|By Charlie Arehart||
|May 2, 2002 12:00 AM EDT||
CFMX, the new release of ColdFusion, will allow us to use JSP custom tags within our ColdFusion programs. Some may say, "So what?"
In this article I hope to show you why it's definitely worth looking into this new possibility.
At the time of this writing CFMX, previously known as Neo, is still in beta and the nondisclosure agreement prevents people writing about its features, but one of the few things that have been public knowledge since last year's DevCon is the ability to leverage JSP custom tags.
I've been given the OK by Macromedia (indeed the encouragement) to show this stuff to you. But be aware that what I'm showing is how things work as of beta 3. It's possible that things may change prior to the production release, but again, this functionality has been shown in its current form for nearly a year.
JSP Custom Tags Are Coming
In CFMX it may soon not be unusual to see something like the following in some ColdFusion code:
<cal:calendar month="3" year="2002" />
This is an example of calling a JSP custom tag. This one (which really does exist) will generate an HTML calendar for March 2002, as shown in Figure 1. Pretty nifty. We don't have such a tag in ColdFusion, and it's not that trivial to build calendars, so to be able to generate one so easily with a single tag is powerful.
Some will quickly point out that it's certainly possible that someone could write (and indeed has surely written) a similar sort of ColdFusion custom tag and make it available at the Macromedia Developer's Exchange (at http://devex.macromedia.com/developer/gallery/). Custom tags have been around in ColdFusion for a long time, and they're certainly an underused resource for many.
But this is a JSP custom tag. Don't let that throw you. Does that example above look really all that different to you as a CF developer? Sure, the syntax is a little different from a normal CF custom tag call. Where perhaps we may have used <cf_calendar>, if a tag of that name existed, this one uses <cal:calendar>. That's curious and will be explained in a moment.
But other than that, you don't need to know how the tag works (or how it's built) - all you need to do is call it. And this particular one has many more features than the simple example above demonstrates (you can easily make hyperlinks on given dates, add next/previous month links, and more).
This is a perfect example of a custom tag: something that didn't exist in the language, that someone else created, that we can easily reuse to add functionality to our programs, and that has lots of flexibility.
A New Source for Custom Tags
What's more important about this example is that this Calendar tag came (for free) from a site devoted to JSP custom tags, at http://coldjava.hypermart.net/servlets/. Don't be fooled by the name "coldjava" in the URL. This site really has nothing to do with ColdFusion. It's a total coincidence that the name might suggest a relationship to CF.
It's simply one of many such sites that serve as JSP tag library repositories for JSP developers. I've listed several more later in this article. They're not writing these tags for us, but for the world of JSP developers, and that's a pretty big world, which in many cases is itself only just becoming aware of the possibilities of custom tags.
So what we're talking about here is opening the door to an even larger network of possible sources where we can find reusable custom tags. The fact that they're JSP custom tags is nearly transparent to us.
A Closer Look
Let's look a little closer at the example above. I left out a few pretty important points, such as how to get the custom tag, where to put it, and some other important details.
First, this particular tag is available at http://coldjava.hypermart.net/servlets/caltag.htm. If you can, take a look at that page. As I said, the tag will generate an HTML calendar for you, and the site shows the various syntax alternatives as well as the results of running many of its available variations.
Indeed, in the simplest JSP examples shown there, the use of the custom tag is nearly identical to the way we'd use it in CF. In fact, here's how it might show the example we used below above:
<%@ taglib uri="taglib.tld" prefix="cal" %>
<cal:calendar month="3" year="2002" />
<cal:calendar month="3" year="2002" />
These two lines are indeed an example of a fully functioning JSP page, albeit a very simple one. The only truly foreign thing is that first line, which is a JSP statement. We can't use that specific line of code but will change it to a corresponding CF equivalent. See the sidebar below for more on this.
So, the first line in the preceding sample tells the JSP page where to find the custom tag, meaning where on the server the page should locate the custom tag. We'll change that to a corresponding CF tag in a moment.
