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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • Web Interfaces not opening even after Port Forwarding is said to be working!

    - by Ahmad
    I'm encountering this strange problem which has baffled me to the ground, and which I haven't encountered even after years of doing port forwarding .. ! I am hoping somebody here can help me solve this mystery .. :) My network configuration is as follows: I have a DSL modem (custom made and branded by my ISP) which is receiving a DSL stream ... it has an external IP which is visible to the world, say, 11.22.33.44 ... This modem has DHCP enabled, has an internal IP for itself, which is 192.168.1.1 .. it is connected to 2 laptops via and ethernet cable .. Laptop 1 has IP 192.168.1.2, and Laptop 2 has IP 192.168.1.3 ... On Laptop 1, two applications are running, jDownloader and Media Player Classic, which have their web interfaces on ports 8765 and 13579, respectively ... I can access both of these web interfaces from Laptop 2 by opening these addresses: 192.1681.2:8765 and 192.168.1.2:13579 ... both of their web interfaces open up, meaning the web interfaces are working fine .. Moving on, I now want to access these web interfaces from outside my network as well, and so I've configured port forwarding in my PTCL modem to forward all traffic on ports between 8000 and 14000 (both TCP and UDP) to IP 192.168.1.2 ... I have verified that port forwarding is working by testing it using PortForward.com's port checker tool, and this website too: [URL]http://www.yougetsignal.com/tools/open-ports/[/URL] When I use the website, if I'm running the applications on Laptop 2, the website reports that the port is open .. if I then close the application, the website reports the port is closed ... This makes sense as nothing is listening on my machine in the latter case .. Also, if I disable port forwarding in my modem, again, the website reports the port is closed ... so, the website's results seem to be okay ... Same of the above can be said when I'm used PortForward.com's port checker tool ... So again, everything okay so far ... Now, here comes the problem !! ... Despite the above tools reporting that port forwarding is working, I am unable to open the web interfaces from outside my network ... So for example, if I tried to browse 11.22.33.44:8765 or 11.22.33.44:13579, nothing opens in my browser ... But if I accessed these web server's locally from Laptop 3, by typing in 192.168.1.2:8765 or 192.168.1.2:13579, they opened ... So where is the problem here ?? The tools report unanimously that port forwarding is working, and yet I am unable to open the web interfaces from outside the network .. Also note that I have disabled the firewall from my computer, and have also made sure that any option in the above programs (whose web interfaces I am trying to open) that says only local connections are to be accepted, is disabled ... So whats the problem ... ?!! Any ideas ??

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  • Wear and tear on server hard drive from filesystem polling by PHP script

    - by jackie
    So I'm working on a discussion platform, and various clients will visit http://host/thread.php, which will render the discussion thread to date in addition to a form to submit a new post. When a new post is submitted, I would like all of the other clients with browser windows open to have it appear in near-real-time. One of the constraints of my script is that it may not use a DBMS and it must stay in the filesystem. Additionally, I can't use any PECL/PEAR extensions like inotify or anything like that for IPC. The flow will look like this: Client A requests thread.php and the thread is so far empty, but nonetheless it opens a Server-Side Event at eventPusher.php. Client B does the same. Client A fills out a post in the form and and submits (POSTs) it to subHandler.php. ??? (subHandler stores the new submission into the main thread storefile which gets read from when a fresh, new client requests thread.php, in addition to somehow signalling to the continually-running eventPusher event-source that a new comment was posted and that it should echo the event-json to the client. How, exactly, it will send this signal I'm yet unsure of, but there are a few options that I've thought of -- this is the crux of the question, so see below for more clarification) eventPusher.php happily pushes the new event to the client and it shows up soon after it was originally submitted on all clients who have the page open's screens. Now for the #4 missing-link mystery-step, I see a few problems. I mean, either way, eventPusher is gonna be doing a while loop of some sort -- it's gonna be polling something, I think that much is clear. (If that's a bad assumption please do let me know.) Now, the simplest way would be subHandler gets invoked on the form submission, writes it to the main store in addition to newComments.xml, then exits without doing anything else. Then eventPusher checks in newComments.xml every X seconds (by the way, what would be a reasonable time interval here?) and if it finds something then it emits an event to the client. Now, my fear with this is that the server's hard drive will have to constantly start spinning up. Maybe this isn't the case, perhaps it would just get cached in RAM and the linux kernel would take care of this transparently such that filesystem access doesn't actually engage the device because the kernel knows that that particular file hasn't changed since last read. * idea #2: I have no idea how to go about this, but perhaps there is a variable scope that gets stored in general RAM on the system which can be read by any process. Like if we mega-exported a bash variable so that $new_post is normally false but it gets toggled to true by subHandler, and then back to flase once it's pushed to the client. I doubt there's such a variable scope in PHP directly, but I struggle with the concept of variable scope, I just can't seem to understand it no matter what I read on it. * idea #3: eventPusher queries ps in its whileloop for another instance of itself. If there's not another eventPusher active then it's highly unlikely that new comments will be getting submitted. It's okay if this only works =90% of the time, it doesn't need to be completely foolproof. * idea #4: eventPusher queries DMESG to see if that file's been written to recently. So to sum everything up, I need to have inter-php-script-communication in near-real-time that will work on a standard mod_php shared hosting setup without any elevated privileges, PHP addon modules, or other system adjustments that can't be done from the PHP script itself at runtime. With*out* spinning up the drive more than a few times. No SQL servers either. Apologies if my english isn't the best, I'm still trying to improve on it.

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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only The hell you are: [root@localhost ~]# mount -o remount,rw /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • Week in Geek: LastPass Rescues Xmarks Edition

    - by Asian Angel
    This week we learned how to breathe new life into an aging Windows Mobile 6.x device, use filters in Photoshop, backup and move VirtualBox machines, use the BitDefender Rescue CD to clean an infected PC, and had fun setting up a pirates theme on our computers. Photo by _nash. Weekly Feature Do you love using the Faenza icon set on your Ubuntu system but feel that there are a few much needed icons missing (or you desire a different version of a particular icon)? Then you may want to take a look at the Faenza Variants icon pack. The icons are available in the following sizes: 16px, 22px, 32px, 48px and scalable sizes. Photo by Asian Angel. Faenza Variants Random Geek Links Another week with extra link goodness to help keep you on top of the news. Photo by Asian Angel. LastPass acquires Xmarks, premium service announced Xmarks announced that it has been acquired by LastPass, a cross-platform password management service. This also means that Xmarks is now in transition from a “free” to a “freemium” business model. WikiLeaks reappears on European Net domains WikiLeaks has re-emerged on a Swiss Internet domain followed by domains in Germany, Finland, and the Netherlands, sidestepping a move that had in effect taken the controversial site off the Internet. Iran: Yes, Stuxnet hurt our nuclear program The Stuxnet worm got some big play from Iranian President Mahmoud Ahmadinejad, who acknowledged that the malware dinged his nuclear program. More Windows Rogues than Just AV – Fake Defragmenter Check Disk Don’t think for a second that rogues are limited to scareware, because as so-called products such as “System Defragmenter”, “Scan Disk” “Check Disk” prove, they’re not. Internet Explorer’s Protected Mode can be bypassed Researchers from Verizon Business have now described a way of bypassing Protected Mode in IE 7 and 8 in order to gain access to user accounts. Can you really see who viewed your Facebook profile? Rogue application spreads virally Once again, a rogue application is spreading virally between Facebook users pretending to offer you a way of seeing who has viewed your profile. More holes in Palm’s WebOS Researchers Orlando Barrera and Daniel Herrera, who both work for security firm SecTheory, have discovered a gaping security hole in Palm’s WebOS smartphone operating system. Next-gen banking Trojans hit APAC With the proliferation of banking Trojans, Web and smartphone users of online banking services have to be on constant alert to avoid falling prey to fraud schemes, warned Etay Maor, project manager for RSA Fraud Action. AVG update cripples 64-bit computers A signature update automatically deployed by the AVG virus scanner Thursday has crippled numerous computers. Article includes link to forums to fix computers affected after a restart. Congress moves to outlaw ‘mystery charges’ for Web shoppers Legislation that makes it illegal for Web merchants and so-called post-transaction marketers to charge credit cards without the card owners’ say-so came closer to becoming law this week. Ballmer Set to “Look Into” Windows Home Server Drive Extender Fiasco Tuesday’s announcement from Microsoft regarding the removal of Drive Extender from Windows Home Server has sent shock waves across the web. Google tweaks search recipe to ding scam artists Google has changed its search algorithm to penalize sites deemed to provide an “extremely poor user experience” following a New York Times story on a merchant who justified abusive behavior towards customers as a search-engine optimization tactic. Geek Video of the Week Watch as our two friends debate back and forth about the early adoption of new technology through multiple time periods (Stone Age to the far future). Will our reluctant friend finally succumb to the temptation? Photo by CollegeHumor. Early Adopters Through History Random TinyHacker Links Fix Issues in Windows 7 Using Reliability Monitor Learn how to analyze Windows 7 errors and then fix them using the built-in reliability monitor. Learn About IE Tab Groups Tab groups is a useful feature in IE 8. Here’s a detailed guide to what it is all about. Google’s Book Helps You Learn About Browsers and Web A cool new online book by the Google Chrome team on browsers and the web. TrustPort Internet Security 2011 – Good Security from a Less Known Provider TrustPort is not exactly a well-known provider of security solutions. At least not in the consumer space. This review tests in detail their latest offering. How the World is Using Cell phones An infographic showing the shocking demographics of cell phone use. Super User Questions See the great answers to these questions from Super User. I am unable to access my C drive. It says it is unable to display current owner. List of Windows special directories/shortcuts like ‘%TEMP%’ Is using multiple passes for wiping a disk really necessary? How can I view two files side by side in Notepad++ Is there any tool that automatically puts screenshots to my Dropbox? How-To Geek Weekly Article Recap Look through our hottest articles from this past week at How-To Geek. How to Create a Software RAID Array in Windows 7 9 Alternatives for Windows Home Server’s Drive Extender Why Doesn’t Disk Cleanup Delete Everything from the Temp Folder? Ask the Readers: How Much Do You Customize Your Operating System? How to Upload Really Large Files to SkyDrive, Dropbox, or Email One Year Ago on How-To Geek Enjoy reading through these awesome articles from one year ago. How To Upgrade from Vista to Windows 7 Home Premium Edition How To Fix No Aero Transparency in Windows 7 Troubleshoot Startup Problems with Startup Repair Tool in Windows 7 & Vista Rename the Guest Account in Windows 7 for Enhanced Security Disable Error Reporting in XP, Vista, and Windows 7 The Geek Note That wraps things up here for this week. Regardless of the weather wherever you may be, we hope that you have an opportunity to get outside and have some fun! Remember to keep sending those great tips in to us at [email protected]. Photo by Tony the Misfit. Latest Features How-To Geek ETC The How-To Geek Guide to Learning Photoshop, Part 8: Filters Get the Complete Android Guide eBook for Only 99 Cents [Update: Expired] Improve Digital Photography by Calibrating Your Monitor The How-To Geek Guide to Learning Photoshop, Part 7: Design and Typography How to Choose What to Back Up on Your Linux Home Server How To Harmonize Your Dual-Boot Setup for Windows and Ubuntu Hang in There Scrat! – Ice Age Wallpaper How Do You Know When You’ve Passed Geek and Headed to Nerd? On The Tip – A Lamborghini Theme for Chrome and Iron What if Wile E. Coyote and the Road Runner were Human? [Video] Peaceful Winter Cabin Wallpaper Store Tabs for Later Viewing in Opera with Tab Vault

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  • Thursday Community Keynote: "By the Community, For the Community"

    - by Janice J. Heiss
    Sharat Chander, JavaOne Community Chairperson, began Thursday's Community Keynote. As part of the morning’s theme of "By the Community, For the Community," Chander noted that 60% of the material at the 2012 JavaOne conference was presented by Java Community members. "So next year, when the call for papers starts, put-in your submissions," he urged.From there, Gary Frost, Principal Member of Technical Staff, AMD, expanded upon Sunday's Strategy Keynote exploration of Project Sumatra, an OpenJDK project targeted at bringing Java to heterogeneous computing platforms (which combine the CPU and the parallel processor of the GPU into a single piece of silicon). Sumatra entails enhancing the JVM to make maximum use of these advanced platforms. Within this development space, AMD created the Aparapi API, which converts Java bytecode into OpenCL for execution on such GPU devices. The Aparapi API was open sourced in September 2011.Whether it was zooming-in on a Mandelbrot set, "the game of life," or a swarm of 10,000 Dukes in a space-bound gravitational dance, Frost's demos, using an Aparapi/OpenCL implementation, produced stunningly faster display results. He indicated that the Java 9 timeframe is where they see Project Sumatra coming to ultimate fruition, employing the Lamdas of Java 8.Returning to the theme of the keynote, Donald Smith, Director, Java Product Management, Oracle, explored a mind map graphic demonstrating the importance of Community in terms of fostering innovation. "It's the sharing and mixing of culture, the diversity, and the rapid prototyping," he said. Within this topic, Smith, brought up a panel of representatives from Cloudera, Eclipse, Eucalyptus, Perrone Robotics, and Twitter--ideal manifestations of community and innovation in the world of Java.Marten Mickos, CEO, Eucalyptus Systems, explored his company's open source cloud software platform, written in Java, and used by gaming companies, technology companies, media companies, and more. Chris Aniszczyk, Operations Engineering,Twitter, noted the importance of the JVM in terms of their multiple-language development environment. Mike Olson, CEO, Cloudera, described his company's Apache Hadoop-based software, support, and training. Mike Milinkovich, Executive Director, Eclipse Foundation, noted that they have about 270 tools projects at Eclipse, with 267 of them written in Java. Milinkovich added that Eclipse will even be going into space in 2013, as part of the control software on various experiments aboard the International Space Station. Lastly, Paul Perrone, CEO, Perrone Robotics, detailed his company's robotics and automation software platform built 100% on Java, including Java SE and Java ME--"on rat, to cat, to elephant-sized systems." Milinkovic noted that communities are by nature so good at innovation because of their very openness--"The more open you make your innovation process, the more ideas are challenged, and the more developers are focused on justifying their choices all the way through the process."From there, Georges Saab, VP Development Java SE OpenJDK, continued the topic of innovation and helping the Java Community to "Make the Future Java." Martijn Verburg, representing the London Java Community (winner of a Duke's Choice Award 2012 for their activity in OpenJDK and JCP), soon joined Saab onstage. Verburg detailed the LJC's "Adopt a JSR" program--"to get day-to-day developers more involved in the innovation that's happening around them."  From its London launching pad, the innovative program has spread to Brazil, Morocco, Latvia, India, and more.Other active participants in the program joined Verburg onstage--Ben Evans, London Java Community; James Gough, Stackthread; Bruno Souza, SOUJava; Richard Warburton, jClarity; and Cecelia Borg, Oracle--OpenJDK Onboarding. Together, the group explored the goals and tasks inherent in the Adopt a JSR program--from organizing hack days (testing prototype implementations), to managing mailing lists and forums, to triaging issues, to evangelism—all with the goal of fostering greater community/developer involvement, but equally importantly, building better open standards. “Come join us, and make your ecosystem better!" urged Verburg.Paul Perrone returned to profile the latest in his company's robotics work around Java--including the AARDBOTS family of smaller robotic vehicles, running the Perrone MAX platform on top of the Java JVM. Perrone took his "Rumbles" four-wheeled robot out for a spin onstage--a roaming, ARM-based security-bot vehicle, complete with IR, ultrasonic, and "cliff" sensors (the latter, for the raised stage at JavaOne). As an ultimate window into the future of robotics, Perrone displayed a "head-set" controller--a sensor directed at the forehead to monitor brainwaves, for the someday-implementation of brain-to-robot control.Then, just when it seemed this might be the end of the day's futuristic offerings, a mystery voice from offstage pronounced "I've got some toys"--proving to be guest-visitor James Gosling, there to explore his cutting-edge work with Liquid Robotics. While most think of robots as something with wheels or arms or lasers, Gosling explained, the Liquid Robotics vehicle is an entirely new and innovative ocean-going 'bot. Looking like a floating surfboard, with an attached set of underwater wings, the autonomous devices roam the oceans using only the energy of ocean waves to propel them, and a single actuated rudder to steer. "We have to accomplish all guidance just by wiggling the rudder," Gosling said. The devices offer applications from self-installing weather buoy, to pollution monitoring station, to marine mammal monitoring device, to climate change data gathering, to even ocean life genomic sampling. The early versions of the vehicle used C code on very tiny industrial micro controllers, where they had to "count the bytes one at a time."  But the latest generation vehicles, which just hit the water a week or so ago, employ an ARM processor running Linux and the ARM version of JDK 7. Gosling explained that vehicle communication from remote locations is achieved via the Iridium satellite network. But because of the costs of this communication path, the data must be sent in very small bursts--using SBD short burst data. "It costs $1/kb, so that rules everything in the software design,” said Gosling. “If you were trying to stream a Netflix video over this, it would cost a million dollars a movie. …We don't have a 'big data' problem," he quipped. There are currently about 150 Liquid Robotics vehicles out traversing the oceans. Gosling demonstrated real time satellite tracking of several vehicles currently at sea, noting that Java is actually particularly good at AI applications--due to the language having garbage collection, which facilitates complex data structures. To close-out his time onstage, Gosling of course participated in the ceremonial Java tee-shirt toss out to the audience…In parting, Chander passed the JavaOne Community Chairperson baton to Stephen Chin, Java Technology Evangelist, Oracle. Onstage in full motorcycle gear, Chin noted that he'll soon be touring Europe by motorcycle, meeting Java Community Members and streaming live via UStream--the ultimate manifestation of community and technology!  He also reminded attendees of the upcoming JavaOne Latin America 2012, São Paulo, Brazil (December 4-6, 2012), and stated that the CFP (call for papers) at the conference has been extended for one more week. "Remember, December is summer in Brazil!" Chin said.

