platform-team/team3.0/logical-physical.html - www.eclipse.org/eclipse - Git at Google


 <table border="0" cellspacing="5" cellpadding="2" width="100%">

     <tr>
       <td align="left" valign="top" bgcolor="#0080c0"> <b><font color="#ffffff" face="Arial,Helvetica">
         Eclipse 3.0 - Plan item</font></b> </td>
     </tr>
 </table>
 <h1>Support Logical Resources</h1>
 This document outlines the state of the Eclipse Platform <strong>Support Logical
 Resources</strong> plan item. Interested parties should review this document and
 verify that their use cases are reflected in the requirements then later that
 the solution provided satisfies their needs. Feedback is strongly encouraged and
 may be provided on the platform-vcm-dev mailing list or in the <a
  href="http://bugs.eclipse.org/bugs/show_bug.cgi?id=37723">bug report</a> for this plan item.
 <P></P>
 <p class=MsoNormal>This is the plan item:</p>

 <blockquote>
   <p>"<em>The Eclipse Platform supports a strong physical view of projects,
     files, and folders in the workspace. However, there are many situations where
     a physical view is not the most salient or useful for many purposes. In some
     cases, multiple distinct objects happen to be stored in a single file, like
     an archive. Conversely, in other cases, something that is logically a single
     object is stored across multiple files. This discrepancy between logical and
     physical creates problems for common operations such as searching, comparing,
     and versioning, which need to work in the physical realm. Eclipse should support
     some way of mapping between a logical view and the physical organization of
     files on disk.</em>"</p>
   <p>Last Modified: July 2nd, 2003</p>
 </blockquote>
 <h1>Motivation</h1>
 <p>By definition Eclipse supports logical resources. It's a "an open extensible
   IDE for anything and nothing in particular". The applications that are
   built with it can be tailored to a particular problem domain and the workbench
   extensions can be used to provide support for the logical model. What Eclipse
   really doesn't support is integrating tools at the logical model. It's simple,
   to integrate two plugins into Eclipse either plugin A and B have to know about
   each other, or both plugins have to depend on some common plugin. While the
   first option is satisfactory for a few cases, the second case is the most common
   and the most problematic. To illustrate, the Eclipse SDK contains several plugins
   that are based on the Resources plugin (e.g. Team, Search, Compare, JDT). When
   an application is packaged based on the SDK, because the plugins in the SDK
   are resource based it isn't possible to integrate plugins at the logical level.</p>
 <p>As you will see later, even the users of the SDK (JDT+CVS+Resources) can observe
   some of the problems associated with the lack of support for logical resources
   and the implicit mapping to physical resources. The lack of a logical integration
   point causes the co-existance of plugins in Eclipse to be error prone for the
   user. The next sections will examine the relationships between logical and physical
   resources and outline the visible problems with Eclipse 2.1. </p>
 <h2>Existing Bugs</h2>
 <p>Bug <A href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=32582">32582</a>
   logical to physical mapping problem , 1 model element = 2 Files problem<br>
   Bug <A href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=3979">3979</a> [CVS
   Decorator] show version info works incorrectly for sub packages (1GFDIEB)</p>
 <h2>Logical Resources</h2>
 <p>Whereas logical resources are elements of the application that model the data/processes
   of a particular problem domain, the physical resources are the file system resources
   (e.g. files and folders) into which an application will eventually transform
   their application model for storage. Applications that don't use file system
   resources are not being considered as part of this plan item. For example, an
   application that stores it's application data directly into a database.</p>
 <p>The following table enumerates concrete examples of how logical and physical
   resources are used in current applications integrated into Eclipse.</p>
 <p><a name="#table1"></a>Table 1: Example logical to physical uses</p>
 <table width="100%" border="1">
   <tr>
     <td width="23%"><div align="center"><strong>Relationships</strong></div></td>
     <td width="77%"><div align="center"><strong>Examples</strong></div></td>
   </tr>
   <tr>
     <td><p>logical (1) &lt;-&gt; (*) physical</p>
       <p>one logical to many physical</p></td>
     <td valign="top"><p><a name="#1a"></a>(<strong>1a</strong>) EJB maps to several physical files:
         (WSAD + XDE Tester). This is the most common case we have found. </p>
       <blockquote>
         <p>/src/org/app/bean.java<br>
           /src/org/app/beanr.java<br>
           /src/org/app/beanlocal.java</p>
       </blockquote>
       <p><em>Note: If one of the logical resource's files was deleted who would
         remember that the file used to exist and is an outgoing deletion or that
         there is an incoming addition to the logical resource?</em></p>
       <p><a name="#1b"></a>(<strong>1b</strong>) Composite Object (logical) maps to several changed
         physical resources. (Rational XDE)</p>
       <p><em>Note</em>: <em>With 1 to many relationship there is always the complication
         that arises if the logical element maps to files in an other project? This
         would cause many problems in the current Team plugin.</em></p></td>
   </tr>
   <tr>
     <td><p>logical (*) &lt;-&gt; (1) physical</p>
       <p>many logical to one physical</p></td>
     <td valign="top"><p><a name="#2a"></a>(<strong>2a</strong>) Methods in a class map to their
         containing class file. (JDT)</p>
       <p><a name="#2b"></a>(<strong>2b</strong>) Archive files (zip, jar) can be seen as a logical
         and the contents of the archive all map to the same physical.(JTD + all)</p></td>
   </tr>
   <tr>
     <td><p>logical (1) &lt;-&gt; (1) physical</p>
       <p>one logical to one physical</p></td>
     <td valign="top"><p><a name="#3a"></a>(<strong>3a</strong>) A Java Package maps to a folder
         but a package does not include sub folders (e.g. they are shallow). (JDT)</p>
       <p><a name="#3b"></a>(<strong>3b</strong>) A UML class maps to a file. For example, in a UML
         application a class could be stored in a single file called 'x435dsds.umlclass'.
         The reason it's a logical is that the user of the application will never
         be concerned about the actual file name or even the folder it's stored
         in. (XDE)</p></td>
   </tr>
 </table>
 <h2>Not very adaptable</h2>
 <p>Object contributions and decorators are key mechanisms for providing rich
   integration between tools. Using object contributions and adaptable objects,
   any plugin

