|By Deepak Vohra||
|September 1, 2011 01:00 PM EDT||
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.
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.
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.
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:
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:
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:
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 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.
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.
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.
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.
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.
SYS-CON Events announced today that Super Micro Computer, Inc., a global leader in high-performance, high-efficiency server, storage technology and green computing, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. 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/Big Data, HPC and Embedded Systems worldwide. Supermi...
Oct. 13, 2015 11:00 PM EDT Reads: 273
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Oct. 13, 2015 10:15 PM EDT Reads: 182
Who are you? How do you introduce yourself? Do you use a name, or do you greet a friend by the last four digits of his social security number? Assuming you don’t, why are we content to associate our identity with 10 random digits assigned by our phone company? Identity is an issue that affects everyone, but as individuals we don’t spend a lot of time thinking about it. In his session at @ThingsExpo, Ben Klang, Founder & President of Mojo Lingo, will discuss the impact of technology on identity. Should we federate, or not? How should identity be secured? Who owns the identity? How is identity ...
Oct. 13, 2015 09:00 PM EDT Reads: 504
This week, the team assembled in NYC for @Cloud Expo 2015 and @ThingsExpo 2015. For the past four years, this has been a must-attend event for MetraTech. We were happy to once again join industry visionaries, colleagues, customers and even competitors to share and explore the ways in which the Internet of Things (IoT) will impact our industry. Over the course of the show, we discussed the types of challenges we will collectively need to solve to capitalize on the opportunity IoT presents.
Oct. 13, 2015 08:30 PM EDT Reads: 168
WebRTC converts the entire network into a ubiquitous communications cloud thereby connecting anytime, anywhere through any point. In his session at WebRTC Summit,, Mark Castleman, EIR at Bell Labs and Head of Future X Labs, will discuss how the transformational nature of communications is achieved through the democratizing force of WebRTC. WebRTC is doing for voice what HTML did for web content.
Oct. 13, 2015 07:00 PM EDT Reads: 1,505
Today’s connected world is moving from devices towards things, what this means is that by using increasingly low cost sensors embedded in devices we can create many new use cases. These span across use cases in cities, vehicles, home, offices, factories, retail environments, worksites, health, logistics, and health. These use cases rely on ubiquitous connectivity and generate massive amounts of data at scale. These technologies enable new business opportunities, ways to optimize and automate, along with new ways to engage with users.
Oct. 13, 2015 07:00 PM EDT Reads: 287
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
Oct. 13, 2015 06:15 PM EDT Reads: 1,234
SYS-CON Events announced today that Dyn, the worldwide leader in Internet Performance, will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Dyn is a cloud-based Internet Performance company. Dyn helps companies monitor, control, and optimize online infrastructure for an exceptional end-user experience. Through a world-class network and unrivaled, objective intelligence into Internet conditions, Dyn ensures traffic gets delivered faster, safer, and more reliably than ever.
Oct. 13, 2015 04:00 PM EDT Reads: 730
SYS-CON Events announced today that Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, will keynote at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA.
Oct. 13, 2015 03:15 PM EDT Reads: 260
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal an...
Oct. 13, 2015 01:00 PM EDT Reads: 230
The Internet of Things (IoT) is growing rapidly by extending current technologies, products and networks. By 2020, Cisco estimates there will be 50 billion connected devices. Gartner has forecast revenues of over $300 billion, just to IoT suppliers. Now is the time to figure out how you’ll make money – not just create innovative products. With hundreds of new products and companies jumping into the IoT fray every month, there’s no shortage of innovation. Despite this, McKinsey/VisionMobile data shows "less than 10 percent of IoT developers are making enough to support a reasonably sized team....
Oct. 13, 2015 01:00 PM EDT Reads: 348
The IoT market is on track to hit $7.1 trillion in 2020. The reality is that only a handful of companies are ready for this massive demand. There are a lot of barriers, paint points, traps, and hidden roadblocks. How can we deal with these issues and challenges? The paradigm has changed. Old-style ad-hoc trial-and-error ways will certainly lead you to the dead end. What is mandatory is an overarching and adaptive approach to effectively handle the rapid changes and exponential growth.
Oct. 13, 2015 01:00 PM EDT Reads: 340
There will be 20 billion IoT devices connected to the Internet soon. What if we could control these devices with our voice, mind, or gestures? What if we could teach these devices how to talk to each other? What if these devices could learn how to interact with us (and each other) to make our lives better? What if Jarvis was real? How can I gain these super powers? In his session at 17th Cloud Expo, Chris Matthieu, co-founder and CTO of Octoblu, will show you!
Oct. 13, 2015 12:00 PM EDT Reads: 311
Developing software for the Internet of Things (IoT) comes with its own set of challenges. Security, privacy, and unified standards are a few key issues. In addition, each IoT product is comprised of at least three separate application components: the software embedded in the device, the backend big-data service, and the mobile application for the end user's controls. Each component is developed by a different team, using different technologies and practices, and deployed to a different stack/target - this makes the integration of these separate pipelines and the coordination of software upd...
Oct. 13, 2015 12:00 PM EDT Reads: 414
As a company adopts a DevOps approach to software development, what are key things that both the Dev and Ops side of the business must keep in mind to ensure effective continuous delivery? In his session at DevOps Summit, Mark Hydar, Head of DevOps, Ericsson TV Platforms, will share best practices and provide helpful tips for Ops teams to adopt an open line of communication with the development side of the house to ensure success between the two sides.
Oct. 13, 2015 12:00 PM EDT Reads: 695
The IoT is upon us, but today’s databases, built on 30-year-old math, require multiple platforms to create a single solution. Data demands of the IoT require Big Data systems that can handle ingest, transactions and analytics concurrently adapting to varied situations as they occur, with speed at scale. In his session at @ThingsExpo, Chad Jones, chief strategy officer at Deep Information Sciences, will look differently at IoT data so enterprises can fully leverage their IoT potential. He’ll share tips on how to speed up business initiatives, harness Big Data and remain one step ahead by apply...
Oct. 13, 2015 12:00 PM EDT Reads: 749
Today air travel is a minefield of delays, hassles and customer disappointment. Airlines struggle to revitalize the experience. GE and M2Mi will demonstrate practical examples of how IoT solutions are helping airlines bring back personalization, reduce trip time and improve reliability. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Dr. Sarah Cooper, M2Mi's VP Business Development and Engineering, will explore the IoT cloud-based platform technologies driving this change including privacy controls, data transparency and integration of real time context w...
Oct. 13, 2015 11:00 AM EDT Reads: 306
The Internet of Everything is re-shaping technology trends–moving away from “request/response” architecture to an “always-on” Streaming Web where data is in constant motion and secure, reliable communication is an absolute necessity. As more and more THINGS go online, the challenges that developers will need to address will only increase exponentially. In his session at @ThingsExpo, Todd Greene, Founder & CEO of PubNub, will explore the current state of IoT connectivity and review key trends and technology requirements that will drive the Internet of Things from hype to reality.
Oct. 13, 2015 11:00 AM EDT Reads: 323
"Matrix is an ambitious open standard and implementation that's set up to break down the fragmentation problems that exist in IP messaging and VoIP communication," explained John Woolf, Technical Evangelist at Matrix, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Oct. 13, 2015 07:00 AM EDT Reads: 6,014
Nowadays, a large number of sensors and devices are connected to the network. Leading-edge IoT technologies integrate various types of sensor data to create a new value for several business decision scenarios. The transparent cloud is a model of a new IoT emergence service platform. Many service providers store and access various types of sensor data in order to create and find out new business values by integrating such data.
Oct. 13, 2015 04:00 AM EDT Reads: 684