HATS applications are deployed on an application server, latest version of HATS supports Apache Geronimo, Oracle WebLogic along with IBM WebSphere application server and portal. HATS application end-users initiate a transaction by entering a URL in a browser. This request travels by a TCP/IP network, the request from the client machine goes to WAS and then to HATS application, HATS application is a standard WebSphere application.
Standard HATS system environment.
The HATS application on WAS connects to the IBM 5350, 3270 or VT terminal can generate web based graphical interface on the fly, it can also combine screens, change workflows, execute macros and perform many different modernizations based on the screen customizations and global rules. Global rules are part of the default rendering approach of the HATS.
These global rules allow recognition or patterns and transformation of the input fields from host. Rules can be defined for the entire project or specific to a certain host screen.
HATS engine checks each host screen against the list of screen events. HATS has following two types of events,
- Application events
- Screen events
Application events are the events that are fired automatically by HATS, they are error events or busy event that is fired by HATS engine, when the host is busy.
Screen customization is a very important concept in the development of a Rational HATS based modernization project. HATS engine decides which set of actions to take when a specific host screen is encountered based on defined screen recognition criteria.