   can provide actions and decorators that will show in another plugin's view.  </p>
 <p>Since IResource is the lowest common integration class and
   is strongly mapped to its physical storage as files and folders, the integration
   point for actions and decorators cannot be the logical types in the view.
   The actions will consequently  use the adaptable type from the selection
   to perform the
   action or the decorator the resource from the getImage request.</p>
 <p>Here is an example to illustrate the problem with the CVS plugin. When running
   a CVS commit action in the packages view the action doesn't know that the IFolder
   is a Java package and is a shallow namespace. It will use the selection and
   traverse the selected IContainer using IContainer.members() and commit all child
   resources. This is the same when the CVS outgoing decorator is shown on a package.
   It will reflect the deep outgoing state of the IContainer. This can lead to
   unexpected behavior because the user expected the action to run on the model
   that the action was displayed on.</p>
 <p>Example object contribution for the CVS commit action:</p>
 <pre>
 &lt;extension point="org.eclipse.ui.popupMenus"&gt;<br> &lt;objectContribution<br>  objectClass="org.eclipse.core.resources.IResource"<br>  adaptable="true"<br>  id="org.eclipse.team.ccvs.ui.IResourceContributions"&gt;<br> &lt;filter<br>  name="projectPersistentProperty"<br>  value="org.eclipse.team.core.repository=org.eclipse.team.cvs.core.cvsnature"&gt;<br> &lt;/filter&gt;<br> &lt;action<br>  label="Commit"<br>  tooltip="Commit resource to CVS repository"<br>  class="org.eclipse.team.internal.ccvs.ui.actions.CommitAction"<br>  menubarPath="team.main/group3"<br>  id="org.eclipse.team.ccvs.ui.commit"&gt;<br> &lt;/action&gt;
  &lt;objectContribution&gt;
 &lt;/extension&gt;
 </pre>
 <p>Example code run in the commit action to calculate the resources to commit:</p>
 <pre>public static Object[] getSelectedAdaptables(ISelection selection)    {
   ArrayList result = null;
   if (!selection.isEmpty()) {
     result = new ArrayList();
     Iterator elements = ((IStructuredSelection) selection).iterator();
     while (elements.hasNext()) {
       Object adapter = getAdapter(elements.next(), IResource.class);
       if (c.isInstance(adapter)) {
         result.add(adapter);
       }
     }
    }
    if (result != null &amp;&amp; !result.isEmpty()) {
    return (Object[])result.toArray((Object[])Array.newInstance(IResource.class, result.size()));
   }
   return (Object[])Array.newInstance(IResource.class, 0);
 }</pre>
 <p>Example code for defining an IResource adaptable decorator:</p>
 <pre>&lt;extension
   point="org.eclipse.ui.decorators"&gt;
     &lt;decorator objectClass="org.eclipse.core.resources.IResource"
      adaptable="true"
      label="%DecoratorStandard.name"
      state="false"
      lightweight= "true"
      quadrant = "BOTTOM_RIGHT"
      class="org.eclipse.team.internal.ccvs.ui.CVSLightweightDecorator"
      id="org.eclipse.team.cvs.ui.decorator"&gt;
     &lt;description&gt;
       %DecoratorStandard.desc
     &lt;/description&gt;
   &lt;/decorator&gt;
 &lt;/extension&gt;</pre>
 <h2>    Decorators</h2>
 <p>When the CVS decorator decorates a logical container in a view, the desire
   is to decorate parents with the dirty indicator if one or more of their logical
   children are dirty. To do this properly, the decorator would need to query the
   dirty status of each of the logical children of the container. This can be a
   costly operation as each child may itself be a logical container. We have optimized
   the dirty decoration by caching folder dirty states. This optimization becomes
   far more complicated with logical models where the caching must be based on
   this alternate model (i.e. the state must be cached for each model).</p>
 <p>


