The API library enables MCP application programs to send messages to Operations Sentinel through a general interface mechanism. The flow of information between an application program and Operations Sentinel is
Application program to API library
API library to the interface software
The interface software to Operations Sentinel server
Application programs that are linked to the API library can send status messages and information messages to Operations Sentinel. Status messages indicate the state of the application program (for example, linked to API). Information messages allow an application program to send specific information.
Application programs use the SEND_MESSAGE procedure to send information messages to Operations Sentinel. When the API library receives a message from an application program that is to be sent to Operations Sentinel, the API library determines
Whether the interface software is running
Whether the application program is linked to the API library
If either test fails, the API library does not send the message. Instead, the API library sends a response to the application program stating why the message was not sent to Operations Sentinel and returns the original message sent by the application program.
If both tests pass, the API library loads the message into a buffer along with the mix number and name of the application program and sends the message to the interface software, which in turns sends the message to Operations Sentinel. The API library also sends a response to the application program stating that the message was sent to Operations Sentinel.
Only application programs that are properly linked to the API can use the SEND_MESSAGE services of the API library. This is controlled by the LINK_APPL_PROGRAM and UNLINK_APPL_PROGRAM procedures. When an application program executes one of these LINK or UNLINK procedures, a corresponding message event is sent to the Operations Sentinel server indicating the linked status of the MCP application program.
The linked status of an application program can also be affected by a preset timeout condition that can be specified when the application program calls the LINK_APPL_PROGRAM procedure. When a timeout condition occurs, a specific message is sent to the Operations Sentinel server indicating that the heartbeat timer has expired.