Taming Cocoon
ApacheCon Europe 2005
Gianugo Rabellino
Agenda
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Introduction
Installing Cocoon
Dissecting Cocoon
Management and configuration
A sitemap tour
Cocoon components and blocks
Understanding continuations and flow
Dealing with forms
Patterns, best practices, pitfalls
Introduction: web developer
nightmares
out.println(“<table border=\”0\”>\n\t<tr>\n\t\t” +
“<td align=\”left\”><font size=\”+1\”>” +
request.getParameter(“lousyjob”) +
“Does your boss know you\'re typing HTML?” +
“</td>\n\t</tr>\n</table>\n”);
Nightmare: managing HTML
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Your IDE can't deal with HTML
Dreamweaver can't deal with business logic
Period.
Oh, and JSPs suck. Big time.
“Separate concerns” - Edsger Dijkstra - 1974
Nightmare: handling state
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HTTP is stateless (did you notice already?)
Where am I now?
Restart required
Sessions == overpopulated mess of dictionaries
Nightmare: managing user input
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Validation hell
Conversion ordeal
Binding torture
The infamous Back button, oh my!
There has to be a better way
“Never let a man do what a machine can do for him”
Blaise Pascal
Apache Cocoon
A fast-paced overview
Apache Cocoon: facts and figures
 Origins
 Started by the Italian student Stefano Mazzocchi
Redesign of Apache.org
 Frustrated by the limitations of HTML
 Wanted to use emerging technologies (XML/XSL)
 Today
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Now one of the most important Apache projects
Incorporates technologies from various project
Just under 2000 registered on all mailing lists
Includes major companies such as HP, IBM
Tucking web devs in, kissing them
goodnight
10.000ft overview
Key Cocoon concepts
 URI space decoupling
 Componentized resource assembling
 Datasource connections and decoupling
 Stateful applications
And their implementation...
 URI space decoupling
 Sitemap
 Componentized resource assembling
 Pipelines
 Datasource connections and decoupling
 Source interface and implementations (file, URL, database,
WebDAV, XMLDB...)
 Stateful applications
 Web continuations
URI space decoupling: the sitemap
 Think <servlet-mapping> on steroids
 Pattern freaks think FrontController
 Uses pluggable algorithms:
 Wildcard
 Regexp
 Your own
 Matching the whole HTTP environment:
 Request URI/parameters/attributes
 Session attributes
 Cookies, context, etc...
 Welcome to the sitemap
A sitemap example
<map:match pattern="news/*" type="wildcard">
<map:generate src="newsfeeds/{1}.xml" type="file"/>
<map:transform src="news2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
<map:match pattern="products/*" type="wildcard">
<map:generate src="products/infos/product_{1}.xml"
type="file"/>
<map:transform src="products2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
Resource assembling: the pipeline
 Task: find the total number of unique hosts visiting the home
page of your site
 Windows solution:
#include <stdlib.h>
...
 Unix solution:
$ grep index.html access.log | awk '{print $2 }' | sort |
uniq | wc -l
 Welcome to the pipeline: specialized components glued
together
The Cocoon pipeline
 Two simple rules:
 Data stream is based on SAX events
 Pipelines start with one Generator (and only one), have 0-n
Transformers, end with one (and only one) Serializer
 Generators: adapters from the outside world to SAX events
 Transformers: SAX event manglers
 Serializers: adapters from SAX events to the outside world
A pipeline example
<map:match pattern="*.html">
<map:generate src=”xdocs/{1}.xml"/>
<map:transform src=“style/xdocs2html.xsl”/>
<map:serialize/>
</map:match>
Datasource virtualization
 Virtualization layer over stream-based data sources
 Provides a java.io.File like interface for a number of data
sources
 Think URLs on steroids
The Source interface
A datasource example
<map:match pattern="news/*" type="wildcard">
<map:generate src="webdav://repo/newsfeeds/{1}.xml" type="file"/>
<map:transform src="xmldb://localhost/db/news2html.xsl"
type="xslt"/>
<map:serialize type="html"/>
</map:match>
<map:match pattern="products/*" type="wildcard">
<map:generate src="cocoon://products/infos/product_{1}.xml"/>
<map:transform src="resource://products2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
Summing it up
 The sitemap decouples URI space from physical
resources
 The pipeline decouples results from the way they're built
 XML decouples content from presentation
 The source abstraction decouples data sources from
physical locations
Result: full Separation of Concerns
(and you ain’t seen nothing yet...)
Web Continuations
The next revolution
Web applications are easy!
But wait, this is stateless HTTP
 Webapps are finite state machines
 Upon every click, processing starts from the beginning
 Again, and again, and again
A typical web application clutter
What are continuations?
“A continuation is an entire set of closures that make up a point of
execution”
“A continuation is an object that, for a given point in your program,
contains a snapshot of the stack trace, including all the local
variables, and the program counter”
Hmmm... so what?
var cart;
var user;
A flowscript example: where the magic
happens
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
}
What are continuations, again?
–
Contents of a continuation
Stack of function calls
● Value of local variables
 Most often a lightweight object
●
 Creating a continuation does not halt a thread
!!
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A continuation object is associated with a
unique identifier available to the view
 Later used to "resurrect" it
Flowscript example, revisited
saved continuations
var cart;
var user;
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
}
Continuations tree
var cart;
var user;
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
}
Don't fear the Back button anymore!
Summing it up
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Continuations give control back to the server
 We always know "where" the browser is
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Allow sophisticated flow screens
 No need for state automata
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Increase security and robustness
 Forbids direct access to form submission URLs
 Handling of "back" and "new window"
A word about forms
Managing user input
Cocoon Forms: nightmares solved!
 MVC based form framework
 Provides:
 Strongly-typed data: a date field is a java.util.Date.
Automatically.
 Validation: declarative. Handled for you. Automatically.
 Binding: to objects (EJB, POJOs...) or to XML, your choice.
Automatically.
Cocoon Forms, a functional view
 Separation of Concerns in forms:
 Model: data typing, validation rules
 View: widget presentation
selections could be drop down lists or checkboxes
 Controller:
flowscript (continuations based)
custom actions (à la Struts) – not recommended
 Data binding:
declarative
JXPath based
Cocoon Forms: a rich framework
 Powerful widget library
 Fields, aggregated fields, dates, selectors, trees and repeaters
 AJAX compliant infrastructure
 Boosts perceived performance
 Integrated add-ons
 HTML editor
 calendar pop-ups
 dynamic double selection lists
Summing it up: RAD development
 Configure, don't code
 Continuations make webapp development a breeze
 Powerful form frameworks ease managing user input
 Separation of Concerns brings maintainability
... and they lived happily ever after.
Installing Cocoon
Finding your way through compilation and blocks
Downloading Cocoon
 http://cocoon.apache.org
 Subversion for the latest version:
http://svn.apache.org/repos/asf/cocoon/branches/BRANCH_2.1
.X
http://svn.apache.org/repos/asf/cocoon/trunk
 … or even WebDAV
Preparing Cocoon
 Task list:
 Edit local.build.properties
Exclude unneeded and heavy tasks (e.g. javadocs / documentation)
 Edit local.blocks.properties
Beware of dependencies
 All done, now run:
$ ./build.sh (Unix)
C\> build.bat (Windows)
Testing the install
 Embedded Jetty:
 Run
$ ./cocoon.sh servlet (Unix)
C\> cocoon.bat servlet (Windows)
 Point your browser to http://localhost:8888/
 Other servlet engines:
 Run
$ ./build.sh war (Unix)
C\> build.bat war (Windows)
 Deploy dist/cocoon*.war
Beware the classloader
 Cocoon uses its own version of Rhino (Javascript engine)
 Might clash with vendor-provided ones (e.g. Websphere/BEA)
 Make sure that your appserver is configured to run Cocoon in an isolated
classloader (as per servlet spec):
 ask your vendor to fix his bug if it doesn’t work
 If it doesn’t work, use the “paranoid” block and the
ParanoidCocoonServlet (but you shouldn’t)
 Mind redirects on WebSphere!