          In addition, often decorators rely on&nbsp;IResource change
   events to re-calculate some new state. In the case of a
   logical elements representing several physical resources there is no easy way of associated
   a IResource change event to its files and the actual logical element.</p>
 <h2>Views</h2>
 <p>It would be nice to see the Java logical view in the Synchronize view or the
   CVS Repositories View. However, the entries in these views may not be IResources
   so an IResource independent mapping mechanism would be required. This could
   be a considerable amount if work for anyone providing a logical model. This
   problem is partly being addressed by the introduction of customizable content
   providers as described in the <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">Generic
   Navigator</a> item.</p>
 <p>Also if an action prompts the user, for example to add resources to CVS, what
   icons and labels are used in the dialog? It would be nice to show those that
   are most familiar to the user. </p>
 <h2>Change Sets</h2>
 <p>Consider a user's action as a logical change, for example, the user renames
   a class using the JDT refactoring action. In the user's mind he 'renamed a class'
   and as a result there has been many other file changes. Currently there is not
   way of capturing these logical actions and associating the set of affected resources.
   This problem manifests itself more in tools where almost every change to the
   model has side effects.</p>
 <h2>File based tools</h2>
 <p>Some tools that integrate into Eclipse are file based and don't use IResources.
   And thus wouldn't be able to operation logical elements.</p>
 <h1>Proposed Solution</h1>
 <p>Part of the solution is to introduce a logical resource element that can be
   the basis for integration between plugins. Our proposed solution will attempt
   to solve the most common uses described in <A href="#table1">Table1</a>, namely
   examples <A href="#1a">1a</a>, <A href="1b">1b</a> and <A href="3a">3a</a>.
   The <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">generic
   navigator</a> plan item should address the <A href="2b">2b</a> and <A href="3b">3b</a>
   examples by providing extensions that would allow a logical model to be available
   to other plugins for display purposes. Finally, <A href="2a">2a</a> is currently
   solved with the existing IResource adapter mechanism.</p>
 <p>Naturally another possible solution would be to change IResource to not be
   analogous to file system resources. However this scope of change is beyond the
   3.0 timeframe and would cause, in my opinion, non-justifiable breaking changes
   to all plugins.</p>
 <h2>ILogicalResource</h2>
 <p>An interface will be added to the Resources plugin that will allow binding
   logical elements to physical ones. The interface is purposely simple with logical
   model manipulations ommitted. A client can't use this interface to display logical
   models or gain any interesting additional knowledge about it. In fact, the only
   way that a plugin will be able to gain access to the model for those purposes,
   would be via the navigator extensions proposed in the <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">generic
   nagivator</a> plan item.</p>
 <p>Current plugins that add object contributions to IResource (CVS, Search, Compare)
   would have to also add them to ILogicalResource and honour the biddings provided
   by the logical resource. Moreover, the plugins that adapted to IResource to
   these object contributions shown in the context menu should no longer adapt
   the IResource and instead implement ILogicalResource.</p>
 <pre>

