As the complexity of distributed applications increases, an increasing amount of processing is done using distributed processes, which typically execute without the direct supervision of an end user. The user must poll these processes periodically to check if they are completed successfully or not. This polling results in unnecessary wastage of network bandwidth as well as computing resources. The user generally cannot see intermediate results or progress reports for long running processes, they must wait till the process is completely finished before viewing the results.
Thus the problem of monitoring events is central in distributed applications and protocols. A repeated need in such applications is to receive notifications when a resource property value changes or event state changes. Current database systems provides mechanisms like constraints, triggers and active database rules. These facilities provides an automated means to ensure the database integrity or perform specific action when data changes. Need for such kind of requirement is fundamental is network applications.
I will describe the Event Notifications Requirements. I will also briefly explain on application of Event Notifications in Software engineering environments.