13. JSF Integration
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## 13. JSF Integration

## 13.1. Introduction

Spring Web Flow provides a JSF integration that simplifies using JSF with Spring. It lets you use the JSF UI Component Model with Spring MVC and Spring Web Flow controllers. Along with the JSF integration Spring Web Flow provides a small Facelets component library (called Spring Faces) for use in JSF 1.2 environments and a Spring Security tag library for use in both JSF 1.2 and JSF 2.0 environments (see Section 13.11, “Using the Spring Security Facelets Tag Library” for more details).

Starting with version 2.2 the JSF integration in Web Flow supports JSF 2.0 including Sun Mojarra and Apache MyFaces runtime environments. Please, note however that JSF 2 partial state saving is not yet supported with Apache MyFaces and needs to be disabled with the `javax.faces.PARTIAL_STATE_SAVING` context parameter in `web.xml`.

Also note that the Spring Faces component library, which provides Ajax and client-side validation capabilities is for JSF 1.2 environments only and will not be upgraded to JSF 2.0. Applications are encouraged to use 3rd party JSF 2 component libraries such as PrimeFaces and RichFaces. The `swf-booking-faces` sample in the Spring Web Flow distribution for example is built with JSF 2 and PrimeFaces components.

Spring Web Flow also supports using JSF in a portlet environment. Spring Web Flow's portlet integration supports Portlets API 2.0 and JSF 1.2 only. Currently JSF 2 is not supported in combination with portlets. See Chapter 14, Portlet Integration for more on Spring Web Flow's portlet integration.

## 13.2. JSF Integration For Spring Developers

Spring Web Flow complements the strengths of JSF, its component model, and provides more sophisticated state management and navigation. In addition you have the ability to use Spring MVC @Controller or flow definitions as controllers in the web layer.

JSF applications using Spring Web Flow applications gain benefits in the following areas:

1. Managed bean facility

2. Scope management

3. Event handling

4. Navigation

5. Modularization and packaging of views

6. Cleaner URLs

7. Model-level validation

8. Progressivy-enhancement sytle client-side validation

9. Progressive-enhancement style Ajax requests with partial page updates

Using these features significantly reduce the amount of configuration required in faces-config.xml. They provide a cleaner separation between the view and controller layers along with better modularization of application functionals. These features are detailed in the sections to follow. The majority of these features build on the flow definition language of Spring Web Flow. Therefore it is assumed that you have an understanding of the foundations presented in Chapter 3, Defining Flows.

## 13.3. Configuring web.xml

The first step is to route requests to the `DispatcherServlet` in the `web.xml` file. In this example, we map all URLs that begin with `/spring/` to the servlet. The servlet needs to be configured. An `init-param` is used in the servlet to pass the `contextConfigLocation`. This is the location of the Spring configuration for your web application.

    <servlet>
        <servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/web-application-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
        <url-pattern>/spring/*</url-pattern>
    </servlet-mapping>

In order for JSF to bootstrap correctly, the `FacesServlet` must be configured in `web.xml` as it normally would even though you generally will not need to route requests through it at all when using JSF with Spring Web Flow.

    <!-- Just here so the JSF implementation can initialize, *not* used at runtime -->
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Just here so the JSF implementation can initialize -->
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>

The use of Facelets instead of JSP typically requires this in web.xml:

    !-- Use JSF view templates saved as *.xhtml, for use with Facelets -->
    <context-param>
        <param-name>javax.faces.DEFAULT_SUFFIX</param-name>
        <param-value>.xhtml</param-value>
    </context-param>

### 13.3.1. Configuring web.xml in JSF 1.2

When using the JSF 1.2 Spring Faces component library, you also need to configure a servlet for serving CSS and JavaScript resources. This servlet must be mapped to /resources/* in order for the URL's rendered by the components to function correctly.

    <!-- Serves static resource content from .jar files such as spring-faces.jar -->
    <servlet>
        <servlet-name>Resource Servlet</servlet-name>
        <servlet-class>org.springframework.js.resource.ResourceServlet</servlet-class>
        <load-on-startup>0</load-on-startup>
    </servlet>

    <!-- Map all /resources requests to the Resource Servlet for handling -->
    <servlet-mapping>
        <servlet-name>Resource Servlet</servlet-name>
        <url-pattern>/resources/*</url-pattern>
    </servlet-mapping>

For optimal page-loading performance use the Spring Faces components `includeStyles` and `includeScripts`. These components will eagerly load the necessary CSS stylesheets and JavaScript files at the position they are placed in your JSF view template. In accordance with the recommendations of the Yahoo Performance Guildlines, these two tags should be placed in the `head` section of any page that uses the Spring Faces components. For example:

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <f:view xmlns="http://www.w3.org/1999/xhtml"
          xmlns:ui="http://java.sun.com/jsf/facelets"
          xmlns:f="http://java.sun.com/jsf/core"
    	  xmlns:c="http://java.sun.com/jstl/core"
    	  xmlns:sf="http://www.springframework.org/tags/faces"
    	  contentType="text/html" encoding="UTF-8">
    <html>
    <head>
    	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    	<title>Hotel Booking Sample Application</title>

    	<sf:includeStyles />
    	<sf:includeScripts />

    	<ui:insert name="headIncludes"/>
    </head>
    ...
    </html>
    </f:view>

This shows the opening of a typical Facelets XHTML layout template that uses these components to force the loading of the needed CSS and JavaScript resources at the ideal position.

