Patent Publication Number: US-5295222-A

Title: Computer-aided software engineering facility

Description:
This is a continuation of application Ser. No. 07/444,060, filed Nov. 30, 1989, entitled COMPUTER-AIDED SOFTWARE ENGINEERING FACILITY, now abandoned. 
    
    
     FIELD OF INVENTION 
     The invention relates to multiprocessor computer systems and in particular to facilities that aid in the development of computer programs for those systems. 
     BACKGROUND OF THE INVENTION 
     Computer-Aided Software Engineering (CASE) software or &#34;facilities&#34; assist computer programmers or system developers in the design, development and testing of a computer program. 
     Traditionally, the steps necessary to implement a computer program were performed manually. Design teams follow a number of discrete steps to create a useful application program from a nascent idea 
     The analysis begins by manually developing a model in which a problem can be solved by computer. Design teams evaluate the needs of the prospective users and the properties that the computer system should possess to meet those needs. 
     In the technical design phase of development, developers begin to define how the application program will be built on a given system. They manually determine the procedural and data elements needed and how the data and procedures will be assembled to form the software solution. At this phase the two major tasks are data-modeling and process-modeling. 
     With the basic design of the program modeled, developers then begin the task of coding the program. Computer programs are generally written in high-level programming language such as BASIC, C, COBOL, FORTRAN or PL/I. The task of reducing the theoretical design of an application to working code is an arduous task that requires many man-hours. Experience in the programming language used to develop the program is necessary. 
     With the code written, the design team&#39;s next problem is to debug the program for syntax errors, and then test the program to determine whether the application performs the desired function. Typically, the debugging and testing phase requires the programmer to evaluate a program at the code level. 
     The programmer&#39;s development tasks become more challenging with the use of multiprocessing systems architecture. 
     Traditionally, there have been two basic hardware configurations employed in the design of computer systems for multiple users. In one configuration all of a system&#39;s processing is performed by one large &#34;mainframe&#34; computer. Each user accesses that system through non-processing terminals. 
     A network system is the second traditional hardware configuration. A network is comprised of a number of individual processing units that are interconnected to allow the sharing of data and software. There may be additional processors to maintain a group&#39;s centralized database and additional processors may be dedicated to the maintenance of the system&#39;s operation. The use of a network of processors each dedicated to specific aspects of a computer system is the essence of multiprocessing. 
     The growth of the use of multiprocessing systems can be traced to the proliferation and development of powerful &#34;micro&#34; or &#34;personal&#34; computers (PC&#39;s). Within certain constraints, a PC can perform many of the same processing tasks that mainframe or mini computers do. However, a PC can perform these tasks with substantial savings of instructions executed by the computer, measured in millions of instructions per second, &#34;MIPS&#34;. Moreover, unlike a mainframe system, a PC is dedicated to a single user. An efficient multiprocessing system encourages data sharing and the use of dedicated PC&#39;s for as many tasks as possible. 
     In multiprocessor systems, an application may be executed on more than one processor. When various parts of an application program are executed on separate processors, the application is &#34;distributed.&#34; Distributed processing can be executed either in a serial sequence or in parallel. 
     The simultaneous execution of a program on many processors is parallel processing. Sequential execution of a program across different hardware environments is serial or &#34;cooperative&#34; processing. 
     Multiprocessing capability brings new challenges to computer system designers. Whereas in a mainframe environment all parts of the program were programmed for a single environment, in multiprocessing systems designers can choose the particular environment where specific aspects of a program will run. 
     Although this freedom to distribute the program results in a highly efficient application, the programmers must now construct programs designed to execute in many hardware environments. 
     The task of programming multiprocessing systems involves difficult problems of swapping data across different, and incompatible environments. For example, a file containing data stored in a PL/I format is not readable by a program written in a different language such as C or COBOL. A programmer must design special software to handle the communication problems inherent in multiprocessing systems. 
     In addition, a programmer must code the various distributed programs in the language supported by that environment. For example, if the PC processors support only programs written in C language, those parts of the program must be in C. Whereas the other parts of the program, such as those on the mainframe, may have to be written in another programming language. 
     Programming in a multiprocessor environment is very complex and time consuming. Staffing requirements for designing an application in a multiprocessor environment alone can make the task cost prohibitive. CASE facilities were created to alleviate some of the burden multiprocessing architecture placed on the programmer. 
     Traditionally, CASE facilities allow a user to input a high-level logical design of a program which is then translated into code in a particular computer language. However, the CASE facilities currently available do not give the system developer a complete integrated system for the design, implementation and maintenance of a software application. The current facilities do not support the development of a program in a centralized location and where translated code is created and distributed to various environments. The current CASE tools also do not provide a method for re-using parts of a previously developed application that may be usable in an application under development. The current CASE facilities do not provide adequate testing and debugging tools. 
     SUMMARY OF THE INVENTION 
     The present invention is a CASE facility providing a method and apparatus for designing, implementing and maintaining software that runs in multiple hardware environments--a distribution that is transparent to the end-user. 
     One aspect of the invention is a method of modeling the program structure and the data used by the program through an entity-relationship modeling technique. 
     Another aspect is a relational database, where data is stored according to the entity-relationship model. 
