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    10 <!DOCTYPE concept

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    12 <concept id="GUID-768CCC6E-16D2-50E8-8EED-EB2C2AF0E9BE" xml:lang="en"><title>Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    13 <p>The SIP Client Resolver defines the architecture used to resolve or identify

    14 the target client when SIP requests are received from the default port. The

    15 Symbian SIP stack is implemented as a Symbian server and uses the default

    16 UDP and TCP port 5060 to send and receive SIP messages. Many applications

    17 or target clients receive SIP messages that use the default port, and the

    18 correct target client must be determined. </p>

    19 <p>The SIP Client Resolver determines the target client based on the SIP request

    20 and the XML-description provided by every SIP Client Resolver API implementation.

    21 It requests the resolved ECOM plug-in to connect to the SIP or another server

    22 which uses SIP. </p>

    23 <section><title>Architectural relationships</title> <p>The Client Resolver

    24 API requires the SIP Codec API and the SIP Codec API. </p> <p>The target clients

    25 that receive SIP requests must implement the API Client Resolver API. The

    26 following are the two methods in which a target client can receive SIP requests: </p> <ul>

    27 <li id="GUID-F3BEAD9E-744E-5154-91EC-E0B66034A8F4"><p> <b>Implement the CSIPResolvedClient

    28 interface and provide an XML description with their capabilities</b>  </p> <p>The

    29 XML description describes the supported content-types and media formats that

    30 use SIP headers and SDP m-lines in the ECOM resource file. Client Resolver

    31 framework determines the target client by comparing the incoming SIP request

    32 to the XML descriptions provided by the <xref href="GUID-F0E4FA44-A41C-3C6F-993E-39CED042A879.dita"><apiname>CSIPResolvedClient</apiname></xref> implementation. </p> </li>

    33 <li id="GUID-07B5DFE5-D376-57F7-8ACB-50BB1EF8351B"><p>Implement the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> interface

    34 and add Request-URIs user-part, plug-ins UID, and the client UID to the SIP

    35 Client Resolver mapping table in the Central Repository </p> <p>The table

    36 maps the user-part of the incoming SIP request’s Request-URI to the related <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> implementation’s

    37 UID. SIP Client Resolver framework gives the SIP request to only the plug-ins

    38 for which a mapping entry is found in the Central Repository. </p> </li>

    39 </ul> <p>This implies that every target client must provide an ECOM plug-in

    40 that is used by the Client Resolver Framework. The Client Resolver Framework

    41 uses the information in the SIP request and matches it with the XML description

    42 or the mapping table entry provided by the target clients. It then decides

    43 which target client plug-in to load. </p> </section>

    44 <section><title>Class structure</title> <p>SIP Client Resolver must create

    45 a class derived from <xref href="GUID-F0E4FA44-A41C-3C6F-993E-39CED042A879.dita"><apiname>CSIPResolvedClient</apiname></xref> or <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> to

    46 receive requests outside the SIP dialogs. If the target client is not running,

    47 it must be started to enable it to receive SIP requests. </p> <fig id="GUID-B8A796EA-6850-5695-A516-E92629BE7971">

    48 <image href="GUID-E77E2E2A-2F2D-549E-ABD6-175E68A406CB_d0e317911_href.png" placement="inline"/>

    49 </fig> <p><b>CSIPResolvedClient</b> </p> <p>The target clients must implement

    50 the <xref href="GUID-F0E4FA44-A41C-3C6F-993E-39CED042A879.dita"><apiname>CSIPResolvedClient</apiname></xref> interface to receive SIP requests

    51 outside SIP dialogs and enable the client resolution mechanism. </p> <p>SIP

    52 uses the data provided in the ECOM resource file or, as requested by the implementation

    53 to decide which target client is used. </p> <p><b>CSIPResolvedClient2</b> </p> <p>The

    54 target clients must implement the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> interface

