IBM E02HMLL-I Implementation Guide - Page 21

A business object reflects a data entity-a collection of data that can be treated as an operative unit. For example, a data entity can be equivalent to a form, inclusive of all of the form's fields. The form might typically be used in an application, or over the Web, to contain business information about customers, or employees, or invoices. Business objects are cached in memory during collaboration execution for fast access, and also stored in a persistent transaction state store to provide robust recovery, rollback, and re-execution of collaborations upon server restarts after failures. The IBM WebSphere Business Integration Server Express system creates business objects that reflect the information contained in entities. In this documentation, a data entity is often referred to in the context of the kind of business information it contains-for example, an employee entity or a customer entity. This section provides a first look at business objects. More detail is provided in the Business Object Development Guide. Roles of a business object A business object can act as an event, a request, or a response. Event A business object can report the occurrence of an application event, an operation that affected a data entity in an application. The application event might be the creation, deletion, or change in value of that collection of data. When a connector detects an application event and sends a business object to an interested collaboration, the business object has the role of representing the event, and so it is called an event in the IBM WebSphere Business Integration Server Express system. For example, a connector might poll an application for new employee entities on behalf of a collaboration. If the application creates a new employee entity, the connector sends an event business object to the collaboration. Request Requests are typically generated in one of two ways: v A collaboration can send a business object as a request to a connector, instructing the connector to insert, change, delete, or retrieve some data in an application. For example, in the service billing collaboration illustrated in Figure 3, the collaboration sends two business objects to connectors, one to retrieve a contract and one to create an invoice. Both are requests. v The Server Access Interface can send a business object as a request to a collaboration, if that collaboration has been designed or customized to accept the Retrieve verb as a trigger. Response When a connector finishes processing a request, it usually returns a response. For example, after a connector receives a request to retrieve employee data from an application, it sends a business object containing the employee data. Structure of a business object A business object is a self-describing unit that contains a type (its name), processing instructions (a verb), and data (attribute values). Figure 5 is an example of a simple business object, showing its type, verb, and attribute values. Chapter 1. Overview of IBM WebSphere Business Integration Server Express 9