ivelin 2002/08/31 22:06:17
Modified: src/documentation/xdocs/howto book.xml
src/documentation/xdocs/plan changes-doc.xml
src/documentation/xdocs/userdocs/generators book.xml
Added: src/documentation/images wsproxy_CompositePage.png
wsproxy_Proxies.png wsproxy_Screenshot1.png
wsproxy_Screenshot2.png wsproxy_Sequence.png
src/documentation/xdocs/userdocs/generators
wsproxy-generator.xml
Log:
added documentation for WebServicePorxyGenerator
Revision Changes Path
1.1 xml-cocoon2/src/documentation/images/wsproxy_CompositePage.png
<<Binary file>>
1.1 xml-cocoon2/src/documentation/images/wsproxy_Proxies.png
<<Binary file>>
1.1 xml-cocoon2/src/documentation/images/wsproxy_Screenshot1.png
<<Binary file>>
1.1 xml-cocoon2/src/documentation/images/wsproxy_Screenshot2.png
<<Binary file>>
1.1 xml-cocoon2/src/documentation/images/wsproxy_Sequence.png
<<Binary file>>
1.10 +2 -11 xml-cocoon2/src/documentation/xdocs/howto/book.xml
Index: book.xml
===================================================================
RCS file: /home/cvs/xml-cocoon2/src/documentation/xdocs/howto/book.xml,v
retrieving revision 1.9
retrieving revision 1.10
diff -u -r1.9 -r1.10
--- book.xml 15 Aug 2002 13:43:18 -0000 1.9
+++ book.xml 1 Sep 2002 05:06:17 -0000 1.10
@@ -1,36 +1,27 @@
<?xml version="1.0"?>
<!DOCTYPE book PUBLIC "-//APACHE//DTD Cocoon Documentation Book V1.0//EN"
"../dtd/book-cocoon-v10.dtd">
-
-<book software="Apache Cocoon"
- title="Apache Cocoon HOWTO Documentation"
- copyright="@year@ The Apache Software Foundation">
-
+<book software="Apache Cocoon" title="Apache Cocoon HOWTO Documentation"
copyright="@year@ The Apache Software Foundation">
<menu label="Navigation">
<menu-item label="Main" href="../index.html"/>
</menu>
-
<menu label="How-Tos">
<menu-item label="Index" href="index.html"/>
</menu>
-
<menu label="Using Cocoon">
<menu-item label="XMLForm" href="xmlform-wizard/howto-xmlform-wizard.html"/>
<menu-item label="Paginator" href="howto-paginator-transformer.html"/>
<menu-item label="HTML-PDF" href="howto-html-pdf-publishing.html"/>
+ <menu-item label="Web Syndication"
href="../userdocs/generators/wsproxy-generator.html"/>
<menu-item label="Chaperon" href="chaperon/howto-chaperon-intro.html"/>
</menu>
-
<menu label="Documentation">
<menu-item label="Author How-To" href="howto-author-howto.html"/>
<menu-item label="Author FAQ" href="howto-author-faq.html"/>
<menu-item label="Author Snippet" href="howto-author-snippet.html"/>
<menu-item label="Author Docs" href="howto-author-core-docs.html"/>
</menu>
-
<menu label="Contribution">
<menu-item label="Prepare patch" href="howto-patch.html"/>
<menu-item label="Bugzilla" href="howto-bugzilla.html"/>
</menu>
-
-
</book>
1.20 +6 -1 xml-cocoon2/src/documentation/xdocs/plan/changes-doc.xml
Index: changes-doc.xml
===================================================================
RCS file: /home/cvs/xml-cocoon2/src/documentation/xdocs/plan/changes-doc.xml,v
retrieving revision 1.19
retrieving revision 1.20
diff -u -r1.19 -r1.20
--- changes-doc.xml 13 Aug 2002 05:02:37 -0000 1.19
+++ changes-doc.xml 1 Sep 2002 05:06:17 -0000 1.20
@@ -43,6 +43,11 @@
Established the new <code>cocoon-docs</code> mailing list.
</action>
+ <action dev="II" type="add" due-to="Ivelin Ivanov"
due-to-email="[EMAIL PROTECTED]">
+ Added WSDL descriptor and a REST style resource version
+ of the XMLForm demo.
