Overview

Architectural relationships

The Client Resolver API requires the SIP Codec API and the SIP Codec API.

The target clients that receive SIP requests must implement the API Client Resolver API. The following are the two methods in which a target client can receive SIP requests:

• Implement the CSIPResolvedClient interface and provide an XML description with their capabilities

  The XML description describes the supported content-types and media formats that use SIP headers and SDP m-lines in the ECOM resource file. Client Resolver framework determines the target client by comparing the incoming SIP request to the XML descriptions provided by the CSIPResolvedClient implementation.

• Implement the CSIPResolvedClient2 interface and add Request-URIs user-part, plug-ins UID, and the client UID to the SIP Client Resolver mapping table in the Central Repository

  The table maps the user-part of the incoming SIP request’s Request-URI to the related CSIPResolvedClient2 implementation’s UID. SIP Client Resolver framework gives the SIP request to only the plug-ins for which a mapping entry is found in the Central Repository.

This implies that every target client must provide an ECOM plug-in that is used by the Client Resolver Framework. The Client Resolver Framework uses the information in the SIP request and matches it with the XML description or the mapping table entry provided by the target clients. It then decides which target client plug-in to load.

Class structure

SIP Client Resolver must create a class derived from CSIPResolvedClient or CSIPResolvedClient2 to receive requests outside the SIP dialogs. If the target client is not running, it must be started to enable it to receive SIP requests.

CSIPResolvedClient

The target clients must implement the CSIPResolvedClient interface to receive SIP requests outside SIP dialogs and enable the client resolution mechanism.

SIP uses the data provided in the ECOM resource file or, as requested by the implementation to decide which target client is used.

CSIPResolvedClient2

The target clients must implement the CSIPResolvedClient2 interface to receive SIP requests outside SIP dialogs and enable the client resolution mechanism.

The SIP stack uses the plug-ins that implement this interface as follows:

1. If the SIP request does not contain the Accept-Contact-header, go to step 2. If it does, the SIP stack calls the CSIPResolvedClient2::MatchAcceptContactsL() method on all the plug-ins and applies the following logic:

   • If none of the clients match, go to step 2.

   • If one of the clients match, send the SIP request to the matching client.

   • If more than one of the clients match, go to step 2.

2. If the SIP request does not contain the Event-header, go to step 3. If it does, SIP stack calls the CSIPResolvedClient2::MatchEventL() method on all the plug-ins and applies the following logic:

   • If none of the clients match, go to step 3.

   • If one of the clients match, send the SIP request to the matching client.

   • If more than one of the clients match, go to step 3.

3. The SIP stack calls the CSIPResolvedClient2::MatchRequestL() method on all the plug-ins and applies the following logic:

   • If none of the clients match, an error response is generated.

   • If one of the clients matches, send the SIP request to the matching client.

   • If more than one of the clients match, one of the client is randomly selected and the SIP request is sent to it. Normally, the ROM-based clients are preferred.

The channel UIDs must be unique across all SIP clients. The clients may use UIDs assigned for the binaries.