Abstract: Under VTAM, or similar-type data communications system, co-executing "partner" processes typically exchange data via SEND and RECEIVE requests that are processed by VTAM. A method in accordance with the invention provides a way for optimizing this data exchange process. The optimized method bypasses VTAM to provide significant savings of system resources and improved execution speed over that required for VTAM to process the same SEND and RECEIVE requests.

Abstract: A computerized method of intercepting SQL processing within a relational database. The relational database includes a relational database management program having SQL processing logic.

Abstract: A data compression method compresses a sequence of characters into a sequence of compression symbols by double-indirect indexing into a dictionary data structure arranged in a novel format, wherein the input characters as used as indirect indexes. The dictionary data structure comprises a set of state vectors, arranged in a tree-like structure, and a set of alpha arrays, arranged in a matrix-like structure. During the compression sequence, each character in the sequence is used as an index into a current alpha array, which is used to determine whether the character can be compressed. If compressible, the current alpha array provides an index to a corresponding state vector, which contains information concerning the next alpha array and the next state vector. The next alpha array becomes the next current alpha array, and the next state vector becomes the current state vector. The process is repeated until the sequence of input characters is exhausted or a non-compressible character is encountered.

Abstract: In a data set containing displacement-dependent data (e.g., data identified by relative byte address), such as a DB2 log data set, data that is determined to be unneeded or otherwise removable is overwritten with a compressible binary pattern such as a sequence of binary zeros. The resulting substitute data set can be compressed to occupy less storage space and require less time for data recovery.

Abstract: A method of reorganizing an IMS database. The method creates, in a storage device, a header data structure containing information about the size and key structure of the database. Next, the number of sequential files to be used for temporary storage of data from the database and the desired number of parallel unload processes to be used in unloading the database are determined. Then, the desired number of unload processes are initiated. These unload processes copy data from the IMS database to one or more sequential files so that hierarchically-related data in the database is copied in sequence. Next, a storage space to contain the IMS database is provided and address ranges of the storage space to the sequential files are assigned. Finally, a plurality of concurrent load processes are initiated. These load processes write data from the specified sequential files to the storage space at the respective address ranges assigned to the specified sequential files.

Abstract: A method of caching I/O requests permits caching in the MVS environment independent of the access method protocol used to initiate an I/O request (e.g., QSAM, VSAM, Media Manager). In addition, objects can be user-prioritized for residence in the cache.

Abstract: A method and apparatus are disclosed for monitoring and managing the applications and resources on a distributed computer network. Preferably, at least one manager software system runs on at least one of the networked computer systems designated as a network management computer system or "console" system. An agent software system runs on each of the server computer systems in the network to be monitored. Each respective agent software system carries out tasks on the computer system in which it is installed such as discovering which resources and applications are present on the computer system, monitoring particular aspects of the resources and applications present on the computer system, and executing recovery actions automatically when such actions are warranted. The agents are capable of intelligent, autonomous operation.

Abstract: A computer performing a method in accordance with the invention receives from an end-user identifier(s) for one or more damaged (or otherwise unavailable) DASD volumes, and, optionally, an identifier for one or more DB2 subsystems. By searching and correlating DB2 and MVS data resources not residing on the damaged volume(s), the computer determines which object(s) on the specified damaged volume(s) are DB2 objects, and which DB2 subsystem(s) own each of these DB2 objects. A list of recoverable DB2 objects is created, and, optionally, provided to a recovery utility program for the purpose of facilitating recovery. The method permits identification of recoverable DB2 objects without needing access to the damaged or unavailable volumes, either before or after the volume failure, thereby advantageously enabling recovery methods after a volume failure has occurred.

Abstract: A single-phase CHECK INDEX operation for DB2 entails creating a special SORT record for each data record and each index entry, collating the special SORT records in a particular way to group together the SORT records for each data record and any associated index entries, and performing diagnostic operations on the sorted records.

Abstract: A method in accordance with the invention is implemented via a set of novel computer programs referred to for convenience as NEWPROG. A "controller NEWPROG," resides in one or more communication controllers on an SNA network as a "front end" processor for the NCP executing in that controller. The controller NEWPROG uses interception techniques to monitor the controller's incoming and outgoing messages and thereby 1) collect statistical information about network performance, and 2) exchange "backchannel" messages with controller NEWPROGs operating in adjacent controllers. The controller NEWPROG can alter dynamically the tuning parameters in that NCP. A "host NEWPROG" executes in a host computer to provide a monitoring and control station for a network administrator. The host NEWPROG communicates with controller NEWPROGs on the network via a virtual logical unit (VLU) executing within at least one controller.

Abstract: A transport mechanism system and method, implemented in software, that permits the coordinated supervision, by an arbitrary number of SUPERVISOR PROGRAMS, of the execution of indirect-addressed interrupt-handling routines in an operating system. The transport mechanism intercepts each call to a supervised interrupt handler, creates a MEMORY MODEL of the then-existing environment, and hands control in sequence to the SUPERVISOR PROGRAMs. Each SUPERVISOR PROGRAM can examine the MEMORY MODEL as well as modify it, and can call a transport mechanism service routine which results in turn in the calling of the normal interrupt-handling routine, but now in the context of the environment specified by the MEMORY MODEL. Such execution is followed by return of control to the calling SUPERVISOR PROGRAM. After all called SUPERVISOR PROGRAMs have completed their execution and returned control to the transport mechanism, the transport mechanism conforms the actual environment to that indicated by the MEMORY MODEL.

