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Chapter 10. In-Memory Connector

The in-memory repository connector is a simple connector that creates a transient, in-memory repository. This repository is used as a very simple in-memory cache or as a standalone transient repository. This connector works well for a readable and writable repository source with small to moderate sized content that need not be permanently saved.

The InMemoryRepositorySource class provides a number of JavaBean properties that control its behavior:

defaultCachePolicy

Optional property that, if used, defines the default for how long this information provided by this source may to be cached by other, higher-level components. The default value is an empty string (or null) and implies that this source does not define a specific duration for caching information provided by this repository source.

defaultWorkspaceName

Optional property that defines the name for the workspace that will be used in cases when clients do not explicitly specify the workspace name. If not specified, "default" will be used.

jndiName

Optional property that, if used, specifies the name in JNDI where an InMemoryRepository instance can be found. This is an advanced property that is infrequently used.

name

Required property that specifies the name of the repository source, which is used by the RepositoryService when obtaining a RepositoryConnection by name.

rootNodeUuid

Optional property that, if used, specifies the UUID that should be used for the root node of each workspace. If no value is specified, a new UUID is generated.

retryLimit

Optional property that, if used, defines the number of times that any single operation on a RepositoryConnection to this source should be retried following a communication failure. The default value is '0'.

One way to configure the in-memory connector is to create JcrConfiguration instance with a repository source that uses the InMemoryRepositorySource class. For example:



JcrConfiguration config = ...
config.repositorySource("IMR Store")
      .usingClass(InMemoryRepositorySource.class)
      .setDescription("The repository for our content")
      .setProperty("predefinedWorkspaceNames", new String[] { "staging", "dev"})
      .setProperty("defaultWorkspaceName", workspaceName);
 

Another way to configure the in-memory connector is to create JcrConfiguration instance and load an XML configuration file that contains a repository source that uses the InMemoryRepositorySource class. For example a file named configRepository.xml can be created with these contents:



<?xml version="1.0" encoding="UTF-8"?>
<configuration xmlns:mode="http://www.modeshape.org/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0">
    <!-- 
    Define the sources for the content.  These sources are directly accessible using the 
    ModeShape-specific Graph API.  In fact, this is how the ModeShape JCR implementation works.  You 
    can think of these as being similar to JDBC DataSource objects, except that they expose 
    graph content via the Graph API instead of records via SQL or JDBC. 
    -->
    <mode:sources jcr:primaryType="nt:unstructured">
        <!-- 
        The 'IMR Store' repository is an in-memory source with a single default workspace (though 
        others could be created, too).
        -->
        <mode:source jcr:name="IMR Store" 
                    mode:classname="org.modeshape.graph.connector.inmemory.InMemoryRepositorySource" 
                    mode:description="The repository for our content" 
                    mode:defaultWorkspaceName="default">
           <mode:predefinedWorkspaceNames>staging</mode:predefinedWorkspaceNames>
                   <mode:predefinedWorkspaceNames>dev</mode:predefinedWorkspaceNames>
                </mode:source>
                               
    </mode:sources>
    
    <!-- MIME type detectors and JCR repositories would be defined below --> 
</configuration>
 

The configuration can then be loaded from Java like this:



JcrConfiguration config = new JcrConfiguration().loadFrom("/configRepository.xml");