Description :

    To be used by DIM Servers - Implements Service creation.
    DimService constructors add a DIM Service to the list of known services.
    The DimServices will only be registered (published) and served after "Starting" the DimServer.
    Please refer to Usage for examples of DimServices.

Constructors :

   First parameter is the Service Name.  Since the clients might request the service at regular time
   intervals the value parameter should be the address of a variable that has a live time similar to the
   DimService itself.

• public DimService ( char * name, int & value) ;
• public DimService ( char * name, float & value) ;
• public DimService ( char * name, double & value) ;
• public DimService ( char * name, short & value) ;
• public DimService ( char * name, longlong & value) ;
• public DimService ( char * name, char * value) ;
• public DimService ( char * name, char * format, void * value, int size) ; The format parameter specifies the contents of the structure in the form described here.

• public ~ DimService ( ) ;  

    Update Methods
        All update methods return the number of clients updated. 

• int updateService ( ) ; The current value of the same variable
• int updateService ( int &value) ; The variable changed address (and size)
• int updateService ( float &value) ;
• int updateService ( double &value) ;
• int updateService ( short &value) ;
• int updateService ( longlong &value) ;
• int updateService ( char * string) ;
• int updateService ( void *structure, int size);

    Selective Update Methods

        Like the Update methods but do not update all clients.

            - Update only the current client (if inside a Command callback) - clientIds = 0

            - Update the list of clients specified by an array of client Ids (terminated by 0).

                Client Ids can be obtained by DimServer::getClientId() inside a Command callback

• int selectiveUpdateService ( int *clientIds) ;
• int selectiveUpdateService ( int &value, int *clientIds) ; 
• int selectiveUpdateService ( float &value, int *clientIds) ;
• int selectiveUpdateService ( double &value, int *clientIds) ;
• int selectiveUpdateService ( short &value, int *clientIds) ;
• int selectiveUpdateService ( longlong &value, int *clientIds) ;
• int selectiveUpdateService ( char * string, int *clientIds) ;
• int selectiveUpdateService ( void *structure, int size, int *clientIds);

• void setQuality ( int quality ) ; The quality flag  - zero by default
• void setTimestamp ( int secs, int millisecs ) ; The time stamp - Set by default to the current time.

Usage :

    DimService creation example:

- The Server Updates the service (i.e. sends it to the client) whenever the contents change

            int run = 123;
            DimService runNumber("DELPHI/RUN_NUMBER",run);
            DimServer::start("DelphiServer");
            ...
            run++;
            runNumber.updateService();

- The Server Does not explicitly Update the service: it will get updated (i.e. sent to the client)
              with the current contents at the time interval specified by each client.

            float trigger_rate;
            DimService runNumber("DELPHI/TRIGGER_RATE",trigger_rate);
            DimServer::start("DelphiServer");
            ...
            trigger_rate = calculate_trigger_rate();