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  • I see no LOBs!

    - by Paul White
    Is it possible to see LOB (large object) logical reads from STATISTICS IO output on a table with no LOB columns? I was asked this question today by someone who had spent a good fraction of their afternoon trying to work out why this was occurring – even going so far as to re-run DBCC CHECKDB to see if any corruption had taken place.  The table in question wasn’t particularly pretty – it had grown somewhat organically over time, with new columns being added every so often as the need arose.  Nevertheless, it remained a simple structure with no LOB columns – no TEXT or IMAGE, no XML, no MAX types – nothing aside from ordinary INT, MONEY, VARCHAR, and DATETIME types.  To add to the air of mystery, not every query that ran against the table would report LOB logical reads – just sometimes – but when it did, the query often took much longer to execute. Ok, enough of the pre-amble.  I can’t reproduce the exact structure here, but the following script creates a table that will serve to demonstrate the effect: IF OBJECT_ID(N'dbo.Test', N'U') IS NOT NULL DROP TABLE dbo.Test GO CREATE TABLE dbo.Test ( row_id NUMERIC IDENTITY NOT NULL,   col01 NVARCHAR(450) NOT NULL, col02 NVARCHAR(450) NOT NULL, col03 NVARCHAR(450) NOT NULL, col04 NVARCHAR(450) NOT NULL, col05 NVARCHAR(450) NOT NULL, col06 NVARCHAR(450) NOT NULL, col07 NVARCHAR(450) NOT NULL, col08 NVARCHAR(450) NOT NULL, col09 NVARCHAR(450) NOT NULL, col10 NVARCHAR(450) NOT NULL, CONSTRAINT [PK dbo.Test row_id] PRIMARY KEY CLUSTERED (row_id) ) ; The next script loads the ten variable-length character columns with one-character strings in the first row, two-character strings in the second row, and so on down to the 450th row: WITH Numbers AS ( -- Generates numbers 1 - 450 inclusive SELECT TOP (450) n = ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2, master.sys.columns C3 ORDER BY n ASC ) INSERT dbo.Test WITH (TABLOCKX) SELECT REPLICATE(N'A', N.n), REPLICATE(N'B', N.n), REPLICATE(N'C', N.n), REPLICATE(N'D', N.n), REPLICATE(N'E', N.n), REPLICATE(N'F', N.n), REPLICATE(N'G', N.n), REPLICATE(N'H', N.n), REPLICATE(N'I', N.n), REPLICATE(N'J', N.n) FROM Numbers AS N ORDER BY N.n ASC ; Once those two scripts have run, the table contains 450 rows and 10 columns of data like this: Most of the time, when we query data from this table, we don’t see any LOB logical reads, for example: -- Find the maximum length of the data in -- column 5 for a range of rows SELECT result = MAX(DATALENGTH(T.col05)) FROM dbo.Test AS T WHERE row_id BETWEEN 50 AND 100 ; But with a different query… -- Read all the data in column 1 SELECT result = MAX(DATALENGTH(T.col01)) FROM dbo.Test AS T ; …suddenly we have 49 LOB logical reads, as well as the ‘normal’ logical reads we would expect. The Explanation If we had tried to create this table in SQL Server 2000, we would have received a warning message to say that future INSERT or UPDATE operations on the table might fail if the resulting row exceeded the in-row storage limit of 8060 bytes.  If we needed to store more data than would fit in an 8060 byte row (including internal overhead) we had to use a LOB column – TEXT, NTEXT, or IMAGE.  These special data types store the large data values in a separate structure, with just a small pointer left in the original row. Row Overflow SQL Server 2005 introduced a feature called row overflow, which allows one or more variable-length columns in a row to move to off-row storage if the data in a particular row would otherwise exceed 8060 bytes.  You no longer receive a warning when creating (or altering) a table that might need more than 8060 bytes of in-row storage; if SQL Server finds that it can no longer fit a variable-length column in a particular row, it will silently move one or more of these columns off the row into a separate allocation unit. Only variable-length columns can be moved in this way (for example the (N)VARCHAR, VARBINARY, and SQL_VARIANT types).  Fixed-length columns (like INTEGER and DATETIME for example) never move into ‘row overflow’ storage.  The decision to move a column off-row is done on a row-by-row basis – so data in a particular column might be stored in-row for some table records, and off-row for others. In general, if SQL Server finds that it needs to move a column into row-overflow storage, it moves the largest variable-length column record for that row.  Note that in the case of an UPDATE statement that results in the 8060 byte limit being exceeded, it might not be the column that grew that is moved! Sneaky LOBs Anyway, that’s all very interesting but I don’t want to get too carried away with the intricacies of row-overflow storage internals.  The point is that it is now possible to define a table with non-LOB columns that will silently exceed the old row-size limit and result in ordinary variable-length columns being moved to off-row storage.  Adding new columns to a table, expanding an existing column definition, or simply storing more data in a column than you used to – all these things can result in one or more variable-length columns being moved off the row. Note that row-overflow storage is logically quite different from old-style LOB and new-style MAX data type storage – individual variable-length columns are still limited to 8000 bytes each – you can just have more of them now.  Having said that, the physical mechanisms involved are very similar to full LOB storage – a column moved to row-overflow leaves a 24-byte pointer record in the row, and the ‘separate storage’ I have been talking about is structured very similarly to both old-style LOBs and new-style MAX types.  The disadvantages are also the same: when SQL Server needs a row-overflow column value it needs to follow the in-row pointer a navigate another chain of pages, just like retrieving a traditional LOB. And Finally… In the example script presented above, the rows with row_id values from 402 to 450 inclusive all exceed the total in-row storage limit of 8060 bytes.  A SELECT that references a column in one of those rows that has moved to off-row storage will incur one or more lob logical reads as the storage engine locates the data.  The results on your system might vary slightly depending on your settings, of course; but in my tests only column 1 in rows 402-450 moved off-row.  You might like to play around with the script – updating columns, changing data type lengths, and so on – to see the effect on lob logical reads and which columns get moved when.  You might even see row-overflow columns moving back in-row if they are updated to be smaller (hint: reduce the size of a column entry by at least 1000 bytes if you hope to see this). Be aware that SQL Server will not warn you when it moves ‘ordinary’ variable-length columns into overflow storage, and it can have dramatic effects on performance.  It makes more sense than ever to choose column data types sensibly.  If you make every column a VARCHAR(8000) or NVARCHAR(4000), and someone stores data that results in a row needing more than 8060 bytes, SQL Server might turn some of your column data into pseudo-LOBs – all without saying a word. Finally, some people make a distinction between ordinary LOBs (those that can hold up to 2GB of data) and the LOB-like structures created by row-overflow (where columns are still limited to 8000 bytes) by referring to row-overflow LOBs as SLOBs.  I find that quite appealing, but the ‘S’ stands for ‘small’, which makes expanding the whole acronym a little daft-sounding…small large objects anyone? © Paul White 2011 email: [email protected] twitter: @SQL_Kiwi

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  • Sporadic disk clicking sound

    - by Abdó
    Hi, I'm having some unusual and sporadic hard disk clicking issues. Here is a cronological description of the facts. I'm using an ASUS P6T-SE with Intel Core i7, 6Gb RAM 600W Power supply and ATI4670 graphics, running Ubuntu 10.10. About one month ago my hard disk (SATA II Seagate Barracuda 1Tb 7200 rpm) started making a clicking sound: a sort of loud tic-tac, every second or so, when involved in disk activity. The system was clearly slower than before at disk access, but it was functional and I could not find any signal of trouble on the linux logs. I disconnected the disk and tried an older SATA drive I had around: no problem with it. Then I reconnected the Seagate disk, and the problem was mysteriously gone. Ubuntu booted normally, usual speed, no clicking. A couple of weeks later, the problem reappeared. I tried disconnecting reconnecting (as it somehow solved the problem before) without luck. So, despite it was a rather new drive, I assumed it was a hardware issue, made backups and bought a new drive. The new drive is a SATA II Seagate Barracuda 1.5 Tb 7200 rpm. I installed both drives at the same time, with the intention of transferring my files from on to the other. To my surprise, when I booted the computer with both drives, both started making the clicking sound !! Even worse, I removed the old drive, leaving the unformated new drive connected, and booted from a LiveCD. It kept clicking ! Puzzled by this, I tried both drives on my laptop with a SATA to USB cable. At the moment I connected any of them, they made one or two unusual clicks and immediately stopped doing that and worked normally. The old drive I thought almost dead, was working like a charm as if nothing happened. Then I thought: "ok, it must be the motherboard. Let's try again". So, I reconnected the old drive to the ASUS P6T motherboard (the same cables and SATA port as before), and it worked as if nothing happened ! The problem was gone again. The new 1.5 Tb drive was also working ok: No clicking nor slowdown. So I left the old 1Tb disk connected and kept using the computer daily during 3 weeks, until today it happened again. Now I don't really know what to do or check. I'm not even sure if it is a hardware issue any more ! This is rather annoying as it seems it happens with a period of 2 or 3 weeks and I have no means of forcing it to happen. Does anyone have a clue of what can causes this behaviour or have any suggestions of things I should check when it happens again ? What I did today is checking some SMART parameters Error log: smartctl -l error /dev/sda. No errors Short selftest: smartctl -t short /dev/sda. No errors Disk Health check: smartctl -H /dev/sda. passed And here are the vendor specific parameters (smartctl -A /dev/sda) Which I'm not quite sure how to interpret. === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 10 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000f 120 099 006 Pre-fail Always - 235962588 3 Spin_Up_Time 0x0003 095 095 000 Pre-fail Always - 0 4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 187 5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 0 7 Seek_Error_Rate 0x000f 072 060 030 Pre-fail Always - 16348045 9 Power_On_Hours 0x0032 096 096 000 Old_age Always - 3590 10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0 12 Power_Cycle_Count 0x0032 100 100 020 Old_age Always - 94 183 Runtime_Bad_Block 0x0032 100 100 000 Old_age Always - 0 184 End-to-End_Error 0x0032 100 100 099 Old_age Always - 0 187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0 188 Command_Timeout 0x0032 100 097 000 Old_age Always - 4295164029 189 High_Fly_Writes 0x003a 100 100 000 Old_age Always - 0 190 Airflow_Temperature_Cel 0x0022 070 057 045 Old_age Always - 30 (Lifetime Min/Max 19/31) 194 Temperature_Celsius 0x0022 030 043 000 Old_age Always - 30 (0 18 0 0) 195 Hardware_ECC_Recovered 0x001a 037 026 000 Old_age Always - 235962588 197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0 240 Head_Flying_Hours 0x0000 100 253 000 Old_age Offline - 73950746906346 241 Total_LBAs_Written 0x0000 100 253 000 Old_age Offline - 1832967731 242 Total_LBAs_Read 0x0000 100 253 000 Old_age Offline - 3294986902 Any clue to this mystery will be really welcome. Thank you very much !!

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  • slow DNS resolution

    - by Ehsan
    I have a DNS server that resolves all queries for an internal group of servers. It is a bind on CentOS 5.5 (same as RHEL5) and I have set it up to allow recursion and resolve direction without any forwarders. The problem I am facing is that it takes a freakishly long amount of time to resolve a name for the first time. (in the magnitudes of 20 sec) This causes clients to give timeout. When I set it to forward all to Google's public DNS, i.e. 8.8.8.8+8.8.4.4, it works very nicely (within a second). I tried monitoring the traffic on the net to see why it is doing this: [root@ns1 ~]# tcpdump -nnvvvA -s0 udp tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 23:06:36.137797 IP (tos 0x0, ttl 64, id 35903, offset 0, flags [none], proto: UDP (17), length: 60) 172.17.1.10.36942 > 172.17.1.4.53: [udp sum ok] 19773+ A? www.paypal.com. (32) E..<[email protected]... .....N.5.(6.M=...........www.paypal.com..... 23:06:36.140594 IP (tos 0x0, ttl 64, id 56477, offset 0, flags [none], proto: UDP (17), length: 71) 172.17.1.4.6128 > 192.35.51.30.53: [udp sum ok] 10105 [1au] A? www.paypal.com. ar: . OPT UDPsize=4096 (43) E..G....@........#3....5.3fR'y...........www.paypal.com.......)........ 23:06:38.149756 IP (tos 0x0, ttl 64, id 13078, offset 0, flags [none], proto: UDP (17), length: 71) 172.17.1.4.52425 > 192.54.112.30.53: [udp sum ok] 54892 [1au] A? www.paypal.com. ar: . OPT UDPsize=4096 (43) [email protected]&.....6p....5.3.q.l...........www.paypal.com.......)........ 23:06:40.159725 IP (tos 0x0, ttl 64, id 43016, offset 0, flags [none], proto: UDP (17), length: 71) 172.17.1.4.24059 > 192.42.93.30.53: [udp sum ok] 11205 [1au] A? www.paypal.com. ar: . OPT UDPsize=4096 (43) E..G....@..@.....*].]..5.3..+............www.paypal.com.......)........ 23:06:41.141403 IP (tos 0x0, ttl 64, id 35904, offset 0, flags [none], proto: UDP (17), length: 60) 172.17.1.10.36942 > 172.17.1.4.53: [udp sum ok] 19773+ A? www.paypal.com. (32) E..<.@..@..@... .....N.5.(6.M=...........www.paypal.com..... 23:06:42.169652 IP (tos 0x0, ttl 64, id 44001, offset 0, flags [none], proto: UDP (17), length: 60) 172.17.1.4.9141 > 192.55.83.30.53: [udp sum ok] 1184 A? www.paypal.com. (32) E..<[email protected].#..5.(...............www.paypal.com..... 23:06:42.207295 IP (tos 0x0, ttl 54, id 38004, offset 0, flags [none], proto: UDP (17), length: 205) 192.55.83.30.53 > 172.17.1.4.9141: [udp sum ok] 1184- q: A? www.paypal.com. 0/3/3 ns: paypal.com. NS ns1.isc-sns.net., paypal.com. NS ns2.isc-sns.com., paypal.com. NS ns3.isc-sns.info. ar: ns1.isc-sns.net. AAAA 2001:470:1a::1, ns1.isc-sns.net. A 72.52.71.1, ns2.isc-sns.com. A 38.103.2.1 (177) E....t..6./A.7S......5#..................www.paypal.com..................ns1.isc-sns.net..............ns2.isc-sns...............ns3.isc-sns.info..,.......... ..p.............,..........H4G..I..........&g.. (this goes on for a few more seconds) If you look carefully, you will see that the first 3-4 root servers did not respond at all. This wastes 7-8 seconds, until one of them responded. Do you think I have setup something wrong here? Interestingly, when I dig directly from the root servers that did not respond, the always respond very fast (showing the firewall/nat is not the issue here). E.g. dig www.paypal.com @192.35.51.30 works perfectly, consistently, and very fast. What do you think about this mystery?

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  • Code Golf: Word Search Solver

    - by Maxim Z.
    Note: This is my first Code Golf challenge/question, so I might not be using the correct format below. I'm not really sure how to tag this particular question, and should this be community wiki? Thanks! This Code Golf challenge is about solving word searches! A word search, as defined by Wikipedia, is: A word search, word find, word seek, word sleuth or mystery word puzzle is a word game that is letters of a word in a grid, that usually has a rectangular or square shape. The objective of this puzzle is to find and mark all the words hidden inside the box. The words may be horizontally, vertically or diagonally. Often a list of the hidden words is provided, but more challenging puzzles may let the player figure them out. Many word search puzzles have a theme to which all the hidden words are related. The word searches for this challenge will all be rectangular grids with a list of words to find provided. The words can be written vertically, horizontally, or diagonally. Input/Output The user inputs their word search and then inputs a word to be found in their grid. These two inputs are passed to the function that you will be writing. It is up to you how you want to declare and handle these objects. Using a strategy described below or one of your own, the function finds the specific word in the search and outputs its starting coordinates (simply row number and column number) and ending coordinates. If you find two occurrences of the word, you must output both's set of coordinates. Example Input: A I Y R J J Y T A S V Q T Z E X B X G R Z P W V T B K U F O E A F L V F J J I A G B A J K R E S U R E P U S C Y R S Y K F B B Q Y T K O I K H E W G N G L W Z F R F H L O R W A R E J A O S F U E H Q V L O A Z B J F B G I F Q X E E A L W A C F W K Z E U U R Z R T N P L D F L M P H D F W H F E C G W Z B J S V O A O Y D L M S T C R B E S J U V T C S O O X P F F R J T L C V W R N W L Q U F I B L T O O S Q V K R O W G N D B C D E J Y E L W X J D F X M Word to find: codegolf Output: row 12, column 8 --> row 5, column 1 Strategies Here are a few strategies you might consider using. It is completely up to you to decide what strategy you want to use; it doesn't have to be in this list. Looking for the first letter of the word; on each occurrence, looking at the eight surrounding letters to see whether the next letter of the word is there. Same as above, except looking for a part of a word that has two of the same letter side-by-side. Counting how often each letter of the alphabet is present in the whole grid, then selecting one of the least-occurring letters from the word you have to find and searching for the letter. On each occurrence of the letter, you look at its eight surrounding letters to see whether the next and previous letters of the word is there.

