Vishnu,

Thanks for using Lightstreamer.

The easiest way to achieve your required behavior is that each user subscribes to a unique itemname (perhaps bound to his username). Then, when another user posts a message for him, the Data Adapter will publish such message as an update to that specific itemname. You can deliver the messages to your Data Adapter in a couple of ways:
- by using the sendMessage function (that delivers the message to the Metadata Adapter, that in turns can send it to the Data Adapter)
- by sending the message to an external server-side component (e.g. PHP page, servlet, etc.) that in turns sends the message to the Data Adapter (through JMS, sockets, db, etc.). You can see an example in the Portfolio Demo code (http://www.lightstreamer.com/portfolioDemo.htm).

Cheers