Internetteknologi 2 (ITNET2)

Internetteknologi 2 (ITNET2) J2EE JavaServer Faces (JSF) Introduction

Agenda • JavaServer Faces (JSF): • Motivation for JSF • Visual Tool Support • JSF Legacy & Elements • Events • Managed Beans • Tool support

Motivation • ASP.NET 2 + VS 2003/2005 • New approach to Web development • JSP/Servlet specification could not compete • JSF introduced to supplement JSP/Servlet • JSF is a Sun Java specification • Implementations from Sun, IBM, Oracle, Exadel • A UI framework for Java Web applications • Easy component-based UI development • Swing like event model • “Code behind” like approach • Designed for visual tool support

Visual Tool Support from IBM WSAD, Netbeans 5.5, JDeveloper 11g

JSF Legacy • JSF uses JSP, EL, JSTL, Servlet technologies • It does NOT replace JSP/Servlet technology • Introduces backing beans and event programming • NOT a must • JSF works with JDBC, JPA, POJO, EJB, WS • JSF supports FrontController pattern out of the box • STRUTS heritage • Good news – all we know may still be applied

Elements of JSF • FacesServlet (central processing unit) • Web.xml (well-known from JSP/Servlet J2EE) • Faces-config.xml (configures navigation and managed beans etc.) • JSF-pages / JSF-tags (view implementations) • Managed Beans (beans controlled by framework) • Backing beans (event handler code) • Navigation Rules (front controller pattern) • Validators (same as .NET) • Converters (same as .NET)

Faces Servlet • Required FrontController • Implemented by the framework – not developers • All JSF request must pass through this • Configured via web.xml • Reads faces-config.xml for navigation and managed beans <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup> 1 </load-on-startup> </servlet> Page navigation is NOT required to use frontController

Faces-config.xml • Configures navigation, managed beans etc. • May be split up into several implementations • Managed-beans.xml • Navigation.xml • And other files • Depending on the tool

Managed-beans.xml <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE faces-config PUBLIC "-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.1//EN" "http://java.sun.com/dtd/web-facesconfig_1_1.dtd"> <faces-config> <managed-bean> <managed-bean-name>SessionBean1</managed-bean-name> <managed-bean-class>visualebtest.SessionBean1</managed-bean-class> <managed-bean-scope>session</managed-bean-scope> </managed-bean> <managed-bean> <managed-bean-name>Page1</managed-bean-name> <managed-bean-class>visualebtest.Page1</managed-bean-class> <managed-bean-scope>request</managed-bean-scope> </managed-bean> <managed-bean> <managed-bean-name>ApplicationBean1</managed-bean-name> <managed-bean-class>visualebtest.ApplicationBean1</managed-bean-class> <managed-bean-scope>application</managed-bean-scope> </managed-bean> <managed-bean> <managed-bean-name>RequestBean1</managed-bean-name> <managed-bean-class>visualebtest.RequestBean1</managed-bean-class> <managed-bean-scope>request</managed-bean-scope> </managed-bean> </faces-config> Backing bean Of “Page1.JSF” Managaed Beans are accessible in all JSF pages via EL: ${Page1.submit}

Navigation.xml <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE faces-config PUBLIC "-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.1//EN" "http://java.sun.com/dtd/web-facesconfig_1_1.dtd"> <faces-config> <navigation-rule> <from-view-id>/Page1.jsp</from-view-id> <navigation-case> <from-outcome>case1</from-outcome> <to-view-id>/Page2.jsp</to-view-id> </navigation-case> </navigation-rule> </faces-config> FrontController pattern implemented by defining a number of cases (actions) which e.g. a button press Might react to – and where to navigate to Counters anti-pattern: spaghetti

JSF Pages / Taglibs • Open to many different technologies • In practice: JSP integration • JSF Views are JSP pages using JSF tags • XML Style • Like ASP.NET 2, UI components are represented as different elements e.g. <h:dataTable /> • Like ASP.NET – you may make your own components

