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<concept id="GUID-AFE7F3DA-6D61-5A4C-A08F-C998C8805A06" xml:lang="en"><title>How
the target Client is Resolved using CSIPResolvedClient2</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The SIP Client Resolver determines the target clients by comparing the
Request-URI of the incoming SIP request to the information stored in SIP Client
Resolver mapping table in the Central Repository. The information required
to access the map table in the Central Repository is defined in the <filepath>sipclientresolverconfigcrkey.h</filepath> file.
The incoming SIP request compares with the Request-URI’s user part in the
Central Repository mapping table. </p>
<p>If a match is found, the related ECOM plug-in is loaded by its UID. The
loaded plug-in matches the incoming SIP requests based on their fields. If
the request matches, the plug-in returns the UID of the matching client. SIP
Client Resolver requests the resolved ECom plug-in to connect to the Symbian
platform server that uses SIP. </p>
<p>The resource (<filepath>.rss</filepath>) file contains the information
in the Central Repository and also the following information: </p>
<ul>
<li id="GUID-6CF8E2D5-5BF3-5E56-93BE-97A0D2054B0E"><p> <codeph> dll_uid</codeph> and <codeph>implementation_uid</codeph>:
These UIDs are obtained from <xref href="http://www.symbiansigned.com" scope="external">Symbian
Signed</xref>. </p> <p> <b>Note:</b> Both these UIDs can be the same. </p> </li>
<li id="GUID-A2F95B01-F707-51D1-AD67-4EB364865C33"><p>The <codeph>interface_uid</codeph> must
be <codeph>0x10282EE5</codeph>. </p> </li>
</ul>
<section id="GUID-D0D9C1C9-C0A1-4C4C-ACA6-14C23D651E38"><title>Resolving the target client using CSIPResolvedClient2</title> <p>The
following illustration shows how the SIP Client Resolver subsystem resolves
the target client implementing <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> and
requests the resolved client to connect to the SIP implementation. </p> <fig id="GUID-750221F0-A98E-5C47-B804-5A6CDD16B2E9">
<title>              Call flow of resolving a target client implementation
using              CSIPResolvedClient2            </title>
<image href="GUID-8EF8CDD3-9FFE-5C39-8303-67A661C67F6B_d0e337871_href.jpg" placement="inline"/>
</fig> <p>The target clients must implement the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> interface
to receive SIP requests including SIP dialogs and enable the client resolution
mechanism. <b/><b>Note</b>: The channel UIDs must be unique across all
SIP clients. For example clients may use UIDs assigned for binaries. </p> <p>The
SIP stack uses the plug-ins that implement the <xref href="GUID-30BC7BC4-0FBE-3C60-A2E4-2E5AE206C61E.dita"><apiname>CSIPResolvedClient2</apiname></xref> interface
as follows: </p> <ol id="GUID-E0C735BE-BBBD-533B-AB2B-59F8936060BA">
<li id="GUID-7854B67A-2143-5EA4-949D-B3C96CA51866"><p>If the SIP request does
not contain an Accept-Contact-header, go to step 2. If it does, the SIP stack
calls <codeph>CSIPResolvedClient2::MatchAcceptContactsL</codeph> for all the
plug-ins and applies the following logic: </p> <ul>
<li id="GUID-E975B348-52DB-519A-9AC0-98821BA27E95"><p>If none of the clients
match, go to step 2 </p> </li>
<li id="GUID-99DB2FEE-470B-5E76-8183-AD2C0E1B6FF0"><p>If one of the client
match, the SIP request is sent to the matching client </p> </li>
<li id="GUID-5F420FD9-2AEE-5517-A216-FA3868941902"><p>If more than one of
the clients match, go to step 2 </p> </li>
</ul> </li>
<li id="GUID-F28D6940-D404-5E0F-B52A-6A47980ADA68"><p>If the SIP request does
not contain an Event-header go to step 3. If it does, the SIP stack calls <codeph>CSIPResolvedClient2::MatchEventL</codeph> for
all the plug-ins and applies the following logic: </p> <ul>
<li id="GUID-390E2FBC-305E-59C0-BE1F-E7C961B47251"><p>If none of the clients
match, go to step 3 </p> </li>
<li id="GUID-6A41D1A5-7636-51CC-864D-F2AB095D97E6"><p>If one of the client
match, the SIP request is sent to the matching client </p> </li>
<li id="GUID-8C51B40C-FC7B-566E-B56F-4279233C192E"><p>If more than one of
the clients match, go to step 3 </p> </li>
</ul> </li>
<li id="GUID-9C094348-B7F4-572D-B49B-B99F81C902F2"><p>The SIP stack calls <codeph>CSIPResolvedClient2::MatchRequestL</codeph> for
all the plug-ins and applies the following logic: </p> <ul>
<li id="GUID-63351732-E32A-58BC-8F32-7BA3832788FD"><p>If none of the clients
match, the SIP generates an error response </p> </li>
<li id="GUID-9E8765F8-A55F-5EA3-A63E-ACBF8A4BEF24"><p>If one of the client
match, the SIP request is sent to the matching client </p> </li>
<li id="GUID-AE679FD1-163D-5F3B-ADE8-1C6AEF490552"><p>If more than one of
the clients match, SIP selects one of these clients randomly and sends the
request to it. The ROM-based clients are preferred. </p> </li>
</ul> </li>
</ol> </section>
<section id="GUID-026A9B43-E096-4D32-AC3B-2DDC7974FFF6"><title>See also</title> <p> <xref href="GUID-0D579DDC-0A8A-5CFA-8194-CAA955B65A57.dita">Example
of a SIP Client Resolver Plug-in</xref>  </p> </section>
</conbody></concept>