xdocs/developer/arch.xml - portals-pluto - Git at Google

 <?xml version="1.0"?>
 <!--
 Copyright 2004 The Apache Software Foundation
 Licensed  under the  Apache License,  Version 2.0  (the "License");
 you may not use  this file  except in  compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed  under the  License is distributed on an "AS IS" BASIS,
 WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
 implied.

 See the License for the specific language governing permissions and
 limitations under the License.
 -->
 <document>
   <properties>
     <author email="unknown">Jean-Baptiste Joret</author>
     <author email="david.AT.daviddewolf.DOT.com">David H. DeWolf</author>
     <title>Pluto Project</title>
   </properties>

 <body>
   <section name="Architecture Overview">

 <p>
     Let's begin by examining Pluto's architecture and underlying concepts.
     First, we briefly explain the portal that runs the RI, and see where
     to find a portlet container inside a portal architecture. Next, we
     investigate Pluto's architecture in detail. Last, we look at how it
     solves one challenging item of the portlet container: portlet deployment.
 </p>

 <p><strong>The Portal</strong>
    <blockquote>
    Pluto normally serves to show how the Portlet API works and
    offers developers a working example platform from which they can test
    their portlets. However, it's cumbersome to execute and test the portlet
    container without a driver, in this case, the portal. Pluto's simple
    portal component is built only on the portlet container's and the JSR
    168's requirements. (In contrast, the more sophisticated, open source
    Apache Jetspeed project concentrates on the portal itself rather than
    the portlet container, and considers requirements from other groups.)
    </blockquote>

    <blockquote>
    Figure 1 depicts the portal's basic architecture. The portal Web
    application processes the client request, retrieves the portlets on
    the user's current page, and then calls the portlet container to
    retrieve each portlet's content. The portal accesses the portlet
    container with the Portlet Container Invoker API, representing the
    portlet container's main interface supporting request-based methods
    to call portlets from a portal's viewpoint. The container's user must
    implement the portlet container's Container Provider SPI (Service
    Provider Interface) callback interface to get portal-related
    information. Finally, the portlet container calls all portlets
    via the Portlet API.
    </blockquote>

    <blockquote>
    <div align="center">
         <p><a href="../images/jw-0801-portal_arch.jpg"><img src="../images/jw-0801-portal_arch-thumb.jpg" alt="Portal Architecture" height="160" width="250" border="0"/></a></p>
         <p><b><i><font size="-1">Figure 1. The simple portal included with Pluto. Click on the picture to enlarge it</font></i></b></p>
    </div>
    </blockquote>
 </p>

 <p><strong>The Portlet Container</strong>
    <blockquote>
    The portlet container, the portlets' runtime environment and a core
    component of each portal, requires knowledge about the portal itself
    and must reuse common code from it. Consequently, the portlet
    container remains completely separated from every other portal component.
    That said, you can embed the standalone portlet container in any portal
    by complying with the portlet container's requirements, such as
    implementing all SPIs.
    </blockquote>

    <blockquote>
    The Portlet Container Invoker API, also called an entrance point, acts
    as the portlet container's main calling interface. The API combines a
    portlet container's lifecycle (init, destroy) with request-based
    calling methods (initPage(), performTitle(), portletService(), and so
    on). Because the portlet container calls a portlet in the end, the
    method signature resembles the Portlet API's main portlet interface,
    except that a portlet identifier must be passed. With this additional
    portlet identifier, the container can determine the portlet and call
    it accordingly.
    </blockquote>

    <blockquote>
    Besides using the APIs to access the portlet container, the portal
    must implement SPIs defined for the portlet container. Therefore,
    the RI introduces container services: pluggable components that can
    be registered at the container to either extend or provide basic
    functionality. The RI includes the following built-in container services
    (the first four must be implemented to run the portlet container, while
    the fifth is optional):
    </blockquote>

    <blockquote>
    <ul>
    <li> Information provider: Gives the portlet container information about
         the portal and its framework. Only known information or information
         that should be stored within the portal is present through this
         interface. Such information includes URL generation with navigational
         state, portlet context, portlet mode, and window-state handling</li>
    <li> Factory manager: Defines how to get an implementation through a
         factory. (A normal portal should already own such an implementation.)</li>
    <li> Log service: Defines a logging facility. (A normal portal should
         already own such an implementation.)</li>
    <li> Config service: Defines how to get configuration values. (A normal portal
         should already own such an implementation.)</li>
    <li> Property manager (optional): A property manager interface implementation
         lets a portal handle properties as defined in the JSR 168 specification.</li>
    </ul>
    </blockquote>

