|Eclipse 3.2 - Repository Roadmap for Logical Model Integration|
The Proposed Support for Logical Model Integration document outlines all the areas that are targeted to be addressed in 3.2 related to logical model integration support in Eclipse. The purpose of this document is to describe the APIs repository providers can use to support logical models.
To provide full support for logical models based on the Eclipse 3.2 API, a repository provider can perform the following steps:
ISynchronizationScopeand supporting API.
IMergeContextinterface and supporting API.
teamContentProvidersfor the models involved in the merge. A
ModelSynchronizeParticipantclass is provided to help manage the relationship between the model content, a merge context and the Compare framework.
Subscriberfor use with the
The following sections describe each of these points in more detail. A pointer to a simple Library example is also provided.
The resource mapping API consists of the following classes:
ResourceMappingclass can be viewed here. The methods of interest are:
Object getModelObject(): The model object from which the mapping was derived (or adapted).
ResourceTraversal getTraversals(ResourceMappingContext, IProgressMonitor): The resource traversal that cover the resources that constitute the model object.
ResourceTraversalcontains a set of resources and a depth flag that indicates the depth to which the resources in the traversal are associated with the originating model object. Resource traversals are provided to a client by a resource mapping in order to describe the contents of a model in such a way that the client (e.g. a repository provider) can perform its operations in as efficient a means as possible. Methods of interest are:
RemoteResourceMappingContextis a bit more complicated and is described later.
There are two types of plugins that should be interested in resource mappings. Those who provide a model that consists of, or is persisted in, resources in the workspace and those that want to perform operations on resources. The former case will be covered in a document targetted at model providers and the later case is covered in the next section.
Plug-ins that contribute extensions to adaptable extension points will have
to make two changes to support the new
IResource(for those for which this is appropriate).
IResourceand respect the depth constraints provided in the traversals.
Plug-ins that add object contributions to
can now add them to
if the action can apply to multiple resources. Here is an XML snippet that contributes
a menu action to objects that adapt to resource mappings:
ResourceMapping will automatically apply to objects
that adapt to
IResource. This transitive association is handled
by the Workbench. Filtering of the contributions to resource mappings can be done using enablement
expressions. An expression for filtering by project persistent property
has been added to allow repository providers to have their menus appear on projects
that are mapped to their repositories.
Actions that have been contributed to the
will be given a selection that contains one or more
It is the actions responsibility to translate the resource mapping into a set
of resources to be operated on. This can be done by calling
to get the traversals of the mapping. Traversals are used to allow the clients
of the traversal to optimize their operations based on the depth of the resources
being traversed. A client may traverse the resource manually or may use the
resource and the depth as input into an operation that the action delegates
to do the work. As an example, if the user performs a CVS update on a java package
and the java package resource mapping maps to a folder of depth one, CVS would
issue an appropriate command ("cvs update -l" for those who are curious) which
would perform a shallow update on the folder the package represents.
Although it is possible to obtain a set of traversals directly from the selected resource mappings, their are model relationships (or repository reltionships) that may require the inclusion of additional resources or model elements in an operation. The next section describes how to ensure that all required resources are included in an operation
For team operations, the selected mappings need to be translated into the set of mappings to be operated on. This process involves consulting all model providers to ensure that they get included in operations on resources that match their enablement rules. The term we use to describe the complete set of resource mappings to be operated on is the operation scope. The following API has been provided for this:
ISynchronizationScope: Interface that defines the API for accessing the scope of the operation. It provides access to all the resource mappings being operated on and the traversals for those mappings as they were calculated during the scope building process.
ISynchronizationScopeManager: Interface that defines the API for creating and managing a scope.
SynchronizationScopeManager: Extendable class that provides a default implementation of the
ModelOperation: Extendable operation class that generates a scope using a provided scope manager and prompts if additional resources or mappings have been included in the operation due to model provider relationships.