   /** * A logical resource is an element of an application that
  models the * data/processes of a particular problem domain. Eventually a
  logical resource * must transform the application model for storage using a
  file system

  * resource. * This class provides the bridge between a logical element and
  the physical * resource(s) into which it is stored. On the other hand it
  doesn't provide * hierarchical access to the
  logical
  model. * *
  @see
 IResource */ public interface ILogicalResource {
 	/**
 	 * Returns the project which contains this logical resource.

 	 * This is a resource handle operation; neither the resource
 	 * nor the resulting project need exist.
 	 *
 	 *
 	 * @return the project handle
 	 */
 	public IProject getProject();

 	/**
 	 * Returns the file system resource(s) for this logical resources. The
 	 * returned resources must be contained within the same project.
 	 * A logical element should return the same list of resources regardless
 	 * of the existance of the files on the file system. For example, if a
 	 * logical resource called "form" maps to "/p1/form.xml" and "/p1/form.java"
     * then whether form.xml or form.java existed, they should be returned
     * by this method.
 	 *
 	 * The traversal of the returned IResources should be done considering
 	 * the <code>isDeep</code> flag. If a logical resource maps to a folder
 	 * then the folder's child resources can only be visited if the folder is
 	 * deep.
 	 *
 	 */
 	public IResource[] getPhysicalResources();

 	/**
 	 * Optimization check for tools that should not run operations that traverse
 	 * into child folders.
 	 * @return
 	 */
 	public boolean isDeep();
 }
 </pre>
 <h2>Issues</h2>
 <p>- ObjectContributions have to be duplicated in the plugins that would like
   to provide both contributions for IResource and ILogicalResource.</p>
 <p>- Logical classes (e.g. java model, UML) have to implement the interface instead
   of adapting to it. This is a limitation of the current objectContribution story
   in the workbench.</p>
 <p>- Plugins that add object contributions will have to modify their actions to
   handle logical resources. There should be some standard UI components for showing
   the mappings. For instance you could show the logical model at the top and in
   a details part the physical files/folders that will be affected by the operation.</p>
 </BODY>
 </html>

	<table border="0" cellspacing="5" cellpadding="2" width="100%">

	<tr>
	<td align="left" valign="top" bgcolor="#0080c0"> <b><font color="#ffffff" face="Arial,Helvetica">
	Eclipse 3.0 - Plan item</font></b> </td>
	</tr>
	</table>
	<h1>Support Logical Resources</h1>
	This document outlines the state of the Eclipse Platform <strong>Support Logical
	Resources</strong> plan item. Interested parties should review this document and
	verify that their use cases are reflected in the requirements then later that
	the solution provided satisfies their needs. Feedback is strongly encouraged and
	may be provided on the platform-vcm-dev mailing list or in the <a
	href="http://bugs.eclipse.org/bugs/show_bug.cgi?id=37723">bug report</a> for this plan item.
	<P></P>
	<p class=MsoNormal>This is the plan item:</p>