JSP Custom Tags vs JSP tags
It's important to clarify that you can not mix JSP and ColdFusion syntax in a single CFMX page. We're talking here about using JSP custom tags, not JSP tags and directives. The use of the JSP custom tag (cal:calendar) is identical to that shown in the simplest JSP code example.
But you may see some examples that show the attribute values for a custom tag being obtained using JSP tags, just as we might use CF variables in the attribute values for a tag. You'd need to change those references before running the code in your CF template. The JSP syntax is often pretty easy to interpret, though not always. Again, we're just talking about translating JSP custom tag documentation into CF.
You may be thinking, "Aha! In CF we don't need to indicate where custom tags are stored. CF figures that out itself." That's true, and it's indeed a nice feature of CF. But, in fact, the CFMX designers have chosen to follow this same logic when using JSP custom tags. To actually run the simple example I showed earlier, I really need to use lines that might look like this:
<CFIMPORT TAGLIB="/WEB-INF/lib/ caltag.jar" PREFIX="cal">
<cal:calendar month="3" year="2002" header="true" />
<cal:calendar month="3" year="2002" header="true" />
That first line looks an awful lot like the JSP code above. It's also a brand-new tag in CFMX. CFIMPORT tells your CF page where on your server to find the JSP custom tag library that you're trying to use. It also names a "prefix" that will describe the means by which you'll refer to tags in this library throughout this page.
Not only does this make our use of tags look more like JSP's use of them, it actually adds some benefit, which in fact will be available to ColdFusion custom tags as well, but that's beyond the scope of this article and would cross the NDA lines to say any more!
Note, too, that I said this CFIMPORT points to the tag library, not the tag itself. That's another difference from CF custom tags. JSP custom tags are generally distributed as libraries of several tags (often called "taglibs", hence the TAGLIB attribute name). It's a more effective way of organizing a set of related custom tags. (Boy, we could sure use a similar capability in organizing collections of related CF custom tags. Wink-wink.)
Just to clarify, the "calendar" after "cal:" is the actual name of the custom tag, or to be more technically accurate, it's the name of the custom tag handler in the taglib. Anyway, for our purposes just know that the documentation for the tag will tell you what to put on the right side of the colon. Don't worry about case sensitivity: CF won't care if the actual tag name is upper- or lowercase. Naturally, you're free to choose your own PREFIX and use that on the left side of the colon; the cases of the PREFIX and the tag name don't have to match..
I said the CFIMPORT tells CF where to find the custom tag library on your server. How do you get it on your server? And where do you place it?
Getting a JSP Custom Tag
If you're interested in leveraging a JSP custom tag library from one of the public sites I refer to here, you simply need to find where on the site it offers a means to download the given custom tag. In the case of the site for the calendar tag offered above, there's a link to the tag's support file at the bottom of the page.
Actually, it offers links to both a ".jar" file and a ".tld" file. The .tld file is another remnant of the JSP specification for custom tags, called the "tag library descriptor" file. It's an XML file. We don't really have to have that or even understand it to leverage the custom tag. We should be able to use TLD's, and the CFMX doc shows it working, but I've had difficulty trying to use it, so I'll chalk it up to beta incompleteness.
All we really need is the .jar file, which is the actual "Java Archive" (get it? "JAR"?) that holds the Java code for the custom tag. Did I scare you just then, talking about Java? Don't worry. You don't need to know Java to use JSP custom tags. Remember, in CF it's just <cal:calendar>, which is really not that foreign.
So you want to click on the link for the .jar file, which should cause your browser to download the file (if not, right-click on the link and choose Save As). If it asks whether to open or save the file, save it. When it offers a location to save it, you'll generally want to put it in a location that's related to where your CFMX application's CF files are stored.
If your CF files are in C:\CFusion MX\wwwroot\ (which is where they might be if you choose to use the built-in CFMX Web server), then you'd also have an underlying C:\CFusionMX\wwwroot\WEB-INF\lib\ directory, and indeed that's where you want to put this .jar file. (Because CFMX is built atop a J2EE platform, this WEB-INF directory structure is a remnant of that, but you'll typically just put your CF files in the wwwroot referred to above or any subdirectory of it.)
