Cocoon and Web-Services

Building a video search application with WS and Cocoon
Michael Hielscher IIM O6
Content
 Introduction on WebServices
 What is a WebService
 How to use WebServices
 How can we use a WS inside of Cocoon
 Building a custom Cocoon-Generator
 Using a custom generator in your Sitemap
 Building an application for searching video files
 WS for searching videos
 Transforming WS-XML to HTML
Introduction on WebServices
 WebServices can be compared with RPC like RMI
or .NET Remoting
 Widely used also from companies like google,
amazon…
 WebServices are XML based
(the entire communication between Client and
Service in general)
 WebServices are platform independent – can be
implemented in many languages and systems.
What is a WebService
 A WebService …
 … is an application running in a WebServer environment





(like a typical web application) like on TomCat, or IIS
… has an URL like a Webpage
… offering one or more methods that the client can use
… communicates over HTTP like a normal web
application
… requests and responses are written in SOAP
(a XML format)
… are self-describing
What is a WebService
WebService
Consumer (Client)
WebService
Provider (Server)
Application
Logic
Application
Logic
WS-Toolkit
WS-Toolkit
Message (SOAP)
DB
What is a WebService
WebService
Consumer (Client)
Application
Logic
WS-Toolkit
Describes
WSDL
Reads
Message (SOAP)
Transport HTTP
Netzwerk TCP/IP
WebService
Provider (Server)
Application
Logic
WS-Toolkit
DB
What is a WebService
 How can a Service describe him self?
public String[] doGoogleSearch (String search)
{
…
}
How can a Scheme
program deal with this ???
Netzwerkprogrammierung
7
What is a WebService
 WSDL Examples:
 http://www.webservicex.net/globalweather.asmx?wsdl
 http://api.google.com/GoogleSearch.wsdl
 WS build with Microsoft .NET offer a testing interface
to explore the methods of a WebService:
 http://www.webservicex.net/globalweather.asmx
 http://www.webservicex.net/CreditCard.asmx

What do you think about the last Service for your business
application?
How to use a WebService
 Many WS offer the so called REST interface and can
accessed like a Servlet
 In larger applications the WSDL is used to generate so
called “proxy” classes – objects that perform the RPC
call in the background (like RMI Stubs).
 Short example of weather WS with Visual Studio 2005
How can we use a WS inside of Cocoon
 A WS provides output in XML 
 Cocoon is processing XML in pipelines
 Idea:
Call a WS and than use the output inside of a pipeline
 We need parameters for the method name and values
like Country=Germany – where to specify inside of our
Sitemap?
How can we use a WS inside of Cocoon
 Typical Sitemap:
<?xml version="1.0" encoding="UTF-8"?>
<map:sitemap xmlns:map="http://apache.org/cocoon/sitemap/1.0">
<map:pipelines>
<map:pipeline>
<map:match pattern="index">
<map:generate type="file" src="helloworld.xml"/>
<map:transform type="xslt" src="helloworld2html.xsl"/>
<map:serialize type="html"/>
</map:match>
</map:pipeline>
</map:pipelines>
</map:sitemap>
How can we use a WS inside of Cocoon
 New WS generator:
<map:match pattern="weather">
<map:generate type="WebService"
src="http://www.webservicex.net/globalweather.asmx">
<map:parameter name="Operation"
value="GetWeather"/>
<map:parameter name="CountryName" value="Germany"/>
<map:parameter name="CityName"
value="Berlin"/>
</map:generate>
<map:transform src="weather2html.xsl"/>
<map:serialize type="xhtml"/>
</map:match>
Building a custom Cocoon-Generator
 Cocoon offers multiple generator base classes we can
derive from.
 The one with the most build in features is the
ServiceableGenerator  we use this one.
 Starting with a static content XML generator
(generates always the same static XML output)
Building a custom Cocoon-Generator
import …; // various imports here
public class WSGenerator extends ServiceableGenerator {
public void generate() throws IOException, SAXException,
ProcessingException {
String message = “<PAGE><TITLE>Testing</TITLE></PAGE>”;
InputSource inputSource = new InputSource(new StringReader(message));
SAXParser parser = null;
try {
parser = (SAXParser) this.manager.lookup(SAXParser.ROLE);
parser.parse(inputSource, super.xmlConsumer);
} catch (SAXException e) { throw e;
} catch (Exception e)
{ throw new ProcessingException("Exception: ", e);
} finally { if (parser != null) this.manager.release(parser); }
}}
Building a custom Cocoon-Generator
 In our Sitemap we used parameters for the generator
 we need to access them inside of the generator
import …; // various imports here
public class WSGenerator extends ServiceableGenerator {
public void generate() throws …{
String message = “<PAGE><TITLE>Testing</TITLE><PARAMS>”;
String[] params = parameters.getNames();
for (int i = 0; i < params.length; i++)
message += “<PARAM>” + params[i] + “</PARAM>”;
message += “</PARAMS></PAGE>”;
... // like in last example
Building a custom Cocoon-Generator
 The Sitemap entry again:
<map:match pattern="weather">
<map:generate type="WebService"
src="http://www.webservicex.net/globalweather.asmx">
<map:parameter name="Operation"
value="GetWeather"/>
<map:parameter name="CountryName" value="Germany"/>
<map:parameter name="CityName"
value="Berlin"/>
</map:generate>
<map:transform src="weather2html.xsl"/>
<map:serialize type="xhtml"/>
</map:match>
Building a custom Cocoon-Generator
import …; // various imports here
public class WSGenerator extends ServiceableGenerator {
public void generate() throws … {
String url = this.source + "/" + parameters.getParameter("Operation");
String[] params = parameters.getNames();
boolean first = true;
for (int i = 0; i < params.length; i++) {
if (params[i].equals("Operation")) continue;
if (first) { url += "?“; first = false; } else { url += "&“; }
try {
url += params[i]+"="+parameters.getParameter(params[i]);
} catch (ParameterException e) {}
}
Building a custom Cocoon-Generator
String message = "";
URL Service = new URL(url);
try { InputStream urlStream = Service.openStream();
// read in entire file
byte b[] = new byte[1000];
int numRead = urlStream.read(b);
message = new String(b, 0, numRead);
while (numRead != -1) {
numRead = urlStream.read(b);
if (numRead != -1) {
String newCommands = new String(b,0,numRead);
message += newCommands;
}
}
urlStream.close();
} catch (IOException e) { throw new ProcessingException("Web service error", e); }
... // like in last example
Using a custom generator in your Sitemap
 How can we use our generator now?
 We need to declare the generator in the component
section of the sitemap
 Than we can use it like any other generator in Cocoon
Using a custom generator in your Sitemap
<?xml version="1.0" encoding="UTF-8"?>
<map:sitemap xmlns:map="http://apache.org/cocoon/sitemap/1.0">
<map:components>
<map:matchers default="wildcard">
<map:matcher name="wildcard“
src="org.apache.cocoon.matching.WildcardURIMatcher"/>
</map:matchers>
<map:generators>
<map:generator name="WebService"
src="WebServiceGenerator.WSGenerator"/>
</map:generators>
</map:components>
<map:pipelines>
Building an application for searching video files
 We could define a lot of projects using our new
WebService generator
 I have choose a WS with a lot of features so we can see
the power of cocoon and WS
 Goal:
 We all know the google image search
 It would be great to have a similar search engine for
video files on platforms like YouTube, MyVideo …
 We want a tiny and fast search (no advertisement)
Building an application for searching video files
 The search is performed by a WS offered by
blinkx.com
 We need to call the WS and transform the XML output
into a beautiful HTML page 
 We don’t want to program any cocoon-action or
something in Java – only use the Sitemap and XSL
Building an application for searching video files
 Defining the Sitemap and use request parameters:
<map:pipelines>
<map:pipeline>
<map:match pattern="video">
<map:act type="request">
<map:parameter name="parameters" value="true"/>
<map:generate type="WebService“
src="http://usp1.blinkx.com/partnerapi/user/">
<map:parameter name="Operation" value="api.php"/>
<map:parameter name="uid" value="d3ac0e"/>
<map:parameter name="Text" value="{searchtext}"/>
<map:parameter name="Start" value="{pos}"/>
<map:parameter name="MaxResults" value="{results}"/>
<map:parameter name="AdultFilter" value="{adultfilter}"/>
</map:generate>
<map:transform src="video2html.xsl"/>
<map:serialize type="xhtml"/>
</map:act>
</map:match>
</map:pipeline>
</map:pipelines>
WS for searching video files
 For XSL we need to look on the output of the WS first:
<?xml version="1.0" encoding="UTF-8" ?>
<autnresponse xmlns:autn="http://schemas.autonomy.com/aci/">
<action>QUERY</action>
<response>SUCCESS</response>
<responsedata>
<autn:numhits>10</autn:numhits>
<autn:totalhits>317648</autn:totalhits>
<autn:hit>
<autn:reference>http://www.blinkx.com/…</autn:reference>
<autn:title>Firefighter Catches 3 People Who Jumped Out
Window</autn:title>
<autn:summary>
Stockton Firefighter Mick Connolly is no stranger to fierce flames. Last night,
lives were immediate danger.
</autn:summary>
WS for searching video files
<autn:content>
<DOCUMENT>
<CHANNEL>CBSSacramento</CHANNEL>
<TYPE>Video</TYPE>
<DOMAIN>http://www.cbs13.com/video</DOMAIN>
<FOOTERIMAGE>http://cdn99.blinkx.com/store/images/footers/cbssacramento.gif</FOOTERIMAGE>
<ALTIMAGE>http://cdn99.blinkx.com/store/images/defaultswf/cbs.jpg</ALTIMAGE>
<STATICPREVIEW>http://…</STATICPREVIEW>
<IMAGE>http://…/22760563_swf_0.swf</IMAGE>
<MEDIA_TYPE>video/x-ms-wmv</MEDIA_TYPE>
<MEDIA_TYPE_STRING>Windows Media</MEDIA_TYPE_STRING>
</DOCUMENT>
</autn:content>
<autn:date>1181356390</autn:date>
<autn:datestring>7 hours ago</autn:datestring>
… many of such hits
WS for searching video files
 We get a lot of information from the WS
 We don’t need all of them.
 Selecting only a few that for our search engine like:
preview image, title of the clip, URL where to watch
the movie, number of hits, …
 Logic (Turn pages, number of results displayed per
page,…) is done in JavaScript embedded into the
HTML
Transforming WS-XML to HTML
 XSLT is used to transform XML to HTML
 One fixed size box for each video we found containing
the preview image, title and a link for watching the
movie.
 About one A4 page for the XSL file (not too big at all)
Result – Video Search Application
 Try your self:
http://84.16.228.218:8080/cocoon/WebService/video
Conclusion
 WebServices can be used with XML pipelines like
Cocoon really well 
 Without “programming” we can create a useful
application
 Creating own generators can be useful in Cocoon but
is not very well documented 