     Another aspect is the high-level Rules Language in which the logic of a program can be specified in a highly modular form, promoting ease of re usability. 
     The invention provides the capability for generating source-code for the program in a language supported by various hardware entities in the multiprocessing system, using the entity-relationship model and the high-level Rules Language modules. 
     To generate the program&#39;s source-code the invention provides basic program elements to execute the program in a multiprocessing environment. These program components and low-level routines are combined with the Rules Language modules and data type entities to create the program. 
     The invention further provides facilities to distribute, assemble and compile the program developed using the CASE facility of the present invention, as well as test and modify the program. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration of a three-tiered computer system. 
     FIG. 2 is a diagrammatic representation of the program elements according to the present invention. 
     FIG. 3 is a diagrammatic representation of a sample entity-relationship according to the present invention. 
     FIG. 4 is a diagrammatic representation of a sample entity decomposition according to the present invention. 
     FIGS. 5 and 6 are diagrammatic representations of the entity-relationship model for application programs according to the present invention. 
     FIG. 7 is a diagrammatic representation of the Process Flow for a sample program using entity-relationship modeling techniques according to the presented invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A. Hardware 
     A typical hardware configuration for a computer system using the CASE facility of the present invention is shown in FIG. 1. The figure describes a &#34;three tiered&#34; computer system, named for the three distinct types of processors networked: the mainframe computer 1, as for example, an IBM 3090, a mini or supermini computer 2, as for example an IBM S/88 or Stratus, and a plurality of micro-computer workstations 3, as for example IBM PC workstations. A system using the CASE facility of the present invention is not limited to only this hardware configuration. For example, a similar CASE facility can be constructed to develop code distributed in a two-tiered environment such as a system. employing only a mainframe and PC workstations. The CASE facility can be tailored to fit any hardware configuration. The basic principles of code generation, the maintenance of a centralized database and the use of a rules-based language used in this invention are the same regardless of a particular hardware configuration. 
     Flexibility in hardware configuration is one advantage of the CASE facility according to the present invention over those CASE facilities currently available. The CASE facility of the present invention allows flexible architectural designs by creating a centralized data base called a Repository where the logic of the programs is stored, and translated code is distributed automatically to the different hardware environments. 
     Typical processors preferred for each of these tiers are the IBM mainframe sold under the trademark &#34;Model 3090&#34;, running the IBM MVS/XA operating system; the Stratus minicomputer sold under the trademark &#34;Model XA2000&#34;, running the Stratus Computer, Inc. VOS operating system, and the IBM micro-computer sold under the trademark &#34;PS2&#34;, executing the Microsoft Corporation operating system sold under the trademark &#34;MS-DOS.&#34; (For further information on these processors or their operating systems, the reader is referred to the following publications that are hereby expressly incorporated by reference: &#34;IBM System/370 Bibliography&#34;, document number 6024448; and &#34;Introduction to VOS&#34;, by Stratus Computer, Inc., document number R0001.) 
     B. CASE Facility Elements 
     The CASE facility of the present invention comprises a number of programmed elements, as depicted in FIG. 2: a Repository 1; a Rules Language 2; a Communications Manager 3; a Testing/Debugging Facility 4; a PC User-Interface Facility 5, including a Rules Painter 6; a Work Station Utility comprising a Work Station Manager 7, a Window Painter 8, and a Workstation Converse 9; a Documentation Facility 10; and a Systems Generator 11 including a Code Generator 12, a Data Access Generator 13, and Systems Assembler 14. Although the programs created by the CASE facility are centrally-stored, the CASE system program elements may be located in any of the hardware environments used in a configuration. 
     The Repository 1 is a central database used to store all information about all of the application programs created with the CASE facility of the present invention. The Repository 1 could exist in any hardware environment supporting a standard relational database. For example on the three-tiered environment shown in FIG. 1, the Repository could exist on the mainframe computer 1, using the IBM relational database management system DB2. 
     For purposes of a preferred embodiment of this invention, it is preferred that the IBM relational database sold under the trademark &#34;DB2&#34; be employed. (For background information on DB2, the reader is referred to the following IBM publications which are hereby expressly incorporated by reference: &#34;IBM DATABASE 2 Introduction to SQL&#34; (document number GC26-4082); &#34;IBM DATABASE 2 Reference&#34; (document number SC26-4078); &#34;OS/VS2 TSO Command Language Reference&#34; (document number GC28-0646); &#34;TSO Extensions Command Language Reference&#34;  (document number SC28-1307); &#34;Interactive System Productivity Facility/Program Development Facility for MBS: Program Reference&#34; (document number SC34-2089); &#34;Interactive System Productivity Facility/ Program Development Facility of MVS: Dialog Management Services&#34; (document number SC34-2137) and &#34;DB2 Application Programming Guide for TSO and Batch Users.&#34; 
     The information stored in the Repository 1 includes models provided by the present invention to form the basis for an application program and high-level logic modules defined by the present invention for use in the generation of an executable program, as will appear. For each program, a data-model and a process-model are developed through the use of an entity-relationship modeling system and stored in the Repository 1. The high-level logic modules stored in the Repository 1 are written in a Rules Language defined by the present invention as described below. The information is environment independent and is structured to provide a high degree of re-use. 