Once the file is placed there, at least in my experience with the beta, you need to restart the CFMX server. Perhaps that will change by the time it goes to production.
Pointing to the TagLib
Now, with your .jar file in place, you're ready to use the CFIMPORT. Note, again, that the JSP example shows:
<%@ taglib uri="taglib.tld" prefix="cal" %>
But we're going to change that to:
<CFIMPORT TAGLIB="/WEB-INF/lib/caltag.jar" PREFIX="cal">
There are a couple of differences. Not only do we use a TAGLIB attribute rather than a URI attribute, but I'm also going to recommend (for now) that you change the latter's reference from the .tld to the .jar file you downloaded. (If I learn I've missed something about using TLD files, I'll share it in the comment area of the online version of this article at the SYS-CON Web site.)
Note also that the slashes must be "/" and not "\"; otherwise you'll get a "cannot find file" error. And if you do a copy and paste of a JSP taglib directive, don't forget to remove the "%" at the end of the tag before the ">" or you'll get an "invalid token" error.
One last thing: you may think, "But what if I want to use this JSP custom tag in multiple CF templates? I'll just put that CFIMPORT in my application.cfm". Sorry, you can't do that. At least not as of beta 3. Similarly, you can't even put it in a file and CFINCLUDE it. It's a bummer, but for now you must place that tag wherever you intend to use a custom tag. And there's no default central repository for JSP custom tags to be shared by all apps on a CF server.
Otherwise, that's all there is to it. The steps are:
- Find a suitable custom tag that may seem helpful.
- Download it.
- Place the .jar in the WEB-INF/lib directory.
- Create a CFIMPORT naming that directory and .jar file name and a prefix.
- Create references to the prefix and actual custom tag name in your template.
Finding More Custom Tag Libraries
I mentioned previously that there are several repositories of custom tags, each with dozens or more custom tags. I've found ones for such generally useful things as creating state and country SELECT lists, performing stock quote lookups, and doing credit card number validity checking. Of course, there are CF custom tags and UDFs to do most of these sorts of things as well. But I've also found some for caching page content, SOAP processing, WAP coding, and other things that perhaps CFers may not have thought of yet.
Perhaps the best places to start are some sites set up as "portals" to keep track of available custom tags and taglibs of all sorts (see sidebar below). They're also good places to visit occasionally to see what may be new in the JSP custom tag world.
Among the sites the URLs will point to are a few specialized libraries that may or may not be generically useful for CF applications. Some of the JSP custom tags will indeed be useful only on real JSP pages, but I've found that many of them can be used perfectly well within CFMX
A few taglibs are part of projects to bring standard use of JSP custom tags (and in some cases entire frameworks) to JSP developers. These in-clude things like the Sun JSP Standard Tag Library (JSTL), the Jakarta Taglib project, and the Jakarta Struts project. These offer new frameworks for JSP developers in the form of taglibs, but they may be beyond the interest and reach of CF developers.
Actually, some of the tag libraries offer JSP developers the kind of easy, tag-based control over page flow and database query processing that we've always enjoyed natively in CF. That's kind of interesting to observe, making it seem like CF is the ultimate tag library.
Be careful with that phrase, though. CFMX is not "CF as a JSP tag library." It's really much more than that. Still, some JSPers may indeed see CFMX as a new, easier alternative to JSP itself, even with the many taglibs out there trying to offer a more complete framework.
Finally, a few tag libraries are intended for use with specific J2EE application servers, such as those for JRun, iPlanet, Orion, Gefion, and Oracle Java Web servers. It's likely that few of the tags in these libraries may be generally useful, but they're worth a look. You can't predict when someone in that community may think of something that may be broadly useful.
Admittedly, some of the tags out there in publicly available JSP tag libraries are no more clever than those we already have available in Cold-Fusion custom tags, such as those at the Developer's Exchange. But you never know. It's like finding a new directory in the Developer's Exchange, but it's a much bigger world of developers out there building JSP custom tags.
