5.3 CCS: Server-Side

Once a request arrives on a CCS server socket, the CCS server runtime looks up the appropriate handler and calls it. If no handler is found, the runtime prints a diagnostic and ignores the message.

CCS calls its handlers in the usual CONVERSE fashion- the request data is passed as a newly-allocated message, and the actual user data begins CmiMsgHeaderSizeBytes into the message. The handler is responsible for CmiFree'ing the passed-in message.

The interface for the server side of CCS is included in ``converse.h''; if CCS is disabled (in conv-mach.h), all CCS routines become macros returning 0.

The handler registration interface is:

void CcsUseHandler(char *id, int hdlr);
int CcsRegisterHandler(char *id, CmiHandler fn);
Associate this handler ID string with this function. hdlr is a CONVERSE handler index; fn is a function pointer. The ID string cannot be more than 32 characters, including the terminating NULL.

After a handler has been registered to CCS, the user can also setup a merging function. This function will be passed in to CmiReduce to combine replies to multicast and broadcast requests.

void CcsSetMergeFn(const char *name, CmiReduceMergeFn newMerge);
Associate the given merge function to the CCS identified by id. This will be used for CCS request received as broadcast or multicast.

These calls can be used from within a CCS handler:

int CcsEnabled(void);
Return 1 if CCS routines are available (from conv-mach.h). This routine does not determine if a CCS server port is actually open.

int CcsIsRemoteRequest(void);
Return 1 if this handler was called via CCS; 0 if it was called as the result of a normal CONVERSE message.

void CcsCallerId(skt_ip_t *pip, unsigned int *pport);
Return the IP address and TCP port number of the CCS client that invoked this method. Can only be called from a CCS handler invoked remotely.

void CcsSendReply(int size, const void *reply);
Send the given data back to the client as a reply. Can only be called from a CCS handler invoked remotely. In case of broadcast or multicast CCS requests, the handlers in all processors involved must call this function.

CcsDelayedReply CcsDelayReply(void);
Allows a CCS reply to be delayed until after the handler has completed. Returns a token used below.

void CcsSendDelayedReply(CcsDelayedReply d,int size, const void *reply);
Send a CCS reply for the given request. Unlike CcsSendReply, can be invoked from any handler on any processor.