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<!DOCTYPE task

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

<task id="GUID-AB7E58EB-F698-4CAD-B9BF-ECE712C6DB04" xml:lang="en"><title>Create

the service class</title><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context>       <p>Create the server service support class, derived from <codeph>CApaAppServiceBase</codeph> or

a suitable System-GUI specialization of this class. This class adapts the

IPC protocol to a set of virtual functions which the server application can

override to implement the service. This class has the following responsibilities:</p><ul>

<li><p>Receiving and decoding the IPC messages from the client</p></li>

<li><p>Defining and calling virtual functions which the server application

can override to implement the service</p></li>

<li><p>Checking all parameters sent from the client for validity </p></li>

<li><p>Supporting the security policy of the server application for this service.</p></li>

</ul><p>This example shows a server-side service support class for a chat

service. This class implements the code necessary for sending messages to

the client, but provides a pure virtual <codeph>Receive()</codeph> function

for the server application to implement its own handling of messages received

from the client.</p><codeblock xml:space="preserve">class CChatService : public CApaAppServiceBase

    {

    public:

        CChatService();

        ~CChatService();

        void Send(const TDesC& aMessage);

        virtual void Receive(TDes& aMessage) = 0;

    private:

        void ServiceL(const RMessage2& aMessage);

        TBool ReceivePending() const;

    private:

        RMessagePtr2 iReceiveMsg;

        TInt iReceiveLen;

    };

</codeblock></context>