This recipe explains how to define a web service with operations that return a value to the client. The methods that are returning values are used in synchronous and asynchronous communication. The best practice when using multiple parameters in web service methods is to define the complex elements and their corresponding complex objects. This also applies to the returning types.
However, we don't always have the ability to define by the best practice. Indeed, when integrating existing applications, we usually bump into legacy methods which we are not able to change.
We will use the book library example that we have used throughout the chapter and enable one of the non-exposed class methods to become a web service operation that returns a value to the client.
The steps involved in defining a web service methods that return values are as follows:
- In JDeveloper, open the
BookLibrary.javainterface class. In front of theaddBookmethod, add the@WebMethodannotation and save the file.@WebMethod public int addBook(int id, String Author, String Title, int Year); - Now open the
BookLibraryImpl.javaimplementation class. Remove the annotation from theaddBookmethod as shown in the following code:@WebMethod(exclude = true) public int addBook(int id, String Author, String Title, int Year) { - Now we have a method that returns a value (
book id) to the client.
Let's examine the WSDL document that describes the newly defined operation. The operation consists of an input and output message. No fault message is defined. The following is the code:
<operation name="addBook"> <input message="tns:addBook"/> <output message="tns:addBookResponse"/> </operation>
The input message consists of four parameters defining the book as shown in the following code:
<xs:complexType name="addBook">
<xs:sequence>
<xs:element name="arg0" type="xs:int"/>
<xs:element name="arg1" type="xs:string" minOccurs="0"/>
<xs:element name="arg2" type="xs:string" minOccurs="0"/>
<xs:element name="arg3" type="xs:int"/>
</xs:sequence>
</xs:complexType>The output (response) message is more interesting. This message consists of one parameter defining the ID of the added book as shown in the following code:
<xs:complexType name="addBookResponse">
<xs:sequence>
<xs:element name="return" type="xs:int"/>
</xs:sequence>
</xs:complexType>Note that the web service operation now returns the value of type integer and holds the ID of the added book.