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<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-8C5A65E6-D753-472F-B885-FD0409589036" xml:lang="en"><title>HTTP
Whole Message Filter Example</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The following diagram illustrates the class relationship between the <codeph>MHTTPDataOptimiser</codeph> interface
and the <codeph>RHTTPSession</codeph> class: </p>
<fig id="GUID-25859A19-F3C8-5FBD-B491-C58E5C973424">
<title>              Class relationship between MHTTPDataOptimiser and   
          RHTTPSession            </title>
<image href="GUID-9DCAB1DC-D085-576C-A0B9-713E3BF2CAD5_d0e284962_href.png" placement="inline"/>
</fig>
<p>For more information about <xref href="GUID-F34F7481-00CF-3A1B-8D45-D053AD6769A8.dita"><apiname>MHTTPTransactionCallback</apiname></xref>,
see <xref href="GUID-1D32D093-1B7B-5CE8-B57D-5469C1E8E4B9.dita">A simple HTTP Client
session</xref>. </p>
<p>The following code segment illustrates how to define the header file required
for implementing the HTTP Whole Message Filter APIs: </p>
<codeblock id="GUID-1D7FA528-68D6-5AEE-B9F3-CBACC03855AB" xml:space="preserve">#include &lt;http.h&gt;

class CMyHTTPClient: public CBase,
                    public MHTTPTransactionCallback,
                    public MHttpDataOptimiser
{
public: // methods from MHTTPTransactionCallback
    virtual void MHFRunL(RHTTPTransaction aTransaction, const THTTPEvent&amp; aEvent);
    virtual TInt MHFRunError(TInt aError, RHTTPTransaction aTransaction, const THTTPEvent&amp; aEvent);
    
public: // methods from MHttpDataOptimiser
    virtual void EncodeL (const TDesC8&amp; aHttpData, HBufC8*&amp; aEncodedData);
    virtual void DecodeL (const TDesC8&amp; aData, HBufC8*&amp; aHttpData, TBool&amp; aTransFail);
};</codeblock>
<p>The following code segment illustrates how HTTP Whole Message Filter APIs
can be used to enable support for Web Acceleration: </p>
<codeblock id="GUID-2F062305-2D15-534C-8239-FAE4002DB79E" xml:space="preserve">#include "CMyHTTPClient.h"

//    CMyHTTPClient.cpp
//
//    defines CMyHTTPClient class: CMyHTTPClient
// Literals used in the file
_LIT8(KHttpAuthenticationUrl,        "http://remix.kwed.org");


void CMyHTTPClient::CreateTransactionL()
    {
    TUriParser8 up;
    up.Parse(KHttpAuthenticationUrl);

    RHTTPSession session;
    RHTTPTransaction trans;
    
    // Open the HTTP session
    session.OpenL();
    CleanupClosePushL(session);

    RStringPool strP = session.StringPool();

  //To enable MHTTPDataOptimiser for transaction

    // Open a GET transaction, specifying this object as the request body data supplier
    trans = session.OpenTransactionL(up, *this, strP.StringF(HTTP::EGET,RHTTPSession::GetTable()));
    CleanupClosePushL(trans);
    trans.SetupHttpDataOptimiser(*this);

 trans.SubmitL();
    CleanupStack::PopAndDestroy(&amp;trans);
    CActiveScheduler::Start();
    
    CleanupStack::PopAndDestroy(&amp;session); //Closes the session

    }

TInt CMyHTTPClient::MHFRunError(TInt aError, RHTTPTransaction aTransaction, const THTTPEvent&amp; aEvent)
    {
    // Handle Error appropriately
    }

void CMyHTTPClient::MHFRunL(RHTTPTransaction aTransaction, const THTTPEvent&amp; aEvent)
    {
    // Handle events from the framework.
    switch (aEvent.iStatus)
        {
        case KErrHttpOptimiserFailsTrans:
            {
            INFO_PRINTF1(_L("Cancelling/Failing Transaction\n"));
            aTransaction.Fail(THTTPFilterHandle::EProtocolHandler);
            } break;

        }
    return;
    //The following statement is used to eliminate leavescan errors
    User::Leave(KErrGeneral);
    }

void CMyHTTPClient::EncodeL (const TDesC8&amp; aHttpData, HBufC8* &amp;aEncodedData)
    {
    //Provide your own custom encoding implementation
    }

void CMyHTTPClient::DecodeL (const TDesC8&amp; aData, HBufC8*&amp; aHttpData, TBool&amp; aTransFail)
    {
    //Provide your own custom decoding implementation
    }</codeblock>
<p>This code enables the <codeph>MHTTPDataOptimiser</codeph> for a transaction
by using <codeph>RHTTPTransaction::SetupHTTPDataOptimiser()</codeph> and also
illustrates where custom encoding and decoding mechanisms are implemented. </p>
<p> <b>Note:</b> Alternatively, in this code, you can use the following code
segment to enable <codeph>MHTTPDataOptimiser</codeph> for a particular session. </p>
<p> <codeph>session.SetupHttpDataOptimiser(*this); </codeph>  </p>
</conbody></concept>