Eclipse integration
 Run:
$ ./build.sh eclipse-project (Unix)
C\> build.bat eclipse-project (Windows)
 Inside Eclipse:
 New Java Project
 Navigate to $COCOON_HOME
 Your project will appear automagically!
Files you want to know
 Main sitemap:
$COCOON_HOME/build/webapp/sitemap.xmap
 Log configuration:
$COCOON_HOME/build/webapp/WEB-INF/logkit.xconf
 Component configuration:
$COCOON_HOME/build/webapp/WEB-INF/cocoon.xconf
 Mount table:
$COCOON_HOME/mount-table.xml
Management and configuration
Handling Cocoon in production
Configuring Cocoon
 Web Application Configuration
 Cocoon runs as a servlet
 Configuration controlled by web.xml
 Find it in the WEB-INF directory
 Most important entry
 Name and location of the actual configuration file
 Default: WEB-INF/cocoon.xconf
<!-This parameter points to the main configuration file for Cocoon. Note
that the path is specified in absolute notation but it will be
resolved relative to the servlets webapp context path
-->
<init-param>
<param-name>configurations</param-name>
<param-value>/WEB-INF/cocoon.xconf</param-value>
</init-param>
Configuring Cocoon
 cocoon.xconf
 XML format
 Contains Avalon component configuration
 But not (!!) the sitemap components
They are in the sitemap
 cocoon.xconf rarely needs changing
Moving from test to production
Replacing the XML parser
Configuring Cocoon
 cocoon.xconf
<?xml version="1.0"?>
<cocoon version="2.0">
<parser
class="org.apache.cocoon.components.parser.XercesParser"/>
<hsqldb-server
class="org.apache.cocoon.components.hsqldb.ServerImpl"
pool-max="1" pool-min="1">
<parameter name="port" value="9002"/>
<parameter name="silent" value="true"/>
<parameter name="trace" value="false"/>
</hsqldb-server>...
</cocoon>
Configuring Cocoon
 cocoon.xconf
 No namespace
 Each component defined inside <cocoon>
 Logical names matched to implementations
e.g. parser; hsqldb-server
 Configuration using <parameter>
Contains name-value pairs
 pool-min and pool-max
We will look at those later (pooling)
Configuring Cocoon
 cocoon.xconf
 Another important piece of information
Location and name of the sitemap
<sitemap file="context://sitemap.xmap"
check-reload="yes"/>
 Reloading
Triggers on incoming request
Synchronous
• New sitemap will be generated and then handles the request
 What do you do if an error occurs ............
Configuring Cocoon
 LogKit Configuration
 Each component in Cocoon logs using LogKit
 There are five log levels
DEBUG
INFO
WARNING
ERROR
FATAL_ERROR
 In testing: DEBUG
 In production: ERROR or FATAL_ERROR
 Location of the LogKit configuration file
Is in the web.xml:
<init-param>
<param-name>logkit-config</param-name>
<param-value>/WEB-INF/logkit.xconf</param-value>
</init-param>
Configuring Cocoon
 LogKit Configuration
 Consists of several parts
Factories for logging targets
• Implementations are not "hard-wired"
• Defines components that are to receive the log messages
Targets
• Configured with Factory
• And file name, output format, size/rotation information
Categories
• Actual "receiver" of the log messages
• Configured with (multiple) targets
• And log level
Configuring Cocoon
 LogKit Configuration
<logkit>
<factories>
<factory type="cocoon" class="org.apache.cocoon.util.log.CocoonTargetFactory"/>
</factories>
<targets>
<cocoon id="cocoon">
<filename>${context-root}/WEB-INF/logs/cocoon.log</filename>
<format type="cocoon">
%7.7{priority} %{time}
[%8.8{category}] (%{uri}) %{thread}/%{class:short}:
%{message}\n%{throwable}
</format>
<append>true</append>
<rotation type="revolving" init="1" max="4">
<or>
<size>100m</size>
<time>01:00:00</time>
</or>
</rotation>
</cocoon>
<filter/>
</targets>
<categories>
<category name="cocoon" log-level="DEBUG">
<log-target id-ref="cocoon"/>
<log-target id-ref="filter"/>
</category>
</categories>
</logkit>
Configuring Cocoon
 LogKit Configuration
 (Normally) No need to change the setting
Apart from log-levels
Not reflected automatically
Touch cocoon.xconf
 DEBUG logfiles can become very large
Hard drives have a limited capacity 
And slow performance down
 Default level: ERROR for all categories
Dissecting Cocoon
A sitemap tour
Cocoon anatomy
Cocoon physiology
The sitemap disemboweled
 The sitemap contains:
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Component definitions and configurations
Views
Resources
Action sets
Flow
Pipelines
 … all neatly packaged as a namespaced XML file
<map:sitemap xmlns:map="http://xml.apache.org/cocoon/sitemap/1.0">
<map:components/>
<map:views/>
<map:resources/>
<map:action-sets/>
<map:flow/>
<map:pipelines/>
</map:sitemap>
Sitemap components
 Configured as children of the <map:components> section
 Contains:
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Generators
Transformers
Serializers
Readers
Matchers
Selectors
Actions
Pipes
…and their configuration
 Each section declaration can have a default component
Sitemap components Tour
 Generator, Transformers and Serializers are typical Cocoon
components for pipelines
 Readers are used for binary resources
 Think of a “collapsed” Generator and Serializer
 Matchers are used to route requests
 Selectors implement branching (if… then… else) logic
 Actions implement business logic based switching (old
fashioned, flow is now the preferred way)
 Pipes define different pipeline implementation (which differ
mainly for caching policies)
 Examples will follow
A word about Actions
 Actions are reusable snippets of business logic
 Actions wrap pipeline snippets
 Actions can return either:
 null: the pipeline snippet is skipped
 A Map containing business values, which can be reused in the
pipeline snippet
<map:act type="clear-cache">
<map:generate src="status" type="status"/>
<map:transform src="context://stylesheets/system/status2html.xslt">
<map:parameter name="contextPath" value="{request:contextPath}"/>
</map:transform>
<map:serialize/>
</map:act>
Sitemap components example
<map:components>
<map:generators/>
<map:transformers default="xslt">
<map:transformer logger="sitemap.transformer.xslt"
name="xslt" pool-max="32"
src="org.apache.cocoon.transformation.TraxTransformer">
<use-request-parameters>false</use-request-parameters>
<use-session-parameters>false</use-session-parameters>
<use-cookie-parameters>false</use-cookie-parameters>
<xslt-processor-role>xalan</xslt-processor-role>
<check-includes>true</check-includes>
</map:transformer>
</map:transformers>
<map:serializers/>
<map:readers/>
<map:actions/>
<map:pipes/>
</map:components>
Tip: reusing components
 Components can be re-defined with different configurations,
 Names have to be unique
<map:transformer logger="sitemap.transformer.xalan" name="xalan" poolmax="32" src="org.apache.cocoon.transformation.TraxTransformer">
<use-request-parameters>false</use-request-parameters>
<use-session-parameters>false</use-session-parameters>
<use-cookie-parameters>false</use-cookie-parameters>
<xslt-processor-role>xalan</xslt-processor-role>
<check-includes>true</check-includes>
</map:transformer>
<map:transformer logger="sitemap.transformer.xsltc" name="xsltc"
pool-max="32" src="org.apache.cocoon.transformation.TraxTransformer">
<use-request-parameters>false</use-request-parameters>
<use-session-parameters>false</use-session-parameters>
<use-cookie-parameters>false</use-cookie-parameters>
<xslt-processor-role>xsltc</xslt-processor-role>
<check-includes>true</check-includes>
</map:transformer>
Understanding views
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Views are “exit points” in pipeline processing
Original motivation: semantic search
Current use: mainly debug
Configuration:
 name: unique identifier
 from-label: explicit exit point
 from-position: implicit (automatic) exit point
first: right after the generator
last: right before the serializer
 Activated by cocoon-view=view-name
 Warning! Views are not inherited by subsitemaps
 Warning! Views can be a security concern
