {
moduleCoreInstance.dispose();
}
}
}
</pre>
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<p>
<i>Figure 4: Creating a WorkbenchModule</i>
</p>
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<p>
For clients that would like to take an existing project an add Flexible
Project Support, use the ModuleCoreNature.addModuleCoreIfNecessary() API
to prepare the project to support flexible module structures. the
existing metamodel, then acquire the ModuleCore instance for modification.
<table cellspacing="10" cellpadding="10">
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<td>
<pre>
...
import org.eclipse.emf.common.util.URI;
...
public static void makeFlexible(IProject aTargetProject) {
ModuleCore moduleCoreInstance = null;
try {
ModuleCoreNature.addModuleCoreNatureIfNecessary(aTargetProject);
moduleCoreInstance = ModuleCore.getModuleCoreForWrite(aTargetProject);
... work with moduleCoreInstance and underlying model ...
moduleCoreInstance.saveIfNecessary(aProgressMonitor);
} finally {
if (moduleCoreInstance != null) {
moduleCoreInstance.dispose();
}
}
}
</pre>
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<p>
<i>Figure 5: Add Flexible Project support to a new or existing project</i>
</p>
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