At each of these sites you'll generally find help on how to use the tags. Sometimes the documentation for using a JSP custom tag may show it using JSP syntax, but it will often be readable enough for CF programmers. More to the point, perhaps more CF people will start sharing their discoveries of useful JSP custom tag libraries, including documentation of how to use them within CF. Indeed, what we really need is a repository for people to share their observations of useful JSP custom tags. I'll start one at www.systemanage.com/taglibs/.
As far as learning more about using JSP custom tags within CFMX, you should look to the CFMX documentation (and release notes, new features guides, etc.) that will be made public when the product goes into production.
As for learning more about the general subject of JSP custom tags, several books cover it from a Java or JSP perspective. They can be helpful, but mostly for those creating JSP custom tags or using them within JSPs. I'll point you to a couple. There are certainly others. Perhaps the most complete book on the subject is Mastering JSP Custom Tags and Tag Libraries, by James Goodwill. It's just come out.
There are chapters in other books, as well as several articles and tutorials of the same sort online. Perhaps the best place to point you is a repository listing many of them at www.jspinsider.com/tutorials/jsp/taglibraries.view.
When All's Said and Done...
Now you have it: what JSP custom tags are, how and why you might use them within CF, and where to find them and more information about them. Should you be interested in such possibilities? I think so. And, again, you definitely don't need any Java or JSP experience to benefit from them. They can simply provide some useful, reusable functionality that you can leverage in your CF (or JSP) pages. There's quite a bit more that we could discuss about them, but this should be enough to get you started.
|charles arehart 09/08/02 04:56:00 AM EDT|
|Charles Arehart 08/07/02 01:08:00 PM EDT|
Folks, I'm sad to have to report that I've now confirmed that the use of CFIMPORT to call JSP custom tags does NOT work in the Pro edition of CF. It will work in Enterprise, as well as the Trial (which is enterprise) and the Developer Edition (which the Trial becomes after 30 days, reverting to a single-user version).
|charles arehart 05/22/02 04:58:00 PM EDT|
Folks, here's another update of info I've learned since the article. First, you don't HAVE to place your jar file in the web-inf\lib directory as I (and the docs) had stated. I've found that you can indeed put them in the same directory as your CF template that's calling them, and then just say
That's useful if you work in an environment where you may find th web-inf directory locked down for any reason.
Also, in the preview release candidate, you can now refer to TLD files in the CFIMPORT, and again they can be located either in web-inf\ or in the same dir as your code.
Of course, when I say you can put these in the same dir as your code, I also mean you can put them in some other dir in the web root and use a relative reference to point to it.
|charles arehart 05/22/02 04:54:00 PM EDT|
Folks, just wanted to add some info for you. If you try out these tags as I have offered in the article, you may find that you get the error:
The type for attribute xxx of tag yyy could not be determined.
where xxx is the attribute you're using and yyy is the tag whose attributes it's complaining about.
Though I didn't mention that error specifically, I did say that it was my experience that you needed to restart the server upon placing a new tag into the web-inf\lib directory.
This error is what you'll see if you don't.
Disruptive macro trends in technology are impacting and dramatically changing the "art of the possible" relative to supply chain management practices through the innovative use of IoT, cloud, machine learning and Big Data to enable connected ecosystems of engagement. Enterprise informatics can now move beyond point solutions that merely monitor the past and implement integrated enterprise fabrics that enable end-to-end supply chain visibility to improve customer service delivery and optimize supplier management. Learn about enterprise architecture strategies for designing connected systems tha...
Oct. 2, 2014 06:15 AM EDT Reads: 1,068
The Internet of Things (IoT) is going to require a new way of thinking and of developing software for speed, security and innovation. This requires IT leaders to balance business as usual while anticipating for the next market and technology trends. Cloud provides the right IT asset portfolio to help today’s IT leaders manage the old and prepare for the new. Today the cloud conversation is evolving from private and public to hybrid. This session will provide use cases and insights to reinforce the value of the network in helping organizations to maximize their company’s cloud experience.