More on views: placing labels
 Labels are set using the label attribute on either:
 A Generator or Transformer declaration in the components section
(will work anywhere)
 A Generate or Transform directive in a pipeline (specific to the
pipeline)
 An Aggregate or Part directive (more on this later)
View examples
 Defining views:
<map:views>
<map:view from-label="content" name="content">
<map:serialize type="xml"/>
</map:view>
<map:view from-label="content" name="pretty-content">
<map:transform src="stylesheets/system/xml2html.xslt"/>
<map:serialize type="html"/>
</map:view>
</map:views>
 Defining labels:
<map:generator label="content" logger="sitemap.generator.file"
name="file" pool-max="32”
src="org.apache.cocoon.generation.FileGenerator"/>
Resources
 Reusable pipeline fragments
 Useful for repetitive tasks
 Will be (mostly) replaced by Virtual Sitemap Components
 Warning! Resources are not inherited by subsitemaps
A resource example
 Defining a resource:
<map:resources>
<map:resource name="simple-page2html">
<map:transform
src="context://samples/common/style/xsl/html/simple-page2html.xsl">
<map:parameter name="contextPath"
value="{request:contextPath}"/>
<map:parameter name="servletPath"
value="{request:servletPath}"/>
<map:parameter name="sitemapURI"
value="{request:sitemapURI}"/>
<map:parameter name="file" value="{file}"/>
<map:parameter name="remove" value="{../0}"/>
</map:transform>
</map:resource>
</map:resources>
 Calling a resource
<map:call resource="simple-page2html">
<map:parameter name="file" value="forms/form1_success.xsp"/>
</map:call>
Action-sets
 Define a set of actions to be executed as a unit of work either:
 Unconditionally (upon every invocation)
 When explicitely called, using a cocoon-action parameter
<map:action-sets>
<map:action-set name="shop-actions">
<map:act type="session-invalidator" action="logoff"/>
<map:act type="session-validator"/> <!-- Always executed -->
<map:act type="cart-add" action="addItem"/>
<map:act type="cart-remove" action="removeItem"/>
<map:act type="cart-remove-all" action="removeAll"/>
<map:act type="cart-update" action="updateQty"/>
<map:act type="order-add" action="addOrder"/>
<map:act type="order-verify" action="verifyOrder"/>
<map:act type="navigator" src="{1}"/> <!-- Always executed -->
</map:action-set>
</map:action-sets>
Declaring flow scripts
 Flow is a new way to insert page flow control in your
application (much more on that later)
 Scripts and/or classes are declared in the flow section of the
sitemap
<map:flow language="javascript">
<map:script src="calc.js"/>
</map:flow>
<map:flow language="java">
<map:script
src="org.apache.cocoon.samples.flow.java.CalculatorFlow"/>
<map:script src="org.apache.cocoon.samples.flow.java.FormFlow"/>
<map:script
src="org.apache.cocoon.samples.flow.java.PersistenceFlow"/>
</map:flow>
The pipelines section
 The “heart” of Cocoon, where things get done
 Contains 1+ <map:pipeline> declarations
 Any pipeline section represents a logical division
 Different pipelines serve different purposes:
 Visibility: internal-only pipelines can only be just using the
cocoon: protocol;
 Caching, as pipelines can be:
 non-cached (always executed)
 cached delegating validity to the pipeline components (executed if
nothing has changed in the pipeline)
 cached beforehand using the expires directive (executed only once
during the validity period)
Cocoon pipelines dissected
Pipelines are “recipes” building resources
SAX events travel through the pipeline
The TLA is GTS: Generator, Transformer, Serializer
Generators are adapters from the outside world to SAX events
Transformers are SAX filters
Serializers are the opposite of Generators, adapting SAX
events to the outside world
 The obligatory diagram:
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What’s in a pipeline?
 Well, components in action: from nouns to verbs
 Content production:
 generate [- transform ] - serialize
 aggregate - part [ - part …]
 read
 Branching:
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match
select
act
call
So what’s the sitemap, again?
 Central switchboard (or FrontController, if you like
patterns)
 Contains component declarations (yes, even business
components)
 Locates (match) and builds (pipelines) the final result
 In most cases, it’s the only file you’ll need to touch
A typical request cycle in Cocoon
1. The environment is checked for the proper pipeline to use
(normally via matching/selecting)
2. The pipeline is evaluated:
1. Sitemap components are looked up via type references or
default assignment
2. The pipeline is setup.
3. The pipeline is executed
Warning: no dynamic sitemap routing!
Zen and the art of matching
A perfectly valid pipeline example
<map:pipeline>
<map:generate src=”hello.xml" type="file"/>
<map:transform src=”hello2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:pipeline>
 Would match any request and greet the user
 … which is probably not what you want
Matchers kick in
 Matchers associate the actual environment to a pipeline
<map:pipeline>
<map:match pattern=”hello” type="wildcard">
<map:generate src=”hello.xml" type="file"/>
<map:transform src=”hello2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
<map:pipeline>
 Hit http://localhost:8888/hello
Semantic problem
 Warning, pitfall ahead!
 Formally a pipeline is everything included in <map:pipeline>
 Colloquially, though, a pipeline is normally the G-T-S part
<map:pipeline>
<map:match pattern=”hello” type="wildcard">
<map:generate src=”hello.xml" type="file"/>
<map:transform src=”hello2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
<map:match pattern=”goodbye” type="wildcard">
<map:generate src=”goodbye.xml" type="file"/>
<map:transform src=”bye2html.xsl" type="xslt"/>
<map:serialize type="html"/>
</map:match>
<map:pipeline>
Why the fuss?
 A pipeline, formally, is everything that starts with a Generator
and ends with a Serializer
 This sample, then, is perfectly valid:
1:<map:pipeline>
2:
<map:match pattern=”hello” type="wildcard">
3:
<map:generate src=”hello.xml" type="file"/>
4:
</map:match>
5:
<map:match pattern=”goodbye” type="wildcard">
5:
<map:generate src=”goodbye.xml" type="file"/>
7:
</map:match>
8:
<map:transform src=”greeting2html.xsl" type="xslt"/>
9:
<map:serialize type="html"/>
10:<map:pipeline>
To make things further complicated…
 This one is valid as well:
1:<map:pipeline>
2:
<map:match pattern=”hello” type="wildcard">
3:
<map:generate src=”hello.xml" type="file"/>
4;
<map:transform src=”greeting2html.xsl" type="xslt"/>
5:
<map:serialize type="html"/>
6:
</map:match>
7:
<map:match pattern=”goodbye” type="wildcard">
8:
<map:generate src=”goodbye.xml" type="file"/>
9:
</map:match>
10:
<map:transform src=”greeting2html.xsl" type="xslt"/>
11:
<map:serialize type="html"/>
12:<map:pipeline>
Argh! Where is my aspirin?
 … but this one could not be:
1:<map:pipeline>
2:
<map:generate src=”hello.xml" type="file"/>
3:
<map:match pattern=”hello” type="wildcard">
4:
<map:generate src=”hello.xml" type="file"/>
5:
<map:transform src=”greeting2html.xsl" type="xslt"/>
6:
<map:serialize type="html"/>
7:
</map:match>
8:
<map:match pattern=”goodbye” type="wildcard">
9:
<map:generate src=”goodbye.xml" type="file"/>
10:
</map:match>
11:
<map:transform src=”greeting2html.xsl" type="xslt"/>
12:
<map:serialize type="html"/>
13:<map:pipeline>
Bottom line
 Cocoon will process the sitemap and try to build a G-[T]-S
pipeline
 Cocoon will stop processing when a Serializer is met
 Beware the “Generator already set” errors!
 You can’t have a “Serializer already set” error
Understanding matchers
 Matchers will “route” a user request through Cocoon pipelines
 Matchers are evaluated in order: first match wins
 Matchers are available for the whole environment, matching
on:






Request URI
Request parameters
Request Attributes
Session Attributes
Cookies
… and more
 Matchers are pluggable: write your own!
