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HATS fantastic!
Integrating host applications in an SOA environment
BY VIKRAM GULATI
In today’s mainframe and core-systems
environments, applications and processes
built on traditional languages, such as
COBOL and PL/1, and runtimes, such as
CICS and IMS, continue to deliver a wealth
of mission-critical benefits to enterprises of
all sizes. Many of these existing applications
run on the zSeries platform and are
accessible through either 3270 terminals or
terminal emulation programs.
These applications and processes might
be the most valuable assets an enterprise
owns. After all, they do run the business.
However, much of this existing technology
wasn’t designed to address today’s changing
market and business conditions. More
and more, enterprises are realizing that
to respond effectively to these changing
business conditions, the existing applications
need to integrate with other IT environments
across the entire enterprise and across the
internet with business partners, suppliers,
and customers.
This article explores the use of IBM
WebSpere Application Server Host Access
Transformation Services (HATS), which
is designed to expose business logic from
terminal based zSeries applications to
perform a business activity. This business
activity can then be integrated into a
business process using WebSphere
Process Server.
Service Oriented Architecture
overview
Service Oriented Architecture (SOA)
is a standards-based integration and
development architecture that is independent
of the differences in platforms, software
architectures, languages, and network
protocols. Even terminal access based
applications can integrate into an SOA
environment. Industry standard Web services
provide a well-defined, scalable, and flexible
implementation mechanism for SOA.
Web services allow applications to
communicate with each other in a platform
and programming language-independent
manner. Applications work together by
exchanging service messages back and forth.
SOA communication relies on open standards
that include:
• Simple Object Access Protocol (SOAP)
• Web Services Description Language
(WSDL)
• Universal Description, Discovery and
Integration (UDDI).
Web services are designed to cut the amount
of time and money needed for systems
integration—the single biggest IT expense
of most companies. SOA, Web services, and
HATS allow you to integrate current z/OS
terminal application programs into your
overall business processes.
HATS consists of two components:
• HATS toolkit with a set of wizards and
editors that create J2EE applications
using the IBM Rational ® Software
Development Platform
• A runtime program that provides
connection management—the runtime
program is packaged within the J2EE
application built by the toolkit.
HATS macros and Integration
Objects
You can build Web services using HATS
macros and Integration Objects. Integration
Objects are JavaBeans that run HATS
macros. A HATS macro is a script that
defines navigations through a set of host
terminal screens. Each screen in a macro
includes:
• A description of the screen
• The actions to perform for that screen
• The screen or screens that are presented
after the actions are performed.
For optimal performance, you can configure
connection pooling plus connect and
disconnect macros. A connect macro
“primes” a connection in a pool by
navigating to the screen at which a ‘data’
macro can begin. A data macro prompts for
input, navigates through the application to
extract data based on the input, and then
navigates back to where it can prompt for the
next input.
Once macros are recorded to capture the
actions on the terminal screen to complete
a business activity, you need to construct
HATS Integration Objects using the HATS
toolkit. HATS Integration Objects have input
properties for all macro prompts, and output
properties for all macro extracts. You can use
the feature of chaining to compose one or
more interactive flows through the terminal
application. Integration Object chaining is
necessary when a single major task can take
different screen navigation paths based on
programmatic decisions.
HATS and Web services
Once Integration Objects are created in
HATS, you can use the HATS toolkit to
create Web services. These Web services
provide the interface needed to invoke
the business logic captured in the macros.
Hence, with support for SOA in HATS,
you can now extend existing terminal
applications as Web services and make
them “integration ready” to link to new
applications. This enables “on-the-fly”
integration among existing applications
and across multiple business units across
the enterprise. You can then link or
integrate these applications into end-to-end,
automated business processes — the essence
of being an On Demand Business. This
integration can be extended to partners,
suppliers and customers to further automate
business processes and drive higher
productivity and efficiencies.
WebSphere Business Modeler and
WebSphere Integration Developer
Within the context of business integration,
there is a definite requirement for an
integration framework that bridges the gap
between the business people and the IT
world. Business Process Execution Language
for Web Services (BPEL4WS) fulfills this
requirement by providing a
standard XML language
for expressing business
processes consisting
of functions defined
through Web services
interfaces.
A business
analyst can use
WebSphere Business
Modeler (WBM) to
choreograph business
functions into a
logical process
model. WBM
provides
February 2006 z/OS HOT TOPICS Newsletter, Issue 14 39