The `includeStyles` component includes the necessary resources for the Dojo widget theme. By default, it includes the resources for the "tundra" theme. An alternate theme may be selected by setting the optional "theme" and "themePath" attributes on the `includeStyles` component. For example:

    <sf:includeStyles themePath="/styles/" theme="foobar"/>

will try to load a CSS stylesheet at "/styles/foobar/foobar.css" using the Spring JavaScript ResourceServlet.

## 13.4. Configuring Web Flow for use with JSF

This section explains how to configure Web Flow with JSF. The next section provides more details specific to using Web Flow with JSF 2. The following is sample configuration for Web Flow and JSF:

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:webflow="http://www.springframework.org/schema/webflow-config"
        xmlns:faces="http://www.springframework.org/schema/faces"
        si:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/webflow-config
            http://www.springframework.org/schema/webflow-config/spring-webflow-config-2.3.xsd
            http://www.springframework.org/schema/faces
            http://www.springframework.org/schema/faces/spring-faces-2.2.xsd">

        <!-- Executes flows: the central entry point into the Spring Web Flow system -->
        <webflow:flow-executor id="flowExecutor">
            <webflow:flow-execution-listeners>
                <webflow:listener ref="facesContextListener"/>
            </webflow:flow-execution-listeners>
        </webflow:flow-executor>

        <!-- The registry of executable flow definitions -->
        <webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" base-path="/WEB-INF">
            <webflow:flow-location-pattern value="**/*-flow.xml" />
        </webflow:flow-registry>

        <!-- Configures the Spring Web Flow JSF integration -->
        <faces:flow-builder-services id="flowBuilderServices" />

        <!-- A listener maintain one FacesContext instance per Web Flow request. -->
        <bean id="facesContextListener"
            class="org.springframework.faces.webflow.FlowFacesContextLifecycleListener" />

    </beans>

The main points are the installation of a `FlowFacesContextLifecycleListener` that manages a single FacesContext for the duration of Web Flow request and the use of the `flow-builder-services` element from the `faces` custom namespace to configure rendering for a JSF environment.

See the swf-booking-faces reference application in the distribution for a complete working example.

## 13.5. Configuring Spring MVC for JSF 2

In a JSF 2 environment you'll also need this Spring MVC related configuration:

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:faces="http://www.springframework.org/schema/faces"
           xsi:schemaLocation="
               http://www.springframework.org/schema/beans
               http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
               http://www.springframework.org/schema/faces
               http://www.springframework.org/schema/faces/spring-faces-2.2.xsd">

        <faces:resources />

        <bean class="org.springframework.faces.webflow.JsfFlowHandlerAdapter">
            <property name="flowExecutor" ref="flowExecutor" />
        </bean>

    </beans>

The `resources` custom namespace element delegates JSF 2 resource requests to the JSF 2 resource API. The `JsfFlowHandlerAdapter` is a replacement for the `FlowHandlerAdapter` normally used with Web Flow. This adapter initializes itself with a `JsfAjaxHandler` instead of the `SpringJavaSciprtAjaxHandler` previously used with Spring Faces components.

## 13.6. Configuring faces-config.xml

In JSF 1.2 you need to provide the below configuration in `faces-config.xml` in order to use Facelets. If you are using JSP and not using the Spring Faces components, you do not need to add anything to your `faces-config.xml`

    <faces-config>
        <application>
            <!-- Enables Facelets -->
            <view-handler>com.sun.facelets.FaceletViewHandler</view-handler>
        </application>
    </faces-config>

In JSF 2.0 your faces-config.xml should use the faces-config schema version 2.0. Also you should remove the FaceletViewHandler shown above (if it is present) as Facelets are now the default rendering technology in JSF 2.

    <?xml version='1.0' encoding='UTF-8'?>
    <faces-config xmlns="http://java.sun.com/xml/ns/javaee"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
            version="2.0">

    </faces-config>

## 13.7. Replacing the JSF Managed Bean Facility

When using JSF with Spring Web Flow you can completely replace the JSF managed bean facility with a combination of Web Flow managed variables and Spring managed beans. It gives you a good deal more control over the lifecycle of your managed objects with well-defined hooks for initialization and execution of your domain model. Additionally, since you are presumably already using Spring for your business layer, it reduces the conceptual overhead of having to maintain two different managed bean models.

