Click here to close now.

Welcome!

You will be redirected in 30 seconds or close now.

ColdFusion Authors: Yakov Fain, Maureen O'Gara, Nancy Y. Nee, Tad Anderson, Daniel Kaar

Related Topics: ColdFusion

ColdFusion: Article

Facing the Challenges Part 2

Facing the Challenges Part 2

It's fun developing wireless applications in ColdFusion, but if you don't solve several key challenges it'll be more painful than pleasant.

In this second part of a series, I'll focus on some common problems encountered by CF/WML developers.

In the last issue the focus was on getting you started: an introduction to WAP (the Wireless Access Protocol), the early state of wireless programming, how to get a simulator to begin testing code, resources for learning more about WAP and the markup language for WAP phones, WML (Wireless Markup Language).

I intentionally didn't focus on WML itself or on the details of the WAP architecture. These matters are best left to the many SDK documents, Web sites and the growing number of books on the subject.

In this issue I'll focus on matters not covered by those resources: the problems you'll typically encounter when getting started with wireless programming in conjunction with ColdFusion. There are indeed many challenges that would affect any WML developer. I'll touch on a couple of them, but the real focus is on the CF-specific challenges, as well as some tips and tricks for getting things to work when trouble strikes.

The Key to Doing WML in CF
Before discussing the common challenges, I ought to at least give you a bit of sample code to begin with in case this is your first time reading about WML. As mentioned in the last article, I don't want to repeat too much of what was covered by Ben Forta's intro to WML in his December 1999 article, "No Strings Attached" (Vol. 1, issue 6). Please see that for more introductory WML.

The bottom line is that all you need is a properly formatted CFCONTENT tag to indicate to the browser that the code you're building is WML rather than HTML (ColdFusion's default). This sets the MIME type of the page you're creating. Simply include this at the top of your program:

<CFCONTENT TYPE="text/vnd.wap.wml">
That's not quite all you need. There's a set of basic "prologue" statements that must be specified at the top of any WML page, so the more complete definition of the beginning of a CF/WML page, as offered in a simple "Hello World" example, is:
<CFCONTENT TYPE="text/vnd.wap.wml"><?xml version="1.0"?>
<!DOCTYPE wml PUBLIC"-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card>
<p>
Hello World
</p>
</card>
</wml>
Notice that we've put the first two lines of code on the same line. Many WML developers have found that the ?xml declaration line should be coded without any carriage returns preceding it.

From here you can use any CF code to generate any WML as needed by your application. Again, see other more general-interest WML resources for more about the WML you can use. And you can do this in any version of CF. This leads to a natural question often asked by new CF/WML developers: What version of ColdFusion allows WML programming?

When people notice that Allaire has highlighted new WML support in 4.5, they get the impression that WML can only be done in 4.5 of CF Server. In fact, the new support is really just extensions to CF Studio and HomeSite to support creating, editing and getting help on WML tags, and a new page wizard. We'll review those in a later article.

Any version of ColdFusion (Server and Studio) can support WML programming if you're coding the tags by hand, since all you need is that CFCONTENT tag at the top of the page.

The Inevitable Errors You'll Encounter
If you try this sample code, or when you begin doing more substantial code, you'll inevitably encounter errors. The challenge is determining if it's a CF error or a WML error, and even then what works in one phone may fail in another due to the incompatibilities of phones supporting WML in different ways (which is beyond the scope of this article). But there are some simple issues we can deal with.

Viewing the Code in the Right Browser
First of all, you can't expect to run the preceding code sample from within a browser like IE or Netscape (at least not the current versions). With the CFCONTENT tag in place, you can view the output of the page only in a browser that supports WML (phones or phone simulators, as discussed in the last article). If you try to view it in a normal browser, you'll likely receive a prompt to save the file being sent, since the browser doesn't know what to do with a file of the MIME type specified in the CFCONTENT tag.