    <blockquote>
    Strictly speaking, the Portlet Object Model also acts as an SPI, but has an
    exceptional position among the SPIs. Therefore, don't consider it part of the
    container services as it deals with all portlet objects and comprises a collection
    of interwoven interfaces.
    </blockquote>

    <blockquote>
    <div align="center">
         <p><a href="../images/jw-0801-pluto_arch.jpg"><img src="../images/jw-0801-pluto_arch-thumb.jpg" alt="Pluto Architecture" height="144" width="250" border="0"/></a></p>
         <p><b><i><font size="-1">Figure 2. The portlet container's architecture. Click on the picture to enlarge it</font></i></b></p>
    </div>
    </blockquote>
 </p>
 <p><strong>Portlet Deployment</strong>
    <blockquote>
    The portlet container can leverage the servlet container's functionality, upon
    which the portlet container is built. To accomplish that, the portlet container
    must inject servlet artifacts into each portlet-application war file, as Figure
    3 shows. The portlet component, Deployment, takes the original war file, then
    injects a new or modified web.xml and a servlet to wrap each portlet and uses
    it as a calling point. Then the portlet deployment passes the modified war
    file to the application server deployment, which deploys it into the
    application server's system. During the portlet's invocation, the portlet
    container calls the injected servlet as an entrance point into the deployed
    portlet war file.
    </blockquote>

    <blockquote>
    <div align="center">
        <p><a href="../images/jw-0801-RI_deploy.jpg"><img src="../images/jw-0801-RI_deploy-thumb.jpg" alt="Deployment" height="170" width="250" border="0"/></a></p>
        <p><b><i><font size="-1">Figure 3. Portlet deployment in the RI. Click on thumbnail to view full-size image.</font></i></b></p>
    </div>
    </blockquote>
 </p>


 <p><strong>Pluto and the WSRP standard</strong>
    <blockquote>
    The JSR 168 aligns closely with the Web Services for Remote Portlets (WSRP) standard.
    Both standards, which emerged at the same time, released open source implementations
    capable of all necessary functions described in the respective specifications.
    As a mutual goal, both standards strive to work well together. As a result,
    the portlet container can run WSRP portlets as a consumer as well as a producer.
    </blockquote>

    <blockquote>
    Pluto must be able to run multiple portlet containers in one portal. Consequently,
    Pluto's portlet container can be instantiated multiple times and, more importantly,
    it can be instrumented in different ways. Each portlet container, therefore, can
    use different implementations for SPIs.
    </blockquote>
 </p>
 </section>
 </body>
 </document>
	<?xml version="1.0"?>
	<!--
	Copyright 2004 The Apache Software Foundation
	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
	implied.

	See the License for the specific language governing permissions and
	limitations under the License.
	-->
	<document>
	<properties>
	<author email="unknown">Jean-Baptiste Joret</author>
	<author email="david.AT.daviddewolf.DOT.com">David H. DeWolf</author>
	<title>Pluto Project</title>
	</properties>

	<body>
	<section name="Architecture Overview">

	<p>
	Let's begin by examining Pluto's architecture and underlying concepts.
	First, we briefly explain the portal that runs the RI, and see where
	to find a portlet container inside a portal architecture. Next, we
	investigate Pluto's architecture in detail. Last, we look at how it
	solves one challenging item of the portlet container: portlet deployment.
	</p>

	<p><strong>The Portal</strong>
	<blockquote>
	Pluto normally serves to show how the Portlet API works and
	offers developers a working example platform from which they can test
	their portlets. However, it's cumbersome to execute and test the portlet
	container without a driver, in this case, the portal. Pluto's simple
	portal component is built only on the portlet container's and the JSR
	168's requirements. (In contrast, the more sophisticated, open source
	Apache Jetspeed project concentrates on the portal itself rather than
	the portlet container, and considers requirements from other groups.)
	</blockquote>

	<blockquote>
	Figure 1 depicts the portal's basic architecture. The portal Web
	application processes the client request, retrieves the portlets on
	the user's current page, and then calls the portlet container to
	retrieve each portlet's content. The portal accesses the portlet
	container with the Portlet Container Invoker API, representing the
	portlet container's main interface supporting request-based methods
	to call portlets from a portal's viewpoint. The container's user must
	implement the portlet container's Container Provider SPI (Service
	Provider Interface) callback interface to get portal-related
	information. Finally, the portlet container calls all portlets
	via the Portlet API.
	</blockquote>

	<blockquote>
	<div align="center">
	<p><a href="../images/jw-0801-portal_arch.jpg"><img src="../images/jw-0801-portal_arch-thumb.jpg" alt="Portal Architecture" height="160" width="250" border="0"/></a></p>
	<p><b><i><font size="-1">Figure 1. The simple portal included with Pluto. Click on the picture to enlarge it</font></i></b></p>
	</div>
	</blockquote>
	</p>

