Feature

Java opens the door to XML Apps

Question: What plans are there to offer XML on the AS/400 (or rather OS/400), and what form will those plans take? Also what provision is being made, or is there already, for the AS/400 to support/host Wap applications?

 

Answer: As in previous articles I must substantially confine my comments to capability that is already announced.

The AS/400 Toolbox for Java is the key offering in this area, and I would like to take this opportunity to describe in detail the capabilities offered by the Toolbox. The AS/400 Toolbox for Java is a library of Java classes which support the client-server and internet programming model for an AS/400 server. The classes can be used by Java applets, servlets, and applications, to access AS/400 data and resources. This requires no additional support other than the inherent OS/400 support of the Java Virtual Machine, and of the AS/400 Developer Kit for Java.

The Toolbox for Java provides similar support to that provided by Client Access APIs. These then use OS/400 servers which are included with the operating system to access AS/400 data and resources. Each of these servers runs as a separate job on the AS/400, communicating with a Java client programme using architected data streams on a socket connection. The socket interfaces are hidden from the Java programmer by the Toolbox classes. Java Beans are provided for most public interfaces.

Access is provided to a wide variety of AS/400 resources.

Database - DB2 for AS/400 data can be accessed using a JDBC driver.

Database - physical and logical files can be accessed a record at a time using the interface of these classes.

Integrated File System - Through the IFS, a Java program can carry out a variety of common file system tasks.

Programs - Any AS/400 programme can be called, parameters can be passed to it, and data can be returned to the Java program.

Commands - Any AS/400 batch command (that is not interactive) can be run.

Data Queues - Access to both keyed and sequential data queues.

Print - Using the print classes lists of spooled files, output queues, printers and other print resources can be retrieved.

Jobs - Access AS/400 jobs and job logs allowing you to retrieve information about those jobs including messages in the job log.

Messages - Access messages, message queues and message files on the AS/400; allowing you to send, receive and reply to messages.

Users and Groups - Allowing you to get a list of users and groups on the AS/400 and to retrieve information about each user.

User Spaces - Create, read from, write to and delete AS/400 user spaces.

Digital Certificates - Manage X.509 ANS. encoded digital certificates stored on the AS/400.

Data Areas - Access a variety of data areas. Entries can be added to or removed from a data queue, and data queues can be created or deleted.

System Values - Query and reset system values and network attributes on the AS/400.

System Status - Retrieve system status information such as the total number of user jobs and system jobs running on the system and storage capacity of the system auxiliary storage pool.

Additional classes provide the infrastructure to manage sign-on information, create and maintain sockets connections to AS/400 services, and send and receive data. Data description classes are provided for numeric and character data to allow the Java programme to describe the record format of a buffer of data with an object.

The Toolbox provides a set of Graphical Access classes. These use the access classes described above to retrieve data and then present the data to the user. These classes use Java's Swing 1.1 framework. Graphical APIs are available to access various AS/400 resources, such as the database, integrated file system, command call, and data queues. The AS/400 data is then displayed in various pane formats.

In the area of application development the Toolbox provides a variety of different capabilities, and this of course is where the XML support comes in. It provides a user interface framework to aid in building graphical panels. The framework automatically handles the exchange of data. The application developer creates one or more data beans, and then binds them to the panel components using the Panel Definition Markup Language (PDML).

A user interface framework is provided to create a platform and technology independent representation of graphical panels based on XML (Extensible Markup Language). A pure Java framework for interpreting the XML and constructing user interface panels based on the Java Foundation Classes is also provided. A resource script converter converts Windows dialogues to equivalent Java panels defined in XML. A graphical user interface builder tool is provided to develop Java GUIs.

A program call framework is provided via Program Call Markup Language (PCML), a tag language used for supporting the programme call function of the Toolbox. The language fully describes all parameters, structures, and field relationships required to call an AS/400 program.

The recent Version 4 Release 5 announcement contains a number of enhancements to the AS/400 Toolbox for Java.


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This was first published in July 2000

 

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