In doing pure JSF development, you will quickly find that request scope is not long-lived enough for storing conversational model objects that drive complex event-driven views. In JSF 1.2 the only available option is to begin putting things into session scope, with the extra burden of needing to clean the objects up before progressing to another view or functional area of the application. What is really needed is a managed scope that is somewhere between request and session scope. JSF 2 provides flash and view scopes that can be accessed programmatically via UIViewRoot.getViewMap(). Spring Web Flow provides access to flash, view, flow, and conversation scopes. These scopes are seamlessly integrated through JSF variable resolvers and work the same in JSF 1.2 and in JSF 2.0 applications.

### 13.7.1. Using Flow Variables

The easiest and most natural way to declare and manage the model is through the use of flow variables. You can declare these variables at the beginning of the flow:

    <var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>

and then reference this variable in one of the flow's JSF view templates through EL:

    <h:inputText id="searchString" value="#{searchCriteria.searchString}"/>

Note that you do not need to prefix the variable with its scope when referencing it from the template (though you can do so if you need to be more specific). As with standard JSF beans, all available scopes will be searched for a matching variable, so you could change the scope of the variable in your flow definition without having to modify the EL expressions that reference it.

You can also define view instance variables that are scoped to the current view and get cleaned up automatically upon transitioning to another view. This is quite useful with JSF as views are often constructed to handle multiple in-page events across many requests before transitioning to another view.

To define a view instance variable, you can use the `var` element inside a `view-state` definition:

    <view-state id="enterSearchCriteria">
        <var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>
    </view-state>

### 13.7.2. Using Scoped Spring Beans

Though defining autowired flow instance variables provides nice modularization and readability, occasions may arise where you want to utilize the other capabilities of the Spring container such as AOP. In these cases, you can define a bean in your Spring ApplicationContext and give it a specific web flow scope:

    <bean id="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria" scope="flow"/>

The major difference with this approach is that the bean will not be fully initialized until it is first accessed via an EL expression. This sort of lazy instantiation via EL is quite similar to how JSF managed beans are typically allocated.

### 13.7.3. Manipulating The Model

The need to initialize the model before view rendering (such as by loading persistent entities from a database) is quite common, but JSF by itself does not provide any convenient hooks for such initialization. The flow definition language provides a natural facility for this through its Actions . Spring Web Flow provides some extra conveniences for converting the outcome of an action into a JSF-specific data structure. For example:

    <on-render>
        <evaluate expression="bookingService.findBookings(currentUser.name)"
                  result="viewScope.bookings" result-type="dataModel" />
    </on-render>

This will take the result of the `bookingService.findBookings` method an wrap it in a custom JSF DataModel so that the list can be used in a standard JSF DataTable component:

    <h:dataTable id="bookings" styleClass="summary" value="#{bookings}" var="booking"
                 rendered="#{bookings.rowCount > 0}">
        <h:column>
            <f:facet name="header">Name</f:facet>
            #{booking.hotel.name}
        </h:column>
        <h:column>
        <f:facet name="header">Confirmation number</f:facet>
            #{booking.id}
            </h:column>
        <h:column>
            <f:facet name="header">Action</f:facet>
            <h:commandLink id="cancel" value="Cancel" action="cancelBooking" />
        </h:column>
    </h:dataTable>

### 13.7.4. Data Model Implementations

In the example above result-type="dataModel" results in the wrapping of List<Booking> with custom `DataModel` type. The custom `DataModel` provides extra conveniences such as being serializable for storage beyond request scope as well as access to the currently selected row in EL expressions. For example, on postback from a view where the action event was fired by a component within a DataTable, you can take action on the selected row's model instance:

    <transition on="cancelBooking">
        <evaluate expression="bookingService.cancelBooking(bookings.selectedRow)" />
    </transition>

Spring Web Flow provides two custom DataModel types: `OneSelectionTrackingListDataModel` and `ManySelectionTrackingListDataModel`. As the names indicate they keep track of one or multiple selected rows. This is done with the help of a `SelectionTrackingActionListener` listener, which responds to JSF action events and invokes the appopriate methods on the `SelectinAware` data models to record the currently clicked row.

To understand how this is configured, keep in mind the `FacesConversionService` registers a `DataModelConverter` against the alias "dataModel" on startup. When result-type="dataModel" is used in a flow definition it causes the `DataModelConverter` to be used. The converter then wraps the given List with an instance of `OneSelectionTrackingListDataModel`. To use the `ManySelectionTrackingListDataModel` you will need to register your own custom converter.

## 13.8. Handling JSF Events With Spring Web Flow

Spring Web Flow allows you to handle JSF action events in a decoupled way, requiring no direct dependencies in your Java code on JSF API's. In fact, these events can often be handled completely in the flow definiton language without requiring any custom Java action code at all. This allows for a more agile development process since the artifacts being manipulated in wiring up events (JSF view templates and SWF flow definitions) are instantly refreshable without requiring a build and re-deploy of the whole application.

