Create the client class

Create the client-side service support class, derived from REikAppServiceBase, RApaAppServiceBase, or a suitable System-GUI specialization of this class. This will have the following responsibilities:

• Implementing the client API

• Organizing calls to and from the server over IPC

• Any necessary security checks on the server. For example, restricting the data sent to a server having particular capabilities.

• Parameter checking from the server. Parameters returned from the server application must be checked to ensure that they are valid.

• Time-out support for IPC calls to the server.

The reason for these checks is that the client cannot be sure that the server application is using the appropriate server-side service support classes and may instead be trying to weaken the system by implementing the IPC handling itself.

This example shows the client interface for a chat service implemented in two parts. The active object class CChatter is the main client interface. It uses a class RInterAppChat, derived from REikAppServiceBase, which handles the client-side IPC for the chat service.

class RInterAppChat : public REikAppServiceBase
    {
    public:
        TInt Send(const TDesC& aMessage);
        void Receive(TRequestStatus& aStatus, TDes& aMessage);
        void CancelReceive();
    private:
        TUid ServiceUid() const;
    };
class MChatterReceiver
    {
    public:
        virtual void Receive(const TDesC&) = 0;
    };
class CChatter : public CActive
    {
    public:
        CChatter(MChatterReceiver& aReceiver);
        ~CChatter();
        void ConstructL(TUid aAppUid);
        void SendL(const TDesC& aMsg);
    private:
        void Queue();
        void RunL();
        void DoCancel();
    public:
        RInterAppChat iSub;
        TBuf<KMaxMyMessage> iBuf;
        MChatterReceiver& iReceiver;
    };