Upgrading and Migrating Siebel Janna Applications > Siebel Janna Terminology and Architecture > Siebel Janna Object Architecture >

Object Interaction Between Layers

In response to a user interaction, when a presentation object requires information, it will request that information through the requestor in the presentation layer. The requestor routes the request to the appropriate Siebel Janna Service Object. You can have as many Siebel Janna Service Objects as you wish. The requestor is unique because it does not need to know where a Siebel Janna Service Object resides, just the name of the Siebel Janna Service Object. The requestor will read the registry, which tells it the location and communication method required to access the Siebel Janna Service Object that will fulfill the request from a presentation object.

In the business layer, SJAS runs as an NT Service. Once started, SJAS establishes a pool of database connections to support the multi-tasking of database interactions. Next, the Siebel Janna Application Server starts a series of listener threads that wait for a request to the database from the Presentation Layer. When a request is received, SJAS creates an instance of the appropriate business object designed to handle the request. Once the request is passed to the business object, SJAS returns to its state of listening or processes the next request. SJAS can handle multiple requests simultaneously when deployed in a multiprocessor environment.

The Siebel Janna Service Objects do some intelligent work. If the service consists of a data request, a JDAO thread is captured (or it will wait until a thread is free) and the data request is sent to the database through the JDAO. The database may return a stream of data. This stream is broken into individual packets of information and sent to the Siebel Janna Service Object. These packets are called Siebel Janna Data Objects and usually represent a single record from a table or view in the database. The Siebel Janna Data Objects are returned to the presentation objects that sent the request.


 Upgrading and Migrating Siebel Janna Applications
 Published: 18 April 2003