### 13.8.1. Handling JSF In-page Action Events

A simple but common case in JSF is the need to signal an event that causes manipulation of the model in some way and then redisplays the same view to reflect the changed state of the model. The flow definition language has special support for this in the `transition` element.

A good example of this is a table of paged list results. Suppose you want to be able to load and display only a portion of a large result list, and allow the user to page through the results. The initial `view-state` definition to load and display the list would be:

    <view-state id="reviewHotels">
        <on-render>
            <evaluate expression="bookingService.findHotels(searchCriteria)"
                      result="viewScope.hotels" result-type="dataModel" />
        </on-render>
    </view-state>

You construct a JSF DataTable that displays the current `hotels` list, and then place a "More Results" link below the table:

    <h:commandLink id="nextPageLink" value="More Results" action="next"/>

This commandLink signals a "next" event from its action attribute. You can then handle the event by adding to the `view-state` definition:

    <view-state id="reviewHotels">
        <on-render>
            <evaluate expression="bookingService.findHotels(searchCriteria)"
                result="viewScope.hotels" result-type="dataModel" />
        </on-render>
        <transition on="next">
            <evaluate expression="searchCriteria.nextPage()" />
        </transition>
    </view-state>

Here you handle the "next" event by incrementing the page count on the searchCriteria instance. The `on-render` action is then called again with the updated criteria, which causes the next page of results to be loaded into the DataModel. The same view is re-rendered since there was no `to` attribute on the `transition` element, and the changes in the model are reflected in the view.

### 13.8.2. Handling JSF Action Events

The next logical level beyond in-page events are events that require navigation to another view, with some manipulation of the model along the way. Achieving this with pure JSF would require adding a navigation rule to faces-config.xml and likely some intermediary Java code in a JSF managed bean (both tasks requiring a re-deploy). With the flow defintion language, you can handle such a case concisely in one place in a quite similar way to how in-page events are handled.

Continuing on with our use case of manipulating a paged list of results, suppose we want each row in the displayed DataTable to contain a link to a detail page for that row instance. You can add a column to the table containing the following `commandLink` component:

    <h:commandLink id="viewHotelLink" value="View Hotel" action="select"/>

This raises the "select" event which you can then handle by adding another `transition` element to the existing `view-state` :

    <view-state id="reviewHotels">
        <on-render>
            <evaluate expression="bookingService.findHotels(searchCriteria)"
                result="viewScope.hotels" result-type="dataModel" />
        </on-render>
        <transition on="next">
            <evaluate expression="searchCriteria.nextPage()" />
        </transition>
        <transition on="select" to="reviewHotel">
                <set name="flowScope.hotel" value="hotels.selectedRow" />
        </transition>
    </view-state>

Here the "select" event is handled by pushing the currently selected hotel instance from the DataTable into flow scope, so that it may be referenced by the "reviewHotel" `view-state` .

### 13.8.3. Performing Model Validation

JSF provides useful facilities for validating input at field-level before changes are applied to the model, but when you need to then perform more complex validation at the model-level after the updates have been applied, you are generally left with having to add more custom code to your JSF action methods in the managed bean. Validation of this sort is something that is generally a responsibility of the domain model itself, but it is difficult to get any error messages propagated back to the view without introducing an undesirable dependency on the JSF API in your domain layer.

With Web Flow, you can utilize the generic and low-level `MessageContext` in your business code and any messages added there will then be available to the `FacesContext` at render time.

For example, suppose you have a view where the user enters the necessary details to complete a hotel booking, and you need to ensure the Check In and Check Out dates adhere to a given set of business rules. You can invoke such model-level validation from a `transition` element:

    <view-state id="enterBookingDetails">
        <transition on="proceed" to="reviewBooking">
            <evaluate expression="booking.validateEnterBookingDetails(messageContext)" />
        </transition>
    </view-state>

Here the "proceed" event is handled by invoking a model-level validation method on the booking instance, passing the generic `MessageContext` instance so that messages may be recorded. The messages can then be displayed along with any other JSF messages with the `h:messages` component,

### 13.8.4. Handling Ajax Events In JSF 2.0

JSF 2 provides built-in support for sending Ajax requests and performing partial processing and rendering on the server-side. You can specify a list of id's for partial rendering through the <f:ajax> facelets tag.

In Spring Web Flow you also have the option to specify the ids to use for partial rendering on the server side with the render action:

    <view-state id="reviewHotels">
        <on-render>
            <evaluate expression="bookingService.findHotels(searchCriteria)"
                      result="viewScope.hotels" result-type="dataModel" />
        </on-render>
        <transition on="next">
            <evaluate expression="searchCriteria.nextPage()" />
            <render fragments="hotels:searchResultsFragment" />
        </transition>
    </view-state>

### 13.8.5. Handling File Uploads with JSF

Most JSF component providers include some form of 'file upload' component. Generally when working with these components JSF must take complete control of parsing multi-part requests and Spring MVC's `MultipartResolver` cannot be used.