JSF taglibs Binding to backing bean Table component Navigation link A JSP page with JSF components Created with Visual Designer

Backing Beans • Abstracting event handling and data model away from JSF pages • Somewhat like ”code behind” in ASP.NET • Event Oriented • Actions • ActionListeners

Event Handling • Actions: may change page using ”return” • return: null for post back • return: case1 – frontcontroller -> Page2.jsf • Checks faces-config.xml or navigation.xml • ActionListeners occur before Actions and no page change Java Backing Bean Action Event Handler (ASP.NET = Click) JSF binding to action

Managed Beans • Managed Beans are JavaBeans • JavaBeans must be reflectable • (getter,setter, no-arg constructor) • A Managed Bean is a Value Object pattern • Holding scoped state for the Web application • Application, Session, Request, Page1, User • Like <jsp:useBean /> in JSP • Backing Beans are Managed Beans • May be accessed from anywhere in Web application • JSF using EL: Page1.button1 • Java: Page1 page = (Page1) this.getPage1(); • page.button1.setToolTip("Press for fun");

Databinding • A frequent task is RDBMS access • JSF has widespread support for this • May be done • Manual: JDBC coding (see JSP slides for example) • RowSet (com.sun.sql.rowset.CachedRowSetXImpl) • Entity Beans (JPA, TopLink, Hibernate, EJB 2.1/3.0) • Next we examplify the latter two with Netbeans 5.5 tool support • Drag-n-drop and Wizard

RowSet (”the qucik-n-dirty approach”) • Most J2EE IDE tools have a Runtime tab with database acces • Select database table and drag to designer • Creates a member in ”Session” managed bean

Binding Table to Rowset

JSF Resulting Tags • A ui:Table element is added with colums • EL is used to bind the data sources

Binding to City Drop-Down with City Table

Alternative: Entity Classes • RowSet approach OK for small solutions • Not good in case of business logic code • Instead: use Entity classes • A) Wizard: Generate Entity Classes • B) Wizard: Generate JSF pages from Entity • A) provides a domain layer (model layer) • B) will provide a control / view layer

Entity Classes from Database You may use this layer for Other technologies as well – Including Web services, CORBA, Java RMI, Swing, etc.

Model Generated • Access using JPA – write own DAO layer

JSF Pages from Entities • Will created View and Control / BL layers as well Entity Manager Controls the DB Access including transactions

Persistence.xml • Gets generated by tool – but can write yourself

JSF Pages Generated

Result For now – JSF pages wizard does NOT work With Visual Designer applications …

Architectural Considerations from JSF • FrontController is directly supported – use it • Event based programming -> look out for layer separation (do not write business logic layer code in the event handlers of the backing bean) • Like ASP.NET – Database drag-n-drop is supported with table / component data binding • Watch out for this approach, use only for small systems with little or no business code • Alternative: generate Entity classes (EJB, JPA) and event JSF code

Stefan’s Considerations on JSF • JSF is a strong alternative to ASP.NET – but much to learn • RowSet approach (quick-n-dirty) almost as easy as Visual Studio • Entity (EE) approach much better than ASP.NET • FrontController pattern / navigation.xml is a very strong feature – compared to master-details • JSF wins over ASP.NET for very large projects • ASP.NET / VS 2005 more productive for RAD development of small to medium sized projects • NetBeans requires tons of RAM – but runs extremely well on 2 GB Dual Core machine ;-) Nice to be rich … • But its FREE and runs on Solaris / Linux / Windows • Trying to develop JSF without tool support is doomed to fail!

Advice for Assignment 1 • Consider NOT using JSF (as stated earlier) • Use JSP/Servlets – as you will learn much about server programming from this • Try implementing a few pages also in JSF • But beware of NetBeans not working properly on IHA Lab machines …

Internetteknologi 2 (ITNET2)