Welcome!

Java IoT Authors: Elizabeth White, Carmen Gonzalez, Pat Romanski, Liz McMillan, Yeshim Deniz

Related Topics: Java IoT, Machine Learning

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
SYS-CON Events announced today that Systena America will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Systena Group has been in business for various software development and verification in Japan, US, ASEAN, and China by utilizing the knowledge we gained from all types of device development for various industries including smartphones (Android/iOS), wireless communication, security technology and IoT serv...
SYS-CON Events announced today that Outscale will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Outscale's technology makes an automated and adaptable Cloud available to businesses, supporting them in the most complex IT projects while controlling their operational aspects. You boost your IT infrastructure's reactivity, with request responses that only take a few seconds.
DevOps at Cloud Expo – being held October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real r...
SYS-CON Events announced today that delaPlex will exhibit at SYS-CON's @CloudExpo, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. delaPlex pioneered Software Development as a Service (SDaaS), which provides scalable resources to build, test, and deploy software. It’s a fast and more reliable way to develop a new product or expand your in-house team.
Five years ago development was seen as a dead-end career, now it’s anything but – with an explosion in mobile and IoT initiatives increasing the demand for skilled engineers. But apart from having a ready supply of great coders, what constitutes true ‘DevOps Royalty’? It’ll be the ability to craft resilient architectures, supportability, security everywhere across the software lifecycle. In his keynote at @DevOpsSummit at 20th Cloud Expo, Jeffrey Scheaffer, GM and SVP, Continuous Delivery Busine...
SYS-CON Events announced today that Outscale, a global pure play Infrastructure as a Service provider and strategic partner of Dassault Systèmes, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Founded in 2010, Outscale simplifies infrastructure complexities and boosts the business agility of its customers. Outscale delivers a secure, reliable and industrial strength solution for its customers, which in...
SYS-CON Events announced today that CollabNet, a global leader in enterprise software development, release automation and DevOps solutions, will be a Bronze Sponsor of SYS-CON's 20th International Cloud Expo®, taking place from June 6-8, 2017, at the Javits Center in New York City, NY. CollabNet offers a broad range of solutions with the mission of helping modern organizations deliver quality software at speed. The company’s latest innovation, the DevOps Lifecycle Manager (DLM), supports Value S...
In order to meet the rapidly changing demands of today’s customers, companies are continually forced to redefine their business strategies in order to meet these needs, stay relevant and continue to see profitable growth. IoT deployment and development is integral in this transformation, and today businesses are increasingly seeing the value of investing their resources into IoT deployments. These technologies are able increase ROI through projects such as connecting supply chains or enabling sm...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
Everywhere we turn in our industry we can find strong opinions about the direction, type and nature of cloud’s impact on computing and business. Another word that is used in every context in our industry is “hybrid.” In his session at 20th Cloud Expo, Alvaro Gonzalez, Director of Technical, Partner and Field Marketing at Peak 10, will use a combination of a few conceptual props and some research recently commissioned by Peak 10 to offer a real-world consideration of how the various categories of...
SYS-CON Events announced today that Peak 10, Inc., a national IT infrastructure and cloud services provider, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Peak 10 provides reliable, tailored data center and network services, cloud and managed services. Its solutions are designed to scale and adapt to customers’ changing business needs, enabling them to lower costs, improve performance and focus intern...
SYS-CON Events announced today that Super Micro Computer, Inc., a global leader in compute, storage and networking technologies, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Supermicro (NASDAQ: SMCI), the leading innovator in high-performance, high-efficiency server technology, is a premier provider of advanced server Building Block Solutions® for Data Center, Cloud Computing, Enterprise IT, Hadoop/...
Multiple data types are pouring into IoT deployments. Data is coming in small packages as well as enormous files and data streams of many sizes. Widespread use of mobile devices adds to the total. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the tools and environments that are being put to use in IoT deployments, as well as the team skills a modern enterprise IT shop needs to keep things running, get a handle on all this data, and deli...
In his opening keynote at 20th Cloud Expo, Michael Maximilien, Research Scientist, Architect, and Engineer at IBM, will motivate why realizing the full potential of the cloud and social data requires artificial intelligence. By mixing Cloud Foundry and the rich set of Watson services, IBM's Bluemix is the best cloud operating system for enterprises today, providing rapid development and deployment of applications that can take advantage of the rich catalog of Watson services to help drive insigh...
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend @CloudExpo | @ThingsExpo, June 6-8, 2017, at the Javits Center in New York City, NY and October 31 - November 2, 2017, Santa Clara Convention Center, CA. Learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
SYS-CON Events announced today that EARP Integration will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. EARP Integration is a passionate software house. Since its inception in 2009 the company successfully delivers smart solutions for cities and factories that start their digital transformation. EARP provides bespoke solutions like, for example, advanced enterprise portals, business intelligence systems an...
SYS-CON Events announced today that Progress, a global leader in application development, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Enterprises today are rapidly adopting the cloud, while continuing to retain business-critical/sensitive data inside the firewall. This is creating two separate data silos – one inside the firewall and the other outside the firewall. Cloud ISVs oft...
As cloud adoption continues to transform business, today's global enterprises are challenged with managing a growing amount of information living outside of the data center. The rapid adoption of IoT and increasingly mobile workforce are exacerbating the problem. Ensuring secure data sharing and efficient backup poses capacity and bandwidth considerations as well as policy and regulatory compliance issues.
The 21st International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...