RSC/MP 7.2 Programming Manual

Unsolicited Message Service

HP NonStop Remote Server Call (RSC/MP) Programming Manual—522360-004

8-6

Asynchronous UMS Notification

RSC/MP offers platform-specific asynchronous notification of UMS message receipt on

all platforms. Use of this feature eliminates the need for polling to determine whether

an unsolicited message has been received. RSC/MP offers these methods of

requesting notification of UMS receipt:

•

Semaphores — Notification offered on UNIX and Windows with the RscNotifySem

function. Use this function to identify a semaphore created by the application that

will be cleared by RSC/MP when a UMS addressed to that session arrives.

•

Window messages — Notification offered on Windows with the RscNotifyWin

function. Use this function to specify a message that will be queued to a specified

window handle by RSC/MP when a UMS message addressed to that session

arrives.

•

Thread messages — Notification offered on Windows with the RscNotifyThread

function. Use this function to specify a message that will be queued to a specified

thread by RSC/MP when a UMS message addressed to that session arrives.

When the notification is received, the application must then issue the RscUmsCheck

function to receive the UMS message.

See UMS Workstation Application Example on page 8-8 for a code example that

shows how to receive an unsolicited message.

Responding to Messages

The RscUmsCheck function checks for unsolicited messages received for the session

identified by the ulSessionHandle parameter and retrieves the unsolicited message, if

any. Upon successful completion of the function, the field referred to by puBufferSize

contains the actual number of characters stored in the buffer referenced by pvBuffer.

The value referred to by puIoType determines whether or not to respond to the

unsolicited message. These values can be either:

•

RSC_UMS_WRITE indicates that the sender does not expect a response. Do not

reply to an unsolicited message of this type.

•

RSC_UMS_WRITEREAD indicates that the sender is waiting for a response.

Use the RscUmsReply function to reply to an unsolicited message if the message was

sent using a Guardian WRITEREAD call.

Note. Replies containing a UMS header are returned to the host only when messages are

addressed to a single session alias (not to a group alias).