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<concept id="GUID-9993D750-9116-55B2-812A-7A92C50F467F" xml:lang="en"><title>Apparc

Recognizer for CAF</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The Apparc framework uses data type recognizers derived from <xref href="GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0.dita"><apiname>CApaDataRecognizerType</apiname></xref> to

determine the MIME type of files on the Symbian platform. </p>

<section id="GUID-2D000C2B-A393-4039-9B7E-33E7F929EE09"><title>Overview</title> <p>Apparc supplies the filename and a buffer

containing bytes read from the start of the file. If a file is recognized,

the recognizer must return the MIME type and the degree of confidence in recognizing

the file — a <codeph>TInt</codeph> ranging from <codeph>KMinInt</codeph> (Not

Recognized) to <codeph>KMaxInt</codeph> (Certain). </p> <p>The implementation

of DRM has a problem when determining the MIME type. A DRM file stores one

or more content objects. For example, an OMA file with MIME type <codeph>application/vnd.oma.drm.content</codeph> may

store an image file with MIME type <codeph>image/jpeg</codeph>. Apparc expects

only one MIME type to be returned, not two. </p> <p>The CAF recognizer <filepath>RECCAF.DLL</filepath> determines

whether a file is recognized by CAF and if so, retrieves these two MIME types. </p> <p>The

mapping of these two MIME types returned by CAF to a single MIME type is based

on the following rules: </p> <table id="GUID-3C062759-788F-5A15-A557-F85F77D8AB92">

<tgroup cols="3"><colspec colname="col0"/><colspec colname="col1"/><colspec colname="col2"/>

<tbody>

<row>

<entry><p> <b> File MIME type</b>  </p> </entry>

<entry><p> <b> Content MIME type</b>  </p> </entry>

<entry><p> <b> Apparc MIME type</b>  </p> </entry>

</row>

<row>

<entry><p>Present </p> </entry>

<entry><p>Present </p> </entry>

<entry><p> <i>x-caf-</i>  <codeph>ContentMimeType</codeph> </p> </entry>

</row>

<row>

<entry><p>Present </p> </entry>

<entry><p>Not Present </p> </entry>

<entry><p> <codeph>FileMimeType</codeph>  </p> </entry>

</row>

<row>

<entry><p>Present </p> </entry>

<entry><p> <codeph>application/x-caf</codeph>  </p> </entry>

<entry><p> <codeph>application/x-caf</codeph>  </p> </entry>

</row>

</tbody>

</tgroup>

</table> <p>The following is the rationale for the above mapping: </p> <ul>

<li id="GUID-46BB7500-F4AF-53AC-B1C9-2D538C8C2F21"><p>The <codeph>x-caf-</codeph> prefix

to the content type shows that the file that can be opened by CAF to read

that content type. </p> </li>

<li id="GUID-57AF8B00-B36C-5DD9-BB3E-0F818B71F191"><p>A file that needs to

be passed through the supplier interface before it can be used is recognized

as the file MIME type; the content type is irrelevant before the supply operation. </p> </li>

<li id="GUID-771D11E6-1275-5C12-8E5B-2A9362E857D2"><p>A file containing many

content objects must just be recognized as <codeph>application/x-caf</codeph> as

the packaging of the archive is irrelevant (CAF abstracts the packaging). </p> </li>

</ul> <p>The following diagram illustrates the recognition of an OMA file

with JPEG content. </p> <fig id="GUID-E0654D43-CA6D-54BA-98DF-45BFA67B4180">

<title>              Apparc Recognizer for CAF            </title>

<image href="GUID-212C33A7-19DE-5936-B78E-CB7357FAEB5B_d0e627916_href.png" placement="inline"/>

</fig> </section>

<section id="GUID-5FCA124D-197D-46DA-B702-092E80B7F5DE"><title>Application registration files</title> <p>To use CAF content,

applications must update their registration resource files (for example <filepath>AppName_reg.rss</filepath>)

to include the new CAF MIME types. For example, an image viewer may have only

included <codeph>image/jpeg</codeph> in the list of MIME types it could open.

If the application is updated to use CAF, it must support <codeph>image/jpeg</codeph> and <codeph>x-caf-image/jpeg</codeph> in

order to support unprotected and protected content respectively. See the following

example registration file. </p> <p>All file operations must be conducted through

the CAF framework. </p> <p><b>Registration file that does not use CAF </b> </p> <codeblock id="GUID-DD2CF2E7-D74B-5759-9934-7BCC52A90DB8" xml:space="preserve">...

datatype_list = 

    {

    DATATYPE { priority= EDataTypePriorityHigh ; type="image/jpeg";}, 

    }

...</codeblock> <p><b>Registration file that use CAF </b> </p> <codeblock id="GUID-23F6E57A-8DAB-5AA4-B051-BD511630C481" xml:space="preserve">...

datatype_list = 

    {       

    DATATYPE { priority= EDataTypePriorityHigh ; type="image/jpeg"; }, 

    DATATYPE { priority= EDataTypePriorityHigh ; type="x-caf-image/jpeg"; }, 

    }

...</codeblock> </section>