comment on

Hi monks, I apologize in advance for the length of this one:
My job for the past few months has been retrieving webpages from the internet for a meta search engine. Until now I have done so using basic url queries (e.g http://www.imdb.com/finds=all&q=cats for all movies with cats in the title). For this I have used the LWP::UserAgent with much satisfaction. In the past few weeks I have been trying to understand and retrieve web pages with SOAP. The information I had in my hand on how to do so (besides the web) were a few programs that my predecessor wrote that uses SOAP. In all these programs but one, he used the LWP::UserAgent to retrieve the web pages, sending the SOAP content as part of the request object in POST. This demo is an example of such a search request (it needs IP-authentication to work, but it sends all the required information):

 #!/usr/bin/perl
use HTTP::Cookies;
use strict;
use LWP::UserAgent;
{
    my $ua = new LWP::UserAgent;
    $ua->cookie_jar(HTTP::Cookies->new());
    push @{$ua->requests_redirectable}, 'POST';
    my $search_command = "http://wok-ws.isiknowledge.com/esti/soap/Sea
+rchRetrieve";
    my $content = '<?xml version="1.0" encoding="UTF-8"?><SOAP-ENV:Env
+elope xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:SOA
+P-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="htt
+p://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/
+1999/XMLSchema" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/so
+ap/encoding/"><SOAP-ENV:Body><namesp1:search xmlns:namesp1="http://wo
+k-ws.isiknowledge.com/esti/soap/SearchRetrieve?wsdl"><databaseId xsi:
+type="xsd:string">DIIDW</databaseId><query xsi:type="xsd:string">TS=(
+create)</query><editions xsi:type="xsd:string"/><firstRec xsi:type="x
+sd:int">1</firstRec><numRecs xsi:type="xsd:int">1</numRecs></namesp1:
+search></SOAP-ENV:Body></SOAP-ENV:Envelope>';

    my $header = new HTTP::Headers (
        'Content-Type'   => 'text/xml; charset=utf-8',
        'User-Agent'     => 'PHP SOAP 0.1',
        'Content-Type'   => 'text/xml; charset=utf-8',
        'SOAPAction'     =>  "http://wok-ws.isiknowledge.com/esti/soap
+/SearchRetrieve?wsdl#search",
    );

    my $req = new HTTP::Request('POST',$search_command,$header,$conten
+t);
    my $res = $ua->request($req);
    print $req->as_string."\n";
    my $response = $res->headers_as_string();
    my $response .= $res->content;
    print "---response---\n$response\n";
}
[download]

As I have said, this was the way most of the programs sent their info. However, this particular program used the SOAP::Lite module to create the same search request. The code is:

#!/exlibris/metalib/m4_b/product/bin/perl

sub BEGIN {
    unshift (@INC, $ENV{'aleph_ext'});
    unshift (@INC, "$ENV{'aleph_product'}"."/perl/lib/site_perl/5.005"
+);
    unshift (@INC, "$ENV{'aleph_product'}"."/perl/lib/site_perl/5.005/
+i686-linux");
}

use SOAP::Lite+trace => 'debug';

my $soap_request = SOAP::Lite->new();
$soap_request->uri("http://wok-ws.isiknowledge.com/esti/soap/SearchRet
+rieve?wsdl");
$soap_request->proxy("http://wok-ws.isiknowledge.com/esti/soap/SearchR
+etrieve");

$service = 'search';

my $soap_response = $soap_request->$service(
    SOAP::Data->name(databaseId => 'DIIDW'),
    SOAP::Data->name(query      => 'TS=(create)'),
    SOAP::Data->name(editions   => ""),
    SOAP::Data->name(firstRec   => '1'),
    SOAP::Data->name(numRecs   => '1'),
);
[download]

As you can see, the code is much more simple, and basically creates the same request from scratch. If you run both demos, you should get the same output. In fact, I built the first demo from the second, using the info that was sent through the module to "convert" the transaction. However, when I tried to convert the other programs from the LWP::UserAgent form of transaction to the SOAP::Lite form, I failed miserabely.
Looking at the SOAP::Lite module in CPAN, I haven't been able to find explanations about how to create a SOAP request like my predacessor did(e.g. how do you know what the soap action is). My questions are (and again, sorry for the length):
1) When should I use the LWP::UserAgent, and when should I use SOAP::Lite?
2) When using SOAP::Lite, how and when can I build the SOAP content from scratch. What should I use for the SAOP action (In my demo it was the uri with a prefix, but is that the how its done all the time)?
3) What advantages does SOAP::WSDL give me over SOAP::Lite. Is it more recommended?

Any links to examples and info sites will be greatly appreciated.
Thanks a lot
Guy Naamati (mrguy123)

The rain it raineth on the just, and also on the unjust fella,
But chiefly on the just, because the unjust steals the just's umbrella.
-- Lord Bowen

2006-07-19 Retitled by holli, as per Monastery guidelines
Original title: 'SOAP::Lite vs LWP::UserAgent for SOAP transcations'

In reply to SOAP::Lite vs LWP::UserAgent for SOAP transactions by mrguy123

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