Dealing with "Invalid Content" or "Syntax Errors"
Even when viewed on a real phone (or simulator), you'll encounter errors in your first forays into WML. There are a few things to keep in mind.

First, WML is case-sensitive. You must use lowercase for WML tags and attributes. Also, WML follows the rules of XML programming, so all tags must have a closing tag. Even a <p> tag must have a closing </p>, unlike in HTML, and tags like <br>, which have no closing tag, must be written as <br/>.

Note that you can't send HTML tags to a WML browser. (Well, that's not entirely true. Some WAP gateways can convert HTML to WML, but that's not universal and shouldn't be relied on.) If you send HTML to WML browsers, they'll generally "choke" on it. So be careful – don't intermix HTML and WML. You really need to find some WML resources to learn more. For all their similarity, there are many significant differences between HTML and WML programming, and they're more than just differences in tag names.

Other problems could arise if you have an error in your CF code (causing CF to display an error message), or if you have server-side debugging information turned on, both of which generate HTML, as we'll discuss next.

Turn Off Server-Side Debugging
ColdFusion's HTML heritage can really get in the way when doing WML programming. When debugging is turned on in the Administrator, you normally see the debugging info at the bottom of any CF page. But that information is sent in HTML formatting to the browser, which is fine in a normal browser, but it's death to most WML browsers since they can't read HTML.

You don't need to turn off debugging in the Administrator. As of ColdFusion release 4, you have the option to turn off debugging with the following line of code:

<CFSETTING SHOWDEBUGOUTPUT="no">
This will disable debugging until you turn it on again or until the currently running template ends. If you're running a release of ColdFusion prior to release 4, it's probably best to just turn off server-side debugging.

Why Can't I See ColdFusion Error Messages?
On a related matter, the same problem of CF's HTML heritage has to do with error message handling. When you get an error in CF, you normally see the CF error message display indicating the error and the page and line number of the code in error. But that error is also sent in HTML formatting to the browser, which chokes the WML browser.

This would seem a real dilemma. You can't see the error because the phone doesn't recognize it as valid WML. So how are you supposed to deal with it? Well, fortunately, Allaire has put in place error-handling components to improve the ability of the developer to control the error message display to the user.

You might think that CFERROR, and its ability to create a specially formatted error page, might come to the rescue. Unfortunately, the two older forms of CFERROR pages (type="request" and type="validation") send pure HTML (and an HTML MIME type), which you can't override. Since you can't put any CF tags on those error pages, you can't even add a CFCONTENT.

(This also means, of course, that you can't use CF's hidden field validation to do server-side form validation. The validation error page that it offers is also pure HTML and you can't override it.)

Perhaps Allaire will offer a solution to these dilemmas in the future. For now, if you have release 4.5, you can in many cases at least solve some of the first problem – seeing CF error messages – by taking advantage of the new CFERROR type="exception". This transfers control when an error occurs to a page that is allowed to do CF tags (an incredibly valuable new feature in and of itself), including a CFCONTENT tag. You can then format the error for display to the WML browser.

Formatting the Error Message Itself
You're not quite done, though. The CF error message itself, offered inside such a CFERROR page as the variable CFERROR.Diagnostics, will usually be HTML-formatted. This was fine when sending it for display to an HTML browser, but again it's a problem in WML. Fortunately, you can solve it by using a CF function to convert the HTML tags in the message into their corresponding display codes, such as &gt; for > and &lt; for <.

Allaire offers two solutions for this. In 4.5 there's an XmlFormat() function for just this purpose. In older releases you can use HtmlEditFormat(). It's not the perfect solution, as it'll simply cause any HTML tags in the error message to be displayed to the screen, but it's easier than trying to strip out the HTML tags.

This approach can also be used to format error messages displayed in a CFCATCH (using the "cfcatch.detail" variable).

You may want to create an application.cfm that sets the CFSETTING to disable debugging output (on a release 4 or above server) and sets a CFERROR type="exception" (on a release 4.5 or above server) to point to a template that can format the error message in WML.