Using matchers
 A basic example:
<map:match pattern="">
<map:generate src="welcome.xml"/>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
 Captures an empty URI
Wildcard-based matching
 Wildcard match part of the URI using special chars (*/**)
 A single asterisk matches everything up to the first forward slash
<map:match pattern=”welcome-*">
<map:generate src="welcome.xml"/>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
 Matches http://localhost:8888/welcome-friend
 A double asterisk matches everything
<map:match pattern=”welcome**">
<map:generate src="welcome.xml"/>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
 Matches http://localhost:8888/welcome/friend
Capturing matcher results
 Captured parts of a URI are available for later use
 Ordered list, denoted by position number in curly braces
 Starts at 1
<map:match pattern=”welcome-*">
<map:generate src="welcome-files/{1}.xml"/>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
 Matches http://localhost:8888/welcome-friend
 Uses welcome-files/friend.xml as the generator input
 Can be arbitrarily complex:
<map:match pattern="linkstatus/*/*/**">
<map:generate src="http://{1}:{2}/{3}" type="linkstatus"/>
<map:transform src="stylesheets/system/linkstatus2html.xslt"/>
<map:serialize/>
</map:match>
Nesting matchers
 Matchers can be nested:
<map:match pattern=”welcome-**">
<map:match pattern=”friend-*">
<map:generate src="welcome-files/ {1}.xml"/>
</map:match>
<map:match pattern=”foe-*">
<map:generate src=”goaway/{1}.xml"/>
</map:match>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
Nesting matchers: capturing parent results
 The matched expression on the child matcher doesn’t take into
account the part already matched
 “Parent” captured expressions are available with a tree
navigation syntax:
<map:match pattern=”welcome-**">
<map:match type=”host-matcher” pattern=”localhost">
<map:generate src=”local-files/{../1}.xml"/>
</map:match>
<map:match type=”host-matcher” pattern=”*.mydomain.com">
<map:generate src=”remote-files/{1}/{../1}.xml"/>
</map:match>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
Dealing with Sources
The Source abstraction
 Abstracts a stream based data source
 Sub interfaces define write mode and tree-like navigation (à la
java.io.File)
 URL-like syntax (with some bastardization)
The Source interface
Available sources
 Remote sources:





URLSource: deals with every protocol available for java.net.URL
FileSource: manages local files
WebDAVSource: interoperates with WebDAV repositories
XMLDBSource: connects to NXDs
BlobSource: uses databases blobs
 “Meta” sources:





SitemapSource: uses Cocoon pipelines as data stream sources
ResourceSource: grabs data from classpath
ContextSource: accessed streams from the webapp context
ModuleSource: converts modules into sources
CachedSource: decorates sources adding passive caching
The Sitemap Source
 Calls cocoon pipelines
 Weirdo:
 When used in a generator or transformer, the called pipeline
serializer will be ignored
 When used in a reader, the serializer will be honored
 More weirdos: URL bastardization
 cocoon:/ will call a pipeline starting from the current sitemap
 cocoon:// will call a pipeline starting from the root sitemap
Cocoon Components Tour
A journey through Generators, Transformers,
Serializers, Readers, Matchers, Sub-sitemaps,
Modules, Error handling and more
Components Tour
 Cocoon has roughly 400 components:








66 Generators
65 Transformers
23 Serializers
10 Readers
37 Matchers
31 Selectors
88 Actions
59 Input/Output Modules
 And you might want to write your own
 No way to cover them all… we’ll see the most useful
Useful stuff: FileGenerator
 Actually it’s a SourceGenerator: can deal with every Source
data stream
 … which includes cocoon:// URIs
 Probably the most used generator in Cocoon
Useful stuff: Directory Traversal
 Operate on TraversableSources (directories)
 Provide an XML listing of the requested resources
 Available components:
 DirectoryGenerator
ImageDirectoryGenerator
MP3DirectoryGenerator
 TraversableGenerator
 TraversableSourceDescriptionGenerator
 XPathTraversableGenerator
Useful stuff: more generators
 JXTemplateGenerator: inspired by JSTL, more on this later
 RequestGenerator: XMLized Request object
 SessionAttributeGenerator: streams an object stored in session as
XML
 StreamGenerator: reads and streams XML from a request
InputStream (e.g. POST requests)
 HttpProxyGenerator: accesses an XML stream over HTTP
 HTMLGenerator: grabs HTML from a source, converts to XHTML
using jTidy and streams it away
Useful stuff: TraxTransformer
 Can use either (and concurrently):
 TRAX
 Xalan
 Saxon
 Relevant configuration parameters:
<use-request-parameters>true|false</use-request-parameters>
<use-session-parameters>true|false</use-session-parameters>
<use-cookie-parameters>true|false</use-cookie-parameters>
<xslt-processor-role>trax|xalan|xsltc</xslt-processor-role>
<check-includes>true</check-includes>
 Beware caching impact!
Useful stuff: I18NTransformer
 Incredibly useful for dictionaries and localization
 Golden rule: use it
 Relevant configuration:
<map:transformer name="i18n" logger="sitemap.transformer.i18n"
src="org.apache.cocoon.transformation.I18nTransformer">
<catalogues default="messages">
<catalogue id="messages" name="messages" location="translations"/>
<catalogue id="menu" name="menu" location="translations"/>
<catalogue id="tiered" name="messages">
<location>translations/tiered</location>
<location>translations</location>
</catalogue>
</catalogues>
<cache-at-startup>true</cache-at-startup>
</map:transformer>
Dissecting I18NTransformer
 Resolving catalogue files:
 name, id: unique identifiers and base names for files
 location: a source to be prepended to the base names
 Locale will be appended, in full or short form (en_US or en as a
fallback).
 Finally, “.xml” will complete the file name
 So:
<catalogue id="messages" name="messages” location="translations"/>
 Assuming “en_US” as locale, the transformer will look for:
translations/messages_en_US.xml
translations/messages_en.xml
translations/messages.xml
I18N catalog files
<catalogue xml:lang="en">
<message key="Apache Cocoon i18n Samples">Apache Cocoon i18n
Samples</message>
<message key="Samples">Samples</message>
<message key="Introduction">Introduction</message>
<message key="Static (XML)">Static (XML)</message>
<message key="Dynamic (XSP)">Dynamic (XSP)</message>
<message key="Sitemap source">Sitemap source</message>
<message key="Locales">Locales</message>
<message key="Documentation">Documentation</message>
<message key="i18n transformer docs"><![CDATA[<I18ntransformer>
docs]]></message>
<message key="i18n transformer Javadoc"><![CDATA[<I18ntransformer>
Javadoc]]></message>
<message key="LocaleAction Javadoc"><![CDATA[<LocaleAction>
Javadoc]]></message>
<message key="Credits">Credits</message>
<message key="Konstantin Piroumian">Konstantin Piroumian</message>
<message key="Many others...">Many others...</message>
</catalogue>
Using the I18NTransformer
 From then you can happily translate:
 Elements
<title>
<i18n:text>titletext</i18n:text>
</title>
 Attributes
<para title="first" name="article" i18n:attr="title name">
 Dates
<i18n:date-time pattern="MEDIUM"/>
 Numbers
<i18n:number type="percent" src-locale="en" value="1.2"/>
Useful stuff: CIncludeTransformer
 Dynamically inserts content in XML streams
 Reacts to elements in the http://apache.org/cocoon/include/1.0
namespace
<page
xmlns:cinclude="http://apache.org/cocoon/include/1.0">
<title>Hello</title>
<content>
<para>This is my first Cocoon page!</para>
<cinclude:include src="include.xml" element="included"/>
</content>
</page>
 Can be cached as well:
<map:transform type="cinclude">
<map:parameter name="expires" value="600"/>
</map:transform>
<cinclude:cached-include src="include.xml"/>
Useful stuff: SourceWritingTransformer
 Useful to write XML data to (Writeable) Sources during pipeline
execution
 e.g., save a file
 Reacts to elements in the http://apache.org/cocoon/source/1.0
namespace
 Typically used with XSLT building the source:* stuff
 Read the Javadocs for details
<page>
<source:write create="true”
xmlns:source="http://apache.org/cocoon/source/1.0">
<source:source>file://tmp/test.write</source:source>
<source:fragment>
<title>a title</title>
<content>
...
</content>
</source:fragment>
</source:write>
</page>
Useful stuff: XMLSerializer
 Outputs, well, XML.