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  • Generate JFreeChart in servlet

    - by San4o
    I'm trying to generate graphs using JFreeChart. I added record in web.xml, installed jfreechart library. Compiled servlet. Below code of servlet has shown: import java.io.IOException; import java.io.OutputStream; import java.io.File; import javax.servlet.*; import javax.servlet.http.*; import java.awt.Color; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartUtilities; import org.jfree.chart.JFreeChart; import org.jfree.data.general.DefaultPieDataset; public class diagram extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doTestPieChart(request,response); } protected void doTestPieChart(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { OutputStream out = response.getOutputStream(); try { DefaultPieDataset dataset = new DefaultPieDataset(); dataset.setValue("Graphic Novels", 192); dataset.setValue("History", 125); dataset.setValue("Military Fiction", 236); dataset.setValue("Mystery", 547); dataset.setValue("Performing Arts", 210); dataset.setValue("Science, Non-Fiction", 70); dataset.setValue("Science Fiction", 989); JFreeChart chart = ChartFactory.createPieChart( "Books by Type", dataset, true, false, false ); chart.setBackgroundPaint(Color.white); response.setContentType("image/png"); ChartUtilities.writeChartAsPNG(out, chart, 400, 300); /* ServletContext sc = getServletContext(); String filename = sc.getRealPath("pie.png"); File file = new File(filename); ChartUtilities.saveChartAsPNG(file,chart,400,300); */ } catch (Exception e) { System.out.println(e.toString()); } finally { out.close(); } } } When i launch the servlet, mistake has shown : HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Error instantiating servlet class diagram org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) root cause java.lang.ClassNotFoundException: org.jfree.data.general.PieDataset org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1484) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1329) java.lang.ClassLoader.loadClassInternal(ClassLoader.java:316) java.lang.Class.getDeclaredConstructors0(Native Method) java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) java.lang.Class.getConstructor0(Class.java:2699) java.lang.Class.newInstance0(Class.java:326) java.lang.Class.newInstance(Class.java:308) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) java.lang.Thread.run(Thread.java:619) note The full stack trace of the root cause is available in the Apache Tomcat/6.0.24 logs. Help me to solve a problem. and where is problem?

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  • XMLNodes being appended to an XMLNode are "undefined"? Actionscript 2.0 is being unkind

    - by DigitalMercenary
    If anyone can offer an explanation for this one, I'd LOVE to see it! I was required to append a legacy application to display 20 random questions from an XML data source, as opposed to the total of 70 questions that are part of the original XML. No big deal, right? WRONG! I got it to work just fine in the end, but it's a total HACK! For some reason, some of the nodes that I am appending to a dynamically generated XML document are being returned as "undefined". I kept getting between 16 and 20 questions to render until I modified my iteration from a 'for' loop to a 'do while' loop with the appropriate number of XMLNodes as the condition of the 'do while' loop. Can anyone offer an explanation? Below is the code, with some notes for the reader : function editXML(xml:XML):XML { var node:XMLNode = xml.firstChild; var newNode:XMLNode = new XMLNode(); var nodeArray:Array = new Array(); var usedNodes:Array = new Array(); var totalNodes:Number = node.lastChild.childNodes.length - 1; var nextNode:Number; var returnNode:XMLNode = new XMLNode(); var tempNode:XMLNode; var buildNode:XMLNode; var addNode:Boolean = true; var tempXML:XML = new XML(); var pagesNode:XMLNode = tempXML.createElement("pages"); tempXML.appendChild(pagesNode); tempXML.appendChild(node.childNodes[0]); tempXML.appendChild(node.childNodes[1]); tempXML.appendChild(node.childNodes[2]); var questionsNode:XMLNode = tempXML.createElement("pages"); tempXML.firstChild.appendChild(questionsNode); do { nextNode = Math.floor(Math.random()*totalNodes); **//random number to represent random node** //trace(nextNode + " nextNode"); **//check usedNodes Array to look for node.childNodes[nextNode]. If it already exists, skip and reloop.** trace(node.childNodes[1].childNodes[nextNode] + " : pre building Node " + totalNodes); if(usedNodes.length == 0) { buildNode = new XMLNode(); buildNode.nodeName = node.childNodes[1].childNodes[nextNode].nodeName; buildNode.nodeValue = node.childNodes[1].childNodes[nextNode].nodeValue; tempXML.firstChild.lastChild.appendChild(node.childNodes[1].childNodes[nextNode]) usedNodes.push(node.childNodes[1].childNodes[nextNode]); nodeArray.push(node.childNodes[1].childNodes[nextNode]); trace("adding first node : " + nodeArray.length); addNode = false; } else { for(var j:Number = 0; j < usedNodes.length; j++) { if(usedNodes[j] == node.childNodes[1].childNodes[nextNode]) { addNode = false; trace("skipping node : " + nodeArray.length); } } } **//if node not in usedNodes, add node to XML** if(addNode) { trace(node.childNodes[1].childNodes[nextNode] + " : building Node"); **//This trace statement produced a valid node** tempXML.firstChild.lastChild.appendChild(node.childNodes[1].childNodes[nextNode]); **//Before modifying the code from adding nodes to the xml from an Array called 'nodeArray' in a for loop to adding nodes directly to the xml in a do while loop with the length of the xml node used to retrieve data for the questions as the condition, I was not always getting 20 questions. Some of the nodes were being rendered as 'undefined' and not appended to the xml, even though they were traced and proven valid before the attemp to append them to the xml was made** usedNodes.push(node.childNodes[1].childNodes[nextNode]); } addNode = true; } while(tempXML.firstChild.lastChild.childNodes.length <= 19); trace(tempXML.firstChild.lastChild.childNodes.length + " final nodes Length"); courseXML = tempXML; //removes the old question list of 70 and replaces it with the new question list of 20. Question list is the last node. return tempXML; } If I had my choice, I would have rebuilt the whole application in Flex with AS3. I didn't have that choice. If anyone can explain this mystery, PLEASE DO! Thank you in advance!

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  • Ada and 'The Book'

    - by Phil Factor
    The long friendship between Charles Babbage and Ada Lovelace created one of the most exciting and mysterious of collaborations ever to have resulted in a technological breakthrough. The fireworks that created by the collision of two prodigious mathematical and creative talents resulted in an invention, the Analytical Engine, which went on to change society fundamentally. However, beyond that, we just don't know what the bulk of their collaborative work was about:;  it was done in strictest secrecy. Even the known outcome of their friendship, the first programmable computer, was shrouded in mystery. At the time, nobody, except close friends and family, had any idea of Ada Byron's contribution to the invention of the ‘Engine’, and how to program it. Her great insight was published in August 1843, under the initials AAL, standing for Ada Augusta Lovelace, her title then being the Countess of Lovelace. It was contained in a lengthy ‘note’ to her translation of a publication that remains the best description of Babbage's amazing Analytical Engine. The secret identity of the person behind those enigmatic initials was finally revealed by Prince de Polignac who, seventy years later, wrote to Ada's daughter to seek confirmation that her mother had, indeed, been the author of the brilliant sentences that described so accurately how Babbage's mechanical computer could be programmed with punch-cards. L.F. Menabrea's paper on the Analytical Engine first appeared in the 'Bibliotheque Universelle de Geneve' in October 1842, and Ada translated it anonymously for Taylor's 'Scientific Memoirs'. Charles Babbage was surprised that she had not written an original paper as she already knew a surprising amount about the way the machine worked. He persuaded her to at least write some explanatory notes. These notes ended up extending to four times the length of the original article and represented the first published account of how a machine could be programmed to perform any calculation. Her example of programming the Bernoulli sequence would have worked on the Analytical engine had the device’s construction been completed, and gave Ada an unassailable claim to have invented the art of programming. What was the reason for Ada's secrecy? She was the only legitimate child of Lord Byron, who was probably the best known celebrity of the age, so she was already famous. She was a senior aristocrat, with titles, a fortune in money and vast estates in the Midlands. She had political influence, and was the cousin of Lord Melbourne, who was the Prime Minister at that time. She was friendly with the young Queen Victoria. Her mathematical activities were a pastime, and not one that would be considered by others to be in keeping with her roles and responsibilities. You wouldn't dare to dream up a fictional heroine like Ada. She was dazzlingly beautiful and talented. She could speak several languages fluently, and play some musical instruments with professional skill. Contemporary accounts refer to her being 'accomplished in science, art and literature'. On top of that, she was a brilliant mathematician, a talent inherited from her mother, Annabella Milbanke. In her mother's circle of literary and scientific friends was Charles Babbage, and Ada's friendship with him dates from her teenage zest for Mathematics. She was one of the first people he'd ever met who understood what he had attempted to achieve with the 'Difference Engine', and with whom he could converse as intellectual equals. He arranged for her to have an education from the most talented academics in the country. Ada melted the heart of the cantankerous genius to the point that he became a faithful and loyal father-figure to her. She was one of the very few who could grasp the principles of the later, and very different, ‘Analytical Engine’ which was designed from the start to tackle a variety of tasks. Sadly, Ada Byron's life ended less than a decade after completing the work that assured her long-term fame, in November 1852. She was dying of cancer, her gambling habits had caused her to run up huge debts, she'd had more than one affairs, and she was being blackmailed. Her brilliant but unempathic mother was nursing her in her final illness, destroying her personal letters and records, and repaying her debts. Her husband was distraught but helpless. Charles Babbage, however, maintained his steadfast paternalistic friendship to the end. She appointed her loyal friend to be her executor. For years, she and Babbage had been working together on a secret project, known only as 'The Book'. We have a clue to what it was in a letter written by her nine years earlier, on 11th August 1843. It was a joint project by herself and Lord Lovelace, her husband, and was intended to involve Babbage's 'undivided energies'. It involved 'consulting your Engine' (it required Babbage’s computer). The letter gives no hint about the project except for the high-minded nature of its purpose, and its highly mathematical nature.  From then on, the surviving correspondence between the two gives only veiled references to 'The Book'. There isn't much, since Babbage later destroyed any letters that could have damaged her reputation within the Establishment. 'I cannot spare the book today, which I am very sorry for. At the moment I want it for constant reference, but I think you can have it tomorrow' (Oct 1844)  And 'I will send you the book directly, and you can say, when you receive it, how long you will want to keep it'. (Nov 1844)  The two of them were obviously intent on the work: She writes, four years later, 'I have an engagement for Wednesday which will prevent me from attending to your wishes about the book' (Dec 1848). This was something that they both needed to work on, but could not do in parallel: 'I will send the book on Tuesday, and it can be left with you till Friday' (11 Feb 1849). After six years work, it had been so well-handled that it was beginning to fall apart: 'Don't forget the new cover you promised for the book. The poor book is very shabby and wants one' (20 Sept 1849). So what was going on? The word 'book' was not a code-word: it was a real book, probably a 'printer's blank', plain paper, but properly bound so printers and publishers could show off how the published work might look. The hints from the correspondence are of advanced mathematics. It is obvious that the book was travelling between them, back and forth, each one working on it for less than a week before passing it back. Ada and her husband were certainly involved in gambling large sums of money on the horses, and so most biographers have concluded that the three of them were trying to calculate the mathematical odds on the horses. This theory has three large problems. Firstly, Ada's original letter proposing the project refers to its high-minded nature. Babbage was temperamentally opposed to gambling and would scarcely have given so much time to the project, even though he was devoted to Ada. Secondly, Babbage would have very soon have realized the hopelessness of trying to beat the bookies. This sort of betting never attracts his type of intellectual background. The third problem is that any work on calculating the odds on horses would not need a well-thumbed book to pass back and forth between them; they would have not had to work in series. The original project was instigated by Ada, along with her husband, William King-Noel, 1st Earl of Lovelace. Charles Babbage was invited to join the project after the couple had come up with the idea. What could William have contributed? One might assume that William was a Bertie Wooster character, addicted only to the joys of the turf, but this was far from the truth. He was a scientist, a Cambridge graduate who was later elected to be a Fellow of the Royal Society. After Eton, he went to Trinity College, Cambridge. On graduation, he entered the diplomatic service and acted as secretary under Lord Nugent, who was Lord Commissioner of the Ionian Islands. William was very friendly with Babbage too, able to discuss scientific matters on equal terms. He was a capable engineer who invented a process for bending large timbers by the application of steam heat. He delivered a paper to the Institution of Civil Engineers in 1849, and received praise from the great engineer, Isambard Kingdom Brunel. As well as being Lord Lieutenant of the County of Surrey for most of Victoria's reign, he had time for a string of scientific and engineering achievements. Whatever the project was, it is unlikely that William was a junior partner. After Ada's death, the project disappeared. Then, two years later, Babbage, through one of his occasional outbursts of temper, demonstrated that he was able to decrypt one of the most powerful of secret codes, Vigenère's autokey cipher.  All contemporary diplomatic and military messages used a variant of this cipher. Babbage had made three important discoveries, namely, the mathematical law of this cipher, the principle of the key periodicity, and the technique of the symmetry of position. The technique is now known as the Kasiski examination, also called the Kasiski test, but Babbage got there first. At one time, he listed amongst his future projects, the writing of a book 'The Philosophy of Decyphering', but it never came to anything. This discovery was going to change the course of history, since it was used to decipher the Russians’ military dispatches in the Crimean war. Babbage himself played a role during the Crimean War as a cryptographical adviser to his friend, Rear-Admiral Sir Francis Beaufort of the Admiralty. This is as much as we can be certain about in trying to make sense of the bulk of the time that Charles Babbage and Ada Lovelace worked together. Nine years of intensive work, involving the 'Engine' and a great deal of mathematics and research seems to have been lost: or has it? I've argued in the past http://www.simple-talk.com/community/blogs/philfactor/archive/2008/06/13/59614.aspx that the cracking of the Vigenère autokey cipher, was a fundamental motive behind the British Government's support and funding of the 'Difference Engine'. The Duke of Wellington, whose understanding of the military significance of being able to read enemy dispatches, was the most steadfast advocate of the project. If the three friends were actually doing the work of cracking codes by mathematical techniques that used the techniques of key periodicity, and symmetry of position (the use of a book being passed quickly to and fro is very suggestive), intending to then use the 'Engine' to do the routine cracking of each dispatch, then this is a rather different story. The project was Ada and William's idea. (William had served in the diplomatic service and would be familiar with the use of codes). This makes Ada Lovelace the initiator of a project which, by giving both Britain, and probably the USA, a diplomatic and military advantage in the second part of the Nineteenth century, changed world history. Ada would never have wanted any credit for cracking the cipher, and developing the method that rendered all contemporary military and diplomatic ciphering techniques nugatory; quite the reverse. And it is clear from the gaps in the record of the letters between the collaborators that the evidence was destroyed, probably on her request by her irascible but intensely honorable executor, Charles Babbage. Charles Babbage toyed with the idea of going public, but the Crimean war put an end to that. The British Government had a valuable secret, and intended to keep it that way. Ada and Charles had quite often discussed possible moneymaking projects that would fund the development of the Analytic Engine, the first programmable computer, but their secret work was never in the running as a potential cash cow. I suspect that the British Government was, even then, working on the concealment of a discovery whose value to the nation depended on it remaining so. The success of code-breaking in the Crimean war, and the American Civil war, led to the British and Americans  subsequently giving much more weight and funding to the science of decryption. Paradoxically, this makes Ada's contribution even closer to the creation of Colossus, the first digital computer, at Bletchley Park, specifically to crack the Nazi’s secret codes.

