<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE task

  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-1AAA88BB-19AD-5B8E-993C-11F4B7CD90EB" xml:lang="en"><title>Writing

a MIME Recognizer</title><abstract><p>The Mime Recognizers provide the implementation for data type

(MIME Type) recognition using the MIME recognition framework. </p><p>Each

MIME recognizer specifies the MIME type it supports along with the priority

and confidence of recognition. A MIME recognizer reads a small piece of data

and identifies the data type. Once the data type is identified, it is passed

to the <xref href="GUID-1578590A-FC00-5C3B-8BF9-F6E43CA9D9A0.dita">Application

Architecture </xref> (AppArc). AppArc launches the application

that best handles the identified data type.  </p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context id="GUID-6799E3F3-353E-5C00-A38C-D32F888392AA-GENID-1-10-1-11-1-1-6-1-6-1-4-1-3-1-3-1"><p>Symbian OS v9.1

and onwards, MIME recognizers are <xref href="GUID-9E92EE30-F2E2-5F28-BB2A-391C09EC69D2.dita">ECOM</xref> plug-ins.

They are located in <b>\sys\bin\</b>. </p> <p>Each MIME recognizer is loaded

by the <xref href="GUID-1578590A-FC00-5C3B-8BF9-F6E43CA9D9A0.dita">Application

Architecture (AppArc)</xref> during the startup sequence. </p> </context>

<steps id="GUID-45E4FFC7-5C92-5101-B21B-581C2AFB9CF0">

<step id="GUID-016BE2C1-DFB1-51B0-9A5C-C3A926C48E33"><cmd/>

<info>Create a project file (<filepath>.mmp</filepath>) for the MIME recognizer

and ensure the following parameters are set. </info>

<stepxmp><table id="GUID-8A194C7E-8927-5A8A-B1EA-EB9D7A23CF0C">

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

<tbody>

<row>

<entry><p> <b>Variable Name</b>  </p> </entry>

<entry><p> <b>Value</b>  </p> </entry>

<entry><p> <b>Description</b>  </p> </entry>

</row>

<row>

<entry><p> <codeph>TargetType</codeph>  </p> </entry>

<entry><p> <codeph>plugin</codeph>  </p> </entry>

<entry><p>Specifies the type of binary. </p> </entry>

</row>

<row>

<entry><p> <codeph>Resource</codeph>  </p> </entry>

<entry><p>Use the block <codeph>start resource ... end</codeph>  </p> </entry>

<entry><p>The variable <codeph>Resource</codeph> is set to the registration

resource file (<filepath>.rss)</filepath>)of the MIME recognizer. </p> </entry>

</row>

<row>

<entry><p> <codeph>UID</codeph>  </p> </entry>

<entry><p> <codeph>0x10009D8D</codeph> and the <codeph>DLL UID</codeph>  </p> </entry>

<entry><p>The variable <codeph>UID</codeph> requires two values. The first

value is 0x10009D8D and is constant for all MIME recognizers. The second value

is the UID of the DLL. </p> </entry>

</row>

<row>

<entry><p> <codeph>Capability</codeph>  </p> </entry>

<entry><p> <codeph>Protserv</codeph>  </p> </entry>

<entry><p>The AppArc server has <codeph>protserv</codeph> capability.The MIME

recognizers are loaded by the AppArc server on requirement. The MIME recognizers

must have <codeph>protserv</codeph> capability to be loaded by the AppArc

server. </p> </entry>

</row>

</tbody>

</tgroup>

</table> </stepxmp>

<info>For more details, refer <xref href="GUID-641A276D-F618-50CE-BA5A-658DCC26BAB5.dita">Creating

a Project File</xref>. </info>

<info>The code below shows a sample <filepath>.mmp</filepath> file with the

above parameters set. </info>

<stepxmp><codeblock id="GUID-B21A3AEB-C21C-5C9B-8BE3-715336ECBFD0" xml:space="preserve">target exampleRecognizer.dll

capability          Protserv

targettype          plugin

uid                    0x10009d8d 0x1d1f75ed

vendorid            0x70000001

sourcepath          .

source                 exampleRecognizer.cpp

systeminclude       \EPOC32\INCLUDE

systeminclude       \EPOC32\INCLUDE\ECOM 

library                EUSER.LIB APMIME.LIB 

start resource   1d1f75ed.rss

target           exampleRecognizer.rsc

end</codeblock> </stepxmp>

</step>

<step id="GUID-98A72A42-24D2-5A16-A0DE-15223FD1A685"><cmd/>

<info>Export the factory code function of the MIME recognizer as shown below.

