International Business Machines Corporation

James H Warnes

Jeffrey Mark Nick

Paul Kettley

Peter Siddall

David Arlen Elko

David Harold Surman

Douglas W Westcott

Richard Dievendorff

Dermot Flaherty

Jeffrey Alan Frey

Stephen James Hobson

Mark Phillips

Robert Vaughn Geiner

Anthony John O'Dowd

Paul Hopewell

Dennis Jack Zimmer

John H Eilert

Yih-shin Tan

Provided are a method, computer program product and system for providing indexed queue support for efficient retrieval of messages from a queue. An index key for expediting message retrieval is assigned to a message when the operation of placing the message on a queue is committed. The index key assigned at commit time comprises an attribute (such as a message ID or correlation ID) specified by the sending application program, which placed the message on the queue. This deferred assignment of an index key until commit time means that the index key can be used to search for messages having the particular attribute without any possibility of identifying messages for retrieval before the messages have been committed. This maintains transactional requirements of a transaction-oriented messaging system which requires a message to only be made available for retrieval by receiver application programs after the sender application's put operation has committed.

Implementing a message queuing interface (MQI) indexed queue support that adds a key to the index on put commit

Various enhancements are made to the architecture of a list processor to facilitate its use in implementing a message queue that is shared by queue managers residing across a multisystem complex. A new list structure control&#x2014;a program list entry identifier indicator, or PLEIDI&#x2014;is defined to allow the user to specify whether user-defined entry IDs are used when the list is allocated. A new delete list (DL) command is added that sequentially processes list entries in the order in which they exist on the specified list. A new move list entries (MLES) command provides a performance-optimized means to process an input list of entries. New key comparison functions and list monitoring enhancements have also been added. A new type of key called a secondary list entry key (SLEK) allows the user to specify a secondary key value as a means to identify a list entry.

Method and apparatus for processing a list structure

A method and apparatus for implementing a shared message queue using a list structure. A put list is defined comprising a sequence of list entries, each of which corresponds to a message in the queue and has an associated list entry key. Each list entry key corresponding to an uncommitted message falls within an uncommitted key range defining an uncommitted portion of the put list, while each list entry key corresponding to a committed message falls within a committed key range defining a committed portion of the put list. To write a message to the queue, a list entry is added to the put list having a list entry key within the uncommitted key range.

Method and apparatus for implementing a shared message queue using a list structure

The invention relates to communicating message data between application programs, the message data relating to units of work performed by the application programs. A plurality of message queuing subsystems interface to the application programs and are coupled together through a coupling facility. The message data is communicated in shared queues between the message queuing subsystems by means of data structures contained in the coupling facility. The data structures include an administrative structure listing unit of work descriptors describing operations performed by the queuing subsystems on a shared queue. A connection failure between a queuing subsystem and the shared queue is notified to the remaining queuing subsystems connected to the shared queue. The remaining queuing subsystems interrogate the listed work descriptors so as to identify and to share between them the units of work active in the failed connection, and each of the remaining subsystems recovers its share of the units of work active in the failed connection.

Method and apparatus for improving message availability in a subsystem which supports shared message queues

Provided are a method and apparatus for providing serialization support for computer systems and computer system resources, in particular for application programs which require sequencing and/or consistency of data. The computer system resource includes serialized processes with units of work. A serialization token is provided at the start of a serialized process including at least one unit of work. The serialization token remains in force until the or all of the units of work of the process have been committed or rolled back. The serialization token controls the commencement of other processes of the computer system during the time that it is in force. The serialization is carried out by storing an abstract representation of the process to be serialized in storage which is accessible by all the programs and computers where the serialization applies. In this way, if a process fails, the serialization token remains in force until the process has recovered and has committed or rolled back the units of work in the process. The serialization token can allow only a single thread process or, alternatively, the serialization token can allow a multiple thread process in which the threads have the same serialization token which allows for multiple users.

Method and apparatus for providing serialization support for a computer system

In a coupled data processing system having multiple users, either in a single system or in a multi-system environment, a coupling facility storage structure is used to provide a log management facility. The log management facility provides for a real time physical log merge of the data written into the log stream without interprocessor communication required to process the records in logical sequence. The log management facility supports concurrent write, delete, browse, and asynchronous off-load to dasd processes across multi-users and multi-systems. The log management facility maintains the log records, independent of the log media, in time sequence. A logical block id is assigned to each log record written so that it can be directly accessed at a later time.

Method and system for log management in a coupled data processing system

A method for dynamically assigning and removing task affinity for a resource is disclosed and claimed. A first interrupt handler recognizes a special task interrupt condition which is generated by the hardware. The interrupt condition is generated because a task attempted to execute a special instruction and either a special resource is attached to the central processing unit which issued the special instruction, or a special resource is not attached to the issuing central processing unit, but could be attached to another central processing unit in a central electronic complex. The first interrupt handler then passes control to a second interrupt handler which determines if execution of the current task can continue. If it can, the second interrupt handler creates or reestablishes a special environment and the task is dispatched (either for the first time or again) with a special dynamic affinity to only those central processing units in the central electronic complex that have a special resource attached. Due to the assignment of special affinity the task is dispatched only on a central processing unit with a special resource attached. The task can be suspended and special affinity removed because of non-use of the special resource over a predetermined period of time. Special affinity is automatically determined following a first-issued special instruction as well as one issued by a task whose special affinity was previously suspended.

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Poughkeepsie, NY, United States of America

James H Warnes