Welcome!

Java IoT Authors: SmartBear Blog, Liz McMillan, Elizabeth White, Carmen Gonzalez, Anders Wallgren

Related Topics: Java IoT, IoT User Interface

Java IoT: Article

New Features in JavaServer Faces 2.0

Developing server-side user interfaces (UI) for Java EE applications

JavaServer Faces (JSF) technology is used for developing server-side user interfaces (UI) for Java EE applications. JSF 2.0 architecture has introduced several new features, most of which we shall discuss in this article. The salient new features in JSF 2.0 are State Saving, Facelets, Navigation, Validations, Scopes, AJAX, Resource Handling, Composite Components, View Params, Client Behaviors, Event Handling, and Exception Handling.

State Saving
In JSF 1.2 the full component tree is saved/restored. Attributes are also stored and restored. Saving and restoring the full state has performance and memory issues as the complete state has to be saved and restored and the size of the state saved could be large. In JSF 1.2 each UIComponent saves/restores its own state in the component hierarchy using saveState and resoreState methods in StateHolder. If state saving were to be optimized, it would have to be added to each component class in the hierarchy.

JSF 2.0 has introduced partial state saving in which the initial state of the component tree is marked and only the delta state changes due to modifications are saved, which makes the size of the state saved small. Re-executing the view and subsequently updating with the saved delta state change restores the component tree. Instead of implementing the StateHolder interface, components in JSF 2.0 implement the PartialStateHolder interface, which provides the partial state feature. PartialStateHolder provides methods shown in Table 1.

Table 1

To make it easier for UIComponents to implement PartialSatetHolder the StateHelper, which is a Map-like interface with methods such as add, eval, get, put, remove, is provided to store a component's state such as attributes and listeners. Partial state saving makes the size of the state saved about four times smaller. As the state is restored by re-executing the view, restoring of the component tree could take more time than in JSF 1.2.

By default, JSF 2.0 uses partial state saving. The javax.faces.PARTIAL_STATE_SAVING context-param is provided turn off/on partial state saving. The partial state saving param may be changed using the PARTIAL_STATE_SAVING_PARAM_NAME param.

To implement state saving, JSF 2.0 has introduced tree visiting. In JSF 1.2 only one component could be invoked in a single tree traversal using the UIComponent.invokeOnComponent() method. If multiple components are required to be invoked as in an AJAX request or state saving, multiple tree traversals have to applied. With the tree visiting, multiple components may be invoked in a single tree traversal. Tree visiting is implemented using the visitTree(VisitContext context,VisitCallback callback) method. VisitContext is a context object that holds state for component tree visit. VisitCallback is an interface to visit a specified UIComponent in tree visit.

Facelets
JSF 1.2 used the JSP view technology. JSF 2.0 uses the Facelets view definition language (VDL) as the default view rendering technology. Facelets is an extension to JavaServer Faces (JSF) and uses XHTML syntax to define a JSF page. Facelets are XHTML pages and by default use the .xhtml extension. The default Facelets suffix is specified by the DEFAULT_FACELETS_SUFFIX context parameter. The Facelets view handler in JSF 1.2 had to be specified in faces-config.xml with the following configuration:

<application>|
<view-handler>com.sun.facelets.FaceletViewHandler</view-handler>
</application>
</faces-config>

In JSF 2.0 a view handler is not configured and the default view handler javax.faces.application.ViewHandler is used. The default faces-config.xml for Facelets in JSF 2.0 is an empty file. The default value of the DEFAULT_FACELETS_SUFFIX constant in the ViewHandler view handler is .xhtml. Other Facelets view mappings(view pages to be interpreted as Facelets) may be specified using the javax.faces.FACELETS_VIEW_MAPPINGS context parameter:

<context-param>
<param-name>javax.faces.FACELETS_VIEW_MAPPINGS</param-name>
<param-value>*.jsf;*.jspx</param-value>
</context-param>

Navigation
Navigation in JSF 1.2 is configured using navigation rules based on outcomes from a view id in faces-config.xml. For example, to navigate to output.jsp if the outcome from input.jsp is "success" and to navigate to error.jsp if the outcome is "error", specify the following navigation rule in faces-config.xml:

<navigation-rule>
<from-view-id>/input.jsp</from-view-id>
<navigation-case>
<from-outcome>success</from-outcome>
<to-view-id>/output.jsp</to-view-id>
</navigation-case>
<navigation-case>
<from-outcome>error</from-outcome>
<to-view-id>/error.jsp</to-view-id>
</navigation-case>
</navigation-rule>

JSF 2.0 has simplified navigation with the introduction of implicit navigation with which the navigation is based on the outcome. Implicitly the JSF application navigates to a view id with the same name as the outcome. For example, if the outcome is "output", the navigation handler navigates to output.xhtml, if provided. JSF 2.0 has also introduced conditional navigation with which the navigation handler navigates to a view id based on a condition EL expression specified in faces-config.xml. JSF 2.0 has also introduced the ConfigurableNavigationHandler class for configuring navigation programmatically. Preemptive navigation is another new feature used to determine the destination URL based on outcome. The new components h:button and h:link support preemptive navigation.

