SIP SIMPLE Client SDK

h1. WBSO status

h2. Current Issues (February 17th, 2012)

1. Cannot correlate session with local and remote end-points state (busy, available, on the phone and type of media supported by the remote end-point) (Tickets 144, 118, 130)

2. The approach to implement video did not worked as envisaged (Ticket 18, 135)

3. The address book is unreliable, causing loss of contacts, duplicated contacts or broken synchronization among multiple instances (Ticket 143, 144)

4. Presence Chat and file transfer are perceived as being useless because of lack of interoperability with XMPP users (Gmail, Facebook) (no ticket)

5. Session is unreliable when adding/removing streams and network has packet loss (Ticket 107, 135)

6. TLS transport is not working properly due to assumption that is a general setting (Ticket 120, 135)

h2. Solutions

1. Integration and synchronization of Presence with different media streams (speech, IM, File transfer and video) in only one SIP session.

2. The libraries we relied upon were buggy and poorly supported. It was actually to early to start working on video and it was too complex of a task to approach with only one developer. PJSIP 2.0 has added basic video support in the mean time. We will migrate to PJSIP 2.0 that has support for video libraries that are already integrated into the media layer 

3. The IETF model for contacts management seem to be broken as it allows non-atomic operations. For example when one contact is added, 3 XCAP documents must be saved over the network and if any one fails, there is no way to reliably rollback only parts of the operation. The solution is to use the OMA standards (Open Mobile Alliance) that defines the Presence and Address book together in a main document and the other documents use links to the entries in the main document. This way only one document can be written for a contact add update or delete and this operational can be done atomically.

4. Presence and Chat must be refactored to support XMPP translation in order to interoperate with other users using other protocols

5. All operations in the session must be serialized and applied when they can be performed. This requires refactoring of the session model

6. Each SIP account requires its own encrypted transport because TLS connections have per account settings, for example verify_peer and certificate validation depends on foreign domain

h2. Actual Progress

 * Implemented Presence in middleware

 * Implemented XMMP translation for Chat and Presence

 * The MacOSX version now has all features from the roadmap except Video