Spring Web Flow has been tested with file upload components from PrimeFaces and RichFaces. Check the documentation of your JSF component library for other providers to see how to configure file upload.

#### File Uploads with PrimeFaces

PrimeFaces provides a `<p:fileUpload>` component for uploading files. In order to use the component you need to configure the `org.primefaces.webapp.filter.FileUploadFilter` servlet filter. The filter needs to be configured against Spring MVC's `DispatcherServlet` in your `web.xml`:

    <filter>
    	<filter-name>PrimeFaces FileUpload Filter</filter-name>
    	<filter-class>org.primefaces.webapp.filter.FileUploadFilter</filter-class>
    </filter>
    <filter-mapping>
    	<filter-name>PrimeFaces FileUpload Filter</filter-name>
    	<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
    </filter-mapping>

For more details refer to the PrimeFaces documentation.

#### File Uploads with RichFaces

RichFaces provides a `<rich:fileUpload>` component for uploading files. No special configuration is required to use the component, however, you will need to perform some additional steps in your `fileUploadListener`.

Here is some typical XHTML markup. In this example the `fileUploadBean` refers to Spring singleton bean.

    <rich:fileUpload id="upload"
    	fileUploadListener="#{fileUploadBean.listener}"
    	acceptedTypes="jpg, gif, png, bmp">
    </rich:fileUpload>

Within your `fileUploadBean` you need to tell Web Flow that the response has been handled and that it should not attempt any redirects. The `org.springframework.webflow.context.ExternalContext` interface provides a `recordResponseComplete()` for just such purposes.

In addition, it is imperative that some partial response data is returned to the client. If your `<rich:fileUpload>` component does not specify a `render` attribute you may need to call `processPartial(PhaseId.RENDER_RESPONSE)` on the JSF `PartialViewContext`.

    public class FileUploadBean {

    	public void listener(FileUploadEvent event) throws Exception{
    		FacesContext.getCurrentInstance().getPartialViewContext().processPartial(PhaseId.RENDER_RESPONSE);
    		ExternalContextHolder.getExternalContext().recordResponseComplete();
    		UploadedFile file = event.getUploadedFile();
    		// Do something with the file
    	}
    }

For more details refer to the RichFaces documentation.

### 13.8.6. Handling Ajax Events In JSF 1.2

For JSF 1.2 the Spring Faces `UICommand` components have the ability to do Ajax-based partial view updates. These components degrade gracefully so that the flow will still be fully functional by falling back to full page refreshes if a user with a less capable browser views the page.

Revisiting the earlier example with the paged table, you can change the "More Results" link to use an Ajax request by replacing the standard `commandButton` with the Spring Faces component version (note that the Spring Faces command components use Ajax by default, but they can alternately be forced to use a normal form submit by setting ajaxEnabled="false" on the component):

    <sf:commandLink id="nextPageLink" value="More Results" action="next" />

This event is handled just as in the non-Ajax case with the `transition` element, but now you will add a special `render` action that specifies which portions of the component tree need to be re-rendered:

    <view-state id="reviewHotels">
        <on-render>
            <evaluate expression="bookingService.findHotels(searchCriteria)"
                      result="viewScope.hotels" result-type="dataModel" />
        </on-render>
        <transition on="next">
            <evaluate expression="searchCriteria.nextPage()" />
            <render fragments="hotels:searchResultsFragment" />
        </transition>
    </view-state>

The `fragments="hotels:searchResultsFragment"` is an instruction that will be interpreted at render time, such that only the component with the JSF clientId "hotels:searchResultsFragment" will be rendered and returned to the client. This fragment will then be automatically replaced in the page. The `fragments` attribute can be a comma-delimited list of ids, with each id representing the root node of a subtree (meaning the root node and all of its children) to be rendered. If the "next" event is fired in a non-Ajax request (i.e., if JavaScript is disabled on the client), the `render` action will be ignored and the full page will be rendered as normal.

In addition to the Spring Faces `commandLink` component, there is a corresponding `commandButton` component with the same functionality. There is also a special `ajaxEvent` component that will raise a JSF action even in response to any client-side DOM event. See the Spring Faces tag library docs for full details.

An additional built-in feature when using the Spring Faces Ajax-enabled components is the ability to have the response rendered inside a rich modal popup widget by setting `popup="true"` on a `view-state` .

    <view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
        <on-entry>
            <render fragments="hotelSearchFragment" />
        </on-entry>
        <transition on="search" to="reviewHotels">
            <evaluate expression="searchCriteria.resetPage()"/>
        </transition>
    </view-state>

If the "changeSearchCriteria" `view-state` is reached as the result of an Ajax-request, the result will be rendered into a rich popup. If JavaScript is unavailable, the request will be processed with a full browser refresh, and the "changeSearchCriteria" view will be rendered as normal.