 Configurable encodings and doctypes:
<map:serializer logger="sitemap.serializer.xhtml"
mime-type="application/xhtml+xml" name="xhtml11”
src="org.apache.cocoon.serialization.XMLSerializer">
<doctype-public>-//W3C//DTD XHTML 1.1//EN</doctype-public>
<doctype-system>
http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
</doctype-system>
<encoding>UTF-8</encoding>
</map:serializer>
Useful stuff: FOPSerializer
 Uses Apache FOP to produce:




PDF
PS
PCL
RTF
<map:serializer logger="sitemap.serializer.fo2pdf"
mime-type="application/pdf" name="fo2pdf"
src="org.apache.cocoon.serialization.FOPSerializer">
<user-config>WEB-INF/fop-config.xml</user-config>
<set-content-length>true</set-content-length>
</map:serializer>
<map:serializer logger="sitemap.serializer.fo2ps"
mime-type="application/postscript" name="fo2ps"
src="org.apache.cocoon.serialization.FOPSerializer"/>
<map:serializer logger="sitemap.serializer.fo2pcl"
mime-type="vnd.hp-PCL" name="fo2pcl"
src="org.apache.cocoon.serialization.FOPSerializer"/>
Useful stufff: SVGSerializer
 Takes SVG as input, produces JPEG/PNG as output
 Uses Apache Batik
<map:serializer logger="sitemap.serializer.svg2jpeg"
mime-type="image/jpeg" name="svg2jpeg"
src="org.apache.cocoon.serialization.SVGSerializer">
<parameter name="quality" type="float" value="0.9"/>
</map:serializer>
<map:serializer logger="sitemap.serializer.svg2png"
mime-type="image/png" name="svg2png”
src="org.apache.cocoon.serialization.SVGSerializer"/>
Useful stuff: ImageReader
 Will serve images (surprise!)
 The kick: performing width, height, ratio adjustments (great for
thumbnails)
<map:match pattern="image-size-*">
<map:read type="image" src="logo.jpg">
<map:parameter name="width" value="{1}"/>
<map:parameter name="height" value="{1}"/>
</map:read>
</map:match>
Sub sitemaps
 Sitemaps could become overpopulated and messy (the Perl
effect)
 Solution: modularize using sub-sitemaps
 From the main sitemap match the parent path and mount a
sitemap underneath:
<map:match pattern="xsp/**">
<map:mount uri-prefix="xsp" src="xsp.xmap" />
</map:match>
 Wildcard substitution, of course, works:
<map:match pattern="~*/**">
<map:mount src="/home/{1}/public_html/" uri-prefix="~{1}"/>
</map:match>
Input/Output Modules
 Modules create generic components and plug actual
input/output at runtime
 Example: grab a request parameter and use it in the sitemap
<map:match pattern=”welcome">
<map:generate src=”local-files/{request-param:file}.xml"/>
<map:transform src="welcome.xslt"/>
<map:serialize type="xhtml"/>
</map:match>
 Again: no dynamic routing possible
 Modules are evaluated during the pipeline setup phase
Useful modules: GlobalInputModule
 Allows to configure global variables in the sitemap, with runtime
substitution
 Helps writing maintainable code
<map:component-configurations>
<global-variables>
<staging>webdav://localhost/webdav/step1/</staging>
</global-variables>
</map:component-configurations>
<map:pipeline>
<map:match pattern="repo/">
<map:generate type="traverse" src="{global:staging}repo/">
<map:parameter name="depth" value="1"/>
</map:generate>
<map:serialize type="xml"/>
</map:match>
</map:pipeline>
Useful modules: XMLFileInputModule
 Allows XPath queries on external resources
 Helps maintainability: configuration will be outside the sitemap
 Configured in cocoon.xconf
<component-instance
class="org.apache.cocoon.components.modules.input.XMLFileModule"
logger="core.modules.xml" name=”settings">
<file src="cocoon://${project.mount}/configuration/test.xhtml"
reloadable="false" cacheable="true"/>
</component-instance>
…
<map:generate type="traverse" src="{settings:/html/head/title}">
When things go wrong: error handling
 Error conditions (exception) can be catched in the pipeline
 Each pipeline can have a handle-errors section
 Error handling is inherited
 NotifyingGenerator provides errors in XML format
 ExceptionSelector allows branching according to the
exception
Error handling explained
<map:selector logger="sitemap.selector.exception" name="exception"
src="org.apache.cocoon.selection.ExceptionSelector">
<exception class="o.a.c.ResourceNotFoundException" name="not-found"/>
<exception class="o.a.c.c.flow.InvalidContinuationException"
name="invalid-continuation"/>
</map:selector>
<map:handle-errors>
<map:select type="exception">
<map:when test="not-found">
<map:generate type="notifying"/>
<map:transform src="stylesheets/system/error2html.xslt”/>
<map:serialize status-code="404"/>
</map:when>
<map:when test="invalid-continuation">
<map:generate type="notifying"/>
<map:transform src="stylesheets/system/error2html.xslt">
<map:serialize status-code="404"/>
</map:when>
<map:otherwise>
<map:generate type="notifying"/>
<map:transform src="stylesheets/system/error2html.xslt">
<map:serialize status-code="500"/>
</map:otherwise>
</map:select>
</map:handle-errors>
Flowscript
The magic of web continuations
Overview






Introduction
JavaScript features
View layer
Putting it all together
Session variables
Managing continuations
Introduction
 Need for flow control
 What is "flow control" ?
Control of transition between pages
Driven by application logic
 Aren't actions enough ?
Yes, but they require state management
Quickly becomes complex, hard to understand and to maintain
Introduction
 Flow script : what is it ?
 Simple and effective way to glue together business logic,
presentation and page flow
 Uses scripts written in JavaScript (server-side)
a simple scripting language
can implement the most complex use cases
 Why JavaScript ?
Simpler than Java, although powerful
Integrates well with Java
Well-known in the web world
Allows faster roundtrips (save and reload)
Supports continuations
Introduction
 Flow script example
var cart;
var user;
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
}
Introduction
 JavaScript vs. Java detour
 If you know Java, you already know JavaScript !
Well, mostly.
 JavaScript is dynamically typed (variables don’t have types,
values do)
 Prototype-based inheritance as opposed to class-based
inheritance
 Objects are extensible at runtime : add or remove properties
and methods
Calling the view
 cocoon.sendPage()
 cocoon.sendPage invokes the output page (view) with two
arguments
The view URL, relative to current sitemap
A context Map made available to the view
 Can contain Java or JavaScript objects
cocoon.sendPage("checkout.html",
{user: loggedUser, email: address});
 cocoon.sendPage("view.html") is like redirecting to
"cocoon:/view.html"
 Control then comes back to the script
 Should normally terminate
Calling the view
 cocoon.sendPageAndWait()
 Similar to cocoon.sendPage
Invoke the view with a context object
 The script is suspended after the view is generated
 the whole execution stack saved in a continuation object
 Flow between pages becomes sequential code
 No more complicated state automata
Continuations
 What is it ?
 Contents of a continuation
Stack of function calls
Value of local variables
 Most often a lightweight object
 Creating a continuation does not halt a thread !!
 A continuation object is associated with a unique identifier
available to the view
 Later used to "resurrect" it
Continuations
 Sample flow script revisited
saved continuations
var cart;
var user;
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
}
View layer : JXTemplate
 What is JXTemplate ?
 An XML template language inspired by JSTL
 Doesn't allow code, but only access to context variables
 More simple, more secure
 Flow values are provided as variables :
<jx:forEach var="item" items="${cart.items}">
<p>Name: <jx:out value="${item.name}"/></p>
</jx:forEach>
<a href="kont/${continuation.id}">Continue</a>
 2 expression languages : Jexl and JXPath
View layer : JXTemplate
 Jexl
 JSTL & Velocity's expression language
JavaBean property navigation language
 Property navigation using "."