Validation
Validation in JSF 1.2 is implemented using built-in validators f:validateDoubleRange (for a double value with an optional range), f:validateLongRange(a long value with an optional range), and f:validateLength (a String with a minimum and maximum number of characters). JSF 1.2 also supports custom validators with the f:validator tag and the javax.faces.validator.Validator interface. JSF 1.2 did not have built-in provisions for empty field validation and validation with regular expressions.

JSF 2.0 has introduced validation of empty fields, which is also available for custom validators. Three new built-in validators have been added: f:validateRegex for regular expressions, f:validateRequired for required field, and f:validateBean for Bean validation, which is another new feature. Bean validation is implemented in conjunction with validation constrain annotations, which are defined in the javax.validation.constraints package. Validation constraint annotations annotate managed bean properties. For example the @Size annotation constrains size, and the @Pattern annotation requires conformance with a regular expression. Bean validation is supported with custom validators also.

Scopes and Configuration
As mentioned earlier the faces-config.xml in JSF 2.0 is an empty file. JSF 1.2 faces-config.xml has configuration for managed beans, managed bean properties, scopes, validators, converters, and renderers. JSF 2.0 has introduced annotations-based configuration for managed beans, managed bean properties, scopes, validators, converters, and renderers. New scopes: view, flash, and custom have been added for finer-grained scopes. JSF 2.0 has added a new configuration project stage that indicates the state of a project.

AJAX
JSF 1.2 did not provide built-in support for AJAX, and an AJAX framework such as Ajax4jsf had to be used. Or AJAX had to be implemented with the XMLHttpRequest object without any framework. JSF 2.0 has added support for AJAX with the f:ajax tag, which includes support for partial page rendering and grouped components. AJAX support may also be added using the AJAX JSF library.

Resource Handling
Resources are files required by a JSF application such as CSS, JavaScript, and images. JSF 2.0 has added a ResourceHandler API that is based on path-based packaging conventions for serving resources. JSF 2.0 has also added new tags for resource handling; h:head, h:body, h:outputScript, and h:ouputStylesheet. Some of the other new resource handling features are relocating resources and ordering of multiple faces-config.xml application configuration resources.

Composite Components
JSF 2.0 has introduced a Composite Components tag library for creating composite components. A Composite component is a composite (collection) of other UI components. A composite component consists of a library, which makes use of the new resource handling feature, a definition page, and a using page, which are based on Facelets. A definition page defines a composite component and a using page makes use of a composite component.

View Params
JSF 1.2 includes support for sending parameters only in a POST request. View parameters add the provision to send request parameters in a GET request. View parameters are configured in the f:metadata tag using the f:viewParam tags. View params are EditableValueHolder components and may configured with validators and converters just as other EditableValueHolder components such as h:inputText. View parameters also support component system events using the f:event tag. Preemptive navigation, which was mentioned in the Navigation section, and bookmarking is made feasible with view params. View params may also be used with Faces redirects.

Client Behaviors
Behaviors are objects attached to components to provide additional functionality. Client behaviors are an implementation of behaviors with which scripts may be attached with components to be run from client-side events. A Facelet taglib is required for a client behavior. Client behaviors are added to a Facelets page using tags from the Facelets taglib.

Event Handling and Exception Handling
JSF 2.0 has introduced a new type of events called system events. System events are of two types: application scoped system events and component system events. System events are similar to, but with more precise granularity, to phase events. For event handling in an AJAX request the f:ajax tag includes a onevent attribute to register a callback Java Script function.

ExceptionHandler is a new class to handle unexpected exceptions. The f:ajax tag includes a onerror attribute for error handling callback function.