     Programmers input information to the Repository 1, using a standard database language supported by the hardware. For example where the Repository 1 is constructed from an IBM DB2 data base, a programmer would use the DB2 Structured Query Language, SQL, to model the application. 
     The Rules Language 2 is a high-level language that permits users to specify the logic of a program, independent of the hardware devices used by the system. Program modules written in the Rules Language are translated by the Code Generator 12 into computer code suitable for execution in an environment where the modules are to run. The Rules Language is described more fully below. 
     The Communications Manager 3 performs the run-time transfer of information between hardware environments. For example the Communications Manager 3 would use routers and protocols to handle data transfers between a mainframe, a mini computer and PC Workstations. The Testing Facility 4 known as Rule View enables programmers to step through and debug program code. Rule View can create test data as well as provide regression and stress testing upon an application. The Rule View is explained more fully below. 
     The PC Front-End 5 allows PC based graphic interface to be used for all CASE tool functions. The Rules Painter 6 permits programmers to construct program modules by manipulating graphic representations of the Rules Language statements. The PC Front-End 5 eliminates the need for the programmer to know an operating system language, such as DOS, by offering all PC functions as menus. 
     The Workstation Manager 7 aids in managing user interface in a PC environment. The window Painter 8 is a tool that helps the developer to create user-interface screens for applications. The Workstation Converse 9 manages the display and validation of screen information. 
     The Workstation Manager 7 works in combination with commercialized programs to design user-interface, such as, for example, Microsoft Windows. All of the complexities of using a commercial design tool, like Microsoft Windows, are managed by the Workstation Manager 7. 
     In designing an application or portion thereof for execution on an &#34;IBM PC,&#34; it is preferred that the Microsoft Corporation&#39;s Window program, sold under the trademark &#34;MICROSOFT WINDOWS,&#34; be used. (For more background information on MICROSOFT WINDOWS, the reader is referred to the following Microsoft Corporation publications which are hereby incorporated by reference: &#34;Microsoft Windows Programmer&#39;s Utility Guide&#34;; &#34;Microsoft Windows Application Style Guide&#34;; Microsoft Windows Programmer&#39;s Reference&#34;; and &#34;Microsoft Windows Quick Reference.&#34;) 
     The Documentation Facility 10 generates all technical documentation for a program under development. Documentation includes functional decomposition of the system and hierarchy listings of the Rule Language modules. 
     The System Generator 11 includes the Code Generator 12, the System Assembler 14, and the Data Access Generator 13. The Code Generator 12 translates the Rules Language modules into code in an appropriate programming language. The System Assembler 14 brings the various coded program elements together to form an application program. The Data Access Generator 13 allows the program to access date across hardware environment. Code generation and program execution is discussed more fully below. 
     The Software Distribution System 15 automates and controls migration of an application. The system manages the release of software to targeted computers. The Software Distribution System 15 solves the problem of synchronizing distribution of software located, for example, on hundreds of personal computers. For a more detailed description of a Software Distribution System see U.S. application Ser No. 07/444,102, entitled &#34;Software Distribution System;&#34; filed on even date herewith in the name of Norman Shing et al., which is hereby expressly incorporated by reference. 
     C. Entity-Relationship Modeling 
     1. Entities and Relationships 
     A feature of the CASE facility of the present invention is the systems model. To design any application using the CASE facility, a developer must decompose the application into specified logical parts, and assemble them into a program. The data used by a program are stored in Repository 1, FIG. 2, according to an entity-relationship model of the present invention. The different parts of an application are expressed as entities and are linked by relationships. 
     Defined generally, an entity is something real or abstract about which information is recorded. The information is organized into a set of characteristics, known as attributes. For example, collected information about employees of a company could be placed in an entity type called Employee. The attributes for that entity could be a name, social security number, home address, age, birth date, department, etc. An entity called Organization would include attributes such as organization name, address, type of organization (such as partnership or corporation), etc. This data is stored in a file in the Repository 1 (see FIG. 2). 
     An association between entities is known as a relationship. For example in FIG. 3 the entity, Organization 1, is now linked to the entity, Employee, by the relationship, Employs 3. Relationships are also defined by attributes. 
     2. Functional Design 
     The functional design phase begins the modeling task--there are two tasks to perform: data-modeling and process-modeling. 
     Data-modeling is the method of creating an entity-relationship model for the real-world data to be used by an application program. The method involves identifying an entity, such as a corporation, and decomposing that entity into subentities and attributes. In FIG. 4, the example entity, Corporation 1, is made up of the entities: Product 2, Staff 3, and Customer 4. Customer consists of the attributes: Name 5, and Address 6, and the Entity, Order 7. The Order entity is composed of the attributes Number 8, Date 9, and Status 10. 
     Once the programmer has modeled the real-world data elements, he or she links them using the relationships such as the Employs Relationship 3 illustrated in FIG. 3. 
     In model format, the data are stored in the Repository 1, (See FIG. 2). Using the entity-relationship modeling technique, data for any application can be stored and readily re-used in subsequent applications. 