Keep in mind that none of this CF error handling will help if the error in your page is due to badly formed WML. In this case you'd do well to have a simulator that allows you to see the actual WML being sent to the browser (most real phones won't provide access to that information).

Form Processing Works in Simulator, Fails in Real Phone
This is another thorny problem, and it's not generally CF-specific. Some background will help. When you test code in most simulators, you may be using a form of communication between the simulator and the Web server that's often called "http direct". There is direct communication between the simulator and the server.

This is fine, but real phones use a form of communication that goes from the phone to a gateway (usually within the phone company provider) that then communicates to the Web server on the phone user's behalf. (It acts as both a proxy and a translator, since what's really sent to real phones is an encoded form of WML to minimize data traffic.)

The problem with this scenario is that code that works fine in the "http direct" mode may fail when run on a real phone or in the simulator's gateway mode.

A perfect example of this is "form processing" by way of the "post" method. If the example in Listing 1 is submitted on a simulator, it will work, but on a real phone it may fail.

I don't have room here to explain the unique differences of form processing in WML versus HTML, but the example shows many of the significant features. Note that there's no "form" tag per se, and that the form data is gathered in one place (the input tag), stored in a variable on the phone ("stock") and passed to the server in yet another tag (<go>) when the user presses the "accept" button or equivalent. Very different from HTML! But note the powerful new formatting possibilities in the <input> tag. This allows only up to four alphanumeric characters.

The problem occurs when the page itself is submitted with method="post". In testing on a simulator in HTTP direct mode, this code works fine. In a real phone, however, which goes through a gateway, it will fail to submit. In the Phone.com simulator, using the "up.link" mode to go through a gateway, it fails with an error "500:internal server error". It seems the gateway is simply unable to make a "post" method call to the server.

And it doesn't seem to be restricted to CF Server (I tested the problem against an ASP program and got the same error). It may be restricted to Phone.com gateways, though I've heard it happened to users of Nokia phones and simulators.

The short-term solution is to change the method to "get". ColdFusion will receive the variables as "url." variables (in the example above, the "url.symbol"). Unlike in HTML browsers, this doesn't have the same problem of showing the user the form variables on the URL of the action page since phone users don't see the URLs of sites they're visiting (currently).

There is the security risk that on an SSL-enabled connection (called WTLS in the WAP world) the data passed on the URL isn't encrypted, so this isn't a solution that will work when passing userids and passwords, or credit cards if the goal is to encrypt that data. But that, too, is beyond the scope of this article.

That's All for Now
That's all the time (or rather, room) we have this month. Upcoming articles in this series will cover some other challenges (and solutions) regarding wireless development, such as doing browser detection to serve both HTML and WML browsers, handling sessions in an environment in which cookies aren't always supported, doing CFLOCATION (you have to use Web server root-relative paths, even to send to a file in the same directory), what to do when CFCONTENT simply doesn't work in your CF server, processing multivalued form field submissions, sending notifications and pushing messages to the phone (using COM objects), and the support in Studio for WML.

You can learn about WML and generic challenges as well as more about these CF challenges in the recently released book Professional WAP (Wrox Press). I have a chapter in the book on CF/WML programming. Other WML/WAP books will soon be in the market as well.

More Stories By Charlie Arehart

A veteran ColdFusion developer since 1997, Charlie Arehart is a long-time contributor to the community and a recognized Adobe Community Expert. He's a certified Advanced CF Developer and Instructor for CF 4/5/6/7 and served as tech editor of CFDJ until 2003. Now an independent contractor (carehart.org) living in Alpharetta, GA, Charlie provides high-level troubleshooting/tuning assistance and training/mentoring for CF teams. He helps run the Online ColdFusion Meetup (coldfusionmeetup.com, an online CF user group), is a contributor to the CF8 WACK books by Ben Forta, and is frequently invited to speak at developer conferences and user groups worldwide.