Abstract: A method of dynamically expanding or contracting a DB2 buffer pool, a set of control blocks emulating certain DB2 control blocks is constructed. If the size of the buffer pool is to be increased, the buffer pool expansion routine used by DB2 to accommodate abnormally high storage demand is repeatedly invoked to perform the expansion. However, the contractable-page flag that is set by DB2 for each 4K or 32K page that is added to the buffer pool in this way, indicating that the added page should be removed from the buffer pool as soon as the high storage demand condition has ended, is reset. If the size of the buffer pool is to be decreased, pages are removed from DB2's three queues or chains used to manage the buffer pool, i.e., the never-used chain, the previously-used chain, and the in-use chain, in that order; in the latter two cases the pages are "removed" by marking them as contractable pages so that DB2 itself will soon remove the pages from the appropriate chain as part of its own normal processing.

Abstract: A DB2 thread cancellation method permits operator intervention to terminate a DB2 thread. After the thread to be canceled has been located, a series of one or more SRBs is scheduled to cancel the thread. The basic approach is an iterative one, involving (1) making the thread nondispatchable, i.e., freezing execution of work associated with the thread to prevent such work from making undesirable environmental changes while the thread canceling operation is in progress, (2) testing to ensure that canceling the thread at that moment will not create certain undesirable side effects, primarily in the context of serialization of DB2 resource usage; (3) invoking the DB2 thread cancellation routine; (4) making the thread dispatchable again to permit the cancellation process to begin; (5) receiving a message whether the cancellation request was completed successfully, and (6) returning a status code indicating a successful or unsuccessful cancellation attempt.

Abstract: In a VTAM- or similar-type data communications system, a succession of terminal screen displays are compared over time to determine whether any common display portions can be used as "local formats." If so, local formats are defined and downloaded to the terminal controller and periodically updated if needed.

Abstract: In a novel method of dynamically adding or removing active logs in a DB2 subsystem without the necessity of cycling DB2, a set of control blocks emulating certain DB2 control blocks is constructed. In adding an active log, a call to a DB2 module is made to allocate the new active log data set and create a new LDSD control block for the new active log data set. The NEW and REUSABLE status flags are set in the new LDSD control block, initialization of the new LDSD control block is completed, and the new LDSD control block is added to the LDSD chain off the LMB. The BSDS record(s) and the cached portions of the BSDS information are updated to reflect the addition of the new active log. In removing an active log, the LDSD of the active log is removed from the LDSD chain and an attempt is made to deallocate the active log data set via a call to a DB2 module.

Abstract: A computer-executed method permits one or more of the following three functions to be performed on a DB2 data table: (1) dynamically altering (replacing) the EDITPROC parameter in the DB2 catalog definition of the DB2 data table, without the necessity of unloading the data from the table; (2) dynamically adding an EDITPROC to an existing DB2 data table whose DB2 catalog definitional information does not include an EDITPROC parameter; and (3) dynamically adding a column (field) to an existing DB2 data table that already includes an EDITPROC. The method does not make the assumption, made by IBM's DSNUTILB utility program, that the DBD records for a given database are untrustworthy and that all definitional information therefore must be verified. The method makes use of code to trick DB2 into bringing certain definitional information for the data table in question, including the DBD and OBD records, into memory from DASD (disk) storage.

Abstract: The reorganization method of DB2 data files explores parallel processing, and asynchronous I/O to a great extent. It includes means to estimate an optimum configuration of system resources, such as storage devices (DASD devices), memory, and CPUs, etc, during reorganizations. The method mainly consists of four components, (1) concurrent indexing, (2) concurrent unloading of data file partitions, (3) efficient reloading of DB2 data pages and DB2 space maps, and (4) means to reduce access constraints to the DB2 recovery table.

Abstract: A mapping-type data signal optimizer performs a DEVICE-SPECIFIC ATTRIBUTE ELIMINATION routine. If field attributes in an outgoing signal do not affect the appearance of a data display on, or the operational characteristics of, a peripheral device receiving the outgoing signal (e.g., field attributes are essentially meaningless on printers), then the outgoing signal is reformed so as not to include those attributes.

Abstract: A method and associated computer program operate to optimize signals being exchanged between a host unit and an addressable-buffer peripheral device. The program optimizes an outgoing signal from the host unit by (1) creating an updated-state map representing the state of the peripheral device buffer expected to exist after processing by the peripheral device of the outgoing signal, (2) performing an exclusive-or (XOR) operation using the updated-state map and a present-state map representing the existing state of the buffer, and (3) constructing and transmitting a substitute outgoing signal which represents changes to the buffer, and in which all premodified field flags are turned off. Position-dependent characters, such as attribute bytes, are translated into nondata characters prior to incorporation into a map, and are retranslated into their original form for use in the substitute signal.

Abstract: A method and a computer program for performing the method are disclosed for optimizing signals being exchanged between a host unit and an addressable-buffer peripheral device. The program optimizes an outgoing signal from the host unit by (1) creating an updated-state map representing the state of the peripheral device buffer expected to exist after processing by the peripheral device of the outgoing signal, (2) performing an exclusive-or (XOR) operation using the updated-state map and a present-state map representing the existing state of the buffer, and (3) constructing and transmitting a substitute outgoing signal which represents only changes to the buffer, and in which all premodified field flags are turned off. Position-dependent characters, such as attribute bytes are translated into nondata characters prior to incorporation into a map, and are retranslated into their original form for use in the substitute signal.