     Process-modeling is the method of constructing a model of an application program, using an entity-relationship model. The CASE facility of the present invention requires that all applications be first reduced to an entity-relationship model, before a programs logic is specified. The entity-relationship model is not the actual program. It is separate from the program modules written in the Rules Language. However, the CASE facility uses the entity-relationship model to link the various program modules together as well as to construct and distribute the program through a multiprocessor system. Entities store information on the flow of a program, the data structures used, the user interface, the environments used by the modules and the multiprocessing needs of the program. 
     In addition the entity-relationship model provides a representation of the high-level design of the programs from the entities. The CASE facility can produce technical documentation from the process model. For a given application, the entity-relationship model implicitly represents an amalgamation of a high-level structure-chart and a detailed description of the logic and data requirements necessary to make a program run. 
     The process-modeling method allows users of the CASE facility to maximize efficiency by re-using program elements. The program resulting from the entity-relationship model is highly modular. Because all programs developed with the CASE facility presented by this invention use the same entity types and relationships it is likely that many of the program elements can be re-used. 
     D. Application Model Entities and Relationship 
     All programs built using the CASE facility are broken into ten entity-types and eleven relationships as shown in FIGS. 5 and 6. For each entity and relationship that defines an application a list of attributes and information is kept. 
     1. Entities 
     The Function Entity 1, FIG. 5, is a listing of all the application programs currently on the system. A Function 1 is defined by the following attributes: Function Name, Test Description and Application Identification. 
     A Process 2, FIG. 5, is a logical subdivision of a Function 1. A Function 1 typically is decomposed into two or more Processes 2. Processes 2 can be decomposed into lower level Processes 2 (sub-processes). When a Process 2 is related to another Process, the relationship is always hierarchical. There are three Process types: Root, Leaf and Node. Such relationships define the decomposition of one sub-system into others. The Process Entity 2 is defined by the attributes: Process Name, Description, Menu Description, Sub-Process Menu-Type and Sequence Number. 
     At runtime, a process runs either as a foreground or background process. A Foreground Process is one that executes interactive communication with the end-user. For example, a Foreground Process may comprise the graphics functions, resident on a PC workstation 3, FIG. 1. This is the typical on-line/realtime process. In addition the foreground processes can communicate synchronously with modules on other environments, and they can receive unsolicited data, asynchronously. 
     A Background Process, once started, will process its input, then stop, or wait for further input. This may be a batch process for example running on the mainframe, that receives input from a file, or it may be a continuous process that runs on-line reading from a queue. 
     Rules are the procedural specifications of the logic of a Process. This logic is specified in a high-level language called the Rules Language. The Rules Language is based on the principles of structured design and programming. The syntax of the language along with restrictions built into the architecture ensure a highly modular and concise system specification process. The Rules Language is described in detail below. 
     Using Rules Language statements the CASE facility generates source code for the various environments. The CASE facility generates all code necessary to perform inter-system communication (for example, when a rule in one environment calls a rule in another), inter-process communication (for example, between different processes or regions on the same machine), program-to-program linkage, and user interface. 
     In the entity-relationship model only information about the Rule is stored--not the Rule language statements. A Rule Entity 3, FIG. 5, FIG. 6, is defined by its attributes: Rule Name, Rule Description, Execution Environment; and Mode of Execution (for example, synchronous or asynchronous). 
     As with processes there are three categories of Rules: Root, Frontier and Node Rules. A Root Rule is invoked by a Process 2. Root Rules do not have user I/O capability. A Node Rule is any rule that is not a Root or Frontier Rule. 
     Frontier Rules lie on the boundary of a new environment. Those Rules are grouped in a special category because Communication Manager 3, FIG. 2, must execute all Frontier Rules and their input/output data has to be converted to accommodate changes in environment. 
     The Rule Relationships are modeled using Rule Entities 3 and the Uses Relationship 13. 
     Components are modules of code written in any third generation programming language known to the CASE development system such as C, PL/I or COBOL. Components are used to perform functions not handled by the Rules Language such as calculations, database access, and calls to operating systems. The CASE facility assumes a &#34;black box&#34; structure for Components. A black box has fixed inputs and outputs. Given a specific input, there is always a predetermined output. The same analogy applies to Components. Components have explicitly defined inputs and outputs. 
     The Component Entity 4, FIG. 5, FIG. 6 contains the following attributes: Component Name; Component Description; Language Name (programming language that source code of the component is written in); and Execution Environment. 
     Windows define user interface. They specify what data are to be accepted from a user, how it is to be displayed, and how it is to be accepted. The Window Entity is used to store all information about a screen which is used by the Code Generator 12, FIG. 2, and workstation Converse 9, FIG. 2. 
     A Window Entity 5, FIG. 5 in the entity-relationship model has the following attributes: Window Name, Description. The Window Name contains the name of a Panel File also stored in the Repository which contains the information necessary to produce graphic interface using a graphic interface program such as Microsoft Windows. 
     The View Entity 6, FIG. 5, FIG. 6, is a convenient grouping mechanism for storing data type variables that are used by the Rules Language. The View 6 is a hierarchical set of named scalar or aggregate values. 
     Views 6 are is used in three different ways throughout the system. A File View 6 represents a template of the data constructs saved in a data file. The data constructs used to describe the input and output to Rules and Components are Modular Views 6. The data structures used to handle user interface are called Window Views 6. 
