copyright alphacsp israel 2008 – web framework playoff seminar 1 struts2 reinventing struts1 wheel...

Copyright AlphaCSP Israel 2008 – Web Framework Playoff Seminar

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Struts2 Struts2 Reinventing Struts1 WheelReinventing Struts1 Wheel

Ori DarConsultant and Architect,

AlphaCSP


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AgendaAgenda

Introduction Background Framework features review

Configuration View technology Page flow Form binding Table sorting Pagination Validation AJAX Error handling I18n support Documentation

Summary


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Introduction::In a nutshell (1)Introduction::In a nutshell (1)

• Action Based MVC Framework– FilterDispatcher : controller– Action : POJO model– Result : view

• Comparable to – Struts1– Spring MVC– Stripes


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•First released in Oct. 2006–Merger of Struts1 and WebWork2–Uses WebWork2 architecture

•Modern and clean architecture•Xml or annotations

–Actions–Validators–Datatype convertors


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•Extensible via plugins–Other frameworks integration–Embedding other application modules

•Intuitive, fast learning curve•Other core components

–Interceptors: controlling action pre and post processing–ValueStack: central storage for request model data


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Introduction::HelloWorldIntroduction::HelloWorld

<filter> <filter-name>action2</filter-name> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> </filter>

<filter-mapping> <filter-name>action2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

Controller: FilterDispatcher

web.xmlweb.xml


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Introduction::HelloWorld, ModelIntroduction::HelloWorld, Model

public class HelloWorld {

private String message="Hello World. Time is: ";

public String execute() { message += new Date();

return "success"; }

public String getMessage() { return message; }}

action methodreturns

a result code

We don’t have to extend Action

Boss

We don’t have to extend Action

Boss

… and no request, response in execute()

Boss

… and no request, response in execute()

Boss


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Introduction::HelloWorld, ViewIntroduction::HelloWorld, View

<%@ taglib prefix="s" uri="/struts-tags"%><html> <body>

<s:property value=“message“/> </body></html>

View: HelloWorld.jsp–Utilizes a single struts taglib–The taglib is common for JSP, Velocity and FreeMarker

Prints action’s message property.

Unlike struts1, action is a POJO,

and acts as a model


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Introduction::HelloWorldIntroduction::HelloWorld

<action name=“hello“ class="com.alphacsp.actions.HelloWorld">

<result name=“success“>/pages/HelloWorld.jsp</result> </action>

struts.xml:–Actions mapping–Results mapping

links action to view

http://host:port/app/hello.action

Use action name in URL invocation


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AgendaAgenda



Summary


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BackgroundBackground::S2 Vs. S1::S2 Vs. S1

Struts2 Struts1POJO (with execute) Action Extends Action

Model Action Role Controller

Decoupled Servlet API Dependant

Instance per request Threading Single instance

Action JavaBean properties

Form binding Action Form

Value Stack View binding JSP mechanisms

OGNL EL JSTL EL

xml or annotations Validation Action Form

Independent via interceptors

Lifecycle Shared

Wildcards, annotations Configuration Verbose


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BackgroundBackground::Interceptors::Interceptors

• Actions pre & post processing mechanism

• Like Spring AOP, EJB3 interceptors• Interceptors are packed in stacks• Custom interceptors and stacks can

be added• No equivalent in Struts1

<action name="phoneBook" class="com.alphacsp.actions.PhoneBook">

<interceptor-ref name="acspStack"/> <result>/pages/phoneBook.jsp</result></action> struts.xmlstruts.xml


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BackgroundBackground::Interceptors::Interceptors

<package name="struts-default" abstract="true">

<interceptors> <interceptor name="params" class="…"/>

<interceptor-stack name="basicStack"> <interceptor-ref name="exception"/> <interceptor-ref name="servletConfig"/> <interceptor-ref name="prepare"/> <interceptor-ref name="checkbox"/> <interceptor-ref name="params"/> <interceptor-ref name="conversionError"/> </interceptor-stack> </interceptors>

<default-interceptor-ref name="defaultStack"/></package>

Excerpt from struts-default.xml

interceptor

interceptor stackcontains other interceptors

the default stackfor actions in package

struts-default.xmlstruts-default.xml


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BackgroundBackground::V::ValueStack alueStack