The initialize(IProgressMonitor) method of the
SynchronizationScopeManager class handles the entire process of converting
an input set of resource mappings into the complete set of mappings that need to be operated on as well
as the complete set of traversals that cover these mappings. A repository provider can tailor the process
RemoteResourceMappingContextfor use when obtaining resource traversals from resource mappings.
SynchronizationScopeManagerto tailor the scope management process as required.
The next two sections describe these points in more detail.
In order to guarantee that all necessary resources get included in a team operation, the model provider may need the ability to glimpse at the state of one or more resources in the repository. For some models, this may not be required. For instance, a java package is a container visited to a depth of one, regardless of the remote state of the model. Given this, a repository provider can easily determine that outgoing deletions should be included when committing or that incoming additions should be included when updating. However, the resources that constitute some logical models may change over time. For instance, the resources that constitute a model element may depend of the contents of a manifest file (or some other similar mechanism). In order for the resource mapping to return the proper traversal, it must access the remote contents of the manifest file (if it differs from the local contents) in order to see if there are additional resources that need to be included. These additional resources may not exist in the workspace but the repository provider would know how to make sure they did when the selected action was performed.
In order to support these more complex models, a
can be passed to the
ResourceMapping#getTraversals method. When
a context is provided, the mapping can use it to ensure that all the necessary
resources are included in the traversal. If a context is not provided, the mapping
can assume that only the local state is of interest.
The remote resource mapping context provides three basic queries:
The answer to the first question above depends on the type of operation that is being performed. Typically, updates and merges are three-way while comparisons and replace operations (at least for CVS) are two-way.
The Eclipse Team API includes a
Subscriber class that defines
an API for providing the synchronization state between the local workspace and
a remote server. A
has been created that uses a
Subscriber to access the necessary
remote state. Clients that have a
Subscriber do not need to do
any additional work to get a resource mapping context.
SynchronizationScopeManager class can be subclassed to tailor the scope
generation and management process. The two main reasons for subclassing the scope manager are:
ISynchronizationScopeParticipantinterface defines the API that model providers can use to participate in the scope management process. The
SubscriberScopeManagerclass is a
Subscriberbased subclass of
SynchronizationScopeManagerthat involves participants in the scope management process. An example of why this type of process is needed is working sets. If a working set is one of the resource mappings in a scope, the set of traversals covered by the scope would increase if resources were added to the working set.
The main repository operation type that requires model participation is merging. In many
cases, models only need to participate at the file level. For this, the
API was introduced to allow model providers to contribute mergers that should be used to merge
files of a particular extension or content type. However, in some cases, models may need
additional context to participate properly in a merge. For this purpose, we introduced the
Merge operations are still triggered by actions associated with a repository provider. However, once a merge type operation is requested by the user, the repository provider needs to involve the model providers in the merge process to ensure that the merge does not corrupt the model in some way.
There are two main pieces of repository provider API related to the model-based merging support.
An important aspect of model-based merging is the API used to communicate the synchronization state of the resources involved to the model provider. The following interfaces are used to describe the synchronization state:
Abstract classes are provided for all these interfaces with the convention that the class names match the
interface names with the "I" prefix removed. The only class that repository providers must override is
ResourceDiff class so that appropriate before and after file revisions can be provided.
The IMergeContext interface extends synchronization context with additional methods that support merging. Callback methods exist for:
An abstract MergeContext class is provided that contains default implementations for much of the merging behavior and also uses the IStorageMerger to perform three-way merges. A SubscriberMergeContext class is also provided which handles the population and maintenance of the synchronization state description associated with the merge context.
An operation class,
is provided which uses the
IResourceMappingMerger API to perform a model-based merge operation. Subclasses need
to overriding the
initializeContext(IProgressMonitor) method to return a merge context.