Expressions enclosed in ${…}
You are calling from ${request.remoteHost}
 More suited to Java objects
http://jakarta.apache.org/commons/jexl/
View layer : JXTemplate
 JXPath
 XPath on abitrary object graphs
XML documents, but also JavaBeans
Expressions enclosed in #{…}
You are calling from #{$request/remoteHost}
 Equally suited to XML documents and Java objects
 http://jakarta.apache.org/commons/jxpath/
Putting it all together
 The sitemap
Call a flow
function
<map:flow language="JavaScript">
<map:script src="store.js"/>
</map:flow>
<map:pipelines>
<map:pipeline>
<map:match pattern="checkout/">
<map:call function="checkout"/>
</map:match>
<map:match pattern="*.html"/>
<map:generate src="{1}.jx"/>
<map:transform src="page2html.xsl"/>
<map:serialize/>
</map:match>
Called by the
flow
Ressurect a
continuation
<map:match pattern="kont/*">
<map:call continuation="{1}"/>
</map:match>
…/…
Putting it all together
 Recap
 Controller is composed of flow scripts written in JavaScript
use sendPageAndWait() to send a response and temporarily
suspend execution
 Views are regular pipeline with access to flow data
JPath XSP tag library
JXTemplate generator
 Model : your Java business logic
 Sitemap glues everything together
The "cocoon" global object
 Access to the environment
 "request", "response", "session " and "context" properties
 "parameter" : sitemap parameters
 Access to the framework
 Logging :"log" property
 cocoon.log.debug("Hi there");
 Getting components
 cocoon.getComponent("org.apache.excalibur.xml.Parser")
 cocoon.releaseComponent(parser)
The "cocoon" global object
 Script modularization
 JavaScript has no "import" feature
 cocoon.load("resource://other/script.js")
 Page flow control
 cocoon.sendPage(), cocoon.sendPageAndWait()
 Internal calls to the sitemap
 cocoon.redirectTo("foo.html")
 External redirect sent to the browser
Session variables
 Global scope = session scope
 Global variables are attached to the session
Saved across top-level function invocations
Specific to each user
 Removes most of the needs for session attributes !
Session variables
 Example
var user = null;
Shows the login
screen
only if needed
function login() {
while (user == null) {
sendPageAndWait("login.html");
user = UserRegistry.getUser(
cocoon.request.getParameter("name"),
cocoon.request.getParameter("password") );
}
}
Won't pass through
if not logged !
function placeOrder() {
login();
Accounting.placeOrder(user);
sendPage("orderPlaced.html");
}
Just clear user info
to log out
function logout() {
user = null;
sendPage("bye.html");
}
Managing continuations
 Continuation trees
 Browser "back" or "new window"
var cart;
var user;
function checkout()
{
while(user == null) {
cocoon.sendPageAndWait("login.html");
user = UserRegistry.getUser(cocoon.request.get("name"));
}
cocoon.sendPageAndWait("shippingAddress.html", {who: user});
var address = cocoon.request.get("address");
cocoon.sendPageAndWait("creditCard.html");
var creditCard = cocoon.request.get("creditCard");
cocoon.sendPageAndWait("confirmOrder.html");
EnterpriseSystem.placeOrder(user, cart, address, creditCard);
cocoon.sendPage("orderPlaced.html");
…
}
Managing continuations
 Continuation trees
 Browser "back" : the previous path is lost
 No fear : a continuation is lightweight
 Reference to the parent continuation
 Local variables since the parent continuation
 Browser "new window"
Creates a new branch
 Allows "what if ?" navigation in the application
Managing continuations
 Expiring continuations
 Manual expiration :
sendPageAndWait() returns its continuation k
k.invalidate() invalidates the continuation and its subtree
var k = sendPageAndWait("start.html");
...
BusinessService.commit();
// Cannot go back again
k.invalidate();
 Again, avoids complicated state management
 Automatic expiration
An inactive continuation expires after a delay
Conclusion
 Flow script
 Gives control back to the server
 We always know "where" the browser is
 Allows sophisticated flow screens
 No need for state automata
 Increases security and robustness
 Forbids direct access to form submission URLs
 Handling of "back" and "new window"
Development tools
 Flow script debugger
 Activated in cocoon.xconf
Dealing with forms
The powerful Cocoon forms framework
Introduction
 The need for form handling
 Cocoon started as a publication framework
 Many pages, limited user feedback
 Content was mostly written "outside"
 Evolution towards a general-purpose web framework
 Published content has to be managed
 Used for more and more data-centric applications
 Need for good form handling features
Various attempts before Cocoon Forms…
Cocoon Forms principles
 Main requirements
 Strong typing and formatting
 A date input will give a java.util.Date
 Support for localized input formats
 No requirement for a form bean
 The form has its own data model
 Easy and safe binding to the data model
 Only when the all inputs are valid
 No direct link from request to application data
 Strong separation of form definition and styling
 Extensibility
 Everything is a component
Cocoon Forms principles
 The big picture
Cocoon Forms principles
 The form object model
 Composed of "widgets"
Represents "something" that appears in the form
Can read, parse and validate itself
Can output its XML representation
public interface Widget {
public Widget getParent();
public void setParent(Widget widget);
public Widget getWidget(String id);
public String getId();
public String getFullyQualifiedId();
public
public
public
public
void readFromRequest(FormContext formContext);
Object getValue();
void setValue(Object object);
boolean validate(FormContext formContext);
Naming
Widget
hierarchy
Parsing and
validation
public void generateSaxFragment(ContentHandler contentHandler, Locale locale);
public void generateLabel(ContentHandler contentHandler);
}
XML output
Cocoon Forms principles
 Form definition overview
<fd:form xmlns:fd="http://apache.org/cocoon/forms/1.0#definition">
<fd:widgets>
<fd:field id="name" required="true">
<fd:label>Name:</fd:label>
<fd:datatype base="string">
<fd:validation>
<fd:length min="2"/>
</fd:validation>
</fd:datatype>
</fd:field>
<fd:field id="email" required="true">
<fd:label>Email address:</fd:label>
<fd:datatype base="string">
<fd:validation>
<fd:email/>
</fd:validation>
</fd:datatype>
</fd:field>
…/…
<fd:widgets>
</fd:form>
Cocoon Forms principles
 Form template overview
 Embeds widget references in target markup
<html xmlns:ft="http://apache.org/cocoon/forms/1.0#template">
<head>
<title>Registration form</title>
</head>
<body>
<h1>Registration</h1>
<ft:form-template action="registration" method="POST">
<ft:widget-label id="name"/>
<ft:widget id="name"/>
<br/>
<ft:widget-label id="email"/>
<ft:widget id="email"/>
<br/>
…/…
<input type="submit"/>
</ft:form-template>
</body>
</html>
Cocoon Forms principles
 Resulting output
The form definition file
 Widgets
 Standard widgets
<fd:form> : the main form widget
<fd:field> : "atomic" input field
<fd:booleanfield> : boolean input
<fd:mutivaluefield> : multiple selection in a list
<fd:repeater> : collection of widgets
<fd:output> : unmodifiable widget
<fd:action> : action button
<fd:tree> : a tree-shaped widget
 They're all defined in cocoon.xconf
 Add your own if needed
The form definition file
 The <fd:field> widget
 Definition overview
<fd:field id="..." required="true|false">
<fd:label>...</fd:label>
<fd:datatype base="...">
[...]
</fd:datatype>
<fd:selection-list>
[...]
</fd:selection-list>
</fd:field>
 The label can contain abitrary markup
<fd:label>Your <b>name</b></fd:label>
Including i18n references
<fd:label>
<i18n:text key="name-field-label"/>
</fd:label>
The form definition file
 Defining the data type of a field
 Mandatory "base" type
Defines the Java type
"string", "long", "decimal", "date", "boolean"
 Pluggable components : add your own !
 Optional conversion and validation
Parsing and
formatting
Validation
<fd:datatype base="...">
<fd:convertor>
[...]
</fd:convertor>
<fd:validation>
[...]
</fd:validation>
</fd:datatype>
The form definition file
 Data type parsing and formatting
 Each base type has a set of converters
 Pluggable components : add your own !