## 13.9. Embedding a Flow On a Page

By default when a flow enters a view state, it executes a client-side redirect before rendering the view. This approach is known as POST-REDIRECT-GET. It has the advantage of separating the form processing for one view from the rendering of the next view. As a result the browser Back and Refresh buttons work seamlessly without causing any browser warnings.

Normally the client-side redirect is transparent from a user's perspective. However, there are situations where POST-REDIRECT-GET may not bring the same benefits. For example sometimes it may be useful to embed a flow on a page and drive it via Ajax requests refreshing only the area of the page where the flow is rendered. Not only is it unnecessary to use client-side redirects in this case, it is also not the desired behavior with regards to keeping the surrounding content of the page intact.

To indicate a flow should execute in "page embedded" mode all you need to do is pass an extra flow input attribute called "mode" with a value of "embedded". Below is an example of a top-level container flow invoking a sub-flow in an embedded mode:

    <subflow-state id="bookHotel" subflow="booking">
        <input name="mode" value="'embedded'"/>
    </subflow-state>

When launched in "page embedded" mode the sub-flow will not issue flow execution redirects during Ajax requests.

If you'd like to see examples of an embedded flow please refer to the webflow-primefaces-showcase project. You can check out the source code locally, build it as you would a Maven project, and import it into Eclipse:

    cd some-directory
    svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
    cd webflow-primefaces-showcase
    mvn package
    # import into Eclipse

The specific example you need to look at is under the "Advanced Ajax" tab and is called "Top Flow with Embedded Sub-Flow".

## 13.10. Redirect In Same State

By default Web Flow does a client-side redirect even it it remains in the same view state as long as the current request is not an Ajax request. This is quite useful after form validation failures for example. If the user hits Refresh or Back they won't see any browser warnings. They would if the Web Flow didn't do a redirect.

This can lead to a problem specific to JSF 2 environments where a specific Sun Mojarra listener component caches the FacesContext assuming the same instance is available throughout the JSF lifecycle. In Web Flow however the render phase is temporarily put on hold and a client-side redirect executed.

The default behavior of Web Flow is desirable and it is unlikely JSF 2 applications will experience the issue. This is because Ajax is often enabled the default in JSF 2 component libraries and Web Flow does not redirect during Ajax requests. However if you experience this issue you can disable client-side redirects within the same view as follows:

    <webflow:flow-executor id="flowExecutor">
    	<webflow:flow-execution-attributes>
    		<webflow:redirect-in-same-state value="false"/>
    	</webflow:flow-execution-attributes>
    </webflow:flow-executor>

## 13.11. Using the Spring Security Facelets Tag Library

To use the library you'll need to create a `.taglib.xml` file and register it in `web.xml`.

For JSF 2 create the file `/WEB-INF/springsecurity.taglib.xml` with the following content:

    <?xml version="1.0"?>
    <!DOCTYPE facelet-taglib PUBLIC
      "-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN"
      "http://java.sun.com/dtd/facelet-taglib_1_0.dtd">
    <facelet-taglib>
    	<namespace>http://www.springframework.org/security/tags</namespace>
    	<tag>
    		<tag-name>authorize</tag-name>
    		<handler-class>org.springframework.faces.security.FaceletsAuthorizeTagHandler</handler-class>
    	</tag>
    	<function>
    		<function-name>areAllGranted</function-name>
    		<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areAllGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>areAnyGranted</function-name>
    		<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areAnyGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>areNotGranted</function-name>
    		<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areNotGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>isAllowed</function-name>
    		<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean isAllowed(java.lang.String, java.lang.String)</function-signature>
    	</function>
    </facelet-taglib>

For JSF 1.2 also create the file `/WEB-INF/springsecurity.taglib.xml` but with the following content instead:

    <?xml version="1.0"?>
    <!DOCTYPE facelet-taglib PUBLIC
    	"-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN" "http://java.sun.com/dtd/facelet-taglib_1_0.dtd">
    <facelet-taglib>
    	<namespace>http://www.springframework.org/security/tags</namespace>
    	<tag>
    		<tag-name>authorize</tag-name>
    		<handler-class>org.springframework.faces.security.Jsf12FaceletsAuthorizeTagHandler</handler-class>
    	</tag>
    	<function>
    		<function-name>areAllGranted</function-name>
    		<function-class>org.springframework.faces.security.Jsf12FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areAllGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>areAnyGranted</function-name>
    		<function-class>org.springframework.faces.security.Jsf12FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areAnyGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>areNotGranted</function-name>
    		<function-class>org.springframework.faces.security.Jsf12FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean areNotGranted(java.lang.String)</function-signature>
    	</function>
    	<function>
    		<function-name>isAllowed</function-name>
    		<function-class>org.springframework.faces.security.Jsf12FaceletsAuthorizeTagUtils</function-class>
    		<function-signature>boolean isAllowed(java.lang.String, java.lang.String)</function-signature>
    	</function>
    </facelet-taglib>

