|By Charlie Arehart||
|October 22, 2002 12:00 AM EDT||
Last month I introduced a precompile "batch" file that allowed you to manually compile CFMX templates, saving the penalty paid by the first user to browse a CFMX template after it was created or edited.
But there will be curious folks (and bit-twiddlers) among you who will want to know more - maybe lots more. How much time is this really saving? If it's compiled to disk, how and when does CFMX read it into memory to execute it? What's the cost of that? What happens with CFINCLUDEd files? Where does the compiled code go? Can I look at it? Can I just delete the generated class files instead? How do I determine which class file was generated for which CF template? Can I distribute the compiled code on other servers without the source code?
I'll address these questions and more in this conclusion.
Evaluating the Execution Time
Before going on, it may be helpful to explain something about determining the impact in terms of execution (and other startup) times for running a template. It will be very helpful to turn on the "Report Execution Times" option in the ColdFusion Administrator settings for "Debugging Settings". This will produce a display (see Table 1) at the bottom of a page when executed in a browser.
As in previous releases, you will only see this debugging information if the Administrator has enabled it. Also, if any IP addresses are listed in the "Debugging IP Addresses" page of the Administrator, then you will only see it if you are in that list. If there are no values in that list, all who execute CF templates on the server will see this info. Finally, if you still don't see this information, be sure that your template (or the application.cfm that is called before it) does not have <CFSETTING ShowDebugOutput="no">.
This particular example shows a file called test.cfm, which included a file called test.html, and also had an application.cfm that was called. It also shows a separate value for "startup, parsing, compiling, loading, & shutdown". We'll get to that in a moment. Keep an eye on this set of timing information when trying to evaluate the impact of various choices and settings.
Compilation Doesn't Eliminate All the Waits
So, after reading my previous article you now know how to precompile a template. You've paid the cost of compiling the code to its underlying Java byte code and now it should execute without any parsing/compiling delay (assuming it's not been edited). What if you restart the server? Will the first user really experience no further delay? Not exactly.
You may recall that I said that CFMX writes the compiled code to disk. Did you wonder how it gets from disk into memory, for CFMX to execute? I mentioned at the outset of the previous article that even in ColdFusion 5 and before, the first execution of a template after a server restart would cause CF to interpret the template into "pcode" and then load that into a "template cache". The code was then executed from memory all day, rather than being read from disk (unless the cache filled, in which case the least recently used template would be flushed from the cache). This was a useful solution for making code run as quickly as possible when executed.
CFMX faces the same dilemma. While the compilation of code to a Java class file eliminates the interpretation step the first time the code is executed after each restart, the fact remains that the compiled code needs to be read from disk and loaded into ColdFusion's memory - in that same template cache that existed in previous releases.
The precompile batch file from the previous release does not perform this "load" of the compiled code into CFMX's template cache, so you can't save that time. Similarly, when the server has just been restarted, it will need to be "loaded" into memory. It's just the first user to run the code after restart (or a compile or precompile) that experiences that load time. So be aware that precompiling won't eliminate the entire wait. There's still the time needed to load the code into the template cache the first time it's executed after restart.
Also, be careful in evaluating the impact of these steps. If you watch the precompile.bat file process, you may notice that compiling even a single template seems to take longer than if you simply let CF compile it automatically. The compiler process in the precompile.bat file has some load time itself on the first template it compiles. If only one template is precompiled, you see that time reflected in the time it takes to compile. If multiple files are precompiled at once, you see each individual template taking less time than if it was compiled alone.
Handling Included Files
In my example above I included a test.html file, but what if I had included a cfm file? Do you wonder if there might be an effect on compilation if code in the included file changes? Would you expect ColdFusion to have to recompile the including template?
It does not. Precompiling the including file after the included file has changed isn't necessary. Indeed, if you look at the compile time reported by the precompile tool it will be reported as 0ms. This reiterates the point that CFINCLUDE is a runtime directive, not a compile time one. Many misconstrue that. (Further proof is demonstrated by the fact that the value of the TEMPLATE attribute naming a file in CFINCLUDE can in fact be a variable. It's clearly a runtime directive.)
What's the difference? Say you have a template that includes another and that included file changes often during the day. You will notice a delay in loading the file. But it would have been true in CF 5 and before. Compilation isn't the cause, and precompilation is not the answer. You just need to get CF to reexecute the template so that it runs the CFINCLUDE to detect that changed file and load it into memory. Again, it's a runtime issue.
I've done this and watched the time reported in the debug output on the first execution of the calling template (after the included file has changed). In one example it went from 1000 ms (reported as execution time for the calling template) to 0ms from then on. Note that this change is in the runtime of the template, not its compile time. So it's not really a compilation issue.