Oct. 2, 2014 06:00 AM EDT Reads: 1,229
Cultural, regulatory, environmental, political and economic (CREPE) conditions over the past decade are creating cross-industry solution spaces that require processes and technologies from both the Internet of Things (IoT), and Data Management and Analytics (DMA). These solution spaces are evolving into Sensor Analytics Ecosystems (SAE) that represent significant new opportunities for organizations of all types. Public Utilities throughout the world, providing electricity, natural gas and water, are pursuing SmartGrid initiatives that represent one of the more mature examples of SAE. We have s...
Oct. 2, 2014 06:00 AM EDT Reads: 1,026
IoT is still a vague buzzword for many people. In his session at Internet of @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, will discuss the business value of IoT that goes far beyond the general public's perception that IoT is all about wearables and home consumer services. The presentation will also discuss how IoT is perceived by investors and how venture capitalist access this space. Other topics to discuss are barriers to success, what is new, what is old, and what the future may hold.
Oct. 1, 2014 10:00 PM EDT Reads: 1,829
Whether you're a startup or a 100 year old enterprise, the Internet of Things offers a variety of new capabilities for your business. IoT style solutions can help you get closer your customers, launch new product lines and take over an industry. Some companies are dipping their toes in, but many have already taken the plunge, all while dramatic new capabilities continue to emerge. In his session at Internet of @ThingsExpo, Reid Carlberg, Senior Director, Developer Evangelism at salesforce.com, to discuss real-world use cases, patterns and opportunities you can harness today.
Oct. 1, 2014 08:30 PM EDT Reads: 2,202
All major researchers estimate there will be tens of billions devices – computers, smartphones, tablets, and sensors – connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades. 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!
Oct. 1, 2014 05:00 PM EDT Reads: 2,395
Noted IoT expert and researcher Joseph di Paolantonio (pictured below) has joined the @ThingsExpo faculty. Joseph, who describes himself as an “Independent Thinker” from DataArchon, will speak on the topic of “Smart Grids & Managing Big Utilities.” Over his career, Joseph di Paolantonio has worked in the energy, renewables, aerospace, telecommunications, and information technology industries. His expertise is in data analysis, system engineering, Bayesian statistics, data warehouses, business intelligence, data mining, predictive methods, and very large databases (VLDB). Prior to DataArcho...
Oct. 1, 2014 03:30 PM EDT Reads: 1,095
Software AG helps organizations transform into Digital Enterprises, so they can differentiate from competitors and better engage customers, partners and employees. Using the Software AG Suite, companies can close the gap between business and IT to create digital systems of differentiation that drive front-line agility. We offer four on-ramps to the Digital Enterprise: alignment through collaborative process analysis; transformation through portfolio management; agility through process automation and integration; and visibility through intelligent business operations and big data.
Sep. 30, 2014 10:30 AM EDT Reads: 1,604
There will be 50 billion Internet connected devices by 2020. Today, every manufacturer has a propriety protocol and an app. How do we securely integrate these "things" into our lives and businesses in a way that we can easily control and manage? Even better, how do we integrate these "things" so that they control and manage each other so our lives become more convenient or our businesses become more profitable and/or safe? We have heard that the best interface is no interface. In his session at Internet of @ThingsExpo, Chris Matthieu, Co-Founder & CTO at Octoblu, Inc., will discuss how thes...
Sep. 29, 2014 06:45 AM EDT Reads: 1,926
Last week, while in San Francisco, I used the Uber app and service four times. All four experiences were great, although one of the drivers stopped for 30 seconds and then left as I was walking up to the car. He must have realized I was a blogger. None the less, the next car was just a minute away and I suffered no pain. In this article, my colleague, Ved Sen, Global Head, Advisory Services Social, Mobile and Sensors at Cognizant shares his experiences and insights.
Sep. 28, 2014 09:45 AM EDT Reads: 1,567
We are reaching the end of the beginning with WebRTC and real systems using this technology have begun to appear. One challenge that faces every WebRTC deployment (in some form or another) is identity management. For example, if you have an existing service – possibly built on a variety of different PaaS/SaaS offerings – and you want to add real-time communications you are faced with a challenge relating to user management, authentication, authorization, and validation. Service providers will want to use their existing identities, but these will have credentials already that are (hopefully) ir...
