wxWidgets/interface/dde.h

/////////////////////////////////////////////////////////////////////////////
// Name:        dde.h
// Purpose:     interface of wxDDEConnection
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxDDEConnection
    @wxheader{dde.h}

    A wxDDEConnection object represents the connection between a client and a
    server. It can be created by making a connection using a
    wxDDEClient object, or by the acceptance of a connection by a
    wxDDEServer object. The bulk of a DDE (Dynamic Data Exchange)
    conversation is controlled by
    calling members in a @b wxDDEConnection object or by overriding its
    members.

    An application should normally derive a new connection class from
    wxDDEConnection, in order to override the communication event handlers
    to do something interesting.

    This DDE-based implementation is available on Windows only,
    but a platform-independent, socket-based version
    of this API is available using wxTCPConnection.

    @library{wxbase}
    @category{FIXME}

    @see wxDDEClient, wxDDEServer, @ref overview_ipcoverview "Interprocess
    communications overview"
*/
class wxDDEConnection : public wxObject
{
public:
    //@{
    /**
        Constructs a connection object. If no user-defined connection object is
        to be derived from wxDDEConnection, then the constructor should not be
        called directly, since the default connection object will be provided on
        requesting (or accepting) a connection. However, if the user defines his
        or her own derived connection object, the wxDDEServer::OnAcceptConnection
        and/or wxDDEClient::OnMakeConnection members should be replaced by
        functions which construct the new connection object. If the arguments of
        the wxDDEConnection constructor are void, then a default buffer is
        associated with the connection. Otherwise, the programmer must provide a
        a buffer and size of the buffer for the connection object to use in
        transactions.
    */
    wxDDEConnection();
    wxDDEConnection(void* buffer, size_t size);
    //@}

    //@{
    /**
        Called by the server application to advise the client of a change in
        the data associated with the given item. Causes the client
        connection's OnAdvise()
        member to be called. Returns @true if successful.
    */
    bool Advise(const wxString& item, const void* data, size_t size,
                wxIPCFormat format = wxIPC_PRIVATE);
    bool Advise(const wxString& item, const char* data);
    bool Advise(const wxString& item, const wchar_t* data);
    bool Advise(const wxString& item, const wxString data);
    //@}

    /**
        Called by the client or server application to disconnect from the other
        program; it causes the OnDisconnect() message
        to be sent to the corresponding connection object in the other
        program. The default behaviour of @b OnDisconnect is to delete the
        connection, but the calling application must explicitly delete its
        side of the connection having called @b Disconnect. Returns @true if
        successful.
    */
    bool Disconnect();

    //@{
    /**
        Called by the client application to execute a command on the server. Can
        also be used to transfer arbitrary data to the server (similar
        to Poke() in that respect). Causes the
        server connection's OnExecute() member to be
        called. Returns @true if successful.
    */
    bool Execute(const void* data, size_t size,
                 wxIPCFormat format = wxIPC_PRIVATE);
    bool Execute(const char* data);
    bool Execute(const wchar_t* data);
    bool Execute(const wxString data);
    //@}

    /**
        Message sent to the client application when the server notifies it of a
        change in the data associated with the given item.
    */
    virtual bool OnAdvise(const wxString& topic,
                          const wxString& item,
                          const void* data,
                          size_t size,
                          wxIPCFormat format);

    /**
        Message sent to the client or server application when the other
        application notifies it to delete the connection. Default behaviour is
        to delete the connection object.
    */
    virtual bool OnDisconnect();

    /**
        Message sent to the server application when the client notifies it to
        execute the given data. Note that there is no item associated with
        this message.
    */
    virtual bool OnExecute(const wxString& topic, const void* data,
                           size_t size,
                           wxIPCFormat format);

    /**
        Message sent to the server application when the client notifies it to
        accept the given data.
    */
    virtual bool OnPoke(const wxString& topic, const wxString& item,
                        const void* data,
                        size_t size,
                        wxIPCFormat format);

    /**
        Message sent to the server application when the client
        calls Request(). The server
        should respond by returning a character string from @b OnRequest,
        or @NULL to indicate no data.
    */
    virtual const void* OnRequest(const wxString& topic,
                                  const wxString& item,
                                  size_t* size,
                                  wxIPCFormat format);

    /**
        Message sent to the server application by the client, when the client
        wishes to start an 'advise loop' for the given topic and item. The
        server can refuse to participate by returning @false.
    */
    virtual bool OnStartAdvise(const wxString& topic,
                               const wxString& item);

    /**
        Message sent to the server application by the client, when the client
        wishes to stop an 'advise loop' for the given topic and item. The
        server can refuse to stop the advise loop by returning @false, although
        this doesn't have much meaning in practice.
    */
    virtual bool OnStopAdvise(const wxString& topic,
                              const wxString& item);

