Method of dynamically generating a local format for use by a logical unit in a VTAM-type communications session

• US 5,432,901 A
• Filed: 01/30/1992
• Issued: 07/11/1995
• Est. Priority Date: 01/30/1992
• Status: Expired due to Term

• Current Assignee: BMC Software Incorporated (KKR & Co., Inc.)
• Original Assignee: BMC Software Incorporated (KKR & Co., Inc.)
• Inventors: Harper, Thomas A., Garza, Valdemar Jr., Mead, Philip R.
• Primary Examiner(s): Harrell, Robert B.
• Application Number:
  US07/830,435
• Time in Patent Office: 1,258 Days
• Field of Search: 364/DIG. 1 MS File, 364/DIG. 2 MS File, 395/100, 395/144, 395/145, 395/153, 395/155, 395/157, 395/200, 395/275, 395/650, 395/800
• US Class Current: 715/746
• CPC Class Codes: H04L 69/26 Special purpose or proprietary protocols or architectures network applications for proprietary or special purpose networking environments H04L67/12
• CPC Class Codes: H04L 9/40 Network security protocols

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.

Claims

1. A method, performed by a machine executing a set of instructions referred to as a local-format mapping program, said machine also executing an application program, of generating a local format for display on a display of a logical unit engaged in a communications session with said application program, said display referred to as a logical-unit display, said logical-unit display having information contents, said information contents including at least one attribute byte and at least one nonattribute byte, said method comprising:

(a) receiving a request, issued by the application program, that said machine direct an outgoing data stream to said logical-unit, said outgoing data stream having information contents;

(b) accessing a map of at least a portion of said information contents of said logical-unit display, referred to as a present-state map, said present-state map having information contents;

(c) generating an updated version of said present-state map, referred to as an intended-state map, reflecting the information contents of said outgoing data stream;

(d) creating a bit map of at least a portion of the information contents of said logical-unit display, referred to as a target bit map, in which (1) each of said at least one attribute bytes are represented by a first bit state and (2) each of said at least one nonattribute bytes are represented by a second bit state;

(e) accessing a set of one or more existing bit maps, each said existing bit map representing a local format that is already available for display by said logical unit, referred to as an existing local format, each said existing local format having information contents;

(f) searching in said set of one or more existing bit maps for a match with said target bit map, referred to as a matching bit map;

(g) if a matching bit map is found in said set of one or more existing bit maps, said matching bit map representing a particular existing local format referred to as a trial format, then determining whether any mismatches exist between the information contents of said trial format and the information contents of said updated-state map, referred to as information-content mismatches, and;

(1) if no information-content mismatches are found between said updated-state map and said trial format, then sending to said logical unit a PRESENT ABSOLUTE FORMAT order directing said logical unit to display the trial format on said logical-unit display;

(2) if one or more information-content mismatches are found between the updated-state map and the trial format, but at the points of mismatch the trial format has binary zeros, then sending to said logical unit (i) a PRESENT ABSOLUTE FORMAT order directing the logical unit to display the information contents of said trial format on said logical-unit display, followed by (ii) a substitute outgoing data stream having information contents to be overwritten onto the information contents of said trial format on said logical-unit display;

(3) if some information-content mismatches are found between the updated-state map and the trial format, but at the points of mismatch the trial format has characters other than binary zeros, then (i) refining the trial format by overwriting it with binary zeros at the points of mismatch to produce a refined trial format, (ii) downloading said refined trial format to said logical unit to replace said trial format, (iii) sending to said logical unit a PRESENT ABSOLUTE FORMAT order directing the logical unit to display the trial format on said logical-unit display, and (iv) sending to said logical unit a substitute outgoing data stream to be overwritten onto the information contents of said trial format on said logical-unit display; and

(h) if no matching bit map is found in said set of one or more existing bit maps, then (1) building a new local format from the updated-state map, (2) downloading said new local format to said logical unit, and (3) sending to said logical unit a PRESENT ABSOLUTE FORMAT order directing said logical unit to display said new local format on said logical-unit display.