Sep. 27, 2014 11:30 PM EDT Reads: 1,945
Can call centers hang up the phones for good? Intuitive Solutions did. WebRTC enabled this contact center provider to eliminate antiquated telephony and desktop phone infrastructure with a pure web-based solution, allowing them to expand beyond brick-and-mortar confines to a home-based agent model. It also ensured scalability and better service for customers, including MUY! Companies, one of the country's largest franchise restaurant companies with 232 Pizza Hut locations. This is one example of WebRTC adoption today, but the potential is limitless when powered by IoT. Attendees will learn rea...
Sep. 27, 2014 10:30 PM EDT Reads: 1,857
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at Internet of @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, will share some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, deploy, and manage applications integrating voice, video and data. He is the co-founder ...
Sep. 27, 2014 10:30 PM EDT Reads: 2,320
The Internet of Things (IoT) promises to create new business models as significant as those that were inspired by the Internet and the smartphone 20 and 10 years ago. What business, social and practical implications will this phenomenon bring? That's the subject of "Monetizing the Internet of Things: Perspectives from the Front Lines," an e-book released today and available free of charge from Aria Systems, the leading innovator in recurring revenue management.
Sep. 27, 2014 09:45 PM EDT Reads: 2,543
The Internet of Things will put IT to its ultimate test by creating infinite new opportunities to digitize products and services, generate and analyze new data to improve customer satisfaction, and discover new ways to gain a competitive advantage across nearly every industry. In order to help corporate business units to capitalize on the rapidly evolving IoT opportunities, IT must stand up to a new set of challenges.
Sep. 27, 2014 08:45 PM EDT Reads: 2,423
There’s Big Data, then there’s really Big Data from the Internet of Things. IoT is evolving to include many data possibilities like new types of event, log and network data. The volumes are enormous, generating tens of billions of logs per day, which raise data challenges. Early IoT deployments are relying heavily on both the cloud and managed service providers to navigate these challenges. In her session at 6th Big Data Expo®, Hannah Smalltree, Director at Treasure Data, to discuss how IoT, Big Data and deployments are processing massive data volumes from wearables, utilities and other mach...
Sep. 27, 2014 01:00 PM EDT Reads: 2,087
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at Internet of @ThingsExpo, Erik Lagerway, Co-founder of Hookflash, will walk through the shifting landscape of traditional telephone and voice s...
Sep. 26, 2014 11:45 PM EDT Reads: 1,611
While great strides have been made relative to the video aspects of remote collaboration, audio technology has basically stagnated. Typically all audio is mixed to a single monaural stream and emanates from a single point, such as a speakerphone or a speaker associated with a video monitor. This leads to confusion and lack of understanding among participants especially regarding who is actually speaking. Spatial teleconferencing introduces the concept of acoustic spatial separation between conference participants in three dimensional space. This has been shown to significantly improve comprehe...
Sep. 26, 2014 10:45 PM EDT Reads: 1,529
The Internet of Things is tied together with a thin strand that is known as time. Coincidentally, at the core of nearly all data analytics is a timestamp. When working with time series data there are a few core principles that everyone should consider, especially across datasets where time is the common boundary. In his session at Internet of @ThingsExpo, Jim Scott, Director of Enterprise Strategy & Architecture at MapR Technologies, will discuss single-value, geo-spatial, and log time series data. By focusing on enterprise applications and the data center, he will use OpenTSDB as an example...
Sep. 26, 2014 07:45 PM EDT Reads: 2,345
SYS-CON Events announced today that Gridstore™, the leader in software-defined storage (SDS) purpose-built for Windows Servers and Hyper-V, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Gridstore™ is the leader in software-defined storage purpose built for virtualization that is designed to accelerate applications in virtualized environments. Using its patented Server-Side Virtual Controller™ Technology (SVCT) to eliminate the I/O blender effect and accelerate applications Gridsto...
Sep. 26, 2014 06:15 PM EDT Reads: 1,725