     Field Entities 7, FIG. 5, FIG. 6, are the basic data elements that comprise the variables used in a program. The Field Entity 7 stores all information about data elements, independently of the environment in which the data element is used. The Attributes of this entity define the format, editing specifications, report and screen headings, and any other generic information about a particular data element. 
     A Set 8, FIG. 6 like a View 6, FIG. 5, FIG. 6, is a convenient grouping mechanism that is used to store related literals or constants. Values 9, FIG. 6 are symbolic representations of literals or constants. Values 9 provide the ability or refer to specific data values by symbolic or English names. This eliminates the need to hard-code specific literal values in Rules. 
     Data are stored in files. In a entity-relationship model information concerning data files is stored in the File Entity 10, FIG. 6. 
     2. Relationships 
     The ten entities representing a program are linked together by one of eleven relationships. 
     The Refines Relationship 11, FIG. 5, describes the decomposition of Functions 1 to Processes 2. Its attributes are: Function Name (first participant); Process Name (second participant); and Sequence Number (for menu display). 
     The Defines Relationship 12, FIG. 5, is used to describe the relation between an abstract Process 2 and the Rule Entities 3. Its attributes are: Process Name and Rule Name. 
     The Uses Relationship 13, FIG. 5, is used to describe the link between one executable module and another: (e.g. Rule Uses Rule, Rule Uses Component and Component Uses Component). The attributes of a Uses Relationship are: Module Name and Sub-Module Name. 
     The Converse Relationship 14, FIG. 5, describes the link between a Module and a Window Entity. The attributes of the Converse 14 relation are: Rule Name (first participant) and Window Name (second participant). 
     The Relationship Owns 15, FIG. 5, connects entities to the Views 6 which describe their logical data interfaces. The Rule 3, Component 4, Window 5 and File 10, FIG. 6, entities may own Views. The attributes of the Owns relationship are: Rule/Component/Window or File name; Entity type (either Rule/Component/Window/or file); View Name and View Usage (either In, Out or Inout for user interface I/0). 
     The Includes Relationship 16, FIG. 5 connects data items together to form structures. Views 6 include sub-Views 6 and Fields 7. The Attributes of the Include Relationship 6 are: View Name (first participant higher-level view); View/Field Name (second participant); Entity Type (second participant&#39;s entity type: either view or field); Sequence Number (used to order Sub-Views and Fields); Occurs Number of Times (used to create arrays in structures). 
     The Owns Set Relationship 17, FIG. 6, links executable modules to the literal set values they refer to. A Rule may Own a Set by making a local declaration using the Rules Language DCL statement discussed below. The literal values will then automatically be included in the Rule Module when the code is generated. A Component Entity 4 may also Own 17 Sets 8. The Own Set Relationship Attributes are: Module Name; Module Entity Type (i.e. Rule or Component); Set Name. 
     The Contains Relationship 18, FIG. 6, link literal data items to a common Set 8. A Set 8 Contains 18 member Values 9. The attributes of the Contains Relationship 18 are: Set Name; Value; Symbol Name; Sequence Number. 
     Finally, the CASE system has file relationships: File 10, FIG. 6, is Keyed 19 by Field 7; File 10 Forwards 19 File 20; and A View 6 Describes 21 a File 21. 
     E. Process-Modeling Reduction Technique 
     All Applications developed with the CASE facility must be reduced into the above described entities and relationships. The method begins by defining the Function Entity 1, FIG. 5. A Function is equivalent to any application program to perform any task or function. The Function Entity 1 contains a generalized description of the Application. A Function is decomposed into processes. The processes represent general functions that the program must perform. 
     For example, one of the Process Entities in a application to perform stock market trading could be entitled &#34;Futures Trade Entry.&#34; The Process Entities 2, FIG. 5, store information describing the process. Processes can be decomposed into further processes. On each decomposition the information about the new process is stored in a Process Entity 2. 
     The Function Entity 1 and the Process Entities 2 create a high-level overview of an application. During the modeling phase the CASE facility presented by this invention provides tools to aid development. The programmer can use CASE provided graphics to specify the Process 2 and Function 1 Entities and Refine Relationships 11. The user sees functions and processes listed on menus. The CASE facility also assists the analyst and user in process modeling by allowing this Function/Process decomposition to be prototyped interactively, as for example with an analyst and a programmer. The analyst can enter his thoughts, generate menus reflecting the input, and solicit input (modifications) from the programmer as to whether this is in fact the way the user envisions the way a problem is to be solved. 
     Once the application problem has been reduced to a series of functions and processes, technical design begins. In technical design the program coding specifications are described through the Rule 3, Component 4 and Window 5 Entities. 
     The important aspect of Technical Design is the specification of the Rules and Components, Windows, and Views that are necessary to run the program. FIG. 7 is an example of Process flow diagram using entity-relationship modeling standards. The Square boxes in the FIGS., 1, 2, 3, 4, 5, 6, represent Process and Function Entities. The capsule-shaped boxes, 7-24, represent Rules. The oval-shaped boxes, 25-29, represent Components. The circles, 30, 31, represent Windows. The process flow diagram is used to specify the information contained in the Rule 3, Component 4, Window 5 and View 6 Entities (see FIG. 5) as well as the Relationships between them. 
