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Using the Design Tool

The Design Tool is a component of the Developer Kit for modeling and encapsulating an existing host application for integration into client/server and Web applications.

Host Integrator Web Builder automatically generates projects, including Web applications, .NET class libraries, and Java Beans.

Implementation Options

  • What is the host data you want to integrate into another environment or application?

    If at all possible, plan on building a table that represents the host data in a way that can be queried through an SQL statement. Does the data presentation and logic of the host data as presented on the Web differ from the host application itself? If not, a simple rejuvenation may be sufficient.

  • Will the host data be presented on a Web page for customers or users?

    What is the Web presentation technology? Know the requirements and the environment where the host data will be used. If you're not integrating the data with other applications, a simple rejuvenation of the host application may be sufficient. Otherwise, you should plan on setting up tables and procedures so that an external application, such as a Web service, has access to the host data. This decision has a direct impact on how your build your model.

  • Know the development requirements for the external application.

    Host Integrator provides APIs for integrating host data through SQL, ASP, ASP.NET, JSP, Web Services, COM, and .NET. For a quick implementation, many of these options can be generated using Host Integrator's Web Builder.

    • You can use Host Integrator with Microsoft’s Active Server Pages (ASP),ASP.NET, or a Java Server Pages (JSP) environment. In this environment, you can use Host Integrator to give users access to host data from a Web browser.
    • You can use Host Integrator to make host data available to another client/server application, whether or not it is Web-based.
  • Host Integrator support for object frameworks on application servers include Web Services, the Component Object Model (COM), and .NET. Application server deployments are especially well-suited for situations in which high volume host systems are extended to the Web. Additional business logic can be developed to add more functionality and capabilities to the system without any work or development required in the host system environment.

Design Tool Features

You can use the following features to capture the functionality of your host application:

Connecting to a host

The Design Tool can connect to the following hosts:

Host Models
IBM 3270 Models 2 (24x80) Normal and Extended, 3 (32x80) Normal and Extended, 4 (43x80) Normal and Extended, and 5 (27x132) Normal and Extended
IBM 5250 Models 3179-2, 3180-2 (132 Column Capable), 3196-A1, 3477-FC (132 Column Capable), 3477-FG (132 Column Capable), 3486-BA, 3487-HA (132 Column Capable), 3487-HC (132 Column Capable), 5251-11, and 5291-1
VT VT102, VT400-7, VT400-8, and VT52 terminals
HP HP2392A and HP 70092 terminals

You select the host connection type on the New Model or Session Setup dialog box, accessible from the File or Connection menu respectively.

Using models to encapsulate a host application

The main feature of the Design Tool is the modeling feature, which enables a host expert to create a model of a host application. First, you connect to a host via the Design Tool and then define entities for terminal screens, which may include patterns for identification, attributes to specify the location to input data, and one or more operations to allow programmed traversal of the host application, and variables which can be mapped to various attributes or various entities.

In most cases, you will use tables and procedures to create an abstraction of the host data so that it can be queried through a subset of the industry-standard Structure Query Language (SQL). See "Abstracting a Host Application" below.

The model file (.modelx) is saved in the Design Tool and then copied to a Host Integrator Server. For more information, see The Modeling Process.

Abstracting a host application

You can create procedures (and underlying tables) to add a database abstraction layer on top of your host application model. Client application programmers can then access this database abstraction layer, either by a direct call to a procedure or through a subset of the industry-standard Structured Query Language (SQL). For an SQL query, the client application specifies a table, a set of input parameters, and a set of desired output parameters. Host Integrator then returns the desired data to the client application.

Providing core runtime services

In addition to the definition process, the Design Tool provides server-like services for the modeling and procedure definitions. This permits the user to test and debug models and database procedures prior to deployment. The model layer requires entity recognition, operation execution, and variable reads and writes. The debug layer takes arbitrary input and resolves a query (or returns an error) or executes a specified query.

Recording command lists

The command list recorder records host commands for operations required by the debug layer. On the Model menu, point to Record and then click Start Recording to begin. For information about creating login, logout, and move cursor command lists, see Command List Edit.

Implementing preferences

There are several functional user preferences that can be implemented, including creating default names for attributes, automatic pattern generation, and proposing new operations when appropriate. On the Settings menu, click Preferences for more information.

Providing online and offline design modes

The Design Tool has the ability to display in online and offline design modes. As each entity is defined, two files are created to enable the design mode process.

  • A "screen snapshot," or a snapshot file contains the contents of the display memory and which can then be available to the Design Tool for editing the corresponding entity in offline mode.

  • A Host Emulator trace file is a Telnet trace for the terminal screen that the Host Emulator can send over a Telnet connection to simulate the screen being sent from the host.

Offline mode is available for all emulation options, while Host Emulator is available for IBM 3270 and 5250 emulations only.

Working collaboratively

Host Integrator provides the ability for multiple developers to work similtaneously on a project. Models are saved using the .modelx extension, which gives multiple developers the ability to work collaboratively and merge their changes using a standard version control package, such as Git. When you save a model as a modelx file, all entities, tables, and supporting files are converted into XML, validated by an .xsd file, and saved in the models directory, under the modelx folder. See Working Collaboratively.

You can also import portions of models for use in other models. This makes model creation more efficient. Multiple developers can work on large models simultaneously and pull the various pieces together at a later time. See Importing Model Elements for more information.

Adding event handlers

An event handler gives you the ability to customize the behavior of a model.

The Design Tool offers a variety of features that assist you in creating event handlers. The result is a Java class that conforms to rules for event handling. This class is then mapped (attached) to specific objects of a model to customize its behavior.

You can attach event handlers to events associated with the entire model, a life cycle event, or to entities, attributes, operations, recordsets and recordset fields, and procedures. You can reuse a handler in multiple models or with multiple objects of the same type within the same model.

If you're ready to begin modeling, see The Modeling Process.

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