What can you do, especially if some automated process is causing updates to the included file? You could add to that automated process (or create another) that simply executes the calling page once after the included file has changed. This could be kicked off via CFSCHEDULE or CFHTTP. The point isn't to save the resulting output in any way (which is an option with these tags), but merely to cause execution of (or in other words to "touch") the calling page so that it does what it needs to do to interpret the change in the included file.
Where Does the Compilation Go?
I also mentioned in the previous article that CFMX compiles your cfm (and cfc) templates into .class files, which are Java byte code files. If you're curious, the files are written to (and executed from) the cfclasses subdirectory of [cfusionmx]\wwwroot\WEB-INF\ directory where CFMX is installed. This occurs whether you are using another Web server or have located your file outside the default wwwroot location. CFMX compiles and runs the code from this cfclasses directory, regardless of the location of the source file.
This is the reason why in the previous article we needed to specify the -webinf directive in the batch file, to tell it to place compiled code there. If it's not placed there, it won't run in CFMX.
Be warned, though, that the file names for these class files may not be at all apparent. A CF template named Setsession.cfm might lead to a class file named cfsetsession2ecfm1011928409.class.
All templates from all directories end up in this one cfclasses subdirectory. They're not stored here in any subdirectories related to their original location. Instead, CF includes a hash of the directory name in that set of numbers after the file name. Keep that in mind when trying to associate a given class file with its original cfm template. The hashing process is a bit convoluted. (See my blog entry of Oct. 5 for more details, at cfmxplus.blogspot.com.)
Perhaps the easiest way to detect which class file goes with which source file is to simply edit the file and then execute (or precompile) it. Look in the cfclasses directory for the most recently created class file. Assuming your server is not too busy with many compilations taking place, it should be pretty easy to associate the classname with the CF source code name.
Saving Java Source Code Produced by CFMX
So that's where the compiled source code goes. But what about seeing the actual uncompiled Java source code that your CF template is converted into? Normally it's of no concern to CF developers what CFMX is doing under the covers in converting our CFML to Java.
For the ardently curious among you, did you know that you can ask CFMX to save the Java code it creates, in source form? You can. It's an undocumented feature, and while I've had no trouble doing it, I must warn that this is something you do at your own risk. Neither I, nor SYS-CON, nor Macromedia accept responsibility for your trying this.
The setting can only be enabled by someone with administrative control of the server, and the setting is also server-wide. It will add a slight additional time to the compile process, so it's not something you'd want to turn on in production. It probably ought not be left on in development either.
You need to edit the file web.xml in the [cfusionmx]\wwwroot\WEB-INF directory. There, if you're familiar with XML files, you'll find a parameter called "coldfusion.compiler.saveJava". Change its value from false to true. Save the file. Restart the server.
Now, whenever a new or recently edited file is compiled (whether automatically by CFMX or by our precompile.bat file), CFMX will also create a ".java" file along with the ".class" file. This ".java" file will be found in that same [cfusionmx]\wwwroot\WEB-INF\cfclasses\ directory as the ".class" files (and will be subject to that same issue of the curious file naming mentioned above).
The Idea of Deleting the Generated Class Files
Some have proposed that instead of precompiling their code they'd just as soon delete the underlying Java class file that was created when it was last compiled. That may seem like overkill, but there are times when it might be worth trying. Just note that, as the previous sections discussed, finding the class file that's associated with a given source template can be challenging. While some may simply delete all the class files, that's certainly overkill.
Don't forget that in the previous article I mentioned there is a -f directive you can pass to the compile process (by modifying the precompile.bat file). That will force a recompile of a file even if CF doesn't think it's necessary. Sometimes that solves the same problem that deleting the class file would solve.
The Dream of Distributing Compiled Code Without Source
Finally, all this talk of creating compiled Java code has excited some. They wonder if they might finally be able to distribute the compiled code without the associated source files. From an intellectual property protection standpoint, this makes sense. Being able to do so is important to those who sell ColdFusion applications. They want their clients to be able to use the code, without them (or their competitors) seeing the actual source code.
Unfortunately, this is not going to happen with the current release of CFMX (if at all). Macromedia has designed the process so that the source code must be present for the file to be loaded. That's an interesting key point. Some were excited by a demo by Ben Forta at last year's DevCon where he was able to delete a source code file and the template continued to run. Some have even noticed that that can still work. Not always, though. Only if the trusted cache setting is enabled.