Next, register the above file taglib in web.xml:

    <context-param>
        <param-name>javax.faces.FACELETS_LIBRARIES</param-name>
        <param-value>/WEB-INF/springsecurity.taglib.xml</param-value>
    </context-param>

Now you are ready to use the tag library in your views. You can use the authorize tag to include nested content conditionally:

    <!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <ui:composition xmlns="http://www.w3.org/1999/xhtml"
    	xmlns:ui="http://java.sun.com/jsf/facelets"
    	xmlns:h="http://java.sun.com/jsf/html"
    	xmlns:sec="http://www.springframework.org/security/tags">

    	<sec:authorize ifAllGranted="ROLE_FOO, ROLE_BAR">
    		Lorem ipsum dolor sit amet
    	</sec:authorize>

    	<sec:authorize ifNotGranted="ROLE_FOO, ROLE_BAR">
    		Lorem ipsum dolor sit amet
    	</sec:authorize>

    	<sec:authorize ifAnyGranted="ROLE_FOO, ROLE_BAR">
    		Lorem ipsum dolor sit amet
    	</sec:authorize>

    </ui:composition>

You can also use one of several EL functions in the rendered or other attribute of any JSF component:

    <!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <ui:composition xmlns="http://www.w3.org/1999/xhtml"
    	xmlns:ui="http://java.sun.com/jsf/facelets"
    	xmlns:h="http://java.sun.com/jsf/html"
    	xmlns:sec="http://www.springframework.org/security/tags">

    	<!-- Rendered only if user has all of the listed roles -->
    	<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAllGranted('ROLE_FOO, ROLE_BAR')}"/>

    	<!-- Rendered only if user does not have any of the listed roles -->
    	<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areNotGranted('ROLE_FOO, ROLE_BAR')}"/>

    	<!-- Rendered only if user has any of the listed roles -->
    	<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAnyGranted('ROLE_FOO, ROLE_BAR')}"/>

    	<!-- Rendered only if user has access to given HTTP method/URL as defined in Spring Security configuration -->
    	<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:isAllowed('/secured/foo', 'POST')}"/>

    </ui:composition>

## 13.12. Enhancing The User Experience With Rich Web Forms in JSF 1.2

JSF and Web Flow combine to provide an extensive server-side validation model for your web application, but excessive roundtrips to the server to execute this validation and return error messages can be a tedious experience for your users. The Spring Faces component library provides a number of client-side rich validation controls that can enhance the user experience by applying simple validations that give immediate feedback. Some simple examples are illustrated below. See the Spring Faces taglib docs for a complete tag reference.

### 13.12.1. Validating a Text Field

Simple client-side text validation can be applied with the `clientTextValidator` component:

    <sf:clientTextValidator required="true">
        <h:inputText id="creditCardName" value="#{booking.creditCardName}" required="true"/>
    </sf:clientTextValidator>

This will apply client-side required validation to the child `inputText` component, giving the user a clear indicator if the field is left blank.

### 13.12.2. Validating a Numeric Field

Simple client-side numeric validation can be applied with the `clientNumberValidator` component:

    <sf:clientTextValidator required="true" regExp="[0-9]{16}"
                            invalidMessage="A 16-digit credit card number is required.">
        <h:inputText id="creditCard" value="#{booking.creditCard}" required="true"/>
    </sf:clientTextValidator>

This will apply client-side validation to the child `inputText` component, giving the user a clear indicator if the field is left blank, is not numeric, or does not match the given regular expression.

### 13.12.3. Validating a Date Field

Simple client-side date validation with a rich calendar popup can be applied with the `clientDateValidator` component:

    <sf:clientDateValidator required="true" >
        <h:inputText id="checkinDate" value="#{booking.checkinDate}" required="true">
            <f:convertDateTime pattern="yyyy-MM-dd" timeZone="EST"/>
        </h:inputText>
    </sf:clientDateValidator>

This will apply client-side validation to the child `inputText` component, giving the user a clear indicator if the field is left blank or is not a valid date.

### 13.12.4. Preventing an Invalid Form Submission

The `validateAllOnClick` component can be used to intercept the "onclick" event of a child component and suppress the event if all client-side validations do not pass.

    <sf:validateAllOnClick>
        <sf:commandButton id="proceed" action="proceed" processIds="*" value="Proceed"/>&#160;
    </sf:validateAllOnClick>

This will prevent the form from being submitted when the user clicks the "proceed" button if the form is invalid. When the validations are executed, the user is given clear and immediate indicators of the problems that need to be corrected.