+ </action>
+
<action dev="DS" type="update">
Updated and refactored some planning docs.
</action>
1.4 +2 -9 xml-cocoon2/src/documentation/xdocs/userdocs/generators/book.xml
Index: book.xml
===================================================================
RCS file:
/home/cvs/xml-cocoon2/src/documentation/xdocs/userdocs/generators/book.xml,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- book.xml 15 Aug 2002 13:43:18 -0000 1.3
+++ book.xml 1 Sep 2002 05:06:17 -0000 1.4
@@ -1,15 +1,10 @@
<?xml version="1.0"?>
<!DOCTYPE book PUBLIC "-//APACHE//DTD Cocoon Documentation Book V1.0//EN"
"../../dtd/book-cocoon-v10.dtd">
-
-<book software="Apache Cocoon"
- title="Apache Cocoon Generators"
- copyright="@year@ The Apache Software Foundation">
-
+<book software="Apache Cocoon" title="Apache Cocoon Generators" copyright="@year@
The Apache Software Foundation">
<menu label="Navigation">
<menu-item label="Main" href="../../index.html"/>
<menu-item label="User Documentation" href="../index.html"/>
</menu>
-
<menu label="Generators">
<menu-item label="Overview" href="generators.html"/>
</menu>
@@ -32,6 +27,7 @@
<menu-item label="Error Generator" href="error-generator.html"/>
<menu-item label="Search Generator" href="search-generator.html"/>
<menu-item label="LinkStatus Generator" href="linkstatus-generator.html"/>
+ <menu-item label="Web Service Proxy Generator" href="wsproxy-generator.html"/>
<menu-item label="Text Parser Generator" href="textparser-generator.html"/>
</menu>
<menu label="Optional">
@@ -39,7 +35,4 @@
<menu-item label="XML:DB Generator" href="xmldb-generator.html"/>
<menu-item label="XML:DB Collection Generator"
href="xmldbcollection-generator.html"/>
</menu>
-
</book>
-
-
1.1
xml-cocoon2/src/documentation/xdocs/userdocs/generators/wsproxy-generator.xml
Index: wsproxy-generator.xml
===================================================================
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.0//EN"
"../../dtd/document-v10.dtd">
<document>
<header>
<title>Portal Syndication with Web Services and Cocoon</title>
<authors>
<person name="Ivelin Ivanov" email="[EMAIL PROTECTED]"/>
</authors>
</header>
<body>
<s1 title="What Is Web Syndication?">
<p>
Web Site Syndication has gained popularity as more and more web sites cross
reference each other, not only by a single hyperlink, but also by embedding parts of
their content. The idea was pioneered by Netscape with their Rich Site Summary (RSS)
(<link
href="http://www.oasis-open.org/cover/rss.html";>http://www.oasis-open.org/cover/rss.html</link>)
XML format. RSS was developed in early 1999 to populate Netscape's My Netscape portal
with external newsfeeds ("channels"). Since then RSS has taken on a life of its own
and now thousands of Web sites use RSS as a "what's new" mechanism to drive traffic
their way.
</p>
<p>
The current RSS 1.0 standard is an application of Resource Description Framework
(RDF) (<link
href="http://www.w3.org/TR/rdf-schema/";>http://www.w3.org/TR/rdf-schema/</link>). RDF
is a framework for describing and interchanging metadata. The RDF framework is
extensible and allows adding new types of entities. It also gives meaning to resources
to enable automated processing of Web resources.
</p>
<p>
RSS is unarguably an example of an organically grown and widely accepted standard.
For long it was not endorsed by any of the popular standards committees. Even so it
quickly became popular and found a large number of creative uses. Lately though it has
reached its limits. There is a demand for more advanced portal syndication which RSS
cannot satisfy.
</p>
</s1>
<s1 title="Going beyond RSS with Web services ">
<p>
Latest generation web portals demand more than simply posting cross linked news
stories from RSS. Embedding and personalizing rich content and behavior from remote
portals is becoming necessity. Limited success has been achieved through complex and
sophisticated backend integration via proprietary or Web Services compliant protocols.
