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<concept id="GUID-85CA1089-3F58-5E82-86A4-4674C893B25F" xml:lang="en"><title> Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The SIP Codec API provides functions to encode and decode SIP headers and
their fields. It converts SIP messages from the UTF-8 ASCII format to the
API implementations internal structure and from the API implementations internal
structure to the UTF-8 ASCII format. This implementation validates the SIP
message syntax according to the SIP BNF definition and supports serialization
and de-serialization of objects belonging to the SIP message structure. </p>
<p>This implementation is provided in a shared DLL and is run in the context
of the user. It creates class instances in the user heap area which means
the instances cannot be shared between different users. </p>
<section id="GUID-CB250850-D04A-5993-B0C9-3CC1761C686B"><title>Architectural
relationships</title> <p>The SIP Codec API does not require any interfaces. </p><p><b>Capability
information</b> </p><p>There is no capability required when you use the SIP
Codec API. This API is valid for all platforms running Symbian OS version
9.1. </p><p><b>Extending the API</b> </p><p>SIP Codec API cannot be extended. </p> </section>
<section id="GUID-D3DA4AFB-AE7F-5496-9DA2-B6FFA0A59DF0"><title>Class structure</title> <p>The
logical type of the SIP Codec API is Library API. This interface contains
synchronous functions that do not block, but return immediately and it uses
only local objects. </p> <p>The following illustration shows the relationships
of the SIP Codec API classes. </p> <fig id="GUID-B09DF64C-B185-54BA-A7C3-49B8E561DDCD">
<title>                 Relationships of the SIP Codec classes - Part 1  
            </title>
<image href="GUID-EE556214-BFB8-582E-ACD9-5287D7C64EFA_d0e341238_href.jpg" placement="inline"/>
</fig> <fig id="GUID-76054C58-E841-5103-AB33-27754D80B757">
<title>                 Relationships of the SIP Codec classes - Part 2  
            </title>
<image href="GUID-9D5641BC-226B-538F-B805-48511781B7C1_d0e341247_href.jpg" placement="inline"/>
</fig><p>The SIP Codec API defines the functions required to create the SIP
headers of a SIP message. CSIPHeaderBase is the base class for all SIP headers.
A client creates a new instance of the CSIPXHeader class, where “X” is the
name of the header required, and sets the values of the header with the setter
functions of this class.</p></section>
<section id="GUID-99EFD964-C3AB-5974-8B13-913D271B3232"><title>Memory used</title> <p>The
amount of memory used by every header object of the SIP Codec API is equivalent
to the memory used by the header as text (class + the size of SIP headers). </p> </section>
</conbody></concept>