Chapter 3 Service Endpoint Design

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3.4.1.4

Interfaces with Overloaded Methods

In your service interface, you may overload methods and expose them to the ser 

vice's clients. Overloaded methods share the same method name but have different

parameters and return values. If you do choose to use overloaded methods as part of

your service interface, keep in mind that there are some limitations, as follows:

  If you choose the WSDL to Java approach, there are limitations to represent 

ing overloaded methods in a WSDL description. In the WSDL description, 

each method call and its response are represented as unique SOAP messages. 

To represent overloaded methods, the WSDL description would have to sup 

port multiple SOAP messages with the same name. WSDL version 1.1 does 

not have this capability to support multiple messages with the same name. 

  If you choose the Java to WSDL approach and your service exposes overload 

ed methods, be sure to check how any vendor specific tools you are using rep 

resent these overloaded methods in the WSDL description. You need to ensure 

that the WSDL representation of overloaded methods works in the context of 

your application.

Let's see how this applies in the weather service scenario. As the provider,

you might offer the service to clients, letting them look up weather information by

city name or zip code. If you use the Java to WSDL approach, you might first

define the 

WeatherService

 interface as shown in Code Example 3.4.

public interface WeatherService extends Remote {

public String getWeather(String city) throws RemoteException;

public String getWeather(int zip) throws RemoteException;

}

Code Example 3.4

WeatherService

 Interface for Java to WSDL Approach

After you define the interface, you run the vendor provided tool to create the

WSDL from the interface. Each tool has its own way of representing the

getWeather

 overloaded methods in the WSDL, and your WSDL reflects the par 

ticular tool you use. For example, if you use the J2EE 1.4 SDK from Sun Micro 

systems, its 

wscompile

 tool creates from the 

WeatherService

 interface the WSDL

shown in Code Example 3.5.