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In 4.6 the replication concept remained the same: sipXconfig gathered data from the UI, stores it in the SIPXCONFIG PostgreSQL database and writes it to a location accessible by other services. However, IMDB replication is centered around "reblicable entities"“reblicable entities”. Still there are configuration files but they are handled now by cfengine. Those files are small and do not create OOM on their creation or XML-RPC problems on their transfer. For instance, dialing rules and service configurations are still handled this way.
However, a decision was taken to change the IMDB from fastDB to MongoDB. MongoDB has the advantage of being created to handle large amount of data (mongo comes form humongous) and having its own replication mechanism across nodes. We are also taking advantage of the Mongo's replica set concept. You can read more on MongoDB on their website: http://www.mongodb.org.
One main advantages of the change was that unlike versions prior to 4.6 when editing a user triggered a replication of all users (XMLs held user data in bulk), in 4.6 changing a replicable entity will trigger the insertion in Mongo of just that entity. Replication time for this kind of operation was reduced to a few milliseconds. Regenerating the whole Mongo entity DB takes more time but the time is measured in minutes for even over 30.000 users on a machine with reasonable resources.
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The DataSet generators are in org.sipfoundry.sipxconfig.commserver.imdb package and extend org.sipfoundry.sipxconfig.commserver.imdb.AbstractDataSetGenerator. They are responsible for actually preparing the document that will be written to Mongo. The actual write will be done in ReplicationManagerImpl.
For instance, org.sipfoundry.sipxconfig.commserver.imdb.Aliases generate method will retrieve all aliases of the entity and add them to the object in a well defined structure. org.sipfoundry.sipxconfig.admin.commserver.imdb.Mailstore.generate(Replicable entity, DBObject top) retrieves all information pertinent to a user's user’s mailstore like email address, IMAP server configuration, etc. All the information written to Mongo in a document was once stored in files. For a user we had information scattered around in different files, now the most part is kept in Mongo.
If you take a look at org.sipfoundry.sipxconfig.commserver.imdb.SpeedDials you will see good examples of constructing the Mongo document object. You can also check out Mongo Java API (http://api.mongodb.org/java/2.6.3/).
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Until Mongo introduction replication triggers were scattered across different implementations. While not perfect, we tried to define a common place for all replication triggers, at least for Mongo replications. As in sipXconfig, save*(Object) and delete*(Object) methods are intercepted we figured this would be a good way to trigger Mongo replications. This is where org.sipfoundry.sipxconfig.admin.commserver.imdb.ReplicationTrigger comes into play. It implements DaoEventListener interface which defines two methods - public void onSave(Object entity) and public void onDelete(Object entity) that get triggered by saving or deleting an Object. ReplicationTrigger implementation of the 2 methods will mainly call the replication manager based on some conditions.
However, as it is always the case with helper classes this one got clogged with code that had nothing to do with replication in general or with replication code that could easily stay within a manager. So we decided to keep ReplicationTrigger class just for triggering replication of Replicable entities and for entitites that hold a bunch of users such as Group and Branch. I kept these together since we treat replication of users separately for performance reasons, as explained above. So, I'd say that ReplicationTrigger is pretty much a closed class, i wouldn't put code in there unless necessary. Actually, I can't think of any code that would fit in there except if we invent a new entity that would hold many users.
Replication Manager
The replication manager bean (org.sipfoundry.sipxconfig.admin.commserver.imdb.ReplicationManagerImpl) main function is to initiate the DBCollection, initiate the Mongo document object, delegate the construction of the Mongo document to the relevant DataSet generator and finally save the document to Mongo. It is also responsible for the parallel asynchronous replication of groups of replicable entities (groups, branches) and for the regeneration of the entire entity collection. It used to also hold the business methods to actually build the service config files that needed to be replicated and delegated the actual replication to the supervisor on the specified location. In 4.6 files are replicated using newly introduced cfengine and is not object of this page.
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