Building Server-Side Eclipse based web applications 2010

Building Server-Side Eclipse based web
applications

Tutorial

Building Server-Side Eclipse based web applications | Tutorial
© Copyright 2007, 2008, 2009, 2010 Jochen Hiller, Simon Kaegi, Gunnar Wagenknecht, IBM Corporation;
1 Source code in this presentation is made available under the EPL, v1.0, remainder of the presentation is licensed under Creative Commons Att. Nc Nd 2.5 license

The authors

Jochen Hiller Simon Kaegi
Deutsche Telekom AG, Germany IBM Rational Software, Canada
jo.hiller@googlemail.com simon_kaegi@ca.ibm.com
Equinox, e4 Committer

Gunnar Wagenknecht
AGETO, Germany
gunnar@wagenknecht.org
Eclipse Committer


Overview
• Introduction to Server-Side Eclipse
• Developing Server-Side Eclipse applications
• Deploying Server-Side Eclipse applications
• Monitoring and Debugging Server-Side Eclipse
applications
• Summary


What is Server-Side Eclipse (SSE)?
• Recognition… that many of the features that have made RCP successful are
equally applicable in server-side contexts.
Standardized component model (OSGi)
Pervasive extensibility – Extension Registry
Runtime provisioning

• Integration... with existing server-side infrastructure and technologies
J2EE Application Servers
Servlets and JSPs
Application Frameworks

• The top level project Eclipse Runtime is an umbrella project for a lot of
server-related projects


What motivates developers to use SSE?
Web developer RCP developer Infrastructure developer
JavaTM EE RCP application
application application framework

+ component model + server support + component model
+ use 3rd party plug-ins + re-use plugins • modular
+ distributed • flexible
applications • dynamic


SSE Based Web Applications
• Component based (Bundles)

• Use the OSGi HttpService (Servlet API)
Explicitly (code) or declaratively (extension registry)

• Consistent development story independent of
deployment constraints
Support for an embedded HttpService
Support for running embedded in Application Servers


Overview
applications
• Summary


Integrating Java EE with the OSGi HttpService
• Replaces web deploy descriptor (e.g. “web.xml”)
• URL mapping differences
• Servlet API support
ServletContext / HttpContext differences
Does not provide “direct” support for Filters, Listeners.
• Dynamic Registration
void registerResources(String alias, String name, HttpContext context)
void registerServlet(String alias, Servlet servlet, Dictionary initparams, HttpContext context)
void unregister(String alias)

Supported in Equinox:
void registerFilter(String alias, Filter filter, Dictionary initparams, HttpContext context)
void unregisterFilter(Filter filter)

Source code in this presentation is made available under the EPL, v1.0, remainder of the presentation is licensed under Creative Commons Att. Nc Nd 2.5 license

URL Mapping Differences
void registerResources(String alias, String name, HttpContext context)

• “alias” roughly equivalent to <url-mapping>
alias of “/myContent” is equivalent to
<url-mapping>
/myContent/*
</url-mapping>

• “name” provides a base path when looking up resources in the
HttpContext.
Supported in Equinox

• No support for extension mappings Syntax is:
{path}/*.jsp
• No implicit welcome file support
eg. mapping “/” to “/index.html”


HttpContext
• Maps 1-1 to a ServletContext Method Summary

String getMimeType(String name)
• Allows implementation of custom
HttpContext
URL getResource(String name)

• MIME type retrieval boolean handleSecurity(
• resource retrieval HttpServletRequest request,
HttpServletResponse response)
• authentication

• Does not directly support: Supported in Equinox (via Reflection)
getNamedDispatcher
getResourcePaths Set getResourcePaths(String path)
getInitParameters (*)
“Context Path” (*)


Servlets and Filters
What’s missing… (*) = Workarounds Available:

• Filter • Technique is to wrap-and-adapt your
now fully supported in Helios Servlet or Resource.
Servlet wrapped = new
• HttpSessionListener ContextListenerServletAdaptor(
myServlet, myListener);
• HttpSessionAttributeListener registerServlet(“/myPath”, wrapped,
params, myHttpContext);
• HttpSessionActivationListener
• org.eclipse.equinox.http.helper[s]
• ServletContextListener (*) in the Equinox-Incubator CVS
• ServletContextAttributeListener not currently API but supported