## 13.13. Third-Party Component Library Integration

The Spring Web Flow JSF integration strives to be compatible with any third-party JSF component library. By honoring all of the standard semantics of the JSF specification within the SWF-driven JSF lifecycle, third-party libraries in general should "just work". The main thing to remember is that configuration in web.xml will change slightly since Web Flow requests are not routed through the standard FacesServlet. Typically, anything that is traditionally mapped to the FacesServlet should be mapped to the Spring DispatcherServlet instead. (You can also map to both if for example you are migrating a legacy JSF application page-by-page.) In some cases, a deeper level of integration can be achieved by configuring special flow services that are "aware" of a particular component library, and these will be noted in the examples to follow.

### 13.13.1. Rich Faces Integration (JSF 1.2)

To use the Rich Faces component library with Spring Web Flow, the following filter configuration is needed in web.xml (in addition to the other typical configuration already shown):

    <filter>
        <display-name>RichFaces Filter</display-name>
        <filter-name>richfaces</filter-name>
        <filter-class>org.ajax4jsf.Filter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>richfaces</filter-name>
        <servlet-name>Spring Web MVC Dispatcher Servlet</servlet-name>
        <dispatcher>REQUEST</dispatcher>
        <dispatcher>FORWARD</dispatcher>
        <dispatcher>INCLUDE</dispatcher>
    </filter-mapping>

For deeper integration (including the ability to have a view with combined use of the Spring Faces Ajax components and Rich Faces Ajax components), configure the RichFacesAjaxHandler on your FlowController:

    <bean id="flowController" class="org.springframework.webflow.mvc.servlet.FlowController">
        <property name="flowExecutor" ref="flowExecutor" />
        <property name="ajaxHandler">
            <bean class="org.springframework.faces.richfaces.RichFacesAjaxHandler"/>
        </property>
    </bean>

RichFaces Ajax components can be used in conjunction with the `render` tag to render partial fragments on an Ajax request. Instead of embedding the ids of the components to be re-rendered directly in the view template (as you traditionally do with Rich Faces), you can bind the `reRender` attribute of a RichFaces Ajax component to a special `flowRenderFragments` EL variable. For example, in your view template you can have a fragment that you would potentially like to re-render in response to a particular event:

    <h:form id="hotels">
        <a4j:outputPanel id="searchResultsFragment">
            <h:outputText id="noHotelsText" value="No Hotels Found" rendered="#{hotels.rowCount == 0}"/>
            <h:dataTable id="hotels" styleClass="summary" value="#{hotels}" var="hotel" rendered="#{hotels.rowCount > 0}">
                <h:column>
                    <f:facet name="header">Name</f:facet>
                    #{hotel.name}
                </h:column>
                <h:column>
                    <f:facet name="header">Address</f:facet>
                    #{hotel.address}
                </h:column>
            </h:dataTable>
        </a4j:outputPanel>
    </h:form>

then a RichFaces Ajax `commandLink` to fire the event:

    <a4j:commandLink id="nextPageLink" value="More Results" action="next" reRender="#{flowRenderFragments}" />

and then in your flow definition a `transition` to handle the event:

    <transition on="next">
        <evaluate expression="searchCriteria.nextPage()" />
        <render fragments="hotels:searchResultsFragment" />
    </transition>

### 13.13.2. Apache MyFaces Trinidad Integration (JSF 1.2)

The Apache MyFaces Trinidad library has been tested with the Spring Web Flow's JSF integration and proven to fit in nicely. Deeper integration to allow the Trinidad components and Spring Faces components to play well together has not yet been attempted, but Trinidad provides a pretty thorough solution on its own when used in conjunction with the Spring Web Flow JSF integration.

NOTE: An `AjaxHandler` implementation for Trinidad is not currently provided out-of-the-box. In order to fully integrate with Trinidad's PPR functionality, a custom implementation should be provided. An community-provided partial example can be found here: SWF-1160

Typical configuration when using Trinidad with Web Flow is as follows in web.xml (in addition what has already been shown):

    <context-param>
        <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
        <param-value>server</param-value>
    </context-param>

    <context-param>
        <param-name>
            org.apache.myfaces.trinidad.CHANGE_PERSISTENCE
        </param-name>
        <param-value>session</param-value>
    </context-param>

    <context-param>
        <param-name>
            org.apache.myfaces.trinidad.ENABLE_QUIRKS_MODE
        </param-name>
        <param-value>false</param-value>
    </context-param>

    <filter>
        <filter-name>Trinidad Filter</filter-name>
        <filter-class>
            org.apache.myfaces.trinidad.webapp.TrinidadFilter
        </filter-class>
    </filter>

    <filter-mapping>
        <filter-name>Trinidad Filter</filter-name>
        <servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
    </filter-mapping>

    <servlet>
        <servlet-name>Trinidad Resource Servlet</servlet-name>
        <servlet-class>
            org.apache.myfaces.trinidad.webapp.ResourceServlet
        </servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>resources</servlet-name>
        <url-pattern>/adf/*</url-pattern>
    </servlet-mapping>

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