This is required to create an instance of the MIME recognizer. </info>

<info>The class <codeph>CExampleRecognizer</codeph> is derived from <xref href="GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0.dita"><apiname>CApaDataRecognizerType</apiname></xref>. </info>

<stepxmp><codeblock id="GUID-F61F7E5E-37E0-5F4B-8E9A-E4C106005554" xml:space="preserve">const TInt KImplementationUID = 0x101F7DA1;

CApaDataRecognizerType* CExampleRecognizer::CreateRecognizerL()

       {

         return new (ELeave) CExampleRecognizer;

       }

const TImplementationProxy ImplementationTable[] = 

       {

        IMPLEMENTATION_PROXY_ENTRY(KImplementationUID,CExampleRecognizer::CreateRecognizerL);

       }

EXPORT_C const TImplementationProxy* ImplementationGroupProxy(TInt& aTableCount)

       {

        aTableCount = sizeof(ImplementationTable) / sizeof(TImplementationProxy);

        return ImplementationTable;

    }

</codeblock> </stepxmp>

<info>For more details refer <xref href="GUID-895A685E-83E8-51A3-A823-3A0E07B1E609.dita">Exporting

Implementation Factories.</xref>  </info>

</step>

<step id="GUID-B06E4D48-5CC2-5BEB-8C28-8DE5EFF62FE1"><cmd/>

<info>Implement <codeph>CApaDataRecognizerType</codeph> polymorphic interface. </info>

<substeps id="GUID-C29E1469-92CF-53D6-867F-FA73E223929C">

<substep id="GUID-B670112D-ACEB-5001-8F60-F16DF4240CE7"><cmd/>

<info>The code below shows a sample constructor implementation. </info>

<stepxmp><codeblock id="GUID-F8BD0190-4751-5731-BBF8-BD41644755F5" xml:space="preserve">const TUid KExampleUid = {0x1d1f75ed};

const TInt KNumDataTypes = 1;

CExampleRecognizer::CExampleRecognizer() : CApaDataRecognizerType(KExampleUid,CApaDataRecognizerType::EHigh) 

  { 

     iCountDataTypes = KNumDataTypes;

  } 

</codeblock> </stepxmp>

<info>Specify a UID (the <codeph>DLL UID</codeph> as specified in the plug-in

project definition file) and a <xref href="GUID-EBD1242B-6BD9-5ABB-B471-24ABC78A918C.dita">priority</xref> in

the constructor. </info>

<info>The <codeph>iCountDataTypes</codeph> variable, represents the number

of data types supported by the recognizer can also be set in the constructor.

The value set for this variable should match the implementation of <xref href="GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0.dita#GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0/GUID-FBCE07F2-9566-3AD1-B943-2FFF5C5AAE67"><apiname>CApaDataRecognizerType::SupportedDataTypeL()</apiname></xref>. </info>

</substep>

<substep id="GUID-5F36C1F6-3EDA-5817-801D-9B5C6F9F4927"><cmd/>

<info>Implement the pure virtual function <xref href="GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0.dita#GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0/GUID-FBCE07F2-9566-3AD1-B943-2FFF5C5AAE67"><apiname>CApaDataRecognizerType::SupportedDataTypeL()</apiname></xref>.

It returns the MIME types that the recognizer is capable of recognizing. </info>

<info>The code below shows a sample implementation of <codeph>SupportedDataTypeL()</codeph> for

supporting MIME type/ subtype "text/example". </info>

<stepxmp><codeblock id="GUID-D2DDF2A2-2897-544A-ACA7-DA3A60FB27E9" xml:space="preserve">

_LIT8(KExampleTextMimeType, "text/example"); 

TDataType CExampleRecognizer::SupportedDataTypeL(TInt aIndex) const

    {

        return TDataType(KExampleTextMimeType);

    }</codeblock> </stepxmp>

</substep>

<substep id="GUID-4C2CD90F-17AB-53B5-883A-7022E1231E2E"><cmd/>

<info>Implement <xref href="GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0.dita#GUID-EBE480D9-E377-32F4-9AE5-9C58684BEFF0/GUID-74ED8BEA-52AA-3AC4-92D9-5E4FB4F25DDD"><apiname>CApaDataRecognizerType::DoRecognizeL()</apiname></xref>.

This function executes data type recognition. </info>

<info>The code below shows a sample implementation of <codeph>DoRecognizeL()</codeph> for

recognizing the MIME type <codeph>"/text/example"</codeph> contained in files

with <filepath>.example</filepath> extension with maximum confidence. </info>

<stepxmp><codeblock id="GUID-C8F82861-AF59-5E23-9F1D-8656B2D1EE54" xml:space="preserve">void CExampleRecognizer::DoRecognizeL(const TDesC&amp; aName, const TDesC8&amp; aBuffer)

    {

    _LIT8(KExampleData, "example");

    _LIT(KDotExample, ".Example");

    TParse parse;

    parse.Set(aName,NULL,NULL);

    TPtrC ext=parse.Ext(); // extract the extension from the filename

    if (ext.CompareF(KDotExample)==0 && aBuffer.FindF(KExampleData)!=KErrNotFound)

         {

          iConfidence=ECertain;

          iDataType=TDataType(KExampleTextMimeType); 

        }

    }</codeblock> </stepxmp>

</substep>

</substeps>

</step>

</steps>