More Stories By Deepak Vohra

Deepak Vohra is a Sun Certified Java 1.4 Programmer and a Web developer.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
Companies can harness IoT and predictive analytics to sustain business continuity; predict and manage site performance during emergencies; minimize expensive reactive maintenance; and forecast equipment and maintenance budgets and expenditures. Providing cost-effective, uninterrupted service is challenging, particularly for organizations with geographically dispersed operations.
The Quantified Economy represents the total global addressable market (TAM) for IoT that, according to a recent IDC report, will grow to an unprecedented $1.3 trillion by 2019. With this the third wave of the Internet-global proliferation of connected devices, appliances and sensors is poised to take off in 2016. In his session at @ThingsExpo, David McLauchlan, CEO and co-founder of Buddy Platform, will discuss how the ability to access and analyze the massive volume of streaming data from mil...
WebSocket is effectively a persistent and fat pipe that is compatible with a standard web infrastructure; a "TCP for the Web." If you think of WebSocket in this light, there are other more hugely interesting applications of WebSocket than just simply sending data to a browser. In his session at 18th Cloud Expo, Frank Greco, Director of Technology for Kaazing Corporation, will compare other modern web connectivity methods such as HTTP/2, HTTP Streaming, Server-Sent Events and new W3C event APIs ...
Join us at Cloud Expo | @ThingsExpo 2016 – June 7-9 at the Javits Center in New York City and November 1-3 at the Santa Clara Convention Center in Santa Clara, CA – and deliver your unique message in a way that is striking and unforgettable by taking advantage of SYS-CON's unmatched high-impact, result-driven event / media packages.
SYS-CON Events announced today that FalconStor Software® Inc., a 15-year innovator of software-defined storage solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. FalconStor Software®, Inc. (NASDAQ: FALC) is a leading software-defined storage company offering a converged, hardware-agnostic, software-defined storage and data services platform. Its flagship solution FreeStor®, utilizes a horizonta...
Silver Spring Networks, Inc. (NYSE: SSNI) extended its Internet of Things technology platform with performance enhancements to Gen5 – its fifth generation critical infrastructure networking platform. Already delivering nearly 23 million devices on five continents as one of the leading networking providers in the market, Silver Spring announced it is doubling the maximum speed of its Gen5 network to up to 2.4 Mbps, increasing computational performance by 10x, supporting simultaneous mesh communic...
The cloud promises new levels of agility and cost-savings for Big Data, data warehousing and analytics. But it’s challenging to understand all the options – from IaaS and PaaS to newer services like HaaS (Hadoop as a Service) and BDaaS (Big Data as a Service). In her session at @BigDataExpo at @ThingsExpo, Hannah Smalltree, a director at Cazena, will provide an educational overview of emerging “as-a-service” options for Big Data in the cloud. This is critical background for IT and data profes...
Eighty percent of a data scientist’s time is spent gathering and cleaning up data, and 80% of all data is unstructured and almost never analyzed. Cognitive computing, in combination with Big Data, is changing the equation by creating data reservoirs and using natural language processing to enable analysis of unstructured data sources. This is impacting every aspect of the analytics profession from how data is mined (and by whom) to how it is delivered. This is not some futuristic vision: it's ha...
With the Apple Watch making its way onto wrists all over the world, it’s only a matter of time before it becomes a staple in the workplace. In fact, Forrester reported that 68 percent of technology and business decision-makers characterize wearables as a top priority for 2015. Recognizing their business value early on, FinancialForce.com was the first to bring ERP to wearables, helping streamline communication across front and back office functions. In his session at @ThingsExpo, Kevin Roberts...
Cognitive Computing is becoming the foundation for a new generation of solutions that have the potential to transform business. Unlike traditional approaches to building solutions, a cognitive computing approach allows the data to help determine the way applications are designed. This contrasts with conventional software development that begins with defining logic based on the current way a business operates. In her session at 18th Cloud Expo, Judith S. Hurwitz, President and CEO of Hurwitz & ...
One of the bewildering things about DevOps is integrating the massive toolchain including the dozens of new tools that seem to crop up every year. Part of DevOps is Continuous Delivery and having a complex toolchain can add additional integration and setup to your developer environment. In his session at @DevOpsSummit at 18th Cloud Expo, Miko Matsumura, Chief Marketing Officer of Gradle Inc., will discuss which tools to use in a developer stack, how to provision the toolchain to minimize onboa...
With an estimated 50 billion devices connected to the Internet by 2020, several industries will begin to expand their capabilities for retaining end point data at the edge to better utilize the range of data types and sheer volume of M2M data generated by the Internet of Things. In his session at @ThingsExpo, Don DeLoach, CEO and President of Infobright, will discuss the infrastructures businesses will need to implement to handle this explosion of data by providing specific use cases for filte...
SYS-CON Events announced today that Avere Systems, a leading provider of enterprise storage for the hybrid cloud, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Avere delivers a more modern architectural approach to storage that doesn’t require the overprovisioning of storage capacity to achieve performance, overspending on expensive storage media for inactive data or the overbuilding of data centers ...
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies adopt disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevO...
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management...
SYS-CON Events announced today that Alert Logic, Inc., the leading provider of Security-as-a-Service solutions for the cloud, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Alert Logic, Inc., provides Security-as-a-Service for on-premises, cloud, and hybrid infrastructures, delivering deep security insight and continuous protection for customers at a lower cost than traditional security solutions. Ful...
SYS-CON Events announced today that Interoute, owner-operator of one of Europe's largest networks and a global cloud services platform, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Interoute is the owner-operator of one of Europe's largest networks and a global cloud services platform which encompasses 12 data centers, 14 virtual data centers and 31 colocation centers, with connections to 195 ad...
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
Fortunately, meaningful and tangible business cases for IoT are plentiful in a broad array of industries and vertical markets. These range from simple warranty cost reduction for capital intensive assets, to minimizing downtime for vital business tools, to creating feedback loops improving product design, to improving and enhancing enterprise customer experiences. All of these business cases, which will be briefly explored in this session, hinge on cost effectively extracting relevant data from ...
SYS-CON Events announced today that iDevices®, the preeminent brand in the connected home industry, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. iDevices, the preeminent brand in the connected home industry, has a growing line of HomeKit-enabled products available at the largest retailers worldwide. Through the “Designed with iDevices” co-development program and its custom-built IoT Cloud Infrastruc...