Java Web Services: Up and Running, 2nd Edition

A Perl Client Against a Java RESTful Web Service

The Perl client (see Example 3-1) against the Java predictions2 RESTful service, implemented as an HttpServlet, makes various calls that cover the CRUD operations. (The predictions2 service is from Chapter 2.) Perl comes with most Unixy systems and is available on Windows (see, for example, ActiveState). Although Perl has a quirky syntax—it has been called line-noise interpreted and even worse—its excellent libraries, standard and contributed, more than compensate. In any case, the point of the example is to provide a first look at how a client interacts with a RESTful service. The curl clients from the two previous chapters illustrated all of the CRUD operations against several services; all of the CRUD requests received at least a minimal document in return. Yet the curl utility is meant for making HTTP requests, not processing HTTP responses. The Perl client takes the second step; that is, this client performs all of the CRUD operations and then highlights the challenge of processing response documents. In the case of response documents in XML, the Perl client parses the XML to extract usable information, in this case the id, who, and what of a specified Prediction or of the entire PredictionsList returned from the service.

Example 3-1. A Perl client making CRUD calls against the RESTful predictions2 service

#!/usr/bin/perl -w

# packages
use strict;
use LWP;
use XML::XPath;
use List::MoreUtils qw(each_array);

my $baseUrl = 'http: ...