Rules

When you create a business service class, follow these rules:

• Business service classes are abstract classes and must extend the foundation class BusinessService. BusinessService is the parent class that provides foundation support for transactions and logging.

• Business service classes have only static methods, so to reinforce static behavior and prevent the class from being instantiated, declare an abstract class.

This code sample illustrates extending the BusinessService class and declaring the class as abstract:

public abstract class AddressBookProcessor extends BusinessService {
       
   ...
   }

You design and develop a business service as a static class that processes multiple requests simultaneously. A static class means that only one instance of the class exists in Java virtual memory (JVM), regardless of the number of simultaneous requests being processed. These requests are also called threads.

Static classes reduce object creation. If a business service was not static, one business service would exist for each request. As each request finishes, the class would be released and eventually the system reclaims the memory that the class used. Creating and releasing objects repeatedly causes performance degradation, because more memory is used and more CPU cycles are required.

To ensure that the business service provides a thread-safe environment, you cannot use instance variables in the business service class. An instance variable is a value that is useful to only one request, for example, a counter. A thread-safe environment means that the multiple requests (threads) that are being processed simultaneously do not interfere with each other. The absence of instance variables helps ensure thread safety at compile time. You can include static variables in the business service class. A static variable is a value that is useful to all requests, for example, a cached value that is used to specify a language. A static variable is shared data, independent of a request.