Administration and Programming Guide for OS/400

Why Use Net.Data?

Net.Data is a good choice for creating dynamic Web pages because using the macro language is simpler than writing your own Web server applications and because Net.Data lets you use languages that you already know, such as HTML, SQL, REXX, and JavaScript. Net.Data also provides language environments that access DB2 databases, or use REXX, Perl, and other languages for your applications. In addition, changes to a macro can be seen instantaneously on a browser.

Net.Data complements data management capabilities that already exist on your operating system by enabling both data and related business logic for the Web. More specifically, Net.Data:

• Provides a simple, yet powerful macro language that allows for rapid development of Internet and Intranet applications. The Net.Data Web application environment provides the following features:
• Permits the separation of data generation logic from presentation logic within your Web applications. Net.Data does not impose any restrictions on the method with which the data is presented (such as HTML or Javascript). This separation allows users to easily change the presentation of data using the latest presentation techniques.
• Allows you to use existing skills and business logic to generate Web pages by providing the ability to interface with programs written in C, C++, RPG, COBOL, REXX, Java or other languages.
• Provides the ability to develop complex Internet applications quickly, using a simple macro language.
• Provides high-performance access to data that is stored in DB2 and in any remote DRDA-enabled database.
• Provides easy migration of macros between all operating systems supported by the Net.Data family of products.

Interpreted Macro Language

The Net.Data macro language is an interpreted language. When Net.Data is invoked to process a macro, Net.Data directly interprets each language statement in a sequential fashion, starting from the top of the file. Using this approach, any changes you make to a macro can be immediately seen when you next specify the URL that executes the macro. No recompilation is required.

Free Format

The Net.Data macro language has only a few rules about programming format. This simplicity provides programmers with freedom and flexibility. A single instruction can span many lines, or multiple instructions can be entered on a single line. Instructions can begin in any column. Spaces or entire lines can be skipped. Comments can be used anywhere.

Variables Without Type

Net.Data regards all data as character strings. Net.Data uses built-in functions to perform arithmetic operations on a string that represents a valid number, including those in exponential formats. Macro language variables are discussed in detail in Net.Data Macro Variables.

Built-in Functions

Net.Data supplies built-in functions that perform various processing, searching, and comparison operations for both text and numbers. Other built-in functions provide formatting capabilities and arithmetic calculations.

Error Handling

When Net.Data detects an error, messages with explanations are returned to the client. You can customize the error messages before they are returned to a user at a browser. See Net.Data Reference for more information.