Queue Manager Manual

2 Queue Manager Server Interface
46517 Tandem Computers Incorporated 2–1
UOWs and UOW
Formats
Processes interface with the Wait Manager and the Entry Manager servers through
units-of-work (UOWs) issued within requests.
A process written in SCREEN COBOL issues SEND statements to the Queue
Manager servers. The same SCREEN COBOL program can communicate with
other server classes also.
A process written in COBOL, FORTRAN, TAL, Pascal, or C makes requests by
opening a Queue Manager server and issuing WRITEREAD requests to that server
through the GUARDIAN 90 operating system.
The format of requests issued by a program is the same, whether the request is issued
by a SEND statement in SCREEN COBOL or by a WRITEREAD call in TAL. The data
buffer for each request consists of the following:
A request header that specifies version information, error handling controls, and
space for reply and return codes.
One or more UOWs, each of which specifies a code for an operation plus any
necessary parameters. For example, the DEQ UOW request would include the
name of the queue from which an entry is to be removed.
The reply from a server, which is written in the same format as the request to which it
responds, consists of the following:
A reply header, with reply and return codes supplied by the server.
One or more response UOWs that return requested data or completion status to
the requesting process. For example, the response to a DEQ UOW request would
include the data of the queue entry removed from the queue.
For each UOW in the request there is a corresponding response UOW in the overall
reply. The servers process UOWs in the order in which they appear in the request.
Thus, the response UOWs are returned in the same order as the corresponding UOWs
in the request.
For certain errors, however, no response UOWs are included. The number of UOWs
in the reply is indicated by a field in the reply header. A response UOW will never be
skipped in the reply; the first error that would cause a UOW to be excluded from the
reply will terminate the request.
Each UOW has a standard header that identifies the operation requested. Each
response UOW has a return code that identifies the action taken in response to the
corresponding request UOW.
Server Program Files The Entry Manager and Wait Manager each reside in a single program file.
The Entry Manager server is named EMSERV. This server handles requests one at
a time even when there are multiple openers.
The Wait Manager server is named WMSERV. This server handles multiple
requests concurrently. Each Queue Manager application can include one Wait
Manager.