	<blockquote>
	<p>"<em>The Eclipse Platform supports a strong physical view of projects,
	files, and folders in the workspace. However, there are many situations where
	a physical view is not the most salient or useful for many purposes. In some
	cases, multiple distinct objects happen to be stored in a single file, like
	an archive. Conversely, in other cases, something that is logically a single
	object is stored across multiple files. This discrepancy between logical and
	physical creates problems for common operations such as searching, comparing,
	and versioning, which need to work in the physical realm. Eclipse should support
	some way of mapping between a logical view and the physical organization of
	files on disk.</em>"</p>
	<p>Last Modified: July 2nd, 2003</p>
	</blockquote>
	<h1>Motivation</h1>
	<p>By definition Eclipse supports logical resources. It's a "an open extensible
	IDE for anything and nothing in particular". The applications that are
	built with it can be tailored to a particular problem domain and the workbench
	extensions can be used to provide support for the logical model. What Eclipse
	really doesn't support is integrating tools at the logical model. It's simple,
	to integrate two plugins into Eclipse either plugin A and B have to know about
	each other, or both plugins have to depend on some common plugin. While the
	first option is satisfactory for a few cases, the second case is the most common
	and the most problematic. To illustrate, the Eclipse SDK contains several plugins
	that are based on the Resources plugin (e.g. Team, Search, Compare, JDT). When
	an application is packaged based on the SDK, because the plugins in the SDK
	are resource based it isn't possible to integrate plugins at the logical level.</p>
	<p>As you will see later, even the users of the SDK (JDT+CVS+Resources) can observe
	some of the problems associated with the lack of support for logical resources
	and the implicit mapping to physical resources. The lack of a logical integration
	point causes the co-existance of plugins in Eclipse to be error prone for the
	user. The next sections will examine the relationships between logical and physical
	resources and outline the visible problems with Eclipse 2.1. </p>
	<h2>Existing Bugs</h2>
	<p>Bug <A href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=32582">32582</a>
	logical to physical mapping problem , 1 model element = 2 Files problem<br>
	Bug <A href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=3979">3979</a> [CVS
	Decorator] show version info works incorrectly for sub packages (1GFDIEB)</p>
	<h2>Logical Resources</h2>
	<p>Whereas logical resources are elements of the application that model the data/processes
	of a particular problem domain, the physical resources are the file system resources
	(e.g. files and folders) into which an application will eventually transform
	their application model for storage. Applications that don't use file system
	resources are not being considered as part of this plan item. For example, an
	application that stores it's application data directly into a database.</p>
	<p>The following table enumerates concrete examples of how logical and physical
	resources are used in current applications integrated into Eclipse.</p>
	<p><a name="#table1"></a>Table 1: Example logical to physical uses</p>
	<table width="100%" border="1">
	<tr>
	<td width="23%"><div align="center"><strong>Relationships</strong></div></td>
	<td width="77%"><div align="center"><strong>Examples</strong></div></td>
	</tr>
	<tr>
	<td><p>logical (1) <-> (*) physical</p>
	<p>one logical to many physical</p></td>
	<td valign="top"><p><a name="#1a"></a>(<strong>1a</strong>) EJB maps to several physical files:
	(WSAD + XDE Tester). This is the most common case we have found. </p>
	<blockquote>
	<p>/src/org/app/bean.java<br>
	/src/org/app/beanr.java<br>
	/src/org/app/beanlocal.java</p>
	</blockquote>
	<p><em>Note: If one of the logical resource's files was deleted who would
	remember that the file used to exist and is an outgoing deletion or that
	there is an incoming addition to the logical resource?</em></p>
	<p><a name="#1b"></a>(<strong>1b</strong>) Composite Object (logical) maps to several changed
	physical resources. (Rational XDE)</p>
	<p><em>Note</em>: <em>With 1 to many relationship there is always the complication
	that arises if the logical element maps to files in an other project? This
	would cause many problems in the current Team plugin.</em></p></td>
	</tr>
	<tr>
	<td><p>logical (*) <-> (1) physical</p>
	<p>many logical to one physical</p></td>
	<td valign="top"><p><a name="#2a"></a>(<strong>2a</strong>) Methods in a class map to their
	containing class file. (JDT)</p>
	<p><a name="#2b"></a>(<strong>2b</strong>) Archive files (zip, jar) can be seen as a logical
	and the contents of the archive all map to the same physical.(JTD + all)</p></td>
	</tr>
	<tr>
	<td><p>logical (1) <-> (1) physical</p>
	<p>one logical to one physical</p></td>
	<td valign="top"><p><a name="#3a"></a>(<strong>3a</strong>) A Java Package maps to a folder
	but a package does not include sub folders (e.g. they are shallow). (JDT)</p>
	<p><a name="#3b"></a>(<strong>3b</strong>) A UML class maps to a file. For example, in a UML
	application a class could be stored in a single file called 'x435dsds.umlclass'.
	The reason it's a logical is that the user of the application will never
	be concerned about the actual file name or even the folder it's stored
	in. (XDE)</p></td>
	</tr>
	</table>
	<h2>Not very adaptable</h2>
	<p>Object contributions and decorators are key mechanisms for providing rich
	integration between tools. Using object contributions and adaptable objects,
	any plugin