With what you know from our previous discussion of loading templates and using the trusted cache setting, you may be able to figure out what's happening. If you run a CF template, it's loaded into memory (after being compiled if it changed). Once it's in memory, that's where CF runs it from. And if the trusted cache setting is enabled, then CFMX no longer looks to the source code file to determine if it's changed. Indeed, it also doesn't look to see if it's been deleted.
But if you restart the server, then CF will try to load the template from disk and even with the trusted cache enabled, the first time the template is run, it will look to see if the CF source template has changed since it was last compiled to disk. Only if they disabled that would we be able to truly distribute the source code.
Macromedia folks have further asserted that they won't enable that feature because it's inappropriate to assume that code compiled on one machine would necessarily work on another machine. It's important to note that your ColdFusion code is more than just the underlying Java byte code it's been compiled into. There are libraries that come with CFMX that are called when your code is run. You would at least need to distribute those as well. Whether Macromedia will address this problem for commercial solution developers is still unclear.
The process of compiling and understanding the compilation process for CFMX templates is something that's not well documented. I don't even want to claim to fully understand it. I've encountered some things in preparing this article that still confound me, and since it's undocumented, maybe we can't expect to fully understand it. I just hope that the information shared here will help you, and that it may also motivate Macromedia to decide what aspects of the process they want to make more public.
You could argue that an Admin interface would be a useful addition in doing the compilation process. Perhaps someone has already started working on that. I welcome comments, questions, and concerns you may have about this compilation process. Feel free to e-mail me or post comments below the online version of this article at the www.sys-con.com site.
Trusted Cache Still Applies
I mentioned in the previous article that ColdFusion automatically detects any new or newly edited templates and then automatically compiles them (in CFMX, or interprets them in CF 5 and before). It does this by checking to see if a CF template about to be executed is new or newly updated. And it does this before each invocation of a template, by every user.
That's a rather costly operation, but it's the cost of being able to freely make code changes and see them reflected immediately. If your production environment is designed so that you don't make changes to your code except on a scheduled basis (perhaps overnight), you should enable the "Trusted Cache" setting in the ColdFusion Administrator.
By enabling "Trusted Cache", you're telling ColdFusion that once it loads a program into memory, it should no longer check to see if its underlying source code template has been updated. This will remain in effect until the server is restarted. Sadly, disabling it and re-enabling it does not cause the template cache to be flushed.
One thing that has changed about the "trusted cache" is the specification of its size. Prior to CFMX, the size setting (on the same page in the Administrator) was set in bytes, and it was difficult to calculate an accurate size. Now, the setting is the total number of templates to cache, rather than their size. It still defaults to 1,024.
|Sven 11/14/02 04:59:00 AM EST|
The definition of IoT is not new, in fact it’s been around for over a decade. What has changed is the public's awareness that the technology we use on a daily basis has caught up on the vision of an always on, always connected world. If you look into the details of what comprises the IoT, you’ll see that it includes everything from cloud computing, Big Data analytics, “Things,” Web communication, applications, network, storage, etc. It is essentially including everything connected online from hardware to software, or as we like to say, it’s an Internet of many different things. The difference ...
Nov. 22, 2014 10:00 PM EST Reads: 1,009
An entirely new security model is needed for the Internet of Things, or is it? Can we save some old and tested controls for this new and different environment? In his session at @ThingsExpo, New York's at the Javits Center, Davi Ottenheimer, EMC Senior Director of Trust, reviewed hands-on lessons with IoT devices and reveal a new risk balance you might not expect. Davi Ottenheimer, EMC Senior Director of Trust, has more than nineteen years' experience managing global security operations and assessments, including a decade of leading incident response and digital forensics. He is co-author of t...
Nov. 22, 2014 05:30 PM EST Reads: 1,052
ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ -- IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's platform-as-a-service. The new platform enables developers to build ap...
Nov. 22, 2014 05:30 PM EST Reads: 1,362
Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world.
Nov. 22, 2014 05:30 PM EST Reads: 1,264
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com), moderated by Ashar Baig, Research Director, Cloud, at Gigaom Research, Nate Gordon, Director of T...
Nov. 22, 2014 07:00 AM EST Reads: 1,334
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Architect for the Internet of Things and Intelligent Systems at Red Hat, described how to revolutioniz...
Nov. 21, 2014 09:15 PM EST Reads: 1,253
Technology is enabling a new approach to collecting and using data. This approach, commonly referred to as the "Internet of Things" (IoT), enables businesses to use real-time data from all sorts of things including machines, devices and sensors to make better decisions, improve customer service, and lower the risk in the creation of new revenue opportunities. In his General Session at Internet of @ThingsExpo, Dave Wagstaff, Vice President and Chief Architect at BSQUARE Corporation, discuss the real benefits to focus on, how to understand the requirements of a successful solution, the flow of ...