     F. Constructing the Program 
     With the Entity-relationship model in place program construction can begin. Code is generated from the Rules, Components, Windows, Files, Fields, Views, Values and Sets that are stored in the Repository. Rules, Components, Windows and Files are Program Modules distinct from the Rule Entities 3, Component Entities 4, Window Entities 5 and File Entities 10 stored in the entity-relationship model (see FIGS. 5 and 6). Those Entities store information about the actual program modules from which the application program is created. 
     At this stage of construction much of the work in constructing the program modules is done. The data structures are defined by the View 6, Field 7, Set 8, and Value 9 Entities. The Code Generator Facility 12, FIG. 2, copies these entities into the program modules that are related to them by the Rule 3 and Component 4 Entities (see FIG. 5). Component Modules do not need to be built by the programmer. As they are previously programmed subroutines provided by the CASE facility to perform basic mathematical operations and operating system access. However, the CASE facility permits new components to be stored in the Repository 1, FIG. 2. 
     The tasks left to the programmer are to (1) define the logic of the program using the high-level Rules programming language; and (2) design the user interface Windows. 
     1. Re-Usability Analysis 
     Even before the Rule specification begins, the CASE facility speeds program development because it provides a method to re-use previously generated code. With entity-relationship modeling much of the same logic from one application can be re-used in other applications. It is easier to re-use code that has already been developed and tested than to re-create it. Keeping this in mind, a re-use analysis should be performed. 
     With the entity-relationship model stored in the Repository 1, FIG. 2, the Entities can be queried for usage by other Entities. For example, with the Repository existing on a database supported by IBM DB2, a Where Used query on the Field Entity 7, FIG. 5, returns a list of all the View Entities 6 using that Field 7. The usage of the Views can be queried further to establish what Rules, Components or Windows use those Views. This method allows programmers to discover previously coded Rules and Components. A Find Where query will search all entity attributes throughout the entire database for particular words or character strings. 
     In addition the CASE facility allows programmers to define a keyword for all Rules, Components and Field created. A Search command can be performed to locate entities possessing a certain keyword. A programmer can perform sophisticated searches such as find all keywords starting with, for example, &#34;CU&#34; and ending with &#34;Pp&#34;. 
     Once a programmer has located a module that may be re-usable, he or she can get further information by browsing the description or other attributes associated with the entity. 
     2. The Rules Language 
     The Rules Language is a high-level programming language which supports all standard flow of control constructs. What is unusual about the Rules Language is that it does not require a means of describing elaborate data structures. The description of all the data structures used by a program within the CASE facility is stored in the View and Set Entities in the program&#39;s entity-relationship model. All Rules used by a program share data structures. The sharing of data structures provides strict coordination between the data passed from one Rules Language Module to another. This technique avoids one of the major sources of program errors--a mismatch between the data passed between subroutines. A Rule consists of zero or more declare statements followed by zero or more executable statements. A data type declared must be one of the following type: Smallint, Integer, Char, Varchar, Decimal, Signed Picture or Like (an already declared Item). The declare statement is in the form: 
     DCL 
     declaration; [declaration; . . . ] 
     ENDDCL 
     where the declaration is: 
     identifier [(s) ] [, identifier [(s) ], . . . ] declare type or EXTERN identifier [, identifier, . . . ] SET 
     The data types are more fully explained in Appendix C attached 
     The Rules language supports three types of executable statements: 1) Assignment statements; 2) External flow of control statements; and 3) Internal flow of control statements: 
     
         ______________________________________                                    
             External Flow Internal Flow                                  
Assignment   of Control    of Control                                     
Statements   Statements    Statements                                     
______________________________________                                    
MAP          USE           IF                                             
OVERLAY      RETURN        CASEOF                                         
CLEAR        CONVERSE      DO                                             
             ASYNC                                                        
______________________________________                                    
 
    
     Assignment statements alter the data contained in held by program variables. The MAP Statement places an expressed value in a variable location. The OVERLAY statement replaces the contents of a variable with specified data item. The CLEAR Statement replaces numeric fields with zero values and character fields with space values. The syntax of the assignment statements is: 
     MAP expression TO variable 
     OVERLAY data item TO variable 
     CLEAR variable 
     Four statements in the Rules Language handle the external flow of control between program modules. The USE statement enables one program module to invoke another Rule or Component. It is similar to a subroutine CALL statement in other programming languages. The syntax is: 
     USE MODULE Component 
     USE RULE Rule [NEST ] 
     The Next option indicates that all Windows invoking the Rule will come in &#34;pop up&#34; mode; i.e., it will be displayed over the screen that was previously displayed. 
     The RETURN Statement transfers control back to the Rule that executed the USE statement: 
     RETURN. 
     The CONVERSE statement provides communication between PC-based rules and the user interface. A typical converse statement is: 
     CONVERSE WINDOW window 
     The Rules Language supports Asychronous data flow with the ASYNC statement. For example, in a system using a Stratus mini computer performing in parallel, unsolicited data allows a Stratus-based Rule to send data to a PC-based Rule. This is supported using the following statements: 
     
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˜ ASYNC        ATTACH                                               
˜ ASYNC        DETACH                                               
˜ ASYNC        REFRESH                                              
˜ ASYNC        ROUTE                                                
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     The ASYNC ATTACH command will initiate the receiving of unsolicited input as for example by a PC-based Rule sent by a Stratus-based Rule. The ASYNC DETACH command performs the exact reverse of ATTACH. It may only be used after an ATTACH command, at which point it will discontinue the receiving of unsolicited input. The ASYNC ROUTE command switches data refreshing from one PC Rule to another. The ASYNC REFRESH statement will induce automatic updating of a specific field, so long as the Attach Statement has been used. 