	can provide actions and decorators that will show in another plugin's view. </p>
	<p>Since IResource is the lowest common integration class and
	is strongly mapped to its physical storage as files and folders, the integration
	point for actions and decorators cannot be the logical types in the view.
	The actions will consequently use the adaptable type from the selection
	to perform the
	action or the decorator the resource from the getImage request.</p>
	<p>Here is an example to illustrate the problem with the CVS plugin. When running
	a CVS commit action in the packages view the action doesn't know that the IFolder
	is a Java package and is a shallow namespace. It will use the selection and
	traverse the selected IContainer using IContainer.members() and commit all child
	resources. This is the same when the CVS outgoing decorator is shown on a package.
	It will reflect the deep outgoing state of the IContainer. This can lead to
	unexpected behavior because the user expected the action to run on the model
	that the action was displayed on.</p>
	<p>Example object contribution for the CVS commit action:</p>
	<pre>
	<extension point="org.eclipse.ui.popupMenus"><br> <objectContribution<br> objectClass="org.eclipse.core.resources.IResource"<br> adaptable="true"<br> id="org.eclipse.team.ccvs.ui.IResourceContributions"><br> <filter<br> name="projectPersistentProperty"<br> value="org.eclipse.team.core.repository=org.eclipse.team.cvs.core.cvsnature"><br> </filter><br> <action<br> label="Commit"<br> tooltip="Commit resource to CVS repository"<br> class="org.eclipse.team.internal.ccvs.ui.actions.CommitAction"<br> menubarPath="team.main/group3"<br> id="org.eclipse.team.ccvs.ui.commit"><br> </action>
	<objectContribution>
	</extension>
	</pre>
	<p>Example code run in the commit action to calculate the resources to commit:</p>
	<pre>public static Object[] getSelectedAdaptables(ISelection selection) {
	ArrayList result = null;
	if (!selection.isEmpty()) {
	result = new ArrayList();
	Iterator elements = ((IStructuredSelection) selection).iterator();
	while (elements.hasNext()) {
	Object adapter = getAdapter(elements.next(), IResource.class);
	if (c.isInstance(adapter)) {
	result.add(adapter);
	}
	}
	}
	if (result != null && !result.isEmpty()) {
	return (Object[])result.toArray((Object[])Array.newInstance(IResource.class, result.size()));
	}
	return (Object[])Array.newInstance(IResource.class, 0);
	}</pre>
	<p>Example code for defining an IResource adaptable decorator:</p>
	<pre><extension
	point="org.eclipse.ui.decorators">
	<decorator objectClass="org.eclipse.core.resources.IResource"
	adaptable="true"
	label="%DecoratorStandard.name"
	state="false"
	lightweight= "true"
	quadrant = "BOTTOM_RIGHT"
	class="org.eclipse.team.internal.ccvs.ui.CVSLightweightDecorator"
	id="org.eclipse.team.cvs.ui.decorator">
	<description>
	%DecoratorStandard.desc
	</description>
	</decorator>
	</extension></pre>
	<h2> Decorators</h2>
	<p>When the CVS decorator decorates a logical container in a view, the desire
	is to decorate parents with the dirty indicator if one or more of their logical
	children are dirty. To do this properly, the decorator would need to query the
	dirty status of each of the logical children of the container. This can be a
	costly operation as each child may itself be a logical container. We have optimized
	the dirty decoration by caching folder dirty states. This optimization becomes
	far more complicated with logical models where the caching must be based on
	this alternate model (i.e. the state must be cached for each model).</p>
	<p>



