To provide full support for logical models, a repository provider can perform the following steps:
ResourceMapping.ISynchronizationScope and
supporting API.IMergeContext
interface and supporting API.teamContentProviders
for the models involved in the merge. A ModelSynchronizeParticipant
class is provided to help manage the relationship between the model
content, a merge context and the Compare framework.IFileHistoryProvider APIProjectSetCapability
Subscriber for use with the SynchronizationStateTester API.IChangeGroupingRequestor API.The following sections describe each of these points in more detail. The org.eclipse.ui.examples.filesystem plug-in contain an example that illustrate several of these points. You can check the project out from the Git repository and use it as a reference while you are reading this tutorial. Disclaimer: The source code in the example plug-ins may change over time. To get a copy that matches what is used in this example, you can check out the project using the 3.3 version tag (most likely R3_3) or a date tag of June 30, 2007.
The resource mapping API consists of the following classes:
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.ResourceTraversal contains 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:
getResources()getDepth()ResourceMappingContext
and RemoteResourceMappingContext
is 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 the model roadmap 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 ResourceMapping
APIs:
ResourceMapping
instead of IResource (for those for which this is
appropriate).ResourceMapping
instead of IResource and respect the depth constraints
provided in the traversals.Plug-ins that add object contributions to IResource
can now add them to ResourceMapping instead, 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:
<extension
point="org.eclipse.ui.popupMenus">
<objectContribution
objectClass="org.eclipse.core.resources.mapping.ResourceMapping"
adaptable="true"
id="org.eclipse.team.ccvs.ui.ResourceMapperContributions">
<enablement>
<adapt type="org.eclipse.core.resources.mapping.ResourceMapping">
<test
property="org.eclipse.core.resources.projectPersistentProperty"
args="org.eclipse.team.core.repository,org.eclipse.team.cvs.core.cvsnature" />
</adapt>
</enablement>
<action
label="%UpdateAction.label"
definitionId="org.eclipse.team.cvs.ui.update"
class="org.eclipse.team.internal.ccvs.ui.actions.UpdateAction"
tooltip="%UpdateAction.tooltip"
menubarPath="team.main/group2"
id="org.eclipse.team.cvs.ui.update">
</action>
...
</objectContribution>
</extension>
Contributions to 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 ResourceMapping
class will be given a selection that contains one or more ResourceMappings.
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 getTraversals
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, there are model relationships (or repository relationships) 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 ISynchronizationScopeManager
API.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 by:
RemoteResourceMappingContext for use
when obtaining resource traversals from resource mappings.SynchronizationScopeManager to 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 RemoteResourceMappingContext
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 SubscriberResourceMappingContext
is provided 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.
The SynchronizationScopeManager class can be
subclassed to tailor the scope generation and management process. The
two main reasons for subclassing the scope manager are:
ISynchronizationScopeParticipant
interface defines the API that model providers can use to participate
in the scope management process. The SubscriberScopeManager
class is a Subscriber based subclass of SynchronizationScopeManager
that 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 IStorageMerger 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 IResourceMappingMerger
and IMergeContext APIs.
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 the 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, ModelMergeOperation
is provided which uses the IResourceMappingMerger API to
perform a model-based merge operation. Subclasses need to override the initializeContext(IProgressMonitor)
method to return a merge context. The operation uses this context 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 ModelParticipantMergeOperation
that provides preview capabilities using a ModelSynchronizeParticipant.
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.teamContentProviders
extension point. Team providers access these content providers through
the ITeamContentProviderManager.
There are several places where a team provider may wish to display logical models:
ModelOperation class provides
a prompt that uses the registered team content providers to inform the
user of a scope expansion.The 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:
ModelSynchronizeParticipantISynchronizePageConfiguration.P_VIEWER_ID
to the id of the viewer specified in the previous step.MergeActionGroup in order to tailor the
appearance of the merge related actions.ModelParticipantMergeOperation
for handling the transition from a model-based merge to a preview in a
dialog or Synchronize view.The following XML snipets illustrate how the CVS 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 that do not map directly to files. The History view is a page-based view which obtains a page for the selected element in the following way:
RepositoryProvider associated with the project that
contains the resource to an IHistoryPageSource.
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
file-system scheme registered with the
org.eclipse.core.filesystem.filesystems
extension point. Team providers can optionally 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 receive a label update when the underlying resources change.
To address this issue, the ITeamStateProvider was introduced in order to give model
providers access to state changes that may affect team decorations. In addition,
model views can use a SynchronizationStateTester to determine when the
labels of logical model elements need to be updated. This API relies on
the ITeamStateProvider interface to determine when the team state
of resource has changed and can be passed to a team decorator as part of an IDecorationContext.
RepositoryProviderType
to an instance of
IChangeGroupingRequestor.
This API allows models to request that a set of files get committed or checked-in as a single unit.