• ServletRequestListener
• ServletRequestAttributeListener


Dynamic Registration
• Code-based
Lifecycle: tied to Bundle START and STOP
More Complex but provides greater control

• Extension Registry (org.eclipse.equinox.http.registry)
Lifecycle: tied to Bundle RESOLVED and UNRESOLVED
Simpler in most cases

• Declarative Services
Lifecycle: tied to Bundle START and STOP
Requires writing a component file

URL Space is also dynamic and shared across all registrations
No more than one registration per “alias”
Worth planning – useful techniques with relative URLs


JSP Support
• Provided by:
org.eclipse.equinox.jsp.jasper.JspServlet

<< public JspServlet(Bundle bundle, String bundleResourcePath, String alias) >>

• No default constructor
Requires compilation / runtime context from “bundle”

• JSP lookup consistent with OSGi HttpService resource
registration.


JSP Support – Extension Registry
• Extension Registry Support provided by:
org.eclipse.equinox.jsp.jasper.registry.JspFactory
• ExecutableExtensionFactory
<extension point="org.eclipse.equinox.http.registry.servlets">
<servlet
alias="/myPath/*.jsp“
class="org.eclipse.equinox.jsp.jasper.registry.JSPFactory:/bundlePath">
</servlet>
</extension>

• Use “{path}/*.jsp” style alias for JSPs.
Allows a “{path}” resource registration to support more efficiently serving
static resources without an alias namespace collision.


Exercises
• Start Eclipse & configure target platform
• Hello Servlet
• Hello Filter
• Hello JSP
• Hello Servlet Registry
• Hello Filter Registry
• Hello JSP Registry


Overview
applications
• Summary


Recommended deployment scenarios
Deployment depends on target infrastructure:

• Standalone Equinox server application
Embedded HttpService
Lightweight solution – good choice for development
Distribute like Eclipse RCP application

• Run application in External Application Server
Recommended as production solution
Deploy as standard WAR application (scripts provided)


Equinox embedding an HttpService
• Run Equinox as standalone application
• Multiple processes isolated
• Embedded HttpService (e.g. Jetty)
• Application functionality based on bundles, Servlets, JSPs, ...
• Add web services as bundle
• Server management based on bundles

Source: Jeff McAffer, Eclipse Summit Europe, Server-Side Symposium, Oct 12nd 2006


Deploying standalone Equinox server
• Choose target platform
• Add platform specific launchers if required
• Add common services and bundles (see Eclipse Orbit!)
• Add application plug-ins
• Group bundles / plug-ins as features
Servlet JSP Bundles ... ... Application plug-ins

Common services
Launcher

commons- Update
Jetty Jasper 3rdParty
logging, ... Configurator (see Orbit)
Equinox Server-Side Eclipse

Operating System


Deploying Standalone Equinox server
• Deploy like an RCP application
Plugins / Feature / Product based export
You have to include SSE related plugins
Maintain config.ini for starting bundles
• Important config.ini settings:
osgi.console=true # start an OSGi console
osgi.noShutdown=true # do NOT shutdown OSGi
eclipse.ignoreApp=true # do NOT start an Eclipse application
• Or use commandline arguments when using Eclipse starter:
-console # enable OSGi console
-noExit # same as osgi.noShutdown=true


Deploy Standard Equinox – Running the Server
• Start Equinox server
java –Dorg.osgi.service.http.port=8080
–jar pluginsorg.eclipse.equinox.launcher_<version>.jar
–console -noExit


Application Server running an embedded Equinox
• Launch Equinox in traditional application server
• Isolation between multiple web applications/Equinox instances
• Forwarding (Lite) HttpService exposes application server
capabilities
• Application functionality based on bundles, Servlets, JSPs, ...
• Bridging aspect is referred to as the Servletbridge

Servlet JSP Servlet JSP

Bundles Servletbridge HTTP Service Bundles Servletbridge HTTP Service

Equinox Equinox

Equinox WAR … Equinox WAR
Bridge Servlet Bridge Servlet

App Server

OS


What is the Servletbridge?
… a bridge between the servlet and OSGi world

Servlet - side OSGi - side
• Eclipse framework launcher • Proxy Servlet that registers with
• Bridge Servlet with a call-back Bridge Servlet
registration point • OSGi HttpService

1 5
Bridge Servlet Proxy Servlet

2 Servlet OSGi 4

3
Framework Launcher HttpService


What is the Servletbridge?
Servlet OSGi

Incoming Request Registered Request Handler
Servletbridge
OSGi HttpService
registerResource(…)
registerServlet(…)

Incoming requests are “proxied” through the
Servletbridge to registered request handlers.