     The Rules language has three different statements to order the flow of control within a Rule. 
     An IF statement controls execution based on a specified condition: 
     
         ______________________________________                                    
IF condition     [executable stmt . . . ]                                 
[ ELSE           [executable stmt . . . ] ]                               
ENDIF                                                                     
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     The CASEOF statement selects one of several alternative execution paths based on the value of a variable. The syntax is 
     
         ______________________________________                                    
CASEOF variable                                                           
CASE constant [constant . . . ] [executable stmt                          
. . . ]                                                                   
[CASE constant [constant . . . ] [executable                              
stmt . . . ]                                                              
[CASE OTHER                                                               
ENDCASE                                                                   
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     A DO statement controls the execution of repetitive loops. The syntax is 
     
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DO [FROM data item] [TO data item] [BY data                               
item] [INDEX variable] [executable stmt . . . ]                           
[WHILE condition [executable stmt . . . ] ]                               
ENDDO                                                                     
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     All data items and variables specified to execute a DO loop must be integer numbers. The defaults for the DO statement are: FROM=1, TO=n, BY=1, where n is an integer. 
     Conditions occur within the IF, CASEOF, and DO statements. A simple condition is: 
     
         ______________________________________                                    
expression  logical  operator  expression                                 
or  expression  INSET  Set                                                
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     where logical operator is one of the following: 
     
         ______________________________________                                    
        =             &lt;=                                                  
        &lt;&gt;            &gt;                                                   
        &lt;             &gt;=                                                  
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     A condition is built from simple conditions or other conditions: 
     
         ______________________________________                                    
               simple condition                                           
or             (condition)                                                
or             NOT condition                                              
or             condition AND condition                                    
or             condition OR condition                                     
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     The INSET statement is used to determine whether a given variable or constant appears as a value within a SET. For example suppose X is a data item whose data type is compatible to the data type of the set: 
     
         ______________________________________                                    
X            INSET       SET NAME                                         
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     is a condition which evaluates to either TRUE or FALSE depending on whether or not at least one of the values, in SET NAME matches the value of X. 
     A programmer uses the Rules Language statements to write out the logic of the program. For further information on the Rules Language, reference should be made to Appendices A-F attached hereto. 
     3. User Interface Windows 
     The user interface for any application is constructed using the CASE facilities Window Painter 8, FIG. 2. The Window Painter is a program which is designed to help build user interface with the aid of a commercially available graphics display program. For example, the Window Painter 8 can be built to run using Microsoft Windows. The Window Painter 8 would then feature the mouse-based Windows interface that is standard to Microsoft Windows. The screens produced with the Panel Builder would also resemble Microsoft Windows interface to the user. 
     The Window Painter 8 is used to create screen mappings of data designated in the Field 7 and View Entitles 6 (see FIG. 5). The Window Painter 8, FIG. 2, creates a file, (for example, using Microsoft Windows it is called a .vu file). That file contains data to create a screen mapping of the Window View. After creating and saving the panel, the CASE facility of the invention also generates other files, for example, a .PNL and a .MNU files using Microsoft Windows. The PNL file contains the code for the &#34;painted&#34; panel. The .MNU file contains the code for menu structures used by a panel. (See references cited, supra.) 
     G. Code Generation 
     Once an application has been modeled, and the Rules, Components and Windows have been created, the CASE facility produces source code. 
     Preparation is the code generation phase. When an application is prepared, the Views 6 and Sets 8, FIG. 5, are used to create copybooks. A copybook is a file which is copied into the source code of a program module. The CASE facility creates a copybook for each data structure and includes a copy of that file in every executable Rule, Window or Component related to a particular View or Set. 
     Preparation also generates environment-specific source code for each Rule Language module. The Rule Entity 3, FIG. 5, contains an attribute specifying the environment destination of each Rule Module. The Code Generator, 12, FIG. 2, takes high-level Rules Language statements and translates them into source code in a language supported by the hardware environment of the Rule&#39;s destination. For example, if a Rule was to be executed on a Personal Computer that supported only the C language, the Code generator would translate the Rule Language Statements in C. 
     If the Rule Language statements specified in a module can be successfully generated into source code the code is stored in files in the Repository. However, if there are logical errors in the Rule Language statements, no code is saved and error messages detailing the unsuccessful result are saved in a Failed Results File. 
     Once preparation has been performed, detailed reports can be made for each Entity in the entity-relationship model. Those reports are a program&#39;s technical documentation. 
     H. Distribution 
     When the modules of an application have been successfully prepared, they are ready to be transported to their target environments. The capability is provided by the Software Distribution System 15, as shown in FIG. 2. (See U.S. application incorporated by reference, supra.) 