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  • Metro: Understanding the default.js File

    - by Stephen.Walther
    The goal of this blog entry is to describe — in painful detail — the contents of the default.js file in a Metro style application written with JavaScript. When you use Visual Studio to create a new Metro application then you get a default.js file automatically. The file is located in a folder named \js\default.js. The default.js file kicks off all of your custom JavaScript code. It is the main entry point to a Metro application. The default contents of the default.js file are included below: // For an introduction to the Blank template, see the following documentation: // http://go.microsoft.com/fwlink/?LinkId=232509 (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; app.oncheckpoint = function (eventObject) { // TODO: This application is about to be suspended. Save any state // that needs to persist across suspensions here. You might use the // WinJS.Application.sessionState object, which is automatically // saved and restored across suspension. If you need to complete an // asynchronous operation before your application is suspended, call // eventObject.setPromise(). }; app.start(); })(); There are several mysterious things happening in this file. The purpose of this blog entry is to dispel this mystery. Understanding the Module Pattern The first thing that you should notice about the default.js file is that the entire contents of this file are enclosed within a self-executing JavaScript function: (function () { ... })(); Metro applications written with JavaScript use something called the module pattern. The module pattern is a common pattern used in JavaScript applications to create private variables, objects, and methods. Anything that you create within the module is encapsulated within the module. Enclosing all of your custom code within a module prevents you from stomping on code from other libraries accidently. Your application might reference several JavaScript libraries and the JavaScript libraries might have variables, objects, or methods with the same names. By encapsulating your code in a module, you avoid overwriting variables, objects, or methods in the other libraries accidently. Enabling Strict Mode with “use strict” The first statement within the default.js module enables JavaScript strict mode: 'use strict'; Strict mode is a new feature of ECMAScript 5 (the latest standard for JavaScript) which enables you to make JavaScript more strict. For example, when strict mode is enabled, you cannot declare variables without using the var keyword. The following statement would result in an exception: hello = "world!"; When strict mode is enabled, this statement throws a ReferenceError. When strict mode is not enabled, a global variable is created which, most likely, is not what you want to happen. I’d rather get the exception instead of the unwanted global variable. The full specification for strict mode is contained in the ECMAScript 5 specification (look at Annex C): http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf Aliasing the WinJS.Application Object The next line of code in the default.js file is used to alias the WinJS.Application object: var app = WinJS.Application; This line of code enables you to use a short-hand syntax when referring to the WinJS.Application object: for example,  app.onactivated instead of WinJS.Application.onactivated. The WinJS.Application object  represents your running Metro application. Handling Application Events The default.js file contains an event handler for the WinJS.Application activated event: app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; This WinJS.Application class supports the following events: · loaded – Happens after browser DOMContentLoaded event. After this event, the DOM is ready and you can access elements in a page. This event is raised before external images have been loaded. · activated – Triggered by the Windows.UI.WebUI.WebUIApplication activated event. After this event, the WinRT is ready. · ready – Happens after both loaded and activated events. · unloaded – Happens before application is unloaded. The following default.js file has been modified to capture each of these events and write a message to the Visual Studio JavaScript Console window: (function () { "use strict"; var app = WinJS.Application; WinJS.Application.onloaded = function (e) { console.log("Loaded"); }; WinJS.Application.onactivated = function (e) { console.log("Activated"); }; WinJS.Application.onready = function (e) { console.log("Ready"); } WinJS.Application.onunload = function (e) { console.log("Unload"); } app.start(); })(); When you execute the code above, a message is written to the Visual Studio JavaScript Console window when each event occurs with the exception of the Unload event (presumably because the console is not attached when that event is raised).   Handling Different Activation Contexts The code for the activated handler in the default.js file looks like this: app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; Notice that the code contains a conditional which checks the Kind of the event (the value of e.detail.kind). The startup code is executed only when the activated event is triggered by a Launch event, The ActivationKind enumeration has the following values: · launch · search · shareTarget · file · protocol · fileOpenPicker · fileSavePicker · cacheFileUpdater · contactPicker · device · printTaskSettings · cameraSettings Metro style applications can be activated in different contexts. For example, a camera application can be activated when modifying camera settings. In that case, the ActivationKind would be CameraSettings. Because we want to execute our JavaScript code when our application first launches, we verify that the kind of the activation event is an ActivationKind.Launch event. There is a second conditional within the activated event handler which checks whether an application is being newly launched or whether the application is being resumed from a suspended state. When running a Metro application with Visual Studio, you can use Visual Studio to simulate different application execution states by taking advantage of the Debug toolbar and the new Debug Location toolbar.  Handling the checkpoint Event The default.js file also includes an event handler for the WinJS.Application checkpoint event: app.oncheckpoint = function (eventObject) { // TODO: This application is about to be suspended. Save any state // that needs to persist across suspensions here. You might use the // WinJS.Application.sessionState object, which is automatically // saved and restored across suspension. If you need to complete an // asynchronous operation before your application is suspended, call // eventObject.setPromise(). }; The checkpoint event is raised when your Metro application goes into a suspended state. The idea is that you can save your application data when your application is suspended and reload your application data when your application resumes. Starting the Application The final statement in the default.js file is the statement that gets everything going: app.start(); Events are queued up in a JavaScript array named eventQueue . Until you call the start() method, the events in the queue are not processed. If you don’t call the start() method then the Loaded, Activated, Ready, and Unloaded events are never raised. Summary The goal of this blog entry was to describe the contents of the default.js file which is the JavaScript file which you use to kick off your custom code in a Windows Metro style application written with JavaScript. In this blog entry, I discussed the module pattern, JavaScript strict mode, handling first chance exceptions, WinJS Application events, and activation contexts.

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  • Set-Cookie Headers getting stripped in ASP.NET HttpHandlers

    - by Rick Strahl
    Yikes, I ran into a real bummer of an edge case yesterday in one of my older low level handler implementations (for West Wind Web Connection in this case). Basically this handler is a connector for a backend Web framework that creates self contained HTTP output. An ASP.NET Handler captures the full output, and then shoves the result down the ASP.NET Response object pipeline writing out the content into the Response.OutputStream and seperately sending the HttpHeaders in the Response.Headers collection. The headers turned out to be the problem and specifically Http Cookies, which for some reason ended up getting stripped out in some scenarios. My handler works like this: Basically the HTTP response from the backend app would return a full set of HTTP headers plus the content. The ASP.NET handler would read the headers one at a time and then dump them out via Response.AppendHeader(). But I found that in some situations Set-Cookie headers sent along were simply stripped inside of the Http Handler. After a bunch of back and forth with some folks from Microsoft (thanks Damien and Levi!) I managed to pin this down to a very narrow edge scenario. It's easiest to demonstrate the problem with a simple example HttpHandler implementation. The following simulates the very much simplified output generation process that fails in my handler. Specifically I have a couple of headers including a Set-Cookie header and some output that gets written into the Response object.using System.Web; namespace wwThreads { public class Handler : IHttpHandler { /* NOTE: * * Run as a web.config set handler (see entry below) * * Best way is to look at the HTTP Headers in Fiddler * or Chrome/FireBug/IE tools and look for the * WWHTREADSID cookie in the outgoing Response headers * ( If the cookie is not there you see the problem! ) */ public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; HttpResponse response = context.Response; // If ClearHeaders is used Set-Cookie header gets removed! // if commented header is sent... response.ClearHeaders(); response.ClearContent(); // Demonstrate that other headers make it response.AppendHeader("RequestId", "asdasdasd"); // This cookie gets removed when ClearHeaders above is called // When ClearHEaders is omitted above the cookie renders response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); // *** This always works, even when explicit // Set-Cookie above fails and ClearHeaders is called //response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); response.Write(@"Output was created.<hr/> Check output with Fiddler or HTTP Proxy to see whether cookie was sent."); } public bool IsReusable { get { return false; } } } } In order to see the problem behavior this code has to be inside of an HttpHandler, and specifically in a handler defined in web.config with: <add name=".ck_handler" path="handler.ck" verb="*" type="wwThreads.Handler" preCondition="integratedMode" /> Note: Oddly enough this problem manifests only when configured through web.config, not in an ASHX handler, nor if you paste that same code into an ASPX page or MVC controller. What's the problem exactly? The code above simulates the more complex code in my live handler that picks up the HTTP response from the backend application and then peels out the headers and sends them one at a time via Response.AppendHeader. One of the headers in my app can be one or more Set-Cookie. I found that the Set-Cookie headers were not making it into the Response headers output. Here's the Chrome Http Inspector trace: Notice, no Set-Cookie header in the Response headers! Now, running the very same request after removing the call to Response.ClearHeaders() command, the cookie header shows up just fine: As you might expect it took a while to track this down. At first I thought my backend was not sending the headers but after closer checks I found that indeed the headers were set in the backend HTTP response, and they were indeed getting set via Response.AppendHeader() in the handler code. Yet, no cookie in the output. In the simulated example the problem is this line:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); which in my live code is more dynamic ( ie. AppendHeader(token[0],token[1[]) )as it parses through the headers. Bizzaro Land: Response.ClearHeaders() causes Cookie to get stripped Now, here is where it really gets bizarre: The problem occurs only if: Response.ClearHeaders() was called before headers are added It only occurs in Http Handlers declared in web.config Clearly this is an edge of an edge case but of course - knowing my relationship with Mr. Murphy - I ended up running smack into this problem. So in the code above if you remove the call to ClearHeaders(), the cookie gets set!  Add it back in and the cookie is not there. If I run the above code in an ASHX handler it works. If I paste the same code (with a Response.End()) into an ASPX page, or MVC controller it all works. Only in the HttpHandler configured through Web.config does it fail! Cue the Twilight Zone Music. Workarounds As is often the case the fix for this once you know the problem is not too difficult. The difficulty lies in tracking inconsistencies like this down. Luckily there are a few simple workarounds for the Cookie issue. Don't use AppendHeader for Cookies The easiest and obvious solution to this problem is simply not use Response.AppendHeader() to set Cookies. Duh! Under normal circumstances in application level code there's rarely a reason to write out a cookie like this:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); but rather create the cookie using the Response.Cookies collection:response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); Unfortunately, in my case where I dynamically read headers from the original output and then dynamically  write header key value pairs back  programmatically into the Response.Headers collection, I actually don't look at each header specifically so in my case the cookie is just another header. My first thought was to simply trap for the Set-Cookie header and then parse out the cookie and create a Cookie object instead. But given that cookies can have a lot of different options this is not exactly trivial, plus I don't really want to fuck around with cookie values which can be notoriously brittle. Don't use Response.ClearHeaders() The real mystery in all this is why calling Response.ClearHeaders() prevents a cookie value later written with Response.AppendHeader() to fail. I fired up Reflector and took a quick look at System.Web and HttpResponse.ClearHeaders. There's all sorts of resetting going on but nothing that seems to indicate that headers should be removed later on in the request. The code in ClearHeaders() does access the HttpWorkerRequest, which is the low level interface directly into IIS, and so I suspect it's actually IIS that's stripping the headers and not ASP.NET, but it's hard to know. Somebody from Microsoft and the IIS team would have to comment on that. In my application it's probably safe to simply skip ClearHeaders() in my handler. The ClearHeaders/ClearContent was mainly for safety but after reviewing my code there really should never be a reason that headers would be set prior to this method firing. However, if for whatever reason headers do need to be cleared, it's easy enough to manually clear the headers out:private void RemoveHeaders(HttpResponse response) { List<string> headers = new List<string>(); foreach (string header in response.Headers) { headers.Add(header); } foreach (string header in headers) { response.Headers.Remove(header); } response.Cookies.Clear(); } Now I can replace the call the Response.ClearHeaders() and I don't get the funky side-effects from Response.ClearHeaders(). Summary I realize this is a total edge case as this occurs only in HttpHandlers that are manually configured. It looks like you'll never run into this in any of the higher level ASP.NET frameworks or even in ASHX handlers - only web.config defined handlers - which is really, really odd. After all those frameworks use the same underlying ASP.NET architecture. Hopefully somebody from Microsoft has an idea what crazy dependency was triggered here to make this fail. IAC, there are workarounds to this should you run into it, although I bet when you do run into it, it'll likely take a bit of time to find the problem or even this post in a search because it's not easily to correlate the problem to the solution. It's quite possible that more than cookies are affected by this behavior. Searching for a solution I read a few other accounts where headers like Referer were mysteriously disappearing, and it's possible that something similar is happening in those cases. Again, extreme edge case, but I'm writing this up here as documentation for myself and possibly some others that might have run into this. © Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • CodePlex Daily Summary for Tuesday, June 25, 2013

    CodePlex Daily Summary for Tuesday, June 25, 2013Popular ReleasesCrmRestKit.js: CrmRestKit-2.6.1.js: Improvments for "ByQueryAll": Instead of defering unit all records are loaded, the progress-handler is invoked for each 50 records Added "progress-handler" support for "ByQueryAll" See: http://api.jquery.com/deferred.notify/* See Unit-tests for details ('Retrieve all with progress notification')VG-Ripper & PG-Ripper: VG-Ripper 2.9.44: changes NEW: Added Support for "ImgChili.net" links FIXED: Auto UpdaterMinesweeper by S. Joshi: Minesweeper 1.0.0.1: Zipped!Alfa: Alfa.Common 1.0.4923: Removed useless property ErrorMessage from StringRegularExpressionValidationRule Repaired ErrorWindow and disabled report button after click action Implemented: DateTimeRangeValidationRule DateTimeValidationRule DateValidationRule NotEmptyValidationRule NotNullValidationRule RequiredValidationRule StringMaxLengthValidationRule StringMinLengthValidationRule TimeValidationRule DateTimeToStringConverter DecimalToStringConverter StringToDateTimeConverter StringToDecima...Document.Editor: 2013.25: What's new for Document.Editor 2013.25: Improved Spell Check support Improved User Interface Minor Bug Fix's, improvements and speed upsStyleMVVM: 3.0.2: This is a minor feature and bug fix release Features: ExportWhenDebuggerIsAttacedAttribute - new attribute that marks an attribute to only be exported when the debugger is attahced InjectedFilterAttributeFilterProvider - new Attribute Filter provider for MVC that injects the attributes Performance Improvements - minor speed improvements all over, and Import collections is now 50% faster Bug Fixes: Open Generic Constraints are now respected when finding exports Fix for fluent registrat...Base64 File Converter: First release: - One file can be converted at a time. - Bytes to Base64 and Base64 to Bytes conversions are availableADExtractor - work with Active-Directory: V1.3.0.2: 1.3.0.2- added optional value-index to properties - added new aggregation "Literal" to pass-through values - added new SQL commandline-switch --db to override the connection string - added new global commandline-switch --quiet to reduce output to minimum 1.3.0.1- sub-property resolution now working with aggregation (ie. All(member.objectGuid)) 1.3.0.0- added correct formatting for guids (GuidFormatter)EMICHAG: EMICHAG NETMF 4.2: Alpha release of the 4.2 version.WPF Composites: Version 4.3.0: In this Beta release, I broke my code out into two separate projects. There is a core FasterWPF.dll with the minimal required functionality. This can run with only the Aero.dll and the Rx .dll's. Then, I have a FasterWPFExtras .dll that requires and supports the Extended WPF Toolkit™ Community Edition V 1.9.0 (including Xceed DataGrid) and the Thriple .dll. This is for developers who want more . . . Finally, you may notice the other OPTIONAL .dll's available in the download such as the Dyn...Windows.Forms.Controls Revisited (SSTA.WinForms): SSTA.WinForms 1.0.0: Latest stable releaseAscend 3D: Ascend 2.0: Release notes: Implemented bone/armature animation Refactored class hierarchy and naming Addressed high CPU usage issue during animation Updated the Blender exporter and Ascend model format (now XML) Created AscendViewer, a tool for viewing Ascend modelsIndent Guides for Visual Studio: Indent Guides v13: ImportantThis release does not support Visual Studio 2010. The latest stable release for VS 2010 is v12.1. Version History Changed in v13 Added page width guide lines Added guide highlighting options Fixed guides appearing over collapsed blocks Fixed guides not appearing in newly opened files Fixed some potential crashes Fixed lines going through pragma statements Various updates for VS 2012 and VS 2013 Removed VS 2010 support Changed in v12.1: Fixed crash when unable to start...Fluent Ribbon Control Suite: Fluent Ribbon Control Suite 2.1.0 - Prerelease d: Fluent Ribbon Control Suite 2.1.0 - Prerelease d(supports .NET 3.5, 4.0 and 4.5) Includes: Fluent.dll (with .pdb and .xml) Showcase Application Samples (not for .NET 3.5) Foundation (Tabs, Groups, Contextual Tabs, Quick Access Toolbar, Backstage) Resizing (ribbon reducing & enlarging principles) Galleries (Gallery in ContextMenu, InRibbonGallery) MVVM (shows how to use this library with Model-View-ViewModel pattern) KeyTips ScreenTips Toolbars ColorGallery *Walkthrough (do...Magick.NET: Magick.NET 6.8.5.1001: Magick.NET compiled against ImageMagick 6.8.5.10. Breaking changes: - MagickNET.Initialize has been made obsolete because the ImageMagick files in the directory are no longer necessary. - MagickGeometry is no longer IDisposable. - Renamed dll's so they include the platform name. - Image profiles can now only be accessed and modified with ImageProfile classes. - Renamed DrawableBase to Drawable. - Removed Args part of PathArc/PathCurvetoArgs/PathQuadraticCurvetoArgs classes. The...Three-Dimensional Maneuver Gear for Minecraft: TDMG 1.1.0.0 for 1.5.2: CodePlex???(????????) ?????????(???1/4) ??????????? ?????????? ???????????(??????????) ??????????????????????? ↑????、?????????????????????(???????) ???、??????????、?????????????????????、????????1.5?????????? Shift+W(????)??????????????????10°、?10°(?????????)???Hyper-V Management Pack Extensions 2012: HyperVMPE2012 (v1.0.1.126): Hyper-V Management Pack Extensions 2012 Beta ReleaseOutlook 2013 Add-In: Email appointments: This new version includes the following changes: - Ability to drag emails to the calendar to create appointments. Will gather all the recipients from all the emails and create an appointment on the day you drop the emails, with the text and subject of the last selected email (if more than one selected). - Increased maximum of numbers to display appointments to 30. You will have to uninstall the previous version (add/remove programs) if you had installed it before. Before unzipping the file...Caliburn Micro: WPF, Silverlight, WP7 and WinRT/Metro made easy.: Caliburn.Micro v1.5.2: v1.5.2 - This is a service release. We've fixed a number of issues with Tasks and IoC. We've made some consistency improvements across platforms and fixed a number of minor bugs. See changes.txt for details. Packages Available on Nuget Caliburn.Micro – The full framework compiled into an assembly. Caliburn.Micro.Start - Includes Caliburn.Micro plus a starting bootstrapper, view model and view. Caliburn.Micro.Container – The Caliburn.Micro inversion of control container (IoC); source code...SQL Compact Query Analyzer: 1.0.1.1511: Beta build of SQL Compact Query Analyzer Bug fixes: - Resolved issue where the application crashes when loading a database that contains tables without a primary key Features: - Displays database information (database version, filename, size, creation date) - Displays schema summary (number of tables, columns, primary keys, identity fields, nullable fields) - Displays the information schema views - Displays column information (database type, clr type, max length, allows null, etc) - Support...New Projectsalgorithm interview: Write some code for programming interview questionsAmbiTrack: AmbiTrack provides marker-free localization and tracking using an array of cameras, e.g. the PlayStation Eye.DSeX DragonSpeak eXtended Editor: Furcadia DragonSpeak EditorEasyProject: easy project is finel engineering project this sys made for easy way to manage emploees of a small business or organization .EDIVisualizer SDK: EDIVisualizer SDK is a software developpement kit (SDK) for creating plugin used by EDIVisualizer program.Flame: Interactive shell for scripting in IronRuby IronPython Powershell C#, with syntax highlighting, autocomplete,and for easily work within a .NET framework consoleFusion-io MS SQL Server scripts: Fusion-io's Sumeet Bansal shows how Microsoft SQL Server users can quickly determine whether their database will benefit from Fusion-io ioMemory products.hotelprimero: Proyecto de hotelImage filters: It's a simple image filter :)JSLint.NET: JSLint.NET is a wrapper for Douglas Crockford's JSLint, the JavaScript code quality tool. It can validate JavaScript anywhere .NET runs.KZ.Express.H: KZ.Express.Hmoleshop: moleshop???asp.net ???????B2C????,????????.net???????????。moleshop??asp.net mvc 4.0???,???.net 4.0??。 moleshop???????,??AL2.0 ????,????????????????,????????。PDF Generator Net Free Xml Parser: PDF Generator Net Free Xml Parser?XML?????????????????????。?????????????????????CSV?????????PDF???????????????????????。ScreenCatcher: ScreenCatcher is a program for creating screenshots.SharePoint Configuration Guidance for 21 CFR Part 11 Compliance – SP 2013: This CodePlex project provides the Paragon Solutions configurations and code to support 21 CFR Part 11 compliance with SharePoint 2013.Sky Editor: Save file editor for Pokémon Mystery Dungeon: Explorers of Sky with limited support for Explorers of Time and DarknessTRANCIS: For foundation and runnning online operations for Trancis.UGSF GRAND OUEST: UGSF GRAND OUESTWP.JS: WP.JS (Windows Phone (dot) Javascript) aims to be a compelling library for developing HTML5-based applications for Windows Phone 8.X-Aurora: X-Aurora ?? MVC3

