Title: MongoDB Support
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As of 0.19, Rave has a [MongoDB][4] module that provides implementations for all of Rave's repository interfaces; thus providing support for MongoDB.  

#Using MongoDB for Persistence
JPA remains the primary supported data access method in the rave-portal & rave-portal-resources projects; but can be easily replaced with MongoDB using the following techniques:

##Build from source

To build a MongoDB version of the demo binaries follow these steps:

1. Obtain the source from the [downloads][0] or from [Source Control][1]
2. From the project root directory execute:       `mvn install -Pmongodb`

The rave-portal, rave-portal-resources & rave-shindig wars created by this process contain everything needed to run Rave with MongoDB persistence.  See [configuring MongoDB][3] for information on how to set the database properties.

##Custom Rave Extension

In a custom build that depends on rave-jpa directly, the only thing that needs to be done is to replace the rave-jpa dependency with rave-mongodb.

If the custom application depends on JPA indirectly, via a dependency on rave-portal-dependencies, add an exclusion of rave-jpa to rave-portal-dependencies as follows:

     <dependency>
        <groupId>org.apache.rave</groupId>
        <artifactId>rave-portal-dependencies</artifactId>
        <type>pom</type>
        <exclusions>
           <exclusion>
              <groupId>org.apache.rave</groupId>
              <artifactId>rave-jpa</artifactId>
           </exclusion>
        </exclusions>
     </dependency>
     <dependency>
         <groupId>org.apache.rave</groupId>
         <artifactId>rave-mongodb</artifactId>
     </dependency>

Configure the properties files for portal & shindig as described in [configuring MongoDB][3]

##Demo Binaries

To replace the JPA implementation with Mongo in an extracted demo binary or other packaged Rave instance, take the following steps.  This method is **NOT** recommended for production deployments.  The preferred method is to modify a custom extension, or build, of Rave to as noted above:

1.  Start the demo binary as normal to allow it to extract the war archives
2.  Remove rave-jpa.jar from webapps/portal/WEB-INF/lib & webapps/ROOT/WEB-INF/lib
3.  Configure the properties files located in webapps/portal/WEB-INF/classes & webapps/ROOT/WEB-INF/classes per [configuring MongoDB][3] 


<a name="configure">&nbsp;</a>
##Configuring MongoDB
Both portal.properties & rave.shindig.properties have entries for connecting to MongoDB. 

    mongo.host=localhost
    mongo.port=27017  
    mongo.database=rave
    mongo.username=
    mongo.password=  

#Architecture

Rave leverages Spring Data MongoDB to simplify interactions with the MongoDB database using the [MongoOperations][2] model serialization pattern.  One the the primary benefits of using MongoDB for Rave persistence is that entire object hierarchies can be deserialized from the database in a single call.  For example, rather than making a call to the database for a Page object, its Regions and RegionWidgets, we can now just deserialize the entire page in one call.  Since Rave currently has repositories for many of the sub-components of a hierarchy, we needed a way to access the same object type from multiple repositories.  This lead to the following component architecture:

    |_ Rave MongoDB repository implementations
       | 
       |_ MongoModelOperations implementations 
          |
          |_ Spring MongoOperations
             |
             |_ Mongo Driver

As with any Rave component, MongoModelOperations instances can be wired in by interface or class name to custom components. 

*NOTE:  Since some simple Rave objects such as PortalPreference & PageLayout instances don't have sub-component repositories, not every Rave model object has a corresponding MongoModelOperations instance.*

[0]: /downloads.html
[1]: /source.html
[2]: http://static.springsource.org/spring-data/mongodb/docs/current/api/org/springframework/data/mongodb/core/MongoOperations.html  
[3]: #configure
[4]: http://www.mongodb.org