	<p><strong>The Portlet Container</strong>
	<blockquote>
	The portlet container, the portlets' runtime environment and a core
	component of each portal, requires knowledge about the portal itself
	and must reuse common code from it. Consequently, the portlet
	container remains completely separated from every other portal component.
	That said, you can embed the standalone portlet container in any portal
	by complying with the portlet container's requirements, such as
	implementing all SPIs.
	</blockquote>

	<blockquote>
	The Portlet Container Invoker API, also called an entrance point, acts
	as the portlet container's main calling interface. The API combines a
	portlet container's lifecycle (init, destroy) with request-based
	calling methods (initPage(), performTitle(), portletService(), and so
	on). Because the portlet container calls a portlet in the end, the
	method signature resembles the Portlet API's main portlet interface,
	except that a portlet identifier must be passed. With this additional
	portlet identifier, the container can determine the portlet and call
	it accordingly.
	</blockquote>

	<blockquote>
	Besides using the APIs to access the portlet container, the portal
	must implement SPIs defined for the portlet container. Therefore,
	the RI introduces container services: pluggable components that can
	be registered at the container to either extend or provide basic
	functionality. The RI includes the following built-in container services
	(the first four must be implemented to run the portlet container, while
	the fifth is optional):
	</blockquote>

	<blockquote>
	<ul>
	<li> Information provider: Gives the portlet container information about
	the portal and its framework. Only known information or information
	that should be stored within the portal is present through this
	interface. Such information includes URL generation with navigational
	state, portlet context, portlet mode, and window-state handling</li>
	<li> Factory manager: Defines how to get an implementation through a
	factory. (A normal portal should already own such an implementation.)</li>
	<li> Log service: Defines a logging facility. (A normal portal should
	already own such an implementation.)</li>
	<li> Config service: Defines how to get configuration values. (A normal portal
	should already own such an implementation.)</li>
	<li> Property manager (optional): A property manager interface implementation
	lets a portal handle properties as defined in the JSR 168 specification.</li>
	</ul>
	</blockquote>

	<blockquote>
	Strictly speaking, the Portlet Object Model also acts as an SPI, but has an
	exceptional position among the SPIs. Therefore, don't consider it part of the
	container services as it deals with all portlet objects and comprises a collection
	of interwoven interfaces.
	</blockquote>

	<blockquote>
	<div align="center">
	<p><a href="../images/jw-0801-pluto_arch.jpg"><img src="../images/jw-0801-pluto_arch-thumb.jpg" alt="Pluto Architecture" height="144" width="250" border="0"/></a></p>
	<p><b><i><font size="-1">Figure 2. The portlet container's architecture. Click on the picture to enlarge it</font></i></b></p>
	</div>
	</blockquote>
	</p>
	<p><strong>Portlet Deployment</strong>
	<blockquote>
	The portlet container can leverage the servlet container's functionality, upon
	which the portlet container is built. To accomplish that, the portlet container
	must inject servlet artifacts into each portlet-application war file, as Figure
	3 shows. The portlet component, Deployment, takes the original war file, then
	injects a new or modified web.xml and a servlet to wrap each portlet and uses
	it as a calling point. Then the portlet deployment passes the modified war
	file to the application server deployment, which deploys it into the
	application server's system. During the portlet's invocation, the portlet
	container calls the injected servlet as an entrance point into the deployed
	portlet war file.
	</blockquote>

	<blockquote>
	<div align="center">
	<p><a href="../images/jw-0801-RI_deploy.jpg"><img src="../images/jw-0801-RI_deploy-thumb.jpg" alt="Deployment" height="170" width="250" border="0"/></a></p>
	<p><b><i><font size="-1">Figure 3. Portlet deployment in the RI. Click on thumbnail to view full-size image.</font></i></b></p>
	</div>
	</blockquote>
	</p>


	<p><strong>Pluto and the WSRP standard</strong>
	<blockquote>
	The JSR 168 aligns closely with the Web Services for Remote Portlets (WSRP) standard.
	Both standards, which emerged at the same time, released open source implementations
	capable of all necessary functions described in the respective specifications.
	As a mutual goal, both standards strive to work well together. As a result,
	the portlet container can run WSRP portlets as a consumer as well as a producer.
	</blockquote>

	<blockquote>
	Pluto must be able to run multiple portlet containers in one portal. Consequently,
	Pluto's portlet container can be instantiated multiple times and, more importantly,
	it can be instrumented in different ways. Each portlet container, therefore, can
	use different implementations for SPIs.
	</blockquote>
	</p>
	</section>
	</body>
	</document>