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  • The case of the phantom ADF developer (and other yarns)

    - by Chris Muir
    A few years of ADF experience means I see common mistakes made by different developers, some I regularly make myself.  This post is designed to assist beginners to Oracle JDeveloper Application Development Framework (ADF) avoid a common ADF pitfall, the case of the phantom ADF developer [add Scooby-Doo music here]. ADF Business Components - triggers, default table values and instead of views. Oracle's JDeveloper tutorials help with the A-B-Cs of ADF development, typically built on the nice 'n safe demo schema provided by with the Oracle database such as the HR demo schema. However it's not too long until ADF beginners, having built up some confidence from learning with the tutorials and vanilla demo schemas, start building ADF Business Components based upon their own existing database schema objects.  This is where unexpected problems can sneak in. The crime Developers may encounter a surprising error at runtime when editing a record they just created or updated and committed to the database, based on their own existing tables, namely the error: JBO-25014: Another user has changed the row with primary key oracle.jbo.Key[x] ...where X is the primary key value of the row at hand.  In a production environment with multiple users this error may be legit, one of the other users has updated the row since you queried it.  Yet in a development environment this error is just plain confusing.  If developers are isolated in their own database, creating and editing records they know other users can't possibly be working with, or all the other developers have gone home for the day, how is this error possible? There are no other users?  It must be the phantom ADF developer! [insert dramatic music here] The following picture is what you'll see in the Business Component Browser, and you'll receive a similar error message via an ADF Faces page: A false conclusion What can possibly cause this issue if it isn't our phantom ADF developer?  Doesn't ADF BC implement record locking, locking database records when the row is modified in the ADF middle-tier by a user?  How can our phantom ADF developer even take out a lock if this is the case?  Maybe ADF has a bug, maybe ADF isn't implementing record locking at all?  Shouldn't we see the error "JBO-26030: Failed to lock the record, another user holds the lock" as we attempt to modify the record, why do we see JBO-25014? : Let's verify that ADF is in fact issuing the correct SQL LOCK-FOR-UPDATE statement to the database. First we need to verify ADF's locking strategy.  It is determined by the Application Module's jbo.locking.mode property.  The default (as of JDev 11.1.1.4.0 if memory serves me correct) and recommended value is optimistic, and the other valid value is pessimistic. Next we need a mechanism to check that ADF is issuing the LOCK statements to the database.  We could ask DBAs to monitor locks with OEM, but optimally we'd rather not involve overworked DBAs in this process, so instead we can use the ADF runtime setting –Djbo.debugoutput=console.  At runtime this options turns on instrumentation within the ADF BC layer, which among a lot of extra detail displayed in the log window, will show the actual SQL statement issued to the database, including the LOCK statement we're looking to confirm. Setting our locking mode to pessimistic, opening the Business Components Browser of a JSF page allowing us to edit a record, say the CHARGEABLE field within a BOOKINGS record where BOOKING_NO = 1206, upon editing the record see among others the following log entries: [421] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[422] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[423] Where binding param 1: 1206  As can be seen on line 422, in fact a LOCK-FOR-UPDATE is indeed issued to the database.  Later when we commit the record we see: [441] OracleSQLBuilder: SAVEPOINT 'BO_SP'[442] OracleSQLBuilder Executing, Lock 1 DML on: BOOKINGS (Update)[443] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[444] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[445] Update binding param 1: N[446] Where binding param 2: 1206[447] BookingsView1 notify COMMIT ... [448] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [449] EntityCache close prepared statement ....and as a result the changes are saved to the database, and the lock is released. Let's see what happens when we use the optimistic locking mode, this time to change the same BOOKINGS record CHARGEABLE column again.  As soon as we edit the record we see little activity in the logs, nothing to indicate any SQL statement, let alone a LOCK has been taken out on the row. However when we save our records by issuing a commit, the following is recorded in the logs: [509] OracleSQLBuilder: SAVEPOINT 'BO_SP'[510] OracleSQLBuilder Executing doEntitySelect on: BOOKINGS (true)[511] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[512] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[513] Where binding param 1: 1205[514] OracleSQLBuilder Executing, Lock 2 DML on: BOOKINGS (Update)[515] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[516] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[517] Update binding param 1: Y[518] Where binding param 2: 1205[519] BookingsView1 notify COMMIT ... [520] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [521] EntityCache close prepared statement Again even though we're seeing the midtier delay the LOCK statement until commit time, it is in fact occurring on line 412, and released as part of the commit issued on line 419.  Therefore with either optimistic or pessimistic locking a lock is indeed issued. Our conclusion at this point must be, unless there's the unlikely cause the LOCK statement is never really hitting the database, or the even less likely cause the database has a bug, then ADF does in fact take out a lock on the record before allowing the current user to update it.  So there's no way our phantom ADF developer could even modify the record if he tried without at least someone receiving a lock error. Hmm, we can only conclude the locking mode is a red herring and not the true cause of our problem.  Who is the phantom? At this point we'll need to conclude that the error message "JBO-25014: Another user has changed" is somehow legit, even though we don't understand yet what's causing it. This leads onto two further questions, how does ADF know another user has changed the row, and what's been changed anyway? To answer the first question, how does ADF know another user has changed the row, the Fusion Guide's section 4.10.11 How to Protect Against Losing Simultaneous Updated Data , that details the Entity Object Change-Indicator property, gives us the answer: At runtime the framework provides automatic "lost update" detection for entity objects to ensure that a user cannot unknowingly modify data that another user has updated and committed in the meantime. Typically, this check is performed by comparing the original values of each persistent entity attribute against the corresponding current column values in the database at the time the underlying row is locked. Before updating a row, the entity object verifies that the row to be updated is still consistent with the current state of the database.  The guide further suggests to make this solution more efficient: You can make the lost update detection more efficient by identifying any attributes of your entity whose values you know will be updated whenever the entity is modified. Typical candidates include a version number column or an updated date column in the row.....To detect whether the row has been modified since the user queried it in the most efficient way, select the Change Indicator option to compare only the change-indicator attribute values. We now know that ADF BC doesn't use the locking mechanism at all to protect the current user against updates, but rather it keeps a copy of the original record fetched, separate to the user changed version of the record, and it compares the original record against the one in the database when the lock is taken out.  If values don't match, be it the default compare-all-columns behaviour, or the more efficient Change Indicator mechanism, ADF BC will throw the JBO-25014 error. This leaves one last question.  Now we know the mechanism under which ADF identifies a changed row, what we don't know is what's changed and who changed it? The real culprit What's changed?  We know the record in the mid-tier has been changed by the user, however ADF doesn't use the changed record in the mid-tier to compare to the database record, but rather a copy of the original record before it was changed.  This leaves us to conclude the database record has changed, but how and by who? There are three potential causes: Database triggers The database trigger among other uses, can be configured to fire PLSQL code on a database table insert, update or delete.  In particular in an insert or update the trigger can override the value assigned to a particular column.  The trigger execution is actioned by the database on behalf of the user initiating the insert or update action. Why this causes the issue specific to our ADF use, is when we insert or update a record in the database via ADF, ADF keeps a copy of the record written to the database.  However the cached record is instantly out of date as the database triggers have modified the record that was actually written to the database.  Thus when we update the record we just inserted or updated for a second time to the database, ADF compares its original copy of the record to that in the database, and it detects the record has been changed – giving us JBO-25014. This is probably the most common cause of this problem. Default values A second reason this issue can occur is another database feature, default column values.  When creating a database table the schema designer can define default values for specific columns.  For example a CREATED_BY column could be set to SYSDATE, or a flag column to Y or N.  Default values are only used by the database when a user inserts a new record and the specific column is assigned NULL.  The database in this case will overwrite the column with the default value. As per the database trigger section, it then becomes apparent why ADF chokes on this feature, though it can only specifically occur in an insert-commit-update-commit scenario, not the update-commit-update-commit scenario. Instead of trigger views I must admit I haven't double checked this scenario but it seems plausible, that of the Oracle database's instead of trigger view (sometimes referred to as instead of views).  A view in the database is based on a query, and dependent on the queries complexity, may support insert, update and delete functionality to a limited degree.  In order to support fully insertable, updateable and deletable views, Oracle introduced the instead of view, that gives the view designer the ability to not only define the view query, but a set of programmatic PLSQL triggers where the developer can define their own logic for inserts, updates and deletes. While this provides the database programmer a very powerful feature, it can cause issues for our ADF application.  On inserting or updating a record in the instead of view, the record and it's data that goes in is not necessarily the data that comes out when ADF compares the records, as the view developer has the option to practically do anything with the incoming data, including throwing it away or pushing it to tables which aren't used by the view underlying query for fetching the data. Readers are at this point reminded that this article is specifically about how the JBO-25014 error occurs in the context of 1 developer on an isolated database.  The article is not considering how the error occurs in a production environment where there are multiple users who can cause this error in a legitimate fashion.  Assuming none of the above features are the cause of the problem, and optimistic locking is turned on (this error is not possible if pessimistic locking is the default mode *and* none of the previous causes are possible), JBO-25014 is quite feasible in a production ADF application if 2 users modify the same record. At this point under project timelines pressure, the obvious fix for developers is to drop both database triggers and default values from the underlying tables.  However we must be careful that these legacy constructs aren't used and assumed to be in place by other legacy systems.  Dropping the database triggers or default value that the existing Oracle Forms  applications assumes and requires to be in place could cause unexpected behaviour and bugs in the Forms application.  Proficient software engineers would recognize such a change may require a partial or full regression test of the existing legacy system, a potentially costly and timely exercise, not ideal. Solving the mystery once and for all Luckily ADF has built in functionality to deal with this issue, though it's not a surprise, as Oracle as the author of ADF also built the database, and are fully aware of the Oracle database's feature set.  At the Entity Object attribute level, the Refresh After Insert and Refresh After Update properties.  Simply selecting these instructs ADF BC after inserting or updating a record to the database, to expect the database to modify the said attributes, and read a copy of the changed attributes back into its cached mid-tier record.  Thus next time the developer modifies the current record, the comparison between the mid-tier record and the database record match, and JBO-25014: Another user has changed" is no longer an issue. [Post edit - as per the comment from Oracle's Steven Davelaar below, as he correctly points out the above solution will not work for instead-of-triggers views as it relies on SQL RETURNING clause which is incompatible with this type of view] Alternatively you can set the Change Indicator on one of the attributes.  This will work as long as the relating column for the attribute in the database itself isn't inadvertently updated.  In turn you're possibly just masking the issue rather than solving it, because if another developer turns the Change Indicator back on the original issue will return.