• The ValueStack is a storage for request domain model

• Serves as context per request • “Glues” model and view• Accessed by interceptors & views• Stores action properties• Also stores message bundles


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BackgroundBackground::OGNL::OGNL

•ValueStack is referenced and manipulated by OGNL •OGNL is also used instead of JSTL<s:textfield name="contact.email"/>

<s:text name="email"/>

phoneBook.jspphoneBook.jsp


retrieves email propertyof actions’ contact property

from stack using OGNL

retrieves localized messageusing email as key

from stack using OGNL


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BackgroundBackground::::Other featuresOther features

• Tag Library– Form component tags– Ajax UI component tags– Control tags: iterator, if/else… – Data tags: manipulate the ValueStack

• Datatype conversion framework• Themes: templates for customizing

components markup


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BackgroundBackground:::: Theme example Theme example

<s:form action="login" namespace="/" validate="true"> <s:textfield cssClass="loginField" size="25" key="username"/> <s:password cssClass="loginField" size="25" key="password"/> <s:submit value="Login" cssClass="button" align="center"/></s:form>

Xhtml theme generates table and validation feedback.

No themes in Struts1

login.jsplogin.jsp


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BackgroundBackground::::Other featuresOther features

• Reasonable defaults: struts-default– Result types– Interceptor stacks

• Actions extending ActionSupport– facilitates validation– facilitates localization

• Spring integration– Dependency Injection interceptor– Full Spring lifecycle management


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AgendaAgenda



Summary


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FeaturesFeatures::Action Configuration::Action Configuration

<action name="listEmployees" class="actions.model.Employee" method="list"><result name="list" type="dispatcher">/WEB-INF/list.jsp</result>

</action>

result typethe view technology

(default value: “dispatcher”for rendering JSP)

result nameaction method should returna matching result code string

(default value: “success”)

action methodwithin action class

(default value: “execute”)action class

action name matched by a URL


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FeaturesFeatures:: Action Configuration:: Action Configuration

<action name="list*s" class="actions.model.{1}" method="list">

<result name="list">/WEB-INF/list{1}s.jsp</result></action>

•Wildcards can be used for mapping•Mandates naming convention•Makes XML much less verbose

listEmployees.action is mapped to Employee class and listEmployees.jsplistDepartments.action is mapped to Department class and listDepartmrnts.jsp…


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FeaturesFeatures::Annotation Config.::Annotation Config.

@Result(name="list", value="/WEB-INF/list.jsp")public class Employee extends ActionSupport{ public String listEmployees() { // business logic goes here

return "list"; }}

•Annotation based configuration –Can make XML utterly redundant–Struts scans packages for action classes–Results are expressed via @Result

“list” result codeis mapped to JSP.

By extending ActionSupport,Employee is mapped

as action by the package scanning

mechanism


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FeaturesFeatures::::View technologyView technology

• Result types– JSP : dispatcher– Velocity– FreeMarker– XSLT– Stream : PDF, MS Word etc.

• Plugins– JasperReports– JFreeChart– JSON


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FeaturesFeatures::Page flow::Page flow

1

3

4

5

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7

8

2


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FeaturesFeatures::::Form bindingForm binding

<s:form action="login" validate="true" namespace="/">

<s:textfield cssClass="loginField" key="username"/>

<s:submit key="login" cssClass="button" align="center"/>

</s:form>login.jsplogin.jsp

public class Login {

private String username;

public void setUsername(String username) {this.username = username;

}}

Login.javaLogin.java

Form field parameters are injected into setter

methods by the params interceptor


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FeaturesFeatures::Table sorting::Table sorting

1. Using Table Tags plugin– Undocumented– Looks inactive– Lack of evidence

2. Using Dojo + JSON – Too complex

3. YUI DataTable – Buggy, beta

4. Display tag library


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FeaturesFeatures::Table sorting::Table sorting

<display:table class="grid" defaultsort="1" id=“contact" name=“contacts" pagesize="5" requestURI="phoneBook.acsp" sort="list">

<display:column class="grid" escapeXml="true" headerClass="grid" property="fullName" title="Name" sortable="true" defaultorder="ascending"/>

<display:column class="grid" escapeXml="false" headerClass="grid" title="Email" style="border-left: 1px solid #5680AA;">

<s:textfield value="%{#attr.contact.email}" theme="simple"/>

</display:column></display:table>

From demo application



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FeaturesFeatures::::PaginationPagination