     1. Assembly 
     When all the source code modules of an application have been distributed, they must be assembled into a running computer program. The steps are to: 1) Compile the source code; 2) Enable communication routines to allow interaction of program modules across environments; and 3) Bind or link the compiled code. 
     Assembly must be executed in each environment where program modules were distributed. For example, on a system incorporating PC processing, the PC will have a PC-based System Assembler 14, FIG. 2, that will enable a programmer to compile and bind the PC-based rules. 
     In the same example, separate assembly would have to be completed on a mini computer. For example on a IBM S/88 or Stratus mini computer, a command &#34;Build the Rule Router Application&#34; takes Frontier Rules and links them to every other Rule source code module existing in the mini-environment. The function also binds the code into an executable module. 
     Mainframe program modules also must be separately assembled. For example, in an IBM environment supported by CICS and DB2, a mainframe-based System Assembler 14, FIG. 2, provides assembly functions for the Rule and Component source code. For a Rule, an assembler would: 
     verify that the Rule is a valid mainframe rule; 
     verify that the Rule has completed the code generation process; 
     prompt the user to indicate if the Rule is to be setup as a Frontier Rule; 
     read the Bind file to load the on-line VSAM Views File and the on-line VSAM Relationship File for runtime PCI and Conversion use; 
     load the source code to the online VSAM Source file for rule View use; 
     automatically perform the DB2 Bind based upon the relationships defined to the Repository for Frontier Rules that use Components which issue DB2 calls; 
     display a list of other Rules and Components affected by the setup of a particular Rule; 
     assign a unique CICS TRANSID and a unique DB2 Plan name for Frontier Rules that use Components which issue DB2 calls; 
     Rebind a DB2 Plan for a Frontier Rule when one of the Rule&#39;s related Components, that issue DB2 calls, has been modified; 
     remove the rule from the CICS environment when the Rule is no longer needed; 
     A Component assembler in a CICS environment would perform these functions: 
     provide the facilities for a programmer to compile his Component in a language supported by the system such as with options for CICS INTERTEST and DB2; 
     allow the programmer to view the results of his compile (compile listing and link edit map); 
     display a list of other Rules and Components affected by the setup of a particular Component; 
     allow the user to edit the source code of a mainframe Component; 
     J. Execution 
     Upon successful assembly of the application modules in each hardware environment the program can now be executed and tested. The CASE facility provides the ability to execute and test the application from any environment in the hardware architecture. For example, using the hardware architecture comprised of an IBM Mainframe, an IBM Stratus mini computer and PC workstation, as in FIG. 1, a programmer seated at a PC would have the option to: 
     Execute the PC based portion of an application; no links will be created with modules executing in Stratus or Mainframe other environment; 
     Test the modules and modular executing in one other environment. In this case links are created with utilities other environments. This permits communication between environments; 
     Execute or test the entire program. In this case links are created with each of the required execution environments. 
     K. Revising an Application 
     The process of changing the elements in an application using the Entity/Relationship Modeling system and the Rules Language is a straightforward process. The database is entered and the program element is changed. However, small changes in this system can have large consequences. In general any entity type that Owns, Uses, or Includes Entities that have been changed will have to be reprepared or &#34;Modified&#34;. The CASE facility accomplishes the modification through the Software Distribution System 15, FIG. 2. (See U.S. application incorporated by reference, supra.) 
     L. Testing Facility 
     Finally, the CASE system provides debugging and testing facility that enables users to evaluate the performance of a application. 
     Generally the applications are first inputed on the computer at code level. Traditional code debugging tools are designed for testing at the code level only. Instead, the CASE facility presented by this invention provides a high-level debugging tool called Rule View which is part of the Testing Facility 4 depicted in FIG. 1. A version of Rule View would exist in each of the operating environments in a hardware configuration. Applications spanning more than one environment require a separate testing for the modules in each environment. 
     Calls to Rule View are automatically embedded by the CASE facility when code is generated. Rule View runs the application in a Rules-level debugger locating errors and problems that occur. It can be used interactively to step through a Rules process and examine the contents a View Copybook at any point. Rule View gives programmers the ability to: 
     1. Initiate the execution of a Rule. 
     2. Break the interface between a Rule and a Second Rule or Component. 
     3. Step into the logic of a Rule. 
     4. Step over Rule or Component Module. 
     5. Step back to the beginning of a Module. 
     6. Examine and modify any Field within a View owned by the active Rule. 
     7. Review the active Rule&#39;s source code. 
     8. Save any View data for future reference and re-use. 
     9. Print the Rule source code and View data. 
     Rule View will assemble at each breakpoint, a list of Views that can be examined and edited. The number of Views displayed depends on where and how Rule View is used. In most cases, the Views available for display will contain the input, output of the Rule being executed. In more advanced situations--where asynchronous Rules are being debugged or multiple applications are being tested--many Views may be available for examination. The contents of a View can be printed or saved in a file. 
     The Rule View editor permits the programmer to edit any data by using a Field Editor. With the Field Editor, a programmer can change any data by typing over the old information. The editor also permits the user to restore the contents of any field to its original value. 
     To review a Rule&#39;s source code, a Text Editor provides an option where the line of source code currently being executed is highlighted at all times. If multiple modules are running under Rule View, the source that is displayed will be the source code that Owns the data in the current View. ##SPC1##