Recognizing the growing demand, influential organizations have attempted to develop
new languages such as:
</p>
<s2 title="Web Services Experience Language (WSXL)">
<p>
(<link
href="http://www.webservices.org/index.php/article/articleview/345/";>http://www.webservices.org/index.php/article/articleview/345/</link>)
</p>
<p>
<em>
"WSXL is a Web services centric component model for interactive Web
applications. WSXL is designed to achieve two main goals: enable businesses to
distribute Web applications through multiple revenue channels, and enable new
services or applications to be created by leveraging existing applications
across the Web."
</em>
</p>
</s2>
<s2 title="Web Services Inspection Language (WSIL)">
<p>
(<link
href="http://www.webservices.org/index.php/article/articleview/85/";>http://www.webservices.org/index.php/article/articleview/85/</link>)
</p>
<p>
<em>
"The specification allows a Web services provider to publish a WS-Inspection
(WSIL) document which lists the services on offer and their corresponding WSDL (Web
services description language) files. The convention is that the WSIL document should
be called "inspection.wsil" and be located at a common entry point to the web site.
This paves the way for future Web services "crawlers" to locate and parse WSIL
documents for Web service search engines."
</em>
</p>
</s2>
<s2 title="Web Services for Remote Portals (WSRP)">
<p>
(<link
href="http://www.oasis-open.org/committees/wsrp/";>http://www.oasis-open.org/committees/wsrp/</link>)
</p>
<p>
<em>
"Defining an XML and Web services standard that will allow the plug-n-play of
visual, user-facing Web services with portals or other intermediary Web applications"
</em>
</p>
</s2>
<s2 title="Web Services for Interactive Applications ">
<p>
(<link
href="http://www.oasis-open.org/committees/wsia/";>http://www.oasis-open.org/committees/wsia/</link>)
</p>
<p>
<em>
"Create an XML and web services centric framework for interactive web
applications. The designs must achieve two main goals: enable businesses to distribute
web applications through multiple revenue channels, and enable new services or
applications to be created by leveraging existing applications across the Web. "
</em>
</p>
</s2>
<p>
While these efforts are certainly worthwhile and promising, it will most likely take
years before they pass the filters of real life use before they can claim widespread
adoption. All of them ask for a thick infrastructure layer to support implementations.
While possible, it is unlikely that mainstream deployment will be achieved instantly.
</p>
<p>
Not all is lost though. Fortunately, there is way to satisfy a large portion of the
syndication requirements by applying already established technologies and tools. We
will illustrate the architecture of a possible solution using an open source framework
for XML Publishing - Apache Cocoon.
</p>
</s1>
<s1 title="Apache Cocoon">
<p>
(<link
href="http://xml.apache.org/cocoon/index.html";>http://xml.apache.org/cocoon/index.html</link>)
</p>
<p>
<em>
"Apache Cocoon is an XML publishing framework that raises the usage of XML and
XSLT technologies for server applications to a new level. Designed for performance and
scalability around pipelined SAX processing, Cocoon offers a flexible environment
based on a separation of concerns between content, logic, and style. To top this all
off, Cocoon's centralized configuration system and sophisticated caching help you to
create, deploy, and maintain rock-solid XML server applications"
</em>
</p>
<p>
First, let's describe a typical use case scenario: User logs in to a familiar portal
and happily surfs about. At some point the user clicks on a link which leads to a
strange page. It has the portal logo, even shows the same login id but still looks
very different and unfriendly... After some time and frustration the user gets used to
switching back and forth between the two faces of the portal... while looking for
another provider which offers both services in a coherent graphical interface.
</p>
<p>
For those who have never had similar experience, we will give a popular example.
Yahoo! Autos (<link
href="http://autos.yahoo.com/finance.html?refsrc=autos/insurance";>http://autos.yahoo.com/finance.html?refsrc=autos/insurance</link>)
offers an easy to use interactive catalog of cars. However when it comes to insuring
an automobile, applying for a loan or buying a car, the web site hyperlinks to a
co-branded page of another company. For example Lending Tree
(<link
href="https://www.lendingtree.com/newauto/secure/ctl_borrower.asp?page=loan_selection&verb=continue&O_loan_type=LOAN_TYPE_AUTO&bp=yahooautos&source=40050&alliance=true&SITEID=&templxlname=&templxssn1=&templxssn2=&templxssn3=";>https://www.lendingtree.com/newauto/.....</link>
)
will show Yahoo! Autos logo at the top of the screen, however the rest of the page
looks very different than any other Yahoo! page. All the personalization spoils that a
Yahoo! user enjoys are lost as soon as the application for a loan begins. Not only the
colors and layout are different. A login session with Yahoo! does not carry over to
Lending Tree. On top of that a pop-up window appears when switching between the two
sites, which reads "You are about to view pages over a secure connection...". When
added up these "negligible" inadequacies, lead to an overall poor experience, which is
certainly not the original intent of the Yahoo! content producers.
