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<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>

</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& aEvent);

    virtual TInt MHFRunError(TInt aError, RHTTPTransaction aTransaction, const THTTPEvent& aEvent);

public: // methods from MHttpDataOptimiser

    virtual void EncodeL (const TDesC8& aHttpData, HBufC8*& aEncodedData);

    virtual void DecodeL (const TDesC8& aData, HBufC8*& aHttpData, TBool& 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(&trans);

    CActiveScheduler::Start();

    CleanupStack::PopAndDestroy(&session); //Closes the session

    }

TInt CMyHTTPClient::MHFRunError(TInt aError, RHTTPTransaction aTransaction, const THTTPEvent& aEvent)

    {

    // Handle Error appropriately

    }

void CMyHTTPClient::MHFRunL(RHTTPTransaction aTransaction, const THTTPEvent& 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& aHttpData, HBufC8* &aEncodedData)

    {

    //Provide your own custom encoding implementation

    }

void CMyHTTPClient::DecodeL (const TDesC8& aData, HBufC8*& aHttpData, TBool& 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>