    //@{
    /**
        Called by the client application to poke data into the server. Can be
        used to transfer arbitrary data to the server. Causes the server
        connection's OnPoke() member
        to be called. Returns @true if successful.
    */
    bool Poke(const wxString& item, const void* data, size_t size,
              wxIPCFormat format = wxIPC_PRIVATE);
    bool Poke(const wxString& item, const char* data);
    bool Poke(const wxString& item, const wchar_t* data);
    bool Poke(const wxString& item, const wxString data);
    //@}

    /**
        Called by the client application to request data from the server. Causes
        the server connection's OnRequest() member to be called. Returns a
        character string (actually a pointer to the connection's buffer) if
        successful, @NULL otherwise.
    */
    const void* Request(const wxString& item, size_t* size,
                        wxIPCFormat format = wxIPC_TEXT);

    /**
        Called by the client application to ask if an advise loop can be started
        with the server. Causes the server connection's OnStartAdvise()
        member to be called. Returns @true if the server okays it, @false
        otherwise.
    */
    bool StartAdvise(const wxString& item);

    /**
        Called by the client application to ask if an advise loop can be
        stopped. Causes the server connection's OnStopAdvise() member
        to be called. Returns @true if the server okays it, @false otherwise.
    */
    bool StopAdvise(const wxString& item);
};



/**
    @class wxDDEClient
    @wxheader{dde.h}

    A wxDDEClient object represents the client part of a client-server DDE
    (Dynamic Data Exchange) conversation.

    To create a client which can communicate with a suitable server,
    you need to derive a class from wxDDEConnection and another from wxDDEClient.
    The custom wxDDEConnection class will intercept communications in
    a 'conversation' with a server, and the custom wxDDEServer is required
    so that a user-overridden wxDDEClient::OnMakeConnection member can return
    a wxDDEConnection of the required class, when a connection is made.

    This DDE-based implementation is
    available on Windows only, but a platform-independent, socket-based version
    of this API is available using wxTCPClient.

    @library{wxbase}
    @category{FIXME}

    @see wxDDEServer, wxDDEConnection, @ref overview_ipcoverview "Interprocess
    communications overview"
*/
class wxDDEClient : public wxObject
{
public:
    /**
        Constructs a client object.
    */
    wxDDEClient();

    /**
        Tries to make a connection with a server specified by the host
        (machine name under UNIX, ignored under Windows), service name (must
        contain an integer port number under UNIX), and topic string. If the
        server allows a connection, a wxDDEConnection object will be returned.
        The type of wxDDEConnection returned can be altered by overriding
        the OnMakeConnection() member to return your own
        derived connection object.
    */
    wxConnectionBase* MakeConnection(const wxString& host,
                                     const wxString& service,
                                     const wxString& topic);

    /**
        The type of wxDDEConnection returned from a MakeConnection() call can
        be altered by deriving the @b OnMakeConnection member to return your
        own derived connection object. By default, a wxDDEConnection
        object is returned.
        The advantage of deriving your own connection class is that it will
        enable you to intercept messages initiated by the server, such
        as wxDDEConnection::OnAdvise. You may also want to
        store application-specific data in instances of the new class.
    */
    wxConnectionBase* OnMakeConnection();

    /**
        Returns @true if this is a valid host name, @false otherwise. This always
        returns @true under MS Windows.
    */
    bool ValidHost(const wxString& host);
};



/**
    @class wxDDEServer
    @wxheader{dde.h}

    A wxDDEServer object represents the server part of a client-server DDE
    (Dynamic Data Exchange) conversation.

    This DDE-based implementation is
    available on Windows only, but a platform-independent, socket-based version
    of this API is available using wxTCPServer.

    @library{wxbase}
    @category{FIXME}

    @see wxDDEClient, wxDDEConnection, @ref overview_ipcoverview "IPC overview"
*/
class wxDDEServer
{
public:
    /**
        Constructs a server object.
    */
    wxDDEServer();

    /**
        Registers the server using the given service name. Under UNIX, the
        string must contain an integer id which is used as an Internet port
        number. @false is returned if the call failed (for example, the port
        number is already in use).
    */
    bool Create(const wxString& service);

    /**
        When a client calls @b MakeConnection, the server receives the
        message and this member is called. The application should derive a
        member to intercept this message and return a connection object of
        either the standard wxDDEConnection type, or of a user-derived type. If the
        topic is "STDIO'', the application may wish to refuse the connection.
        Under UNIX, when a server is created the OnAcceptConnection message is
        always sent for standard input and output, but in the context of DDE
        messages it doesn't make a lot of sense.
    */
    virtual wxConnectionBase* OnAcceptConnection(const wxString& topic);
};



// ============================================================================
// Global functions/macros
// ============================================================================

/**
    Called when wxWidgets exits, to clean up the DDE system. This no longer needs
    to be
    called by the application.
    See also wxDDEInitialize().
*/
void wxDDECleanUp();

/**
    Initializes the DDE system. May be called multiple times without harm.
    This no longer needs to be called by the application: it will be called
    by wxWidgets if necessary.
    See also wxDDEServer, wxDDEClient, wxDDEConnection,
    wxDDECleanUp().
*/
void wxDDEInitialize();