Used the display tag library internal pagination support– Supports internal and external

pagination– Forces you to use HTTP GET– Adds pagination parameter to request


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FeaturesFeatures::Validation::Validation

• Uses 12 out-of-box field validators• Uses expression validators for

complex validations• Validators can be declared using xml• Validators can be declared using

annotations– Field validators for setter methods– Expression validator for action methods


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FeaturesFeatures::Validation::Validation

@EmailValidator(fieldName = "email", key="wrongEmailFormat", message="Wrong Email Format")

public void setEmail(String email) { this.email = email;}

PhoneBook.javaPhoneBook.java

<validators><field name="email"> <field-validator type="email"> <message key="wrongEmailFormat">

Wrong Email Format </message> </field-validator> </field></validators> PhoneBook_validation.xmlPhoneBook_validation.xml

Annotation vs. xml example(No annotated version for Struts1)


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FeaturesFeatures::Client side validation::Client side validation

<s:actionerror cssClass="feedback"/>

<s:form action="login" namespace="/" validate="true" > <s:textfield cssClass="loginField" size="25" key="username"/> <s:password cssClass="loginField" size="25" key="password"/> <s:submit value="Login" cssClass="button" align="center"/></s:form>

•Automatic creation of client side validation

–No client side for expression validators–Apply a theme for generating error feedback markup

login.jsplogin.jsp


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FeaturesFeatures::Ajax::Ajax

• Dojo is embedded for Ajax tags• Dojo head tag enables JS debugging• Ajax requests are handled by actions• DWR integration is enabled via plugin• YUI integration is enabled via plugin• Ajax file upload via plugin• Ajax behaviour for component tags


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FeaturesFeatures::::Ajax autocompleterAjax autocompleter

View

Action

<s:url id="acUrl" action="getDepts"/>

<s:autocompleter name="dept" href="%{acUrl}" cssClass="acSearchField"/>

private List<String> deptList;

public String execute() { deptList = service.findAllDepartments(); return ActionSupport.SUCCESS;}

public List<String> getDeptList() { return deptList; }


PhoneBook.javaPhoneBook.java

>action name="getDepts" class="DeptsAutoComplete" <

>result type="json" <>param name="root">deptList</param <

/>result </>action <

struts-default.xmlstruts-default.xml


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FeaturesFeatures::Error handling::Error handling

• Validation error feedback tags– actionerror– actionmessage– fielderror: per form field

• Two framework supporting interfaces– Validatable: for programmatic validation– ValidationAware: for UI feedback

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FeaturesFeatures::Error handling::Error handling

 <global-results> <result name="sysError">/pages/systemError.jsp</result> </global-results>

<global-exception-mappings> <exception-mapping exception="java.lang.Exception" result="sysError"/> </global-exception-mappings>

•Exception interceptor–maps exceptions to result error pages–should be first in interceptor stack

struts.xmlstruts.xml


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FeaturesFeatures::I18N support::I18N support

• Built on top of Java I18N support• Bundles can be defined in:

– action.properties – package.properties– global resource properties

• Bundles pushed to ValueStack• Validation errors can be localized• Locale interceptor to switch locale


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FeaturesFeatures::Documentation::Documentation

•Apache Struts 2 Documentation•WIKI •Struts Showcase•Plugins


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AgendaAgenda



Summary


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Summary::ProsSummary::Pros

Extensible plugin frameworkModular and clean architecture Annotation or xml configurationCustomized lifecycle via interceptorsNeat form & view binding Easy client side validationMarkup generation with themes


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Summary::ProsSummary::Pros

Fast learning curveIntuitiveRestful URL action mapperEasy to test (POJOs) using pluginsDI via lightweight containersDecoration with tiles, sitemash


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Summary::ConsSummary::Cons

Unorganized documentationLack of API documentationNo clear roadmapActionSupport dependencyLack of @ActionLack of @InterceptorCases when fallback to Servlet API is needed Weakly typed sessions


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Summary::When to useSummary::When to use

• Use when– Migrating from legacy framework– Natural around HTTP request response

paradigm– Suitable for streaming– POC, prototype, RAD

• Don’t use when– Heavily utilized RIA is needed– Your developers have Swing orientation


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Thank Thank You !You !

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