Deploying Equinox Inside an Application Server
• Deploy similar to an RCP application but in a Web Archive
/WEB-INF
/launch.ini
(contains framework properties that will allow override of any eclipse specific System
Properties)
/web.xml
(with one servlet entry assigning all incoming requests to the BridgeServlet)
/lib/org.eclipse.equinox.servletbridge_<version>.jar
(the classes associated with the equinox.servletbridge)
/configuration
(contains config.ini which lists the bundles you want to have available at startup)
/features
/plugins

• Uses the PDE Product Export Wizard
Uncheck “The product includes native launcher artifacts” and select “Eclipse
Product Export Wizard”
Set the “root directory” to WEB-INF and press “Finish”
For sample products see:
org.eclipse.equinox.server.examples.servletbridge.product
server.core.product (Basic Servletbridge Product)
server.core.p2.product (Servletbridge Product with p2 support for provisioning)


Deploying Equinox inside Application Server
• Online Demo


Exercises
• Export standalone server using product export
• Create & deploy WAR file using Servlet bridge


Overview
applications
• Summary


Logging in Equinox Jetty 6 Integration
• Jetty logging controllable in 3.5+

• -Dorg.eclipse.equinox.http.jetty.log.stderr.threshold=<level>

"debug", "info", "warn", "error", and "off“
Default is “warn”

• Log will happen to STDERR only (for now)

• Outlook: deeper integration with Extended Equinox
Log Service (3.7)


Debugging: Where to hook in
• Hook either in
OSGi world
ServetBridge
• Startup problems:
FrameworkLauncher
• Central access:
ProxyServlet
Hook in processAlias


Servlet Bridge Management Commands

“web.xml” allows configuration of initial parameters:
• commandLine Allows all non-VM command line parameterizations of Eclipse.
The default value is "-console“ which should be cleared for production.
• enableFrameworkControls (true / false) - Controls whether or not the sp_* control URLs are
accessible
sp_deploy - Copies the contents of /platform to the install area (the servlet context tempdir is used -
parameterizable someday)
sp_undeploy - Removes the copy of Eclipse from the install area
sp_redeploy - Resets the platform (e.g. stops, undeploys, deploys, starts)
sp_start - Starts a deployed platform
sp_stop - Stops the platform
sp_test - Provides a sanity check and determines if an OSGi based servlet is ready to accept requests
• frameworkLauncherClass – allows customization of the launcher
• extendedFrameworkExports – additional java package exports from the web application.
Servlet API is automatically exported.


Knopflerfish HTTP Console
• Provides convenient way to manage bundles at
runtime
• Works within Servlet Bridge


Overview
applications
• Summary


Summary - Looking forward...
• Eclipse >3.3 supports building OSGi based web applications for:
Equinox based RCP and headless applications
Equinox embedded in an application server

• Outlook for Eclipse 3.7
Jetty 7
JSP 2.1

• New Specifications from OSGi Enterprise Expert Group
OSGi Web Container (RFC 66)
JNDI and OSGi Integration (RFC 142)


OSGi Web Container (RFC 66)
• New concept… “Web Application Bundle”
• Includes a “web.xml” in the bundle
• Same deployment model and same features as current web
applications
• …but is a real bundle that can use OSGi Services

• Syntactic sugar? Tasty?


JNDI and OSGi Integration (RFC 142)
• Current JNDI implementations use Context Class Loader for
lookup.

• Clever Idiom?
ClassLoader original = Thread.currentThread().getContextClassLoader();
try {
Thread.currentThread().setContextClassLoader(BridgeServlet.class.getClassLoader());
// Do JNDI Calls here
} finally {
Thread.currentThread().setContextClassLoader(original);
}

• JNDI Service will provide a more sensible “bundle” scoped
lookup.


For more information...
Project hub:
http://www.eclipse.org/equinox/server

Newsgroup:
news://news.eclipse.org/eclipse.technology.equinox

Dev Mailing List:
equinox-dev@eclipse.org

Thank-you


Legal Notices
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Microsystems, Inc. in the United States, other countries, or both

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of Microsoft Corporation in the United States, other countries, or both.

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Building Server-Side Eclipse based web applications 2010

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