	In addition, often decorators rely on IResource change
	events to re-calculate some new state. In the case of a
	logical elements representing several physical resources there is no easy way of associated
	a IResource change event to its files and the actual logical element.</p>
	<h2>Views</h2>
	<p>It would be nice to see the Java logical view in the Synchronize view or the
	CVS Repositories View. However, the entries in these views may not be IResources
	so an IResource independent mapping mechanism would be required. This could
	be a considerable amount if work for anyone providing a logical model. This
	problem is partly being addressed by the introduction of customizable content
	providers as described in the <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">Generic
	Navigator</a> item.</p>
	<p>Also if an action prompts the user, for example to add resources to CVS, what
	icons and labels are used in the dialog? It would be nice to show those that
	are most familiar to the user. </p>
	<h2>Change Sets</h2>
	<p>Consider a user's action as a logical change, for example, the user renames
	a class using the JDT refactoring action. In the user's mind he 'renamed a class'
	and as a result there has been many other file changes. Currently there is not
	way of capturing these logical actions and associating the set of affected resources.
	This problem manifests itself more in tools where almost every change to the
	model has side effects.</p>
	<h2>File based tools</h2>
	<p>Some tools that integrate into Eclipse are file based and don't use IResources.
	And thus wouldn't be able to operation logical elements.</p>
	<h1>Proposed Solution</h1>
	<p>Part of the solution is to introduce a logical resource element that can be
	the basis for integration between plugins. Our proposed solution will attempt
	to solve the most common uses described in <A href="#table1">Table1</a>, namely
	examples <A href="#1a">1a</a>, <A href="1b">1b</a> and <A href="3a">3a</a>.
	The <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">generic
	navigator</a> plan item should address the <A href="2b">2b</a> and <A href="3b">3b</a>
	examples by providing extensions that would allow a logical model to be available
	to other plugins for display purposes. Finally, <A href="2a">2a</a> is currently
	solved with the existing IResource adapter mechanism.</p>
	<p>Naturally another possible solution would be to change IResource to not be
	analogous to file system resources. However this scope of change is beyond the
	3.0 timeframe and would cause, in my opinion, non-justifiable breaking changes
	to all plugins.</p>
	<h2>ILogicalResource</h2>
	<p>An interface will be added to the Resources plugin that will allow binding
	logical elements to physical ones. The interface is purposely simple with logical
	model manipulations ommitted. A client can't use this interface to display logical
	models or gain any interesting additional knowledge about it. In fact, the only
	way that a plugin will be able to gain access to the model for those purposes,
	would be via the navigator extensions proposed in the <a href="http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-ui-home/navigator-proposal/general_purpose_navigator_proposal.html">generic
	nagivator</a> plan item.</p>
	<p>Current plugins that add object contributions to IResource (CVS, Search, Compare)
	would have to also add them to ILogicalResource and honour the biddings provided
	by the logical resource. Moreover, the plugins that adapted to IResource to
	these object contributions shown in the context menu should no longer adapt
	the IResource and instead implement ILogicalResource.</p>
	<pre>

	/** * A logical resource is an element of an application that
	models the * data/processes of a particular problem domain. Eventually a
	logical resource * must transform the application model for storage using a
	file system

	* resource. * This class provides the bridge between a logical element and
	the physical * resource(s) into which it is stored. On the other hand it
	doesn't provide * hierarchical access to the
	logical
	model. * *
	@see
	IResource */ public interface ILogicalResource {
	/**
	* Returns the project which contains this logical resource.

	* This is a resource handle operation; neither the resource
	* nor the resulting project need exist.
	*
	*
	* @return the project handle
	*/
	public IProject getProject();

	/**
	* Returns the file system resource(s) for this logical resources. The
	* returned resources must be contained within the same project.
	* A logical element should return the same list of resources regardless
	* of the existance of the files on the file system. For example, if a
	* logical resource called "form" maps to "/p1/form.xml" and "/p1/form.java"
	* then whether form.xml or form.java existed, they should be returned
	* by this method.
	*
	* The traversal of the returned IResources should be done considering
	* the <code>isDeep</code> flag. If a logical resource maps to a folder
	* then the folder's child resources can only be visited if the folder is
	* deep.
	*
	*/
	public IResource[] getPhysicalResources();

	/**
	* Optimization check for tools that should not run operations that traverse
	* into child folders.
	* @return
	*/
	public boolean isDeep();
	}
	</pre>
	<h2>Issues</h2>
	<p>- ObjectContributions have to be duplicated in the plugins that would like
	to provide both contributions for IResource and ILogicalResource.</p>
	<p>- Logical classes (e.g. java model, UML) have to implement the interface instead
	of adapting to it. This is a limitation of the current objectContribution story
	in the workbench.</p>
	<p>- Plugins that add object contributions will have to modify their actions to
	handle logical resources. There should be some standard UI components for showing
	the mappings. For instance you could show the logical model at the top and in
	a details part the physical files/folders that will be affected by the operation.</p>
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