    55 to receive SIP requests outside SIP dialogs and enable the client resolution

    56 mechanism. </p> <p>The SIP stack uses the plug-ins that implement this interface

    57 as follows: </p> <ol id="GUID-E3325143-0AA4-5A60-885C-875F388EF0E3">

    58 <li id="GUID-816770B7-3A85-5894-9868-64BEE12FD50C"><p>If the SIP request does

    59 not contain the Accept-Contact-header, go to step 2. If it does, the SIP stack

    60 calls the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita#GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E/GUID-2C145D8C-DB4C-33C9-9CCE-193433909937"><apiname>CSIPResolvedClient2::MatchAcceptContactsL()</apiname></xref> method

    61 on all the plug-ins and applies the following logic: </p> <ul>

    62 <li id="GUID-5457D39D-DE84-5A3F-8E8B-7E79C863E118"><p>If none of the clients

    63 match, go to step 2. </p> </li>

    64 <li id="GUID-BE1A9D22-BD88-519E-AC4A-242FC6D3B098"><p>If one of the clients

    65 match, send the SIP request to the matching client. </p> </li>

    66 <li id="GUID-3A027E2A-C805-595D-B43C-28B19BC07609"><p>If more than one of

    67 the clients match, go to step 2. </p> </li>

    68 </ul> </li>

    69 <li id="GUID-7F822965-0220-52A8-8CAF-EACA4D87E75D"><p>If the SIP request does

    70 not contain the Event-header, go to step 3. If it does, SIP stack calls the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita#GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E/GUID-9DB2CFFE-09ED-367D-9C14-6917F8E3DCF4"><apiname>CSIPResolvedClient2::MatchEventL()</apiname></xref> method

    71 on all the plug-ins and applies the following logic: </p> <ul>

    72 <li id="GUID-8E85F9F9-D645-53D7-A4D8-6717951B0D1C"><p>If none of the clients

    73 match, go to step 3. </p> </li>

    74 <li id="GUID-B713BE42-D8AF-51D6-8832-D0B221CFF4D8"><p>If one of the clients

    75 match, send the SIP request to the matching client. </p> </li>

    76 <li id="GUID-93037264-2B67-5DD4-990B-9D3EEEDE6C4D"><p>If more than one of

    77 the clients match, go to step 3. </p> </li>

    78 </ul> </li>

    79 <li id="GUID-BFCEF7B8-4068-58E6-B960-27035A5A52D6"><p>The SIP stack calls

    80 the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita#GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E/GUID-9C9E49C8-602B-3C1C-B036-A176FF323A54"><apiname>CSIPResolvedClient2::MatchRequestL()</apiname></xref> method on all

    81 the plug-ins and applies the following logic: </p> <ul>

    82 <li id="GUID-86228E63-7E10-571E-B465-EB4D14E8855D"><p>If none of the clients

    83 match, an error response is generated. </p> </li>

    84 <li id="GUID-6F578483-34E7-5CFB-A565-2209FFF82D28"><p>If one of the clients

    85 matches, send the SIP request to the matching client. </p> </li>

    86 <li id="GUID-C1BD2E18-CFEB-558F-9F10-60EF6B9539E7"><p>If more than one of

    87 the clients match, one of the client is randomly selected and the SIP request

    88 is sent to it. Normally, the ROM-based clients are preferred. </p> </li>

    89 </ul> </li>

    90 </ol><p>The channel UIDs must be unique across all SIP clients. The clients

    91 may use UIDs assigned for the binaries. </p> </section>

    92 </conbody><related-links>

    93 <link href="GUID-5C215C64-5D3D-5B65-A11F-BE6F8C306CF4.dita"><linktext>How     

    94            the target client is resolved using CSIPResolvedClient</linktext>

    95 </link>

    96 <link href="GUID-AFE7F3DA-6D61-5A4C-A08F-C998C8805A06.dita"><linktext>How     

    97            the target client is resolved using CSIPResolvedClient2</linktext>

    98 </link>

    99 </related-links></concept>