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  • Pain Comes Instantly

    - by user701213
    When I look back at recent blog entries – many of which are not all that current (more on where my available writing time is going later) – I am struck by how many of them focus on public policy or legislative issues instead of, say, the latest nefarious cyberattack or exploit (or everyone’s favorite new pastime: coining terms for the Coming Cyberpocalypse: “digital Pearl Harbor” is so 1941). Speaking of which, I personally hope evil hackers from Malefactoria will someday hack into my bathroom scale – which in a future time will be connected to the Internet because, gosh, wouldn’t it be great to have absolutely everything in your life Internet-enabled? – and recalibrate it so I’m 10 pounds thinner. The horror. In part, my focus on public policy is due to an admitted limitation of my skill set. I enjoy reading technical articles about exploits and cybersecurity trends, but writing a blog entry on those topics would take more research than I have time for and, quite honestly, doesn’t play to my strengths. The first rule of writing is “write what you know.” The bigger contributing factor to my recent paucity of blog entries is that more and more of my waking hours are spent engaging in “thrust and parry” activity involving emerging regulations of some sort or other. I’ve opined in earlier blogs about what constitutes good and reasonable public policy so nobody can accuse me of being reflexively anti-regulation. That said, you have so many cycles in the day, and most of us would rather spend it slaying actual dragons than participating in focus groups on whether dragons are really a problem, whether lassoing them (with organic, sustainable and recyclable lassos) is preferable to slaying them – after all, dragons are people, too - and whether we need lasso compliance auditors to make sure lassos are being used correctly and humanely. (A point that seems to evade many rule makers: slaying dragons actually accomplishes something, whereas talking about “approved dragon slaying procedures and requirements” wastes the time of those who are competent to dispatch actual dragons and who were doing so very well without the input of “dragon-slaying theorists.”) Unfortunately for so many of us who would just get on with doing our day jobs, cybersecurity is rapidly devolving into the “focus groups on dragon dispatching” realm, which actual dragons slayers have little choice but to participate in. The general trend in cybersecurity is that powers-that-be – which encompasses groups other than just legislators – are often increasingly concerned and therefore feel they need to Do Something About Cybersecurity. Many seem to believe that if only we had the right amount of regulation and oversight, there would be no data breaches: a breach simply must mean Someone Is At Fault and Needs Supervision. (Leaving aside the fact that we have lots of home invasions despite a) guard dogs b) liberal carry permits c) alarm systems d) etc.) Also note that many well-managed and security-aware organizations, like the US Department of Defense, still get hacked. More specifically, many powers-that-be feel they must direct industry in a multiplicity of ways, up to and including how we actually build and deploy information technology systems. The more prescriptive the requirement, the more regulators or overseers a) can be seen to be doing something b) feel as if they are doing something regardless of whether they are actually doing something useful or cost effective. Note: an unfortunate concomitant of Doing Something is that often the cure is worse than the ailment. That is, doing what overseers want creates unfortunate byproducts that they either didn’t foresee or worse, don’t care about. After all, the logic goes, we Did Something. Prescriptive practice in the IT industry is problematic for a number of reasons. For a start, prescriptive guidance is really only appropriate if: • It is cost effective• It is “current” (meaning, the guidance doesn’t require the use of the technical equivalent of buggy whips long after horse-drawn transportation has become passé)*• It is practical (that is, pragmatic, proven and effective in the real world, not theoretical and unproven)• It solves the right problem With the above in mind, heading up the list of “you must be joking” regulations are recent disturbing developments in the Payment Card Industry (PCI) world. I’d like to give PCI kahunas the benefit of the doubt about their intentions, except that efforts by Oracle among others to make them aware of “unfortunate side effects of your requirements” – which is as tactful I can be for reasons that I believe will become obvious below - have gone, to-date, unanswered and more importantly, unchanged. A little background on PCI before I get too wound up. In 2008, the Payment Card Industry (PCI) Security Standards Council (SSC) introduced the Payment Application Data Security Standard (PA-DSS). That standard requires vendors of payment applications to ensure that their products implement specific requirements and undergo security assessment procedures. In order to have an application listed as a Validated Payment Application (VPA) and available for use by merchants, software vendors are required to execute the PCI Payment Application Vendor Release Agreement (VRA). (Are you still with me through all the acronyms?) Beginning in August 2010, the VRA imposed new obligations on vendors that are extraordinary and extraordinarily bad, short-sighted and unworkable. Specifically, PCI requires vendors to disclose (dare we say “tell all?”) to PCI any known security vulnerabilities and associated security breaches involving VPAs. ASAP. Think about the impact of that. PCI is asking a vendor to disclose to them: • Specific details of security vulnerabilities • Including exploit information or technical details of the vulnerability • Whether or not there is any mitigation available (as in a patch) PCI, in turn, has the right to blab about any and all of the above – specifically, to distribute all the gory details of what is disclosed - to the PCI SSC, qualified security assessors (QSAs), and any affiliate or agent or adviser of those entities, who are in turn permitted to share it with their respective affiliates, agents, employees, contractors, merchants, processors, service providers and other business partners. This assorted crew can’t be more than, oh, hundreds of thousands of entities. Does anybody believe that several hundred thousand people can keep a secret? Or that several hundred thousand people are all equally trustworthy? Or that not one of the people getting all that information would blab vulnerability details to a bad guy, even by accident? Or be a bad guy who uses the information to break into systems? (Wait, was that the Easter Bunny that just hopped by? Bringing world peace, no doubt.) Sarcasm aside, common sense tells us that telling lots of people a secret is guaranteed to “unsecret” the secret. Notably, being provided details of a vulnerability (without a patch) is of little or no use to companies running the affected application. Few users have the technological sophistication to create a workaround, and even if they do, most workarounds break some other functionality in the application or surrounding environment. Also, given the differences among corporate implementations of any application, it is highly unlikely that a single workaround is going to work for all corporate users. So until a patch is developed by the vendor, users remain at risk of exploit: even more so if the details of vulnerability have been widely shared. Sharing that information widely before a patch is available therefore does not help users, and instead helps only those wanting to exploit known security bugs. There’s a shocker for you. Furthermore, we already know that insider information about security vulnerabilities inevitably leaks, which is why most vendors closely hold such information and limit dissemination until a patch is available (and frequently limit dissemination of technical details even with the release of a patch). That’s the industry norm, not that PCI seems to realize or acknowledge that. Why would anybody release a bunch of highly technical exploit information to a cast of thousands, whose only “vetting” is that they are members of a PCI consortium? Oracle has had personal experience with this problem, which is one reason why information on security vulnerabilities at Oracle is “need to know” (we use our own row level access control to limit access to security bugs in our bug database, and thus less than 1% of development has access to this information), and we don’t provide some customers with more information than others or with vulnerability information and/or patches earlier than others. Failure to remember “insider information always leaks” creates problems in the general case, and has created problems for us specifically. A number of years ago, one of the UK intelligence agencies had information about a non-public security vulnerability in an Oracle product that they circulated among other UK and Commonwealth defense and intelligence entities. Nobody, it should be pointed out, bothered to report the problem to Oracle, even though only Oracle could produce a patch. The vulnerability was finally reported to Oracle by (drum roll) a US-based commercial company, to whom the information had leaked. (Note: every time I tell this story, the MI-whatever agency that created the problem gets a bit shirty with us. I know they meant well and have improved their vulnerability handling/sharing processes but, dudes, next time you find an Oracle vulnerability, try reporting it to us first before blabbing to lots of people who can’t actually fix the problem. Thank you!) Getting back to PCI: clearly, these new disclosure obligations increase the risk of exploitation of a vulnerability in a VPA and thus, of misappropriation of payment card data and customer information that a VPA processes, stores or transmits. It stands to reason that VRA’s current requirement for the widespread distribution of security vulnerability exploit details -- at any time, but particularly before a vendor can issue a patch or a workaround -- is very poor public policy. It effectively publicizes information of great value to potential attackers while not providing compensating benefits - actually, any benefits - to payment card merchants or consumers. In fact, it magnifies the risk to payment card merchants and consumers. The risk is most prominent in the time before a patch has been released, since customers often have little option but to continue using an application or system despite the risks. However, the risk is not limited to the time before a patch is issued: customers often need days, or weeks, to apply patches to systems, based upon the complexity of the issue and dependence on surrounding programs. Rather than decreasing the available window of exploit, this requirement increases the available window of exploit, both as to time available to exploit a vulnerability and the ease with which it can be exploited. Also, why would hackers focus on finding new vulnerabilities to exploit if they can get “EZHack” handed to them in such a manner: a) a vulnerability b) in a payment application c) with exploit code: the “Hacking Trifecta!“ It’s fair to say that this is probably the exact opposite of what PCI – or any of us – would want. Established industry practice concerning vulnerability handling avoids the risks created by the VRA’s vulnerability disclosure requirements. Specifically, the norm is not to release information about a security bug until the associated patch (or a pretty darn good workaround) has been issued. Once a patch is available, the notice to the user community is a high-level communication discussing the product at issue, the level of risk associated with the vulnerability, and how to apply the patch. The notices do not include either the specific customers affected by the vulnerability or forensic reports with maps of the exploit (both of which are required by the current VRA). In this way, customers have the tools they need to prioritize patching and to help prevent an attack, and the information released does not increase the risk of exploit. Furthermore, many vendors already use industry standards for vulnerability description: Common Vulnerability Enumeration (CVE) and Common Vulnerability Scoring System (CVSS). CVE helps ensure that customers know which particular issues a patch addresses and CVSS helps customers determine how severe a vulnerability is on a relative scale. Industry already provides the tools customers need to know what the patch contains and how bad the problem is that the patch remediates. So, what’s a poor vendor to do? Oracle is reaching out to other vendors subject to PCI and attempting to enlist then in a broad effort to engage PCI in rethinking (that is, eradicating) these requirements. I would therefore urge all who care about this issue, but especially those in the vendor community whose applications are subject to PCI and who may not have know they were being asked to tell-all to PCI and put their customers at risk, to do one of the following: • Contact PCI with your concerns• Contact Oracle (we are looking for vendors to sign our statement of concern)• And make sure you tell your customers that you have to rat them out to PCI if there is a breach involving the payment application I like to be charitable and say “PCI meant well” but in as important a public policy issue as what you disclose about vulnerabilities, to whom and when, meaning well isn’t enough. We need to do well. PCI, as regards this particular issue, has not done well, and has compounded the error by thus far being nonresponsive to those of us who have labored mightily to try to explain why they might want to rethink telling the entire planet about security problems with no solutions. By Way of Explanation… Non-related to PCI whatsoever, and the explanation for why I have not been blogging a lot recently, I have been working on Other Writing Venues with my sister Diane (who has also worked in the tech sector, inflicting upgrades on unsuspecting and largely ungrateful end users). I am pleased to note that we have recently (self-)published the first in the Miss Information Technology Murder Mystery series, Outsourcing Murder. The genre might best be described as “chick lit meets geek scene.” Our sisterly nom de plume is Maddi Davidson and (shameless plug follows): you can order the paper version of the book on Amazon, or the Kindle or Nook versions on www.amazon.com or www.bn.com, respectively. From our book jacket: Emma Jones, a 20-something IT consultant, is working on an outsourcing project at Tahiti Tacos, a restaurant chain offering Polynexican cuisine: refried poi, anyone? Emma despises her boss Padmanabh, a brilliant but arrogant partner in GD Consulting. When Emma discovers His-Royal-Padness’s body (verdict: death by cricket bat), she becomes a suspect.With her overprotective family and her best friend Stacey providing endless support and advice, Emma stumbles her way through an investigation of Padmanabh’s murder, bolstered by fusion food feeding frenzies, endless cups of frou-frou coffee and serious surfing sessions. While Stacey knows a PI who owes her a favor, landlady Magda urges Emma to tart up her underwear drawer before the next cute cop with a search warrant arrives. Emma’s mother offers to fix her up with a PhD student at Berkeley and showers her with self-defense gizmos while her old lover Keoni beckons from Hawai’i. And everyone, even Shaun the barista, knows a good lawyer. Book 2, Denial of Service, is coming out this summer. * Given the rate of change in technology, today’s “thou shalts” are easily next year’s “buggy whip guidance.”

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  • Using WeakReference to resolve issue with .NET unregistered event handlers causing memory leaks.

    - by Eric
    The problem: Registered event handlers create a reference from the event to the event handler's instance. If that instance fails to unregister the event handler (via Dispose, presumably), then the instance memory will not be freed by the garbage collector. Example: class Foo { public event Action AnEvent; public void DoEvent() { if (AnEvent != null) AnEvent(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } If I instantiate a Foo, and pass this to a new Bar constructor, then let go of the Bar object, it will not be freed by the garbage collector because of the AnEvent registration. I consider this a memory leak, and seems just like my old C++ days. I can, of course, make Bar IDisposable, unregister the event in the Dispose() method, and make sure to call Dispose() on instances of it, but why should I have to do this? I first question why events are implemented with strong references? Why not use weak references? An event is used to abstractly notify an object of changes in another object. It seems to me that if the event handler's instance is no longer in use (i.e., there are no non-event references to the object), then any events that it is registered with should automatically be unregistered. What am I missing? I have looked at WeakEventManager. Wow, what a pain. Not only is it very difficult to use, but its documentation is inadequate (see http://msdn.microsoft.com/en-us/library/system.windows.weakeventmanager.aspx -- noticing the "Notes to Inheritors" section that has 6 vaguely described bullets). I have seen other discussions in various places, but nothing I felt I could use. I propose a simpler solution based on WeakReference, as described here. My question is: Does this not meet the requirements with significantly less complexity? To use the solution, the above code is modified as follows: class Foo { public WeakReferenceEvent AnEvent = new WeakReferenceEvent(); internal void DoEvent() { AnEvent.Invoke(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } Notice two things: 1. The Foo class is modified in two ways: The event is replaced with an instance of WeakReferenceEvent, shown below; and the invocation of the event is changed. 2. The Bar class is UNCHANGED. No need to subclass WeakEventManager, implement IWeakEventListener, etc. OK, so on to the implementation of WeakReferenceEvent. This is shown here. Note that it uses the generic WeakReference that I borrowed from here: http://damieng.com/blog/2006/08/01/implementingweakreferencet I had to add Equals() and GetHashCode() to his class, which I include below for reference. class WeakReferenceEvent { public static WeakReferenceEvent operator +(WeakReferenceEvent wre, Action handler) { wre._delegates.Add(new WeakReference<Action>(handler)); return wre; } public static WeakReferenceEvent operator -(WeakReferenceEvent wre, Action handler) { foreach (var del in wre._delegates) if (del.Target == handler) { wre._delegates.Remove(del); return wre; } return wre; } HashSet<WeakReference<Action>> _delegates = new HashSet<WeakReference<Action>>(); internal void Invoke() { HashSet<WeakReference<Action>> toRemove = null; foreach (var del in _delegates) { if (del.IsAlive) del.Target(); else { if (toRemove == null) toRemove = new HashSet<WeakReference<Action>>(); toRemove.Add(del); } } if (toRemove != null) foreach (var del in toRemove) _delegates.Remove(del); } } public class WeakReference<T> : IDisposable { private GCHandle handle; private bool trackResurrection; public WeakReference(T target) : this(target, false) { } public WeakReference(T target, bool trackResurrection) { this.trackResurrection = trackResurrection; this.Target = target; } ~WeakReference() { Dispose(); } public void Dispose() { handle.Free(); GC.SuppressFinalize(this); } public virtual bool IsAlive { get { return (handle.Target != null); } } public virtual bool TrackResurrection { get { return this.trackResurrection; } } public virtual T Target { get { object o = handle.Target; if ((o == null) || (!(o is T))) return default(T); else return (T)o; } set { handle = GCHandle.Alloc(value, this.trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak); } } public override bool Equals(object obj) { var other = obj as WeakReference<T>; return other != null && Target.Equals(other.Target); } public override int GetHashCode() { return Target.GetHashCode(); } } It's functionality is trivial. I override operator + and - to get the += and -= syntactic sugar matching events. These create WeakReferences to the Action delegate. This allows the garbage collector to free the event target object (Bar in this example) when nobody else is holding on to it. In the Invoke() method, simply run through the weak references and call their Target Action. If any dead (i.e., garbage collected) references are found, remove them from the list. Of course, this only works with delegates of type Action. I tried making this generic, but ran into the missing where T : delegate in C#! As an alternative, simply modify class WeakReferenceEvent to be a WeakReferenceEvent, and replace the Action with Action. Fix the compiler errors and you have a class that can be used like so: class Foo { public WeakReferenceEvent<int> AnEvent = new WeakReferenceEvent<int>(); internal void DoEvent() { AnEvent.Invoke(5); } } Hopefully this will help someone else when they run into the mystery .NET event memory leak!

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  • my server suddenly crashes every 2 days or so. Programmer has no idea, please help find the cause, here is the top

    - by Alex
    Every couple of days my server suddenly crashes and I must request hardware reset at data center to get it back running. Today I came back to my shell and saw the server was dead and "top" was running on it, and see below for the "top" right before the crash. I opened /var/log/messages and scrolled to the reboot time and see nothing, no errors prior to the hard reboot. (I checked in /etc/syslog.conf and I see "*.info;mail.none;authpriv.none;cron.none /var/log/messages" , isn't this good enough to log all problems?) Usually when I look at the top, the swap is never used up like this! I also don't know why mysqld is at 323% cpu (server only runs drupal and its never slow or overloaded). Solver is my application. I don't know whats that 'sh' doing and 'dovecot' doing. Its driving me crazy over the last month, please help me solve this mystery and stop my downtimes. top - 01:10:06 up 6 days, 5 min, 3 users, load average: 34.87, 18.68, 9.03 Tasks: 500 total, 19 running, 481 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 96.6%sy, 0.0%ni, 1.7%id, 1.8%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8165600k total, 8139764k used, 25836k free, 428k buffers Swap: 2104496k total, 2104496k used, 0k free, 8236k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4421 mysql 15 0 571m 105m 976 S 323.5 1.3 9:08.00 mysqld 564 root 20 -5 0 0 0 R 99.5 0.0 2:49.16 kswapd1 25767 apache 19 0 399m 8060 888 D 79.3 0.1 0:06.64 httpd 25781 apache 19 0 398m 5648 492 R 79.0 0.1 0:08.21 httpd 25961 apache 25 0 398m 5700 560 R 76.7 0.1 0:17.81 httpd 25980 apache 25 0 10816 668 520 R 75.0 0.0 0:46.95 sh 563 root 20 -5 0 0 0 D 71.4 0.0 3:12.37 kswapd0 25766 apache 25 0 399m 7256 756 R 69.7 0.1 0:39.83 httpd 25911 apache 25 0 398m 5612 480 R 58.8 0.1 0:17.63 httpd 25782 apache 25 0 440m 38m 648 R 55.2 0.5 0:18.94 httpd 25966 apache 25 0 398m 5640 556 R 55.2 0.1 0:48.84 httpd 4588 root 25 0 74860 596 476 R 53.9 0.0 0:37.90 crond 25939 apache 25 0 2776 172 84 R 48.9 0.0 0:59.46 solver 4575 root 25 0 397m 6004 1144 R 48.6 0.1 1:00.43 httpd 25962 apache 25 0 398m 5628 492 R 47.9 0.1 0:14.58 httpd 25824 apache 25 0 440m 39m 680 D 47.3 0.5 0:57.85 httpd 25968 apache 25 0 398m 5612 528 R 46.6 0.1 0:42.73 httpd 4477 root 25 0 6084 396 280 R 46.3 0.0 0:59.53 dovecot 25982 root 25 0 397m 5108 240 R 45.9 0.1 0:18.01 httpd 25943 apache 25 0 2916 172 8 R 44.0 0.0 0:53.54 solver 30687 apache 25 0 468m 63m 1124 D 42.3 0.8 0:45.02 httpd 25978 apache 25 0 398m 5688 600 R 23.8 0.1 0:40.99 httpd 25983 root 25 0 397m 5272 384 D 14.9 0.1 0:18.99 httpd 935 root 10 -5 0 0 0 D 14.2 0.0 1:54.60 kjournald 25986 root 25 0 397m 5308 420 D 8.9 0.1 0:04.75 httpd 4011 haldaemo 25 0 31568 1476 716 S 5.6 0.0 0:24.36 hald 25956 apache 23 0 398m 5872 644 S 5.6 0.1 0:13.85 httpd 18336 root 18 0 13004 1332 724 R 0.3 0.0 1:46.66 top 1 root 18 0 10372 212 180 S 0.0 0.0 0:05.99 init 2 root RT -5 0 0 0 S 0.0 0.0 0:00.95 migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/0 4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 5 root RT -5 0 0 0 S 0.0 0.0 0:00.15 migration/1 6 root 34 19 0 0 0 S 0.0 0.0 0:00 .06 ksoftirqd/1 here is a normal top, when server is working fine: top - 01:50:41 up 21 min, 1 user, load average: 2.98, 2.70, 1.68 Tasks: 271 total, 2 running, 269 sleeping, 0 stopped, 0 zombie Cpu(s): 15.0%us, 1.1%sy, 0.0%ni, 81.4%id, 2.4%wa, 0.1%hi, 0.0%si, 0.0%st Mem: 8165600k total, 2035856k used, 6129744k free, 60840k buffers Swap: 2104496k total, 0k used, 2104496k free, 283744k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2204 apache 17 0 466m 83m 19m S 25.9 1.0 0:22.16 httpd 11347 apache 15 0 466m 83m 19m S 25.9 1.0 0:26.10 httpd 18204 apache 18 0 481m 97m 19m D 25.2 1.2 0:13.99 httpd 4644 apache 18 0 481m 100m 19m D 24.6 1.3 1:17.12 httpd 4727 apache 17 0 481m 99m 19m S 24.3 1.2 1:10.77 httpd 4777 apache 17 0 482m 102m 21m S 23.6 1.3 1:38.27 httpd 8924 apache 15 0 483m 99m 19m S 22.3 1.3 1:13.41 httpd 9390 apache 18 0 483m 99m 19m S 18.9 1.2 1:05.35 httpd 4728 apache 16 0 481m 101m 19m S 14.3 1.3 1:12.50 httpd 4648 apache 15 0 481m 107m 27m S 12.6 1.4 1:18.62 httpd 24955 apache 15 0 467m 82m 19m S 3.3 1.0 0:21.80 httpd 4722 apache 15 0 503m 118m 19m R 1.7 1.5 1:17.79 httpd 4647 apache 15 0 484m 105m 20m S 1.3 1.3 1:40.73 httpd 4643 apache 16 0 481m 100m 20m S 0.7 1.3 1:11.80 httpd 1561 root 15 0 12900 1264 828 R 0.3 0.0 0:00.54 top 4434 mysql 15 0 496m 55m 4812 S 0.3 0.7 0:06.69 mysqld 4646 apache 15 0 481m 100m 19m S 0.3 1.3 1:25.51 httpd 1 root 18 0 10372 692 580 S 0.0 0.0 0:02.09 init 2 root RT -5 0 0 0 S 0.0 0.0 0:00.03 migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0 4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 5 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/1 6 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1 7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1 8 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/2 9 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2 10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2 11 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/3 12 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/3 13 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/3 14 root RT -5 0 0 0 S 0.0 0.0 0:00.03 migration/4 15 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/4 16 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/4 17 root RT -5 0 0 0 S 0.0 0.0 0:00.02 migration/5 18 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/5 19 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/5 20 root RT -5 0 0 0 S 0.0 0.0 0:00.01 migration/6 21 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/6 22 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/6 23 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/7

