When a program instance sends a message, it is queued in a local datastore, until it has been successfully transferred to the ISB. Messages in an outbound queue on the ISB are stored until they are successfully received by the retrieving program instance.

The API provides additional reliability and efficiency for file transfers by enabling chunking. For example, let’s say you are transferring a 100MB file, and after transmitting 70MBs you lose your Internet connection… when the connection is re-established, it picks up from where it left off. This is especially important with wireless connectivity becoming the norm.