Nov. 21, 2014 08:00 PM EST Reads: 1,334
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, and physical persons. In the IoT vision, every new "thing" - sensor, actuator, data source, data con...
Nov. 21, 2014 08:00 PM EST Reads: 1,270
"BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Nov. 21, 2014 07:00 PM EST Reads: 1,211
Focused on this fast-growing market’s needs, Vitesse Semiconductor Corporation (Nasdaq: VTSS), a leading provider of IC solutions to advance "Ethernet Everywhere" in Carrier, Enterprise and Internet of Things (IoT) networks, introduced its IStaX™ software (VSC6815SDK), a robust protocol stack to simplify deployment and management of Industrial-IoT network applications such as Industrial Ethernet switching, surveillance, video distribution, LCD signage, intelligent sensors, and metering equipment. Leveraging technologies proven in the Carrier and Enterprise markets, IStaX is designed to work ac...
Nov. 20, 2014 09:15 PM EST Reads: 1,315
"There is a natural synchronization between the business models, the IoT is there to support ,” explained Brendan O'Brien, Co-founder and Chief Architect of Aria Systems, in this SYS-CON.tv interview at the 15th International Cloud Expo®, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Nov. 20, 2014 07:30 PM EST Reads: 1,500
C-Labs LLC, a leading provider of remote and mobile access for the Internet of Things (IoT), announced the appointment of John Traynor to the position of chief operating officer. Previously a strategic advisor to the firm, Mr. Traynor will now oversee sales, marketing, finance, and operations. Mr. Traynor is based out of the C-Labs office in Redmond, Washington. He reports to Chris Muench, Chief Executive Officer. Mr. Traynor brings valuable business leadership and technology industry expertise to C-Labs. With over 30 years' experience in the high-tech sector, John Traynor has held numerous...
Nov. 20, 2014 06:00 PM EST Reads: 1,268
Bit6 today issued a challenge to the technology community implementing Web Real Time Communication (WebRTC). To leap beyond WebRTC’s significant limitations and fully leverage its underlying value to accelerate innovation, application developers need to consider the entire communications ecosystem.
Nov. 20, 2014 04:45 PM EST Reads: 1,042
The 3rd International @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. 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.
Nov. 20, 2014 01:00 PM EST Reads: 1,508
The Internet of Things is not new. Historically, smart businesses have used its basic concept of leveraging data to drive better decision making and have capitalized on those insights to realize additional revenue opportunities. So, what has changed to make the Internet of Things one of the hottest topics in tech? In his session at @ThingsExpo, Chris Gray, Director, Embedded and Internet of Things, discussed the underlying factors that are driving the economics of intelligent systems. Discover how hardware commoditization, the ubiquitous nature of connectivity, and the emergence of Big Data a...
Nov. 20, 2014 12:30 PM EST Reads: 1,747
Almost everyone sees the potential of Internet of Things but how can businesses truly unlock that potential. The key will be in the ability to discover business insight in the midst of an ocean of Big Data generated from billions of embedded devices via Systems of Discover. Businesses will also need to ensure that they can sustain that insight by leveraging the cloud for global reach, scale and elasticity.
Nov. 18, 2014 09:00 PM EST Reads: 1,986
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, phone and digital TV services to consumers primarily in rural areas.
Nov. 18, 2014 08:15 PM EST Reads: 1,560
SYS-CON Events announced today that IDenticard 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. IDenticard™ is the security division of Brady Corp (NYSE: BRC), a $1.5 billion manufacturer of identification products. We have small-company values with the strength and stability of a major corporation. IDenticard offers local sales, support and service to our customers across the United States and Canada. Our partner network encompasses some 300 of the world's leading systems integrators and security s...
Nov. 18, 2014 08:15 PM EST Reads: 1,500
IoT is still a vague buzzword for many people. In his session at @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, discussed the business value of IoT that goes far beyond the general public's perception that IoT is all about wearables and home consumer services. He also discussed how IoT is perceived by investors and how venture capitalist access this space. Other topics discussed were barriers to success, what is new, what is old, and what the future may hold. Mike Kavis is Vice President & Principal Cloud Architect at Cloud Technology Pa...
Nov. 18, 2014 01:30 PM EST Reads: 1,984
Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world. The next @ThingsExpo will take place November 4-6, 2014, at the Santa Clara Convention Center, in Santa Clara, California. Since its launch in 2008, Cloud Expo TV commercials have been aired and CNBC, Fox News Network, and Bloomberg TV. Please enjoy our 2014 commercial.
Nov. 13, 2014 05:00 AM EST Reads: 3,521