This article will be about the problems I encountered as a beginner in writing a Funambol connector. It aims at avoiding simple stupind things that makes you loosing time. The article will be based on the 3.0 Beta 1 version of Funambol: there are some API changes between Beta 1 and Beta 2, so the following lines might be wrong for the last version.

Vocabulary

• Connector: a set of classes creating a connection between the Funambol DS Server and a data source. This data source could be of any type: email account, Relational databases,  PIM data, JCR and so on.

• Module: a module is a functionnal archive to install on the Funambol DS Server. It will contain all the necessary files for the contained connector(s) to work. A module can contain several connectors: this will be defines in a specific database table.

• Synchronization Source: a class which provides the data items of the external source to the Funambol DS Server.

The basic example: dummy

First of all, to develop a connector, you will have at least to have a serious look at the dummy connector code (see the link for the CVS, tag funambol30b1). You can see there that this connector doesn't do many things and contains only 2 classes:

• the SyncSource providing the items to Funambol
• the Admin Panel to let you create new sources using the funamboladmin program

All the classes are packaged in a jar with the name of your connector (in my case: jcr-sync-0.0.1). The file to install on the Funambol DS server has an s4j extension and contains:

• the classes jar
• all the dependencies jars
• SQL scripts to register the module into the database

There are two solutions to implement your own connector afterwards: a copy-paste of the dummy connector and using this as a base for your connector, or understanding the dummy connector to create your connector. I choose the second solution and had to fight with this problem: I got a server error when I tried to create a SyncSource using my connector source type.

Solving the problem

To solve this problem I had some tools:

• a network sniffer
• the funambol server and admin source code

First thing I tried was to locate the error: for this you can change the server logging preferences to print all the messages. This way you will be able to see quite exactly where it fails. However you won't be able to debug at this point in the code: then the idea is to sniff the messages between the admin program and the serveur. If you are using the bundle as I am, you just have to listen on the local interface for TCP messages on 8080 port.

This way I could see one important point:The server was trying to guess if there wa already SyncSources with the same URI or name than the one I wanted to add. The problem was that these value were not set. Thus here are the conclusions:

1. The URI and Name value are mandatory for a SyncSource
2. You have to call the setter for each property before to send the ActionEvent to the admin panel: otherwise, the values aren't set in the SyncSource and the server will return a NullPointerException