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  • The broken Promise of the Mobile Web

    - by Rick Strahl
    High end mobile devices have been with us now for almost 7 years and they have utterly transformed the way we access information. Mobile phones and smartphones that have access to the Internet and host smart applications are in the hands of a large percentage of the population of the world. In many places even very remote, cell phones and even smart phones are a common sight. I’ll never forget when I was in India in 2011 I was up in the Southern Indian mountains riding an elephant out of a tiny local village, with an elephant herder in front riding atop of the elephant in front of us. He was dressed in traditional garb with the loin wrap and head cloth/turban as did quite a few of the locals in this small out of the way and not so touristy village. So we’re slowly trundling along in the forest and he’s lazily using his stick to guide the elephant and… 10 minutes in he pulls out his cell phone from his sash and starts texting. In the middle of texting a huge pig jumps out from the side of the trail and he takes a picture running across our path in the jungle! So yeah, mobile technology is very pervasive and it’s reached into even very buried and unexpected parts of this world. Apps are still King Apps currently rule the roost when it comes to mobile devices and the applications that run on them. If there’s something that you need on your mobile device your first step usually is to look for an app, not use your browser. But native app development remains a pain in the butt, with the requirement to have to support 2 or 3 completely separate platforms. There are solutions that try to bridge that gap. Xamarin is on a tear at the moment, providing their cross-device toolkit to build applications using C#. While Xamarin tools are impressive – and also *very* expensive – they only address part of the development madness that is app development. There are still specific device integration isssues, dealing with the different developer programs, security and certificate setups and all that other noise that surrounds app development. There’s also PhoneGap/Cordova which provides a hybrid solution that involves creating local HTML/CSS/JavaScript based applications, and then packaging them to run in a specialized App container that can run on most mobile device platforms using a WebView interface. This allows for using of HTML technology, but it also still requires all the set up, configuration of APIs, security keys and certification and submission and deployment process just like native applications – you actually lose many of the benefits that  Web based apps bring. The big selling point of Cordova is that you get to use HTML have the ability to build your UI once for all platforms and run across all of them – but the rest of the app process remains in place. Apps can be a big pain to create and manage especially when we are talking about specialized or vertical business applications that aren’t geared at the mainstream market and that don’t fit the ‘store’ model. If you’re building a small intra department application you don’t want to deal with multiple device platforms and certification etc. for various public or corporate app stores. That model is simply not a good fit both from the development and deployment perspective. Even for commercial, big ticket apps, HTML as a UI platform offers many advantages over native, from write-once run-anywhere, to remote maintenance, single point of management and failure to having full control over the application as opposed to have the app store overloads censor you. In a lot of ways Web based HTML/CSS/JavaScript applications have so much potential for building better solutions based on existing Web technologies for the very same reasons a lot of content years ago moved off the desktop to the Web. To me the Web as a mobile platform makes perfect sense, but the reality of today’s Mobile Web unfortunately looks a little different… Where’s the Love for the Mobile Web? Yet here we are in the middle of 2014, nearly 7 years after the first iPhone was released and brought the promise of rich interactive information at your fingertips, and yet we still don’t really have a solid mobile Web platform. I know what you’re thinking: “But we have lots of HTML/JavaScript/CSS features that allows us to build nice mobile interfaces”. I agree to a point – it’s actually quite possible to build nice looking, rich and capable Web UI today. We have media queries to deal with varied display sizes, CSS transforms for smooth animations and transitions, tons of CSS improvements in CSS 3 that facilitate rich layout, a host of APIs geared towards mobile device features and lately even a number of JavaScript framework choices that facilitate development of multi-screen apps in a consistent manner. Personally I’ve been working a lot with AngularJs and heavily modified Bootstrap themes to build mobile first UIs and that’s been working very well to provide highly usable and attractive UI for typical mobile business applications. From the pure UI perspective things actually look very good. Not just about the UI But it’s not just about the UI - it’s also about integration with the mobile device. When it comes to putting all those pieces together into what amounts to a consolidated platform to build mobile Web applications, I think we still have a ways to go… there are a lot of missing pieces to make it all work together and integrate with the device more smoothly, and more importantly to make it work uniformly across the majority of devices. I think there are a number of reasons for this. Slow Standards Adoption HTML standards implementations and ratification has been dreadfully slow, and browser vendors all seem to pick and choose different pieces of the technology they implement. The end result is that we have a capable UI platform that’s missing some of the infrastructure pieces to make it whole on mobile devices. There’s lots of potential but what is lacking that final 10% to build truly compelling mobile applications that can compete favorably with native applications. Some of it is the fragmentation of browsers and the slow evolution of the mobile specific HTML APIs. A host of mobile standards exist but many of the standards are in the early review stage and they have been there stuck for long periods of time and seem to move at a glacial pace. Browser vendors seem even slower to implement them, and for good reason – non-ratified standards mean that implementations may change and vendor implementations tend to be experimental and  likely have to be changed later. Neither Vendors or developers are not keen on changing standards. This is the typical chicken and egg scenario, but without some forward momentum from some party we end up stuck in the mud. It seems that either the standards bodies or the vendors need to carry the torch forward and that doesn’t seem to be happening quickly enough. Mobile Device Integration just isn’t good enough Current standards are not far reaching enough to address a number of the use case scenarios necessary for many mobile applications. While not every application needs to have access to all mobile device features, almost every mobile application could benefit from some integration with other parts of the mobile device platform. Integration with GPS, phone, media, messaging, notifications, linking and contacts system are benefits that are unique to mobile applications and could be widely used, but are mostly (with the exception of GPS) inaccessible for Web based applications today. Unfortunately trying to do most of this today only with a mobile Web browser is a losing battle. Aside from PhoneGap/Cordova’s app centric model with its own custom API accessing mobile device features and the token exception of the GeoLocation API, most device integration features are not widely supported by the current crop of mobile browsers. For example there’s no usable messaging API that allows access to SMS or contacts from HTML. Even obvious components like the Media Capture API are only implemented partially by mobile devices. There are alternatives and workarounds for some of these interfaces by using browser specific code, but that’s might ugly and something that I thought we were trying to leave behind with newer browser standards. But it’s not quite working out that way. It’s utterly perplexing to me that mobile standards like Media Capture and Streams, Media Gallery Access, Responsive Images, Messaging API, Contacts Manager API have only minimal or no traction at all today. Keep in mind we’ve had mobile browsers for nearly 7 years now, and yet we still have to think about how to get access to an image from the image gallery or the camera on some devices? Heck Windows Phone IE Mobile just gained the ability to upload images recently in the Windows 8.1 Update – that’s feature that HTML has had for 20 years! These are simple concepts and common problems that should have been solved a long time ago. It’s extremely frustrating to see build 90% of a mobile Web app with relative ease and then hit a brick wall for the remaining 10%, which often can be show stoppers. The remaining 10% have to do with platform integration, browser differences and working around the limitations that browsers and ‘pinned’ applications impose on HTML applications. The maddening part is that these limitations seem arbitrary as they could easily work on all mobile platforms. For example, SMS has a URL Moniker interface that sort of works on Android, works badly with iOS (only works if the address is already in the contact list) and not at all on Windows Phone. There’s no reason this shouldn’t work universally using the same interface – after all all phones have supported SMS since before the year 2000! But, it doesn’t have to be this way Change can happen very quickly. Take the GeoLocation API for example. Geolocation has taken off at the very beginning of the mobile device era and today it works well, provides the necessary security (a big concern for many mobile APIs), and is supported by just about all major mobile and even desktop browsers today. It handles security concerns via prompts to avoid unwanted access which is a model that would work for most other device APIs in a similar fashion. One time approval and occasional re-approval if code changes or caches expire. Simple and only slightly intrusive. It all works well, even though GeoLocation actually has some physical limitations, such as representing the current location when no GPS device is present. Yet this is a solved problem, where other APIs that are conceptually much simpler to implement have failed to gain any traction at all. Technically none of these APIs should be a problem to implement, but it appears that the momentum is just not there. Inadequate Web Application Linking and Activation Another important piece of the puzzle missing is the integration of HTML based Web applications. Today HTML based applications are not first class citizens on mobile operating systems. When talking about HTML based content there’s a big difference between content and applications. Content is great for search engine discovery and plain browser usage. Content is usually accessed intermittently and permanent linking is not so critical for this type of content.  But applications have different needs. Applications need to be started up quickly and must be easily switchable to support a multi-tasking user workflow. Therefore, it’s pretty crucial that mobile Web apps are integrated into the underlying mobile OS and work with the standard task management features. Unfortunately this integration is not as smooth as it should be. It starts with actually trying to find mobile Web applications, to ‘installing’ them onto a phone in an easily accessible manner in a prominent position. The experience of discovering a Mobile Web ‘App’ and making it sticky is by no means as easy or satisfying. Today the way you’d go about this is: Open the browser Search for a Web Site in the browser with your search engine of choice Hope that you find the right site Hope that you actually find a site that works for your mobile device Click on the link and run the app in a fully chrome’d browser instance (read tiny surface area) Pin the app to the home screen (with all the limitations outline above) Hope you pointed at the right URL when you pinned Even for you and me as developers, there are a few steps in there that are painful and annoying, but think about the average user. First figuring out how to search for a specific site or URL? And then pinning the app and hopefully from the right location? You’ve probably lost more than half of your audience at that point. This experience sucks. For developers too this process is painful since app developers can’t control the shortcut creation directly. This problem often gets solved by crazy coding schemes, with annoying pop-ups that try to get people to create shortcuts via fancy animations that are both annoying and add overhead to each and every application that implements this sort of thing differently. And that’s not the end of it - getting the link onto the home screen with an application icon varies quite a bit between browsers. Apple’s non-standard meta tags are prominent and they work with iOS and Android (only more recent versions), but not on Windows Phone. Windows Phone instead requires you to create an actual screen or rather a partial screen be captured for a shortcut in the tile manager. Who had that brilliant idea I wonder? Surprisingly Chrome on recent Android versions seems to actually get it right – icons use pngs, pinning is easy and pinned applications properly behave like standalone apps and retain the browser’s active page state and content. Each of the platforms has a different way to specify icons (WP doesn’t allow you to use an icon image at all), and the most widely used interface in use today is a bunch of Apple specific meta tags that other browsers choose to support. The question is: Why is there no standard implementation for installing shortcuts across mobile platforms using an official format rather than a proprietary one? Then there’s iOS and the crazy way it treats home screen linked URLs using a crazy hybrid format that is neither as capable as a Web app running in Safari nor a WebView hosted application. Moving off the Web ‘app’ link when switching to another app actually causes the browser and preview it to ‘blank out’ the Web application in the Task View (see screenshot on the right). Then, when the ‘app’ is reactivated it ends up completely restarting the browser with the original link. This is crazy behavior that you can’t easily work around. In some situations you might be able to store the application state and restore it using LocalStorage, but for many scenarios that involve complex data sources (like say Google Maps) that’s not a possibility. The only reason for this screwed up behavior I can think of is that it is deliberate to make Web apps a pain in the butt to use and forcing users trough the App Store/PhoneGap/Cordova route. App linking and management is a very basic problem – something that we essentially have solved in every desktop browser – yet on mobile devices where it arguably matters a lot more to have easy access to web content we have to jump through hoops to have even a remotely decent linking/activation experience across browsers. Where’s the Money? It’s not surprising that device home screen integration and Mobile Web support in general is in such dismal shape – the mobile OS vendors benefit financially from App store sales and have little to gain from Web based applications that bypass the App store and the cash cow that it presents. On top of that, platform specific vendor lock-in of both end users and developers who have invested in hardware, apps and consumables is something that mobile platform vendors actually aspire to. Web based interfaces that are cross-platform are the anti-thesis of that and so again it’s no surprise that the mobile Web is on a struggling path. But – that may be changing. More and more we’re seeing operations shifting to services that are subscription based or otherwise collect money for usage, and that may drive more progress into the Web direction in the end . Nothing like the almighty dollar to drive innovation forward. Do we need a Mobile Web App Store? As much as I dislike moderated experiences in today’s massive App Stores, they do at least provide one single place to look for apps for your device. I think we could really use some sort of registry, that could provide something akin to an app store for mobile Web apps, to make it easier to actually find mobile applications. This could take the form of a specialized search engine, or maybe a more formal store/registry like structure. Something like apt-get/chocolatey for Web apps. It could be curated and provide at least some feedback and reviews that might help with the integrity of applications. Coupled to that could be a native application on each platform that would allow searching and browsing of the registry and then also handle installation in the form of providing the home screen linking, plus maybe an initial security configuration that determines what features are allowed access to for the app. I’m not holding my breath. In order for this sort of thing to take off and gain widespread appeal, a lot of coordination would be required. And in order to get enough traction it would have to come from a well known entity – a mobile Web app store from a no name source is unlikely to gain high enough usage numbers to make a difference. In a way this would eliminate some of the freedom of the Web, but of course this would also be an optional search path in addition to the standard open Web search mechanisms to find and access content today. Security Security is a big deal, and one of the perceived reasons why so many IT professionals appear to be willing to go back to the walled garden of deployed apps is that Apps are perceived as safe due to the official review and curation of the App stores. Curated stores are supposed to protect you from malware, illegal and misleading content. It doesn’t always work out that way and all the major vendors have had issues with security and the review process at some time or another. Security is critical, but I also think that Web applications in general pose less of a security threat than native applications, by nature of the sandboxed browser and JavaScript environments. Web applications run externally completely and in the HTML and JavaScript sandboxes, with only a very few controlled APIs allowing access to device specific features. And as discussed earlier – security for any device interaction can be granted the same for mobile applications through a Web browser, as they can for native applications either via explicit policies loaded from the Web, or via prompting as GeoLocation does today. Security is important, but it’s certainly solvable problem for Web applications even those that need to access device hardware. Security shouldn’t be a reason for Web apps to be an equal player in mobile applications. Apps are winning, but haven’t we been here before? So now we’re finding ourselves back in an era of installed app, rather than Web based and managed apps. Only it’s even worse today than with Desktop applications, in that the apps are going through a gatekeeper that charges a toll and censors what you can and can’t do in your apps. Frankly it’s a mystery to me why anybody would buy into this model and why it’s lasted this long when we’ve already been through this process. It’s crazy… It’s really a shame that this regression is happening. We have the technology to make mobile Web apps much more prominent, but yet we’re basically held back by what seems little more than bureaucracy, partisan bickering and self interest of the major parties involved. Back in the day of the desktop it was Internet Explorer’s 98+%  market shareholding back the Web from improvements for many years – now it’s the combined mobile OS market in control of the mobile browsers. If mobile Web apps were allowed to be treated the same as native apps with simple ways to install and run them consistently and persistently, that would go a long way to making mobile applications much more usable and seriously viable alternatives to native apps. But as it is mobile apps have a severe disadvantage in placement and operation. There are a few bright spots in all of this. Mozilla’s FireFoxOs is embracing the Web for it’s mobile OS by essentially building every app out of HTML and JavaScript based content. It supports both packaged and certified package modes (that can be put into the app store), and Open Web apps that are loaded and run completely off the Web and can also cache locally for offline operation using a manifest. Open Web apps are treated as full class citizens in FireFoxOS and run using the same mechanism as installed apps. Unfortunately FireFoxOs is getting a slow start with minimal device support and specifically targeting the low end market. We can hope that this approach will change and catch on with other vendors, but that’s also an uphill battle given the conflict of interest with platform lock in that it represents. Recent versions of Android also seem to be working reasonably well with mobile application integration onto the desktop and activation out of the box. Although it still uses the Apple meta tags to find icons and behavior settings, everything at least works as you would expect – icons to the desktop on pinning, WebView based full screen activation, and reliable application persistence as the browser/app is treated like a real application. Hopefully iOS will at some point provide this same level of rudimentary Web app support. What’s also interesting to me is that Microsoft hasn’t picked up on the obvious need for a solid Web App platform. Being a distant third in the mobile OS war, Microsoft certainly has nothing to lose and everything to gain by using fresh ideas and expanding into areas that the other major vendors are neglecting. But instead Microsoft is trying to beat the market leaders at their own game, fighting on their adversary’s terms instead of taking a new tack. Providing a kick ass mobile Web platform that takes the lead on some of the proposed mobile APIs would be something positive that Microsoft could do to improve its miserable position in the mobile device market. Where are we at with Mobile Web? It sure sounds like I’m really down on the Mobile Web, right? I’ve built a number of mobile apps in the last year and while overall result and response has been very positive to what we were able to accomplish in terms of UI, getting that final 10% that required device integration dialed was an absolute nightmare on every single one of them. Big compromises had to be made and some features were left out or had to be modified for some devices. In two cases we opted to go the Cordova route in order to get the integration we needed, along with the extra pain involved in that process. Unless you’re not integrating with device features and you don’t care deeply about a smooth integration with the mobile desktop, mobile Web development is fraught with frustration. So, yes I’m frustrated! But it’s not for lack of wanting the mobile Web to succeed. I am still a firm believer that we will eventually arrive a much more functional mobile Web platform that allows access to the most common device features in a sensible way. It wouldn't be difficult for device platform vendors to make Web based applications first class citizens on mobile devices. But unfortunately it looks like it will still be some time before this happens. So, what’s your experience building mobile Web apps? Are you finding similar issues? Just giving up on raw Web applications and building PhoneGap apps instead? Completely skipping the Web and going native? Leave a comment for discussion. Resources Rick Strahl on DotNet Rocks talking about Mobile Web© Rick Strahl, West Wind Technologies, 2005-2014Posted in HTML5  Mobile   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • ANTS CLR and Memory Profiler In Depth Review (Part 1 of 2 &ndash; CLR Profiler)