 Example : date's "formatting" converter
based on java.text.SimpleDateFormat
 locale-dependent patterns
<fd:datatype base="date">
<fd:convertor type="formatting">
<fd:patterns>
<fd:pattern>yyyy-MM-dd</fd:pattern>
<fd:pattern locale="en">MM/dd/yyyy</fd:pattern>
<fd:pattern locale="fr">dd/MM/yyyy</fd:pattern>
<fd:pattern locale="nl-BE">dd/MM/yyyy</fd:pattern>
<fd:pattern locale="de">dd.MM.yyyy</fd:pattern>
</fd:patterns>
</fd:convertor>
</fd:datatype>
The form definition file
 Data type validation
 A validation rule checks value validity
length, range, regexp, creditcard, assert, email
 Pluggable components : add your own !
 A datatype can have several validation rules
 Example : email input field
<fd:field id="email">
<fd:datatype base="string">
<fd:validation>
<fd:length max='100'/>
<fd:email>
<fd:failmessage>Not a valid email address!</fd:failmessage>
</fd:email>
</fd:validation>
</fd:datatype>
</fd:field>
The form definition file
 Selection lists
 Provide enumerations to the user
 List of items having a value
 Optional item label
<fd:field name="OS">
<fd:datatype base="string"/>
<fd:selection-list>
<fd:item value="Linux"/>
<fd:item value="Windows"/>
<fd:item value="Mac OS"/>
<fd:item value="Solaris"/>
<fd:item value="other">
<fd:label><i18n:text key="other"/></fd:label>
</fd:item>
</fd:selection-list>
</fd:field>
 Selection lists can be external and dynamic
<fd:selection-list src="cocoon:/build-list.xml">
The form definition file
 The <fd:booleanfield> widget
 Boolean values
 Usually rendered as a checkbox
<fd:booleanfield id="somebool">
<fd:label>Put me <em>on</em> or <em>off</em>.</fd:label>
</fd:booleanfield>
The form definition file
 The <fd:multivaluefield> widget
 Allows the selection of several values
The value is an Object[]
 Requires a <fd:selection-list>
<fd:multivaluefield id="drinks">
<fd:label>Indicate your 2 most preferred drinks:</fd:label>
<fd:datatype base="string">
<fd:validation>
<fd:value-count exact="2"/>
</fd:validation>
</fd:datatype>
<fd:selection-list>
<fd:item value="Maes"/>
<fd:item value="Jupiler"/>
<fd:item value="Leffe"/>
<fd:item value="Hoegaarden"/>
<fd:item value="Coca Cola"/>
</fd:selection-list>
</fd:multivaluefield>
The form definition file
 The <fd:repeater> widget
 Repeats a number of child widgets
 Used to manage collections, tables, etc.
<fd:repeater id="contacts">
<fd:field id="firstname">
<fd:label>Firstname</fd:label>
<fd:datatype base="string"/>
</fd:field>
<fd:field id="lastname">
<fd:label>Lastname</fd:label>
<fd:datatype base="string"/>
</fd:field>
</fd:repeater>
The form definition file
 The <fd:output> widget
 Read-only widget
Provides formatting features
But doesn't read its value from the request
<fd:output id="shipping-date">
<fd:label>
<i18n:text key="shipping-date.label"/>
</fd:label>
<fd:datatype base="date">
<fd:convertor type="formatting" style="short"/>
</fd:datatype>
</fd:output>
The form definition file
 The <fd:action> widget
 An action button other than standard "submit"
Allows various actions to be taken on the form
 "action-command" defines the event name
<fd:repeater id="contacts">
<fd:field id="firstname">
<fd:label>Firstname</fd:label>
<fd:datatype base="string"/>
</fd:field>
<fd:field id="lastname">
<fd:label>Lastname</fd:label>
<fd:datatype base="string"/>
</fd:field>
<fd:booleanfield id="select"/>
</fd:repeater>
<fd:action id="add" action-command="add-contact">
<fd:label>Add contact</fd:label>
</fd:action>
<fd:action id="remove" action-command="remove-selected-contacts">
<fd:label>Remove selected contacts</fd:label>
</fd:action>
The form template
 The big picture (again)
The form template
 Role of the Cocoon FormsTransformer
 "Expand" all ft: elements
<html xmlns:ft="http://apache.org/cocoon/forms/1.0#instance">
<html xmlns:ft="http://apache.org/cocoon/forms/1.0#template">
<head>
<head>
<title>Registration form</title>
<title>Registration form</title>
</head>
</head>
<body>
<body>
<h1>Registration</h1>
<h1>Registration</h1>
<fi:form-template action="registration" method="POST">
<ft:form-template action="registration" method="POST">
Name:
<ft:widget-label id="name"/>
<fi:field id="name">
<ft:widget id="name"/>
<fi:label>Name:</fi:label>
<br/>
<fi:value>Cocoon</fi:value>
<ft:widget-label id="email"/>
</fi:field>
<ft:widget id="email"/>
<br/>
<br/>
Email address:
…/…
<fi:widget id="email">
<input type="submit"/>
<fi:label>Email address:</fi:label>
</ft:form-template>
<fi:value>foo</fi:value>
</body>
<fi:validation-message>
</html>
Invalid email address
</fi:validation-message>
</fi:widget>
<br/>
…/…
<input type="submit"/>
Validation
</fi:form-template>
failed
</body>
</html>
The form template
 Role of the FormsTransformer
 Expand all "ft" elements in their "fi" counterpart
 ft = Cocoon Forms template
 fi = Cocoon Forms instance
 Output of the transformer goes to styling
Provided : HTML styling
Other stylings are possible (e.g. WML)
 Cocoon Forms does not hardcode the presentation !
The form template
 The <ft:form-template> element
 Setup the transformer context
 Retrieve the Form object from the environment
 The <ft:widget-label> element
 Copies the content of <fd:label>
 Used to separate label output from the full widget
The form template
 The <ft:widget> element
 Produces the corresponding widget instance
Markup depends on the actual widget
For fields : <fi:label>, <fi:value>, <fi:selection-list>
 <ft:widget> can contain styling information
Drives the styling stylesheet
 Contents of <fi:styling> depends on the styling !
<ft:widget id="fourchars">
<!-- particular styling for the enumeration -->
<fi:styling list-type="listbox" listbox-size="4"/>
</ft:widget>
The form template
 The <ft:repeater-widget> element
 Iterates on the contents of a <fd:repeater>
Use to build e.g. tables
Produces indexed names for each iteration
 <ft:repeater-widget-label>
 Gets the label of a child of the repeater
Useful for table headers
The form template
 The <ft:repeater-widget>
element
<table>
<tr>
<th>
<ft:repeater-widget-label
id="contacts" widget-id="firstname"/>
</th>
<th>
<ft:repeater-widget-label
id="contacts" widget-id="email"/>
</th>
</tr>
<ft:repeater-widget id="contacts">
<tr>
<td>
<ft:widget id="firstname"/>
</td>
<td>
<ft:widget id="email"/>
</td>
</tr>
</ft:repeater-widget>
</table>
<table>
<tr>
<th>Name</th>
<th>Email address</th>
</tr>
<tr>
<td>
<fi:widget id="contacts.0.firstname">
<fi:label>Name</fi:label>
<fi:value>Harry</fi:value>
</fi:widget>
</td>
<td>
<fi:widget id="contacts.0.email">
<fi:label>Email address</fi:label>
<fi:value>harry@potter.com</fi:value>
</fi:widget>
</td>
</tr>
<tr>
<td>
<fi:widget id="contacts.1.firstname">
<fi:label>Name</fi:label>
<fi:value>Anakin</fi:value>
</fi:widget>
</td>
<td>
<fi:widget id="contacts.1.email">
<fi:label>Email address</fi:label>
<fi:value>anakin@sw.com</fi:value>
</fi:widget>
</td>
</tr>
</table>
Built in HTML styling
 The provided stylesheets
 »forms-field-styling.xsl"
Only styles basic inputs (fields & actions)
 many styling variants

»forms-advanced-field-styling.xsl »
Advanced group layout
 fieldsets, tab panels, overlapping panels
Built in HTML styling
 Field styling
 Basic styling : html input
 <fi:styling type="…">
"password"  <input type="password">
"hidden"  <input type="hidden">
"textarea"  <textarea>
"date"  date popup
Built in HTML styling
 Fields with a <selection-list>
 Basic styling : drop-down menu
 <fi:styling type="…">
"listbox"  <select><option>…
"radio"  <input type="radio">
• Additional "orientation" attribute (horizontal/vertical)
 <multivaluefield>
 Basic styling : check-boxes
Built in HTML styling
 <fi:group>
 Instance-only widget providing high-level styling
 No corresponding <fd:> nor <ft:>
Contains items that will be laid out
<fi:group>
<fi:label>Profile header</fi:label>
<fi:styling type="fieldset" layout="columns"/>
<fi:items>
<ft:widget id="revision"/>
<ft:widget id="identification"/>
<ft:widget id="name"/>
<ft:widget id="author"/>
<ft:widget id="classID"/>
<ft:widget id="releaseDate">
<fi:styling type="date"/>
</ft:widget>
<ft:widget id="additional-info"/>
</fi:items>
</fi:group>
Built in HTML styling
 <fi:group> styling
 Contents rendering
"layout" attribute : "columns"
 Automatic 2-column layout of widgets and labels
<fi:group>
<fi:label>Profile header</fi:label>
<fi:styling type="fieldset" layout="columns"/>
<fi:items>
<ft:widget id="revision"/>
[...]
</fi:items>
</fi:group>
type="fieldset"
layout="columns"
Built in HTML styling
 <fi:group> styling
 Container rendering
 "type" attribute : "fieldset", "tabs", "choice"
 Tabs defined with CSS
type="choice"
type="tabs"
Note : items in "tabs" and "choice" are most often subgroups
Binding : linking forms to application data
 An additional binding definition file
 Associates widget names to XPath expressions on the data model
Example : binding to an XML document
Set the context
of included paths
<fb:context
xmlns:fb="http://apache.org/cocoon/forms/1.0#binding"
xmlns:fd="http://apache.org/cocoon/forms/1.0#definition"
path="/data/user" >
<fb:value id="email" path="email" readonly="true"/>
Associates a
widget to a path
<fb:value id="number" path="number/@value">
<fd:convertor datatype="long"/>
</fb:value>
<fb:value id="choose" path="choose/@value">
<fd:convertor datatype="boolean"/>
</fb:value>
</fb:context>
Read-only
widget
Binding convertor
(XML is text)
Usage in flow script
 The form.js library
 Provides a Form class
Constructor takes a form definition file
 Method Form.showForm() to display the form
Does not return until validation is ok !!
 Internal loop on sendPageAndWait()
function edit_header() {
var form = new Form("forms/profile-header-def.xml");
form.showForm("view-profile-header.html", {foo: bar});
var revision-date = form.getModel().releaseDate;
...
sendDialog("Thanks a lot");
}
Application data
for the view
Getting form
data
Usage in flow script
 Advanced features
 Business-level validation
 Because not all constraints can be in the definition file
 Knowing the <fd:action> that was hit
function edit_header() {
var limit = Application.getLimit();
var form = new Form("forms/profile-header-def.xml");
form.validator = function(form) {
var dateWidget = form.getWidget("releaseDate");
if (dateWidget.getValue() > limit) {
dateWidget.setValidationError("Out of limits");
return false;
}
return true;
}
form.showForm("view-profile-header.html", {foo: bar});
if (form.submitID == 'cancel') {
sendDialog("Action cancelled");
} else {
var revision-date = form.getModel().releaseDate;
...
sendDialog("Thanks a lot");
}
}
Form is
redisplayed if
result is false
Test of the
submit button
Usage in flow script
 Advanced features
 Binding form and application data
function edit_header() {
var data = Application.getData();
var form = new Form("forms/profile-header-def.xml");
form.createBinding("forms/profile-header-binding.xml");
form.load(data);
form.showForm("view-profile-header.html", {foo: bar});
form.save(data);
sendDialog("Thanks a lot");
}
Putting it all together : the sitemap
 HTTP method selection
 GET method : start the flow
 POST method : continue
 Advantages
The form's action is "" (submit to the same URL)
Continuation management is hidden
<map:match pattern="edit_*.html">
<map:select type="method">
<!-- GET : start the flow for this screen -->
<map:when test="GET">
<map:call function="editor_{1}"/>
</map:when>
<!-- POST (form submission) : continue the flow -->
<map:when test="POST">
<map:call continuation="{request-param:continuation-id}"/>
</map:when>
</map:select>
</map:match>
Putting it all together : the sitemap
 View pipeline
 Use of JXTemplate generator
Allows the use of application data passed to showForm()
<map:match pattern="view-*.html">
<map:generate type="jxtemplate" src="forms/{1}-tmpl.xml"/>
<map:transform type="forms"/>
<map:transform type="i18n"/>
<map:transform type="xslt" src="resources/editor-layout.xsl"/>
<map:serialize type="html"/>
</map:match>
 Or just a plain file generator, using the template
<map:match pattern="view-*.html">
<map:generate type="file" src="forms/{1}-tmpl.xml"/>
<map:transform type="forms"/>
<map:transform type="i18n"/>
<map:transform type="xslt" src="resources/editor-layout.xsl"/>
<map:serialize type="html"/>
</map:match>
Conclusion
 A powerful form framework
Rich datatypes and validation rules
Easy extension to specific needs
 Flow script makes it really easy
 Future work
 Client-side validation
 Better event handling system
 Overall stabilization
Detailed documentation on http://wiki.cocoondev.org/Wiki.jsp?page=CForms
Summary
 Good for complex / multi forms
 Widget Oriented Approach
 Custom validation rules
 Dependencies
 Strongly type data
 Separation of declarations and templates
 Modular
 Reuse
 Business Integration via Flow
 I18n Support
Tales from the operation room
8 simple rules for building a manageable Cocoon
applications
Cocoon and manageability
 Cocoon is a huge beast to master
 Things tend to get out of hands quickly
 The real Cocoon advantage is about increased manageability
 So plan for it
Plan, plan, plan
 Don’t start coding, start sketching
 Customize the Cocoon environment:




Be ruthless in excluding blocks
Have a solid build system
Use mount-table wisely
Do version control local.build.properties and
local.blocks.properties
Manage configuration files
 You will need to modify configuration files:
 Use Cocoon’s own XConfTool to patch Cocoon configurations
 Separate configuration (patch) files by functionality
 Have further configuration files to overcome the current Cocoon
blocks limitations (why do you need JMS to access WebDAV?)
 Don’t trust components in Cocoon’s main sitemap, declare them
again
Relocation is not an option
 Users might install your application in a number of ways:
 Directly from the webapp root
 From a context path
 As a sub-sitemap
 Resource resolving needs to take this into account:
 Use a mount-point variable
<map:generate src="{global:mount-point}/some/where.xml">
 Perform calculations (upcoming Cocoon versions)
<map:generate src="{request:sitemapURIPrefix}/some/where.xml">
Samples are just samples
 Don’t rely on them for any functionality
 Import the required resources, don’t link to them
 This is especially true for Cocoon Forms
 Newer Cocoon versions have Forms resources packaged in a jar
file
 However, XSLTs are still included in samples
Separate application and user concerns
 In most applications, users are supposed to manage
configuration files
 Keep user-accessible resources separated:
 Client-side CSS, JS, images
 Consider xsl:import (with performance in mind) as override
mechanism
Package and ship
 Ideally, package everything in a jar file
 Yes, even sitemaps:
<map:mount src=”resource://com/pnetx/app/sitemap.xmap"/>
 Don’t forget:
 Error management (map:handle-errors)
 Error logging (logkit.xconf)
Wrapping up
 Long journey, and bumpy ride
 Yet barely scratched the surface
 More Cocoon presentations during ApacheCon:
 DE1348: Tools for Content Management and Publishing in
Apache: An Overview
 DE1258: Single Source Publishing with Apache Forrest
 DE1221: Cocoon - One Hour Portal
 DE1244: Developing Enterprise Web Applications with Cocoon
and Spring
 DE1284: Creating Print on Demand solutions with Cocoon, FOP,
and Lucene
 DE1272: Powering High-volume web sites with Lenya/Cocoon
and mod_cache
Thank you!
Questions?