The operation uses this content to attempt a headless model-based merge. If conflicts exist,
the preview of the merge is left to the subclass. As we'll see in the next section, there is a
that provides preview capabilities using a
Support for the display of logical models in a team operation is provided using the Common
Navigator framework which was introduced in Eclipse 3.2. Logical models can associate a
content extension with a model provider using the org.eclipse.team.ui.teamContentProvider
extension point. Team providers access these content providers through the
There are several places where a team provider may wish to display logical models:
ModelOperationclass provides a prompt that uses the registered team content providers to inform the user of a scope expansion.
ModelSynchronizeParticipant provides integration into the Synchronize view or any container that can display
iSynchronizePages. The participant makes use of both the pre-existing synchronization participant capabilities and the
Common Navigator capabilities to allow for team providers and models to tailor the toolbar, context menu and other aspects of the
merge preview. The
ModelSynchronizeParticipant provides the following:
Here's a checklist of steps for tailoring a model synchronize participant for a particular Team provider:
ISynchronizePageConfiguration.P_VIEWER_IDto the id of the viewer specified in the previous step.
MergeActionGroupin order to tailor the appearance of the merge related actions.
ModelParticipantMergeOperationfor handling the transition from a model-based merge to a preview in a dialog or Synchronize view.
An example of these types of overrides appear in the WorkspaceModelParticipant class. The following XML snipets illustrate how this participant class is registered and how it's viewer is defined.
<extension point="org.eclipse.team.ui.synchronizeParticipants"> <participant name="CVS" icon="$nl$/icons/full/eview16/cvs_persp.gif" class="org.eclipse.team.internal.ccvs.ui.mappings.WorkspaceModelParticipant" id="org.eclipse.team.cvs.ui.workspace-participant"> </participant> </extension> <extension point="org.eclipse.ui.navigator.viewer"> <viewer viewerId="org.eclipse.team.cvs.ui.workspaceSynchronization"> <popupMenu allowsPlatformContributions="false" id="org.eclipse.team.cvs.ui.workspaceSynchronizationMenu"> <insertionPoint name="file"/> <insertionPoint name="edit" separator="true"/> <insertionPoint name="synchronize"/> <insertionPoint name="navigate" separator="true"/> <insertionPoint name="update" separator="true"/> <insertionPoint name="commit" separator="false"/> <insertionPoint name="overrideActions" separator="true"/> <insertionPoint name="otherActions1" separator="true"/> <insertionPoint name="otherActions2" separator="true"/> <insertionPoint name="sort" separator="true"/> <insertionPoint name="additions" separator="true"/> <insertionPoint name="properties" separator="true"/> </popupMenu> </viewer> </extension>
A file history API has been added to allow models to access the history of files. The file history API consists of the following interfaces:
Along with this API, a generic file History view has been added. This will allow Team providers to display their file/resource history in a shared view and also allows models to display model element history for elements tat do not map directly to files. The History view is a page-based view which onbtains a page for the selected element in the following way:
RepositoryProviderassociated with the project that contains thge resource to an IHistoryPageSource.
Methods have been added to
ProjectSetCapability to support the translation between a reference string
used to identify a mapping between a project and remote content and
URIs that identify a filesytem scheme regsitered with the org.eclipse.core.filesystem.filesystems extension point.
Team providers can optionaly provide support for this in order to allow logical models to performing
remote browsing and project loading.
Team providers can decorate model elements by converting their lightweight decorators to work for resource mappings in the same way object contributions are converted to work for resource mappings. However, there is one aspect of logical model element decoration that is problematic. If a model element does not have a one-to-one mapping to a resource, the model element may not recieve a label update when the underlying resources change.
To address this issue, a
SynchronizationStateTester class was added. This class is used by model
views to determine when the labels of logical model elements need to be updated. This API relies on the
interface to determine when the team state of resource has changed. To work properly, repository providers
must override the
RepositoryProviderType#getSubscriber() method in order to return a subscriber
that provides clients access to the team state of workspace resources.
This example, available here, is built on a model that consists of libraries, books and writers.
Changes in version 3.2 M5