</p>
<p>
Now as we have an idea of how things are not supposed to work, we will show that
outsourcing interactive components to a third party site, while preserving the look
& feel of the original portal is still possible when done right. As we mentioned
Cocoon offers a solution. Since Cocoon is a very sophisticated framework, an indepth
analysis of its features is beyond the scope of this text to cover.
</p>
</s1>
<s1 title="Web Services Proxy to the rescue">
<p>
The latest version of Cocoon is 2.1, and it has a new Web Service Proxy component.
It is this component which we shall focus on for the reminder of the text. To follow
the rest of the article, it will be useful (but not essential) to have a basic
knowledge of Cocoon 2.
</p>
<p>
Combined with the <link
href="../../howto/xmlform-wizard/howto-xmlform-wizard.html">XMLForm</link> component
of Cocoon 2 and XSLT, the Web Service Proxy component allows vendors to share
interactive content with little effort. The Web Service Proxy takes advantage of the
fact that a Cocoon web application produces XML content which is later translated into
multiple presentation formats, like HTML or WML. Once the proxy is plugged in the
Cocoon sitemap, it transparently pipes browser requests to a remote web application
and returns the response back to the sitemap for local styling. Receiving a client
independent XML format, allows the local site to pull content and style it with XSLT
with the desired Look & Feel.
</p>
<p>
<strong>
Q. Ok, styling presentation is easy to understand, but how is a form
submitted to the original site?
</strong>
</p>
<p>
The XMLForm component is the answer. It uses W3C XForms included in the XML
content which allows the end user to directly interact with the remote server through
the embedding site. The form markup in the XML content of an embedded page uses
relative URL address for the target action, when the end user submits, the form data
is sent to the containing site, which captures the form data and the relative URL. The
Web Service Proxy then takes this information and re-submits it to the original site.
It then reads the XML response and makes it available to the sitemap for styling again.
</p>
<p>
<strong>
Q. Hmm... a typical web application maintains a user session while
navigating. How is the containing site propagating the end user session to the
embedded site?
</strong>
</p>
<p>
The answer is simple. The Web Service Proxy simply hooks to the end user session,
and automatically starts its own session with the remote site. If the remote site
requires authentication, then the developer of the local web site has to pass the user
credentials as parameters to the WebServiceProxyGenerator.
</p>
<p>
<strong>
Q. What transport protocols are supported?
</strong>
</p>
<p>
HTTP 1.0, HTTP 1.1, HTTPS.
</p>
<p>
Below we will illustrate the architecture of the solution with some example code and
figures.
</p>
<figure src="images/wsproxy_Proxies.png" alt="Figure 1 - Traditional Http
Proxy vs Cocoon Web Service Proxy"/>
<p>
<em>
Figure 1 - Architecture of the Web Service Proxy Solution. As opposed to a
traditional proxy server, the Web Services Proxy captures user input and allows the
web site to remain coherent even when the functionality for some of its components is
delivered remotely.
</em>
</p>
<figure src="images/wsproxy_CompositePage.png" alt="Figure 2 - Illustration of
the data flow for a composite page"/>
<p>
<em>
Figure 2 - Illustration of the data flow for a composite page. Some of the content
is locally constructed, the rest is obtained remotely. Finally the same styling is
applied and the user facing page appears consistent.
</em>
</p>
<p>
Now we will show a snippet of the sitemap which employs the Web Service Proxy.
Notice its brevity! The Web Service Proxy completely handles the content and
navigation logic between the two portals. Only stylesheets are additionally required
to translate the remotely retrieved documents into a user friendly format.
</p>
<source><![CDATA[
<?xml version="1.0"?>
<map:sitemap xmlns:map="http://apache.org/cocoon/sitemap/1.0";>
<!-- =========================== Components ================== -->
<map:components>
<map:generators default="file">
<map:generator name="wsproxy"
src="org.apache.cocoon.generation.WebServiceProxyGenerator"
logger="webapp.wsproxy"/>
</map:generators>
</map:components>
....