    - by ToStringTheory
    One of the things that people might not know about me, is my obsession to make my code as efficient as possible.  Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind…  In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve.  One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well.  In this review, I am going to cover some of the features of the ANTS profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program.  I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction The ANTS Profiler pack provided by Red Gate was something that I had not heard of before receiving an email regarding an offer to review it for a license.  Since I look to make my code efficient, it was a no brainer for me to try it out!  One thing that I have to say took me by surprise is that upon downloading the program and installing it you fill out a form for your usual contact information.  Sure enough within 2 hours, I received an email from a sales representative at Red Gate asking if she could help me to achieve the most out of my trial time so it wouldn’t go to waste.  After replying to her and explaining that I was looking to review its feature set, she put me in contact with someone that setup a demo session to give me a quick rundown of its features via an online meeting.  After having dealt with a massive ordeal with one of my utility companies and their complete lack of customer service, Red Gates friendly and helpful representatives were a breath of fresh air, and something I was thankful for. ANTS CLR Profiler The ANTS CLR profiler is the thing I want to focus on the most in this post, so I am going to dive right in now. Install was simple and took no time at all.  It installed both the profiler for the CLR and Memory, but also visual studio extensions to facilitate the usage of the profilers (click any images for full size images): The Visual Studio menu options (under ANTS menu) Starting the CLR Performance Profiler from the start menu yields this window If you follow the instructions after launching the program from the start menu (Click File > New Profiling Session to start a new project), you are given a dialog with plenty of options for profiling: The New Session dialog.  Lots of options.  One thing I noticed is that the buttons in the lower right were half-covered by the panel of the application.  If I had to guess, I would imagine that this is caused by my DPI settings being set to 125%.  This is a problem I have seen in other applications as well that don’t scale well to different dpi scales. The profiler options give you the ability to profile: .NET Executable ASP.NET web application (hosted in IIS) ASP.NET web application (hosted in IIS express) ASP.NET web application (hosted in Cassini Web Development Server) SharePoint web application (hosted in IIS) Silverlight 4+ application Windows Service COM+ server XBAP (local XAML browser application) Attach to an already running .NET 4 process Choosing each option provides a varying set of other variables/options that one can set including options such as application arguments, operating path, record I/O performance performance counters to record (43 counters in all!), etc…  All in all, they give you the ability to profile many different .Net project types, and make it simple to do so.  In most cases of my using this application, I would be using the built in Visual Studio extensions, as they automatically start a new profiling project in ANTS with the options setup, and start your program, however RedGate has made it easy enough to profile outside of Visual Studio as well. On the flip side of this, as someone who lives most of their work life in Visual Studio, one thing I do wish is that instead of opening an entirely separate application/gui to perform profiling after launching, that instead they would provide a Visual Studio panel with the information, and integrate more of the profiling project information into Visual Studio.  So, now that we have an idea of what options that the profiler gives us, its time to test its abilities and features. Horrendous Example Code – Prime Number Generator One of my interests besides development, is Physics and Math – what I went to college for.  I have especially always been interested in prime numbers, as they are something of a mystery…  So, I decided that I would go ahead and to test the abilities of the profiler, I would write a small program, website, and library to generate prime numbers in the quantity that you ask for.  I am going to start off with some terrible code, and show how I would see the profiler being used as a development tool. First off, the IPrimes interface (all code is downloadable at the end of the post): interface IPrimes { IEnumerable<int> GetPrimes(int retrieve); } Simple enough, right?  Anything that implements the interface will (hopefully) provide an IEnumerable of int, with the quantity specified in the parameter argument.  Next, I am going to implement this interface in the most basic way: public class DumbPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _analyzing = 4; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; //start dividing at 2 //divide until number is reached, or determined not prime for (int i = 2; i < _analyzing && isPrime; i++) { //if (i) goes into _analyzing without a remainder, //_analyzing is NOT prime if (_analyzing % i == 0) isPrime = false; } //if it is prime, add to found list if (isPrime) _foundPrimes.Add(_analyzing); //increment number to analyze next _analyzing++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } This is the simplest way to get primes in my opinion.  Checking each number by the straight definition of a prime – is it divisible by anything besides 1 and itself. I have included this code in a base class library for my solution, as I am going to use it to demonstrate a couple of features of ANTS.  This class library is consumed by a simple non-MVVM WPF application, and a simple MVC4 website.  I will not post the WPF code here inline, as it is simply an ObservableCollection<int>, a label, two textbox’s, and a button. Starting a new Profiling Session So, in Visual Studio, I have just completed my first stint developing the GUI and DumbPrimes IPrimes class, so now I want to check my codes efficiency by profiling it.  All I have to do is build the solution (surprised initiating a profiling session doesn’t do this, but I suppose I can understand it), and then click the ANTS menu, followed by Profile Performance.  I am then greeted by the profiler starting up and already monitoring my program live: You are provided with a realtime graph at the top, and a pane at the bottom giving you information on how to proceed.  I am going to start by asking my program to show me the first 15000 primes: After the program finally began responding again (I did all the work on the main UI thread – how bad!), I stopped the profiler, which did kill the process of my program too.  One important thing to note, is that the profiler by default wants to give you a lot of detail about the operation – line hit counts, time per line, percent time per line, etc…  The important thing to remember is that this itself takes a lot of time.  When running my program without the profiler attached, it can generate the 15000 primes in 5.18 seconds, compared to 74.5 seconds – almost a 1500 percent increase.  While this may seem like a lot, remember that there is a trade off.  It may be WAY more inefficient, however, I am able to drill down and make improvements to specific problem areas, and then decrease execution time all around. Analyzing the Profiling Session After clicking ‘Stop Profiling’, the process running my application stopped, and the entire execution time was automatically selected by ANTS, and the results shown below: Now there are a number of interesting things going on here, I am going to cover each in a section of its own: Real Time Performance Counter Bar (top of screen) At the top of the screen, is the real time performance bar.  As your application is running, this will constantly update with the currently selected performance counters status.  A couple of cool things to note are the fact that you can drag a selection around specific time periods to drill down the detail views in the lower 2 panels to information pertaining to only that period. After selecting a time period, you can bookmark a section and name it, so that it is easy to find later, or after reloaded at a later time.  You can also zoom in, out, or fit the graph to the space provided – useful for drilling down. It may be hard to see, but at the top of the processor time graph below the time ticks, but above the red usage graph, there is a green bar. This bar shows at what times a method that is selected in the ‘Call tree’ panel is called. Very cool to be able to click on a method and see at what times it made an impact. As I said before, ANTS provides 43 different performance counters you can hook into.  Click the arrow next to the Performance tab at the top will allow you to change between different counters if you have them selected: Method Call Tree, ADO.Net Database Calls, File IO – Detail Panel Red Gate really hit the mark here I think. When you select a section of the run with the graph, the call tree populates to fill a hierarchical tree of method calls, with information regarding each of the methods.   By default, methods are hidden where the source is not provided (framework type code), however, Red Gate has integrated Reflector into ANTS, so even if you don’t have source for something, you can select a method and get the source if you want.  Methods are also hidden where the impact is seen as insignificant – methods that are only executed for 1% of the time of the overall calling methods time; in other words, working on making them better is not where your efforts should be focused. – Smart! Source Panel – Detail Panel The source panel is where you can see line level information on your code, showing the code for the currently selected method from the Method Call Tree.  If the code is not available, Reflector takes care of it and shows the code anyways! As you can notice, there does seem to be a problem with how ANTS determines what line is the actual line that a call is completed on.  I have suspicions that this may be due to some of the inline code optimizations that the CLR applies upon compilation of the assembly.  In a method with comments, the problem is much more severe: As you can see here, apparently the most offending code in my base library was a comment – *gasp*!  Removing the comments does help quite a bit, however I hope that Red Gate works on their counter algorithm soon to improve the logic on positioning for statistics: I did a small test just to demonstrate the lines are correct without comments. For me, it isn’t a deal breaker, as I can usually determine the correct placements by looking at the application code in the region and determining what makes sense, but it is something that would probably build up some irritation with time. Feature – Suggest Method for Optimization A neat feature to really help those in need of a pointer, is the menu option under tools to automatically suggest methods to optimize/improve: Nice feature – clicking it filters the call tree and stars methods that it thinks are good candidates for optimization.  I do wish that they would have made it more visible for those of use who aren’t great on sight: Process Integration I do think that this could have a place in my process.  After experimenting with the profiler, I do think it would be a great benefit to do some development, testing, and then after all the bugs are worked out, use the profiler to check on things to make sure nothing seems like it is hogging more than its fair share.  For example, with this program, I would have developed it, ran it, tested it – it works, but slowly. After looking at the profiler, and seeing the massive amount of time spent in 1 method, I might go ahead and try to re-implement IPrimes (I actually would probably rewrite the offending code, but so that I can distribute both sets of code easily, I’m just going to make another implementation of IPrimes).  Using two pieces of knowledge about prime numbers can make this method MUCH more efficient – prime numbers fall into two buckets 6k+/-1 , and a number is prime if it is not divisible by any other primes before it: public class SmartPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _k = 1; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; int potentialPrime; //analyze 6k-1 //assign the value to potential potentialPrime = 6 * _k - 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); if (_foundPrimes.Count() == retrieve) break; //analyze 6k+1 //assign the value to potential potentialPrime = 6 * _k + 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); //increment k to analyze next _k++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } Now there are definitely more things I can do to help make this more efficient, but for the scope of this example, I think this is fine (but still hideous)! Profiling this now yields a happy surprise 27 seconds to generate the 15000 primes with the profiler attached, and only 1.43 seconds without.  One important thing I wanted to call out though was the performance graph now: Notice anything odd?  The %Processor time is above 100%.  This is because there is now more than 1 core in the operation.  A better label for the chart in my mind would have been %Core time, but to each their own. Another odd thing I noticed was that the profiler seemed to be spot on this time in my DumbPrimes class with line details in source, even with comments..  Odd. Profiling Web Applications The last thing that I wanted to cover, that means a lot to me as a web developer, is the great amount of work that Red Gate put into the profiler when profiling web applications.  In my solution, I have a simple MVC4 application setup with 1 page, a single input form, that will output prime values as my WPF app did.  Launching the profiler from Visual Studio as before, nothing is really different in the profiler window, however I did receive a UAC prompt for a Red Gate helper app to integrate with the web server without notification. After requesting 500, 1000, 2000, and 5000 primes, and looking at the profiler session, things are slightly different from before: As you can see, there are 4 spikes of activity in the processor time graph, but there is also something new in the call tree: That’s right – ANTS will actually group method calls by get/post operations, so it is easier to find out what action/page is giving the largest problems…  Pretty cool in my mind! Overview Overall, I think that Red Gate ANTS CLR Profiler has a lot to offer, however I think it also has a long ways to go.  3 Biggest Pros: Ability to easily drill down from time graph, to method calls, to source code Wide variety of counters to choose from when profiling your application Excellent integration/grouping of methods being called from web applications by request – BRILLIANT! 3 Biggest Cons: Issue regarding line details in source view Nit pick – Processor time vs. Core time Nit pick – Lack of full integration with Visual Studio Ratings Ease of Use (7/10) – I marked down here because of the problems with the line level details and the extra work that that entails, and the lack of better integration with Visual Studio. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Especially with its large variety of performance counters, a definite plus! Features (9/10) – Besides the real time performance monitoring, and the drill downs that I’ve shown here, ANTS also has great integration with ADO.Net, with the ability to show database queries run by your application in the profiler.  This, with the line level details, the web request grouping, reflector integration, and various options to customize your profiling session I think create a great set of features! Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (8/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (8/10) – Overall, I am happy with the Performance Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  I WOULD recommend you trying the application and seeing if it would fit into your process, BUT, remember there are still some kinks in it to hopefully be worked out. My next post will definitely be shorter (hopefully), but thank you for reading up to here, or skipping ahead!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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  • Why download popup window in browser not showing up when using JAX-RS v.s. standard servlet?

    - by masato-san
    When I try using standard servlet approach, in my browser the popup window shows up asking me whether to open .xls file or save it. I tried the exactly same code via JAX-RS and the browser popup won't show up somehow. Has anyone encounter this mystery? Standard servlet that works: package local.test.servlet; import java.io.IOException; import java.net.URL; import java.net.URLDecoder; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import local.test.jaxrs.ExcellaTestResource; import org.apache.poi.ss.usermodel.Workbook; import org.bbreak.excella.core.BookData; import org.bbreak.excella.core.exception.ExportException; import org.bbreak.excella.reports.exporter.ExcelExporter; import org.bbreak.excella.reports.exporter.ReportBookExporter; import org.bbreak.excella.reports.model.ConvertConfiguration; import org.bbreak.excella.reports.model.ReportBook; import org.bbreak.excella.reports.model.ReportSheet; import org.bbreak.excella.reports.processor.ReportProcessor; @WebServlet(name="ExcelServlet", urlPatterns={"/ExcelServlet"}) public class ExcelServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { //C:\Users\m-takayashiki\.netbeans\6.9\config\GF3\domain1 // ================== ?????? ======================= URL templateFileUrl = ExcellaTestResource.class.getResource("?????????.xls"); // /C:/Users/m-takayashiki/Documents/NetBeansProjects/KogaAlpha/build/web/WEB-INF/classes/local/test/jaxrs/?????????.xls System.out.println(templateFileUrl.getPath()); String templateFilePath = URLDecoder.decode(templateFileUrl.getPath(), "UTF-8"); String outputFileDir = "MasatoExcelHorizontalOutput"; ReportProcessor reportProcessor = new ReportProcessor(); ReportBook outputBook = new ReportBook(templateFilePath, outputFileDir, ExcelExporter.FORMAT_TYPE); ReportSheet outputSheet = new ReportSheet("??????"); outputBook.addReportSheet(outputSheet); // ======================================================== // --------------- ?????? ------------------------- reportProcessor.addReportBookExporter(new OutputStreamExporter(response)); System.out.println("wtf???"); reportProcessor.process(outputBook); System.out.println("done!!"); } catch(Exception e) { System.out.println(e); } } //end doGet() @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } }//end class class OutputStreamExporter extends ReportBookExporter { private HttpServletResponse response; public OutputStreamExporter(HttpServletResponse response) { this.response = response; } @Override public String getExtention() { return null; } @Override public String getFormatType() { return ExcelExporter.FORMAT_TYPE; } @Override public void output(Workbook book, BookData bookdata, ConvertConfiguration configuration) throws ExportException { System.out.println(book.getFirstVisibleTab()); System.out.println(book.getSheetName(0)); //TODO write to stream try { response.setContentType("application/vnd.ms-excel"); response.setHeader("Content-Disposition", "attachment; filename=masatoExample.xls"); book.write(response.getOutputStream()); response.getOutputStream().close(); System.out.println("booya!!"); } catch(Exception e) { System.out.println(e); } } }//end class JAX-RS way that won't display popup: package local.test.jaxrs; import java.net.URL; import java.net.URLDecoder; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.ws.rs.core.Context; import javax.ws.rs.core.UriInfo; import javax.ws.rs.Path; import javax.ws.rs.GET; import javax.ws.rs.Produces; import org.apache.poi.ss.usermodel.Workbook; import org.bbreak.excella.core.BookData; import org.bbreak.excella.core.exception.ExportException; import org.bbreak.excella.reports.exporter.ExcelExporter; import org.bbreak.excella.reports.exporter.ReportBookExporter; import org.bbreak.excella.reports.model.ConvertConfiguration; import org.bbreak.excella.reports.model.ReportBook; import org.bbreak.excella.reports.model.ReportSheet; import org.bbreak.excella.reports.processor.ReportProcessor; @Path("excellaTest") public class ExcellaTestResource { @Context private UriInfo context; @Context private HttpServletResponse response; @Context private HttpServletRequest request; public ExcellaTestResource() { } @Path("horizontalProcess") @GET //@Produces("application/vnd.ms-excel") @Produces("application/vnd.ms-excel") public void getProcessHