Chapter 1: Introduction

This chapter contains the following sections:

• Introduction to APS

• A Scenario for Using APS

• The APS Tool Set

Introduction to APS

Generate MIS applications automatically

APS for z/OS is a full-function application generator that automates the development and redevelopment of the MIS applications that support your business. With APS you can build simple or complex applications for a variety of IBM SAA production environments. You can generate online and batch applications without manual coding.

Improve application quality

APS improves both the quality of your applications and your efficiency in developing them. Quality improves because you focus on the end user's functional requirements, and not the application's physical implementation. As a result, applications generated with APS are more likely to meet user expectations without extensive modifications.

APS lets developers focus on user needs by working in a variety of development cycles. For example, if your approach is:

• Rapid Application Development (RAD), you use APS to prototype your application user interface and its technical environment. You generate a working application directly from the prototype, without wasting any steps.

• Waterfall, you develop requirements, specifications, and designs in a front-end CASE tool such as Excelerator. In this analysis- and design-driven development, you then transfer that information to APS, where it becomes the basis of the design you use to generate the working application.

• Hybrid, you can start either with prototypes or high-level specifications, and move freely between the two approaches as you refine your models. APS gives you the flexibility to adapt your lifecycle approach to particular project requirements.

• Redevelopment, you can capture high-level information about your existing applications, and then forward engineer applications using APS. APS makes it easy to maintain or enhance applications by reusing design information that defines application screens, databases, and other features.

Improve development productivity

Productivity improves because you can generate a complete working application without first becoming an expert in IMS, CICS, ISPF, SQL, or any other environment that APS supports. Because APS lets you focus on high-level requirements and specifications, novice developers can quickly generate simple designs with minimal training, and soon build incrementally to complex applications.

APS also encourages developers to share and reuse design modules. It lets you store all application design information in one central location on a network or mainframe, so that multiple users can access that information concurrently. As a result, your application designs always reflect the entire team's current work, and it is easy to share data.

Build your knowledge base into APS

APS lets developers share design components that leverage the knowledge and experience of your most senior people. Expert COBOL developers can customize APS so that it supports your organization's requirements for such features as user interface, report writing, and naming conventions. When these senior APS users define in-house standards or solve complex problems, you can incorporate their work into the dynamic APS rules base, where it is available to all users at your site.

Because APS lets you work from high-level designs, you can easily retarget APS applications for multiple environments. You simply specify the new target, and regenerate the application, using the same programs, screens, and other application components. APS lets you use your existing database subschemas, tables, and files in the new applications you generate.

A Scenario for Using APS

Start development with tasks you prefer

APS lets you work in whatever sequence you choose. For example, you can define the user interface before you think about the program logic. Or you can first define the global data that all programs must use. Whether you decide to work top down, bottom up, or middle out, APS lets you proceed from the step you just completed to the one you want to do next. And, if you are maintaining or redeveloping existing applications, APS lets you focus on only those components that must change.

Build applications from high-level specifications

It's often best to begin by defining your application's runtime or target environment. When you select an environment, APS handles the necessary implementation details when it generates the application. APS for z/OS supports the following targets:

Generate applications for multiple targets

If your application must run in several target environments, you can easily specify it to do so. For example, you can generate an application so that it can access more than one kind of database. In each case, APS generates code that runs in the environments you specify in your high-level application design.

Whenever you are ready, you import into APS the subschemas or tables for your existing databases. Your APS applications can then access these existing databases--first for prototype testing within APS, and then for running the final application.

Prototype the application's look and feel

You can next prototype the look and feel of an application, so that end users can review it early in the design process. Then paint the screens that support the user interface you select.

Paint applications

APS lets you paint menu and data entry screens that include data entry and text fields. You can also include message fields that let the application communicate errors.

At this stage of prototyping, you and your end users run the screens to ensure that the application user interface meets end user expectations. You can enter data into data entry fields to ensure that they capture all of the required information. You can test various display sequences of screens to ensure that the screens support an intuitive work flow. Because it is so easy to create, run, and change these prototypes, you can work closely with end users to refine this aspect of the application before you move on to design the underlying details of the application.

Specify application logic

APS also simplifies the task of defining an application's processing logic. You can generate online applications from high-level designs using the default logic that APS produces, or you can tailor the logic to your particular requirements. For example, you can tailor the way that APS processes database calls, error routines, or other program functions.

You create batch applications using whatever combination of specification language, user-defined macros, or COBOL/2 syntax that you prefer. You can combine online and batch programs as you like within a single application.

Automatically generate a working application

When you generate an application, it is ready to install and set up to run in your production environment. Generation produces consistent, high-quality code without run-time modules.

Test run the application

Once you generate an application, you can test run your work within APS using the APS ISPF Prototype Execution facility. This facility emulates the basic functions of the mainframe CICS or IMS DC environments, letting you test the data communication and database functions of your programs. Doing so allows you to find features that do not meet expectations, and then modify and retest those features without first setting up the complete target environment that the application will ultimately run in.

Using this facility, you can test out your application's program navigation and flow--for example, sending screens, passing control from one program to another, and terminating programs. If you have imported your database definitions, you can test the prototype using test data in your actual SQL or VSAM (but not IMS) database; otherwise you can test the processing logic using data that you enter into screens but do not store.

The APS Tool Set

Basic APS painters and facilities

The basic APS toolset lets you generate applications from high-level specifications. The APS tools that support this work are as follows:

• Application Painter lets you specify the target environment. You also use the Application Painter to name the components of the working application, such as its programs; screens or report mockups; and data structures, and to define the relationships among them.

• Database Importers let you use existing databases as part of any APS application.

• Screen Editor lets you paint screens containing global or local data elements.

• Scenario Painter lets you prototype the flow and behavior of screens.

• Online Express lets you define all program logic by using predefined teleprocessing and database function codes, mapping record fields to screens, defining and qualifying database calls, and adding your own program functions to support specialized requirements.

• Specification Painter lets you extend Online Express applications with customized processing logic that supports your coding practices.

• Program Painter is an alternative to Online Express, and lets you create batch and online applications using COBOL II and high-level APS constructs such as database calls, data communication calls, and Report Writer constructs.

• Generators let you create an executable COBOL application from your high-level APS specification.

• Documentation Facility lets you produce reports about your applications.

Advanced APS painters and facilities

If you need to customize your applications to reflect specific in-house coding practices, APS also provides a set of advanced facilities that give you this flexibility. These tools are as follows:

• Data Structure Painter lets you define data elements you can reuse in applications.

• Data Element Facility lets APS Administrators set and enforce in-house standards by creating and maintaining global data elements that all developers use in their applications.

• User Help Facility lets you create online help systems for your applications.

• Customization Facility lets you extend APS applications using macros you define to support your coding practices.

• APS/ENDEVOR Interface lets you link to LEGENT's ENDEVOR software management product to manage the different versions of your application components.

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