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 Dyn, the worldwide leader in Internet Performance, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. 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.
As organizations shift toward IT-as-a-service models, the need for managing and protecting data residing across physical, virtual, and now cloud environments grows with it. CommVault can ensure protection &E-Discovery of your data – whether in a private cloud, a Service Provider delivered public cloud, or a hybrid cloud environment – across the heterogeneous enterprise. In his session at 16th Cloud Expo, Randy De Meno, Chief Technologist - Windows Products and Microsoft Partnerships, will discuss how to cut costs, scale easily, and unleash insight with CommVault Simpana software, the only si...
Cloud data governance was previously an avoided function when cloud deployments were relatively small. With the rapid adoption in public cloud – both rogue and sanctioned, it’s not uncommon to find regulated data dumped into public cloud and unprotected. This is why enterprises and cloud providers alike need to embrace a cloud data governance function and map policies, processes and technology controls accordingly. In her session at 15th Cloud Expo, Evelyn de Souza, Data Privacy and Compliance Strategy Leader at Cisco Systems, will focus on how to set up a cloud data governance program and s...
Even as cloud and managed services grow increasingly central to business strategy and performance, challenges remain. The biggest sticking point for companies seeking to capitalize on the cloud is data security. Keeping data safe is an issue in any computing environment, and it has been a focus since the earliest days of the cloud revolution. Understandably so: a lot can go wrong when you allow valuable information to live outside the firewall. Recent revelations about government snooping, along with a steady stream of well-publicized data breaches, only add to the uncertainty
Roberto Medrano, Executive Vice President at SOA Software, had reached 30,000 page views on his home page - http://RobertoMedrano.SYS-CON.com/ - on the SYS-CON family of online magazines, which includes Cloud Computing Journal, Internet of Things Journal, Big Data Journal, and SOA World Magazine. He is a recognized executive in the information technology fields of SOA, internet security, governance, and compliance. He has extensive experience with both start-ups and large companies, having been involved at the beginning of four IT industries: EDA, Open Systems, Computer Security and now SOA.
The Workspace-as-a-Service (WaaS) market will grow to $6.4B by 2018. In his session at 16th Cloud Expo, Seth Bostock, CEO of IndependenceIT, will begin by walking the audience through the evolution of Workspace as-a-Service, where it is now vs. where it going. To look beyond the desktop we must understand exactly what WaaS is, who the users are, and where it is going in the future. IT departments, ISVs and service providers must look to workflow and automation capabilities to adapt to growing demand and the rapidly changing workspace model.
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focused on understanding how industrial data can create intelligence for industrial operations. Imagine ...
Hadoop as a Service (as offered by handful of niche vendors now) is a cloud computing solution that makes medium and large-scale data processing accessible, easy, fast and inexpensive. In his session at Big Data Expo, Kumar Ramamurthy, Vice President and Chief Technologist, EIM & Big Data, at Virtusa, will discuss how this is achieved by eliminating the operational challenges of running Hadoop, so one can focus on business growth. The fragmented Hadoop distribution world and various PaaS solutions that provide a Hadoop flavor either make choices for customers very flexible in the name of opti...
Operational Hadoop and the Lambda Architecture for Streaming Data Apache Hadoop is emerging as a distributed platform for handling large and fast incoming streams of data. Predictive maintenance, supply chain optimization, and Internet-of-Things analysis are examples where Hadoop provides the scalable storage, processing, and analytics platform to gain meaningful insights from granular data that is typically only valuable from a large-scale, aggregate view. One architecture useful for capturing and analyzing streaming data is the Lambda Architecture, representing a model of how to analyze rea...
SYS-CON Events announced today that Vitria Technology, Inc. will exhibit at SYS-CON’s @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes for use cases across the industrial, enterprise, and consumer segments.
