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Developing Client Applications to Use a Web Service

<%@ taglib prefix="x" uri="/WEB INF/x rt.tld" %>

  Order:

  Status:

  Name:

Code Example 5.13

JSP Generating a Web Service Response

In this example, the J2EE application first places the order details document

received from the service in the request scope using the key 

orderDetailsXML

.

The next lines are JSP code that use the 

x:out

 JSTL tag to access the order details

XML content. These lines of code select fields of interest (such as order identifier,

status, and name fields) using XPath expressions, and convert the data to HTML

for presentation to a browser client. The JSP code relies on JSTL tags to access

these portions of the order details document. For example, the JSTL tag 

x:out

,

which uses XPath expressions, accesses the order identifier, status, and name

fields in the order details document. When the JSP processing completes, the

result is identical to the HTML page shown in Code Example 5.10.

5.3.6 Handling Exceptions

Two types of exceptions occur for client applications that access Web services:

system exceptions and service specific exceptions, which are thrown by a service

endpoint. System exceptions are thrown for such conditions as passing incorrect

parameters when invoking a service method, service inaccessibility, network error,

or some other error beyond the control of the application. Service exceptions, which

are mapped from faults, are thrown when a service specific error is encountered.

The client application must deal with both types of exceptions.

5.3.6.1

System Exceptions

System exceptions generally involve unanticipated errors such as a network

timeout or an unavailable or unreachable server that occur when invoking a Web

service. Although system exceptions are usually out of the control of the client

developer, you should still be aware that these errors may occur, and you should