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<title>modulecore api overview</title>
The ComponentCore API allows clients to work with the Structural
Metamodels that define abstract modules within Eclipse projects.
These metamodels are exposed through the Virtual Path API layer
(see <a href="ComponentCore.html">ComponentCore</a>). Clients
should also review the <b>org.eclipse.wst.common.componentcore.resources</b>
<a name="top"/>
The following document includes information on these topics:
<li><a href="#structural-metamodel">ComponentCore Metamodel (CCM)</a>
used to understand which files should or should not be
included within a module.</li>
<li><a href="#constraints">Constraints</a> enforced by the
<li><a href="#module-core-examples">The API entry-point</a></li>
<a name="structural-metamodel"/>
<h2>ComponentCore Metamodel (CCM)</h2>
<BR />
The ComponentCore Metamodel (CCM) is an EMF model that allows
the tooling to understand most project structures. Each project
has a single CCM which is stored under the project root named
. The XML format is defined by the
<a href="../../../../../overview/componentCore.xsd">ComponentCore schema</a>.
The following diagram is a UML representation of the
ComponentCore Metamodel. This information is published for
potential contributors of editors, but the EMF model is
not exposed directly as API, and could change in view of
changes for WTP 1.1.
<img src="../../../../../overview/componentcore_model.jpg" caption="The Component Core Metamodel" />
Each logical component contained in the project is represented by a
<b>WorkbenchComponent</b> element. The <b>WorkbenchComponent</b> defines
information about the type of component, the resources consumed by the
module from the project, and the referenced components. The
<b>WorkbenchComponent</b> is very generic, and as modeled, does
not necessarily correspond to only J2EE artifacts.
The <b>WorkbenchComponent</b> has a
, which is the name that will be used when the runtime form of the
component is constructed. For a web application, the
might be "MyWebApplication".
The <b>WorkbenchComponent</b> may be uniquely referenced by a URI. The
fully qualified URI to any component must begin with the component
protocol ("component:"), specify a subprotocol ("resource|classpath") and
then a path to the referenced component. A <b>WorkbenchComponent</b> with the
name "MyWebApplication" defined in a project named
"MyWebModulesProject" would be referenced by the following URI:
"component:/resource/MyWebModulesProject/MyWebApplication". As a future
extension, a component referenced on the classpath of a project (perhaps
a Utility Jar or an EJB Client Jar), the URI might be something like:
The <b>WorkbenchComponent</b> has a <b>ComponentType</b>. The
<b>ComponentType</b> defines a <i>componentTypeId</i>
, which indicates the specific kind of component. The Web Tools Platform
uses the <i>componentTypeId</i>
to determine how to work with the content component of the <b>WorkbenchComponent</b>
and prepare the component for deployment. The <b>ComponentType</b> may
also define the runtime-paths of special metadata resources which are
important to the <b>WorkbenchComponent</b>. "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.
The <b>WorkbenchComponent</b> contains a list of ComponentResources. Each
<b>ComponentResource</b> has "sourcePath" and a corresponding
"runtimePath". The "sourcePath" can reference either a file or folder,
but the referenced resource must be contained in the same project as the
<b>WorkbenchComponent</b> definition. The "runtimePath" specifies a location
relative to the deployed structure of the <b>WorkbenchComponent</b> where the
contents of the referenced resource will be represented when the module is
prepared for runtime.
The <b>WorkbenchComponent</b> contains a list of <b>ReferencedComponent</b>s.
Each <b>ReferencedComponent</b> provides a handle that must resolve to a
<b>WorkbenchComponent</b>, a runtimePath that defines where the constructed
component will be placed within the context of the runtime
<b>WorkbenchComponent</b>, and a <b>DependencyType</b>
that can be either "consume" or "use" to indicate how the contents of
that <b>ReferencedComponent</b> should be absorbed by the <b>WorkbenchComponent</b>.
<b>ReferencedComponent</b>s may reference <b>WorkbenchComponent</b>s in
other projects and on current project's classpath (Not yet implemented).
The <b>DependencyType</b> will determine whether the contents of
the <b>ReferencedComponent</b> are absorbed as-is or archived into a *.{w|j|e}ar
The <b>ProjectComponents</b> object provides a root container for all
<b>WorkbenchComponent</b>s defined in a given project.
<b>ComponentCore</b> provides a facade to manage the underlying model for
clients. Static methods
may be used to acquire an ModuleCore adapter, and clients are responsible
for invoking
whenever they are finished using the model.
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<a name="constraints"/>
<h2>Constraints enforced by the CCM</h2>
The following constraints are enforced by the model:
The solution will not check dependencies for components that are
contained in the same project. To get the full benefits of
inter-component dependency checking, components 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.
The solution will not allow a single component to span more than
one project. Within that project, we will have fairly broad
flexibility to specify which resources map to which components.
Each component within a project must have its own source folder,
but a component may contain more than one source folder. Each
source folder may be contained by at most one component. Components
may reference dependent components in other projects (so a Web
Application may reference a Web Library outside of the
project that contains the Web Application).
The solution will not allow more than one server target per
component (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.
Each component in a project may have its own output folder
structure automatically constructed for it. The output
structure will match the J2EE specification output structure
required for the component 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 reference implementation will follow this pattern, but
hooks will be made available to vary this behavior.
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.
Components will be described using a simple XML format, and each
project will contain one
file that will describe all of the components 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
by hand to take advantage of the content assist in the XML
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<a name="module-core-examples"/>
<h2>ComponentCore API: Working with the metamodel</h2>
<BR />
ComponentCore uses a handle based model much like the existing Platform
Resource model. The ComponentCore facade is not tied to any project, and
the handles that it returns may or may not exist. The complexity of
managing the underlying EMF model is handled under the cover for users.
<img src="../../../../../overview/componentcore_package.jpg" caption="The ComponentCore API" />
Clients should use one of
to acquire an instance of ModuleCore.
<codesnippet caption="Acquiring an instance of ComponentCore for read-only access">
IProject currentProject = ...
ModuleCore moduleCoreInstance = ModuleCore.getModuleCoreForRead(currentProject);
WorkbenchComponent[] modules = moduleCoreInstance.getWorkbenchComponents();
... work with modules ...
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.
<codesnippet caption="Creating a WorkbenchComponent">
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 =
/* Create a new module that will be
contained by the current ModuleCore */
WorkbenchComponent newModule =
/* A Java source folder that contains
the classes for the current module */
ComponentResource javaSource =
/* A resource folder that contains
the *.jsp, *.html, .img, ... files */
ComponentResource webContent =
/* A resource that points to a valid web.xml
file that follows the J2EE Web Deployment
Descriptor Specification
ComponentResource deploymentDescriptor =
} finally {
if (moduleCoreInstance != null) {
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.
<codesnippet caption="Add Flexible Project support to a new or existing project">
import org.eclipse.emf.common.util.URI;
public static void makeFlexible(IProject aTargetProject) {
ModuleCore moduleCoreInstance = null;
try {
moduleCoreInstance = ModuleCore.getModuleCoreForWrite(aTargetProject);
... work with moduleCoreInstance and underlying model ...
} finally {
if (moduleCoreInstance != null) {
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