The Internet of Things (IoT) promises to evolve the way the world does business; however, understanding how to apply it to your company can be a mystery. Most people struggle with understanding the potential business uses or tend to get caught up in the technology, resulting in solutions that fail to meet even minimum business goals. In his session at @ThingsExpo, Jesse Shiah, CEO / President / Co-Founder of AgilePoint Inc., showed what is needed to leverage the IoT to transform your business. He discussed opportunities and challenges ahead for the IoT from a market and technical point of vie...
Advanced Persistent Threats (APTs) are increasing at an unprecedented rate. The threat landscape of today is drastically different than just a few years ago. Attacks are much more organized and sophisticated. They are harder to detect and even harder to anticipate. In the foreseeable future it's going to get a whole lot harder. Everything you know today will change. Keeping up with this changing landscape is already a daunting task. Your organization needs to use the latest tools, methods and expertise to guard against those threats. But will that be enough? In the foreseeable future attacks w...
HP and Aruba Networks on Monday announced a definitive agreement for HP to acquire Aruba, a provider of next-generation network access solutions for the mobile enterprise, for $24.67 per share in cash. The equity value of the transaction is approximately $3.0 billion, and net of cash and debt approximately $2.7 billion. Both companies' boards of directors have approved the deal. "Enterprises are facing a mobile-first world and are looking for solutions that help them transition legacy investments to the new style of IT," said Meg Whitman, Chairman, President and Chief Executive Officer of HP...
Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming 16th Cloud Expo at the Javits Center in New York June 9-11 will find fresh new content in a new track called PaaS | Containers & Microservices Containers are not being considered for the first time by the cloud community, but a current era of re-consideration has pushed them to the top of the cloud agenda. With the launch of Docker's initial release in March of 2013, interest was revved up several notches. Then late last...
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...
The explosion of connected devices / sensors is creating an ever-expanding set of new and valuable data. In parallel the emerging capability of Big Data technologies to store, access, analyze, and react to this data is producing changes in business models under the umbrella of the Internet of Things (IoT). In particular within the Insurance industry, IoT appears positioned to enable deep changes by altering relationships between insurers, distributors, and the insured. In his session at @ThingsExpo, Michael Sick, a Senior Manager and Big Data Architect within Ernst and Young's Financial Servi...
The explosion of connected devices / sensors is creating an ever-expanding set of new and valuable data. In parallel the emerging capability of Big Data technologies to store, access, analyze, and react to this data is producing changes in business models under the umbrella of the Internet of Things (IoT). In particular within the Insurance industry, IoT appears positioned to enable deep changes by altering relationships between insurers, distributors, and the insured. In his session at @ThingsExpo, Michael Sick, a Senior Manager and Big Data Architect within Ernst and Young's Financial Servi...
PubNub on Monday has announced that it is partnering with IBM to bring its sophisticated real-time data streaming and messaging capabilities to Bluemix, IBM’s cloud development platform. “Today’s app and connected devices require an always-on connection, but building a secure, scalable solution from the ground up is time consuming, resource intensive, and error-prone,” said Todd Greene, CEO of PubNub. “PubNub enables web, mobile and IoT developers building apps on IBM Bluemix to quickly add scalable realtime functionality with minimal effort and cost.”
Sensor-enabled things are becoming more commonplace, precursors to a larger and more complex framework that most consider the ultimate promise of the IoT: things connecting, interacting, sharing, storing, and over time perhaps learning and predicting based on habits, behaviors, location, preferences, purchases and more. In his session at @ThingsExpo, Tom Wesselman, Director of Communications Ecosystem Architecture at Plantronics, will examine the still nascent IoT as it is coalescing, including what it is today, what it might ultimately be, the role of wearable tech, and technology gaps stil...
In the consumer IoT, everything is new, and the IT world of bits and bytes holds sway. But industrial and commercial realms encompass operational technology (OT) that has been around for 25 or 50 years. This grittier, pre-IP, more hands-on world has much to gain from Industrial IoT (IIoT) applications and principles. But adding sensors and wireless connectivity won’t work in environments that demand unwavering reliability and performance. In his session at @ThingsExpo, Ron Sege, CEO of Echelon, will discuss how as enterprise IT embraces other IoT-related technology trends, enterprises with i...