<!-- =========================== Pipelines ====================== -->
<map:pipelines>
<map:pipeline>
<!-- Interactive Web Application Syndication -->
<map:match pattern="*">
<map:generate type="wsproxy"
src="http://{header:host}/cocoon/samples/xmlform/wizard?cocoon-view=xml";
label="xml"/>
<map:transform src="stylesheets/newWizard2html.xsl" />
<map:transform
src="context://samples/stylesheets/xmlform/xmlform2html.xsl"/>
<map:serialize type="html"/>
</map:match>
</map:pipeline>
</map:pipelines>
</map:sitemap>
<!-- end of file -->
]]></source>
<figure src="images/wsproxy_Sequence.png" alt="Figure 3 - sequence diagram "/>
<p>
<em>
Figure 3 - Above is a sequence diagram outlining the interaction between the key
participants in a syndication session.
</em>
</p>
<figure src="images/wsproxy_Screenshot1.png" alt="screen shot 1"/>
<p>
<em>
Figure 4 - Sample screenshot from a remotely enabled application as it appears
standalone.
</em>
</p>
<figure src="images/wsproxy_Screenshot2.png" alt="screen shot 2" />
<p>
<em>
Figure 5 - Sample screenshot from the same application, embedded in another web
application.
</em>
</p>
<p>
The content of the original XML page behind these two screenshot follows:
</p>
<source><![CDATA[
<?xml version="1.0"?>
<document xmlns:xf="http://xml.apache.org/cocoon/xmlform/2002";>
<xf:form id="form-feedback" view="userIdentity" action="wizard" method="GET">
<xf:caption>Personal Information</xf:caption>
<error>
<xf:violations class="error"/>
</error>
<xf:textbox ref="firstName">
<xf:caption>First Name</xf:caption>
<xf:violations class="error"/>
</xf:textbox>
....
<xf:selectMany ref="role" selectUIType="listbox">
<xf:caption>Professional roles</xf:caption>
<xf:item>
<xf:caption>Geek</xf:caption>
<xf:value>Geek</xf:value>
</xf:item>
<xf:item>
<xf:caption>Hacker</xf:caption>
<xf:value>Hacker</xf:value>
</xf:item>
....
</xf:selectMany>
...
<!-- hidden model attribute -->
<xf:hidden ref="hidden">
<xf:value>true</xf:value>
</xf:hidden>
...
<xf:submit id="next" class="button">
<xf:caption>Next</xf:caption>
</xf:submit>
</xf:form>
<xf:output ref="count" id="show_count" form="form-feedback" class="info">
<xf:caption>Visits Count</xf:caption>
</xf:output>
</document>
]]></source>
<p>
The listing above contains markup in the XMLForm namespace. It is a presentation
independent way to specify input controls. Being XForms compliant it is easy to learn
and use. The XSLT stylesheets used to convert the XML above are very simple and will
not be listed here. They can found in the Cocoon 2.1 distribution.
</p>
</s1>
<s1 title="Conclusion">
<p>
The Web Service Proxy component is tightly integrated with the Cocoon framework and
is particularly convenient to use in combination with XMLForm to enable syndication of
Web site functionality. With the presented sample, we only scratched the service of
the possible applications. It is easy to see though for a creative mind how it can be
extended in multiple directions. Although the solution we offered is conveniently
applied with Cocoon, the concepts are generally applicable outside the framework as
well. Exposing a Web Application functionality via XML is not just a "neat" feature
any more. It opens the gates to a constellation of opportunities, not possible with
the classical Model-2 approach where the business logic is directly tied to a
graphical output like HTML.
</p>
<s2 title="Have more questions? ">
<p>
Look at the online demo available here:
<link
href="/cocoon/samples/webserviceproxy/">/cocoon/samples/webserviceproxy/</link>.
</p>
<p>
Then study the source code and if you still have questions, join the cocoon
users email list and ask. If you have ideas for improvement then you are more than
welcome to discuss it on the cocoon development email list and eventually submit a
patch through the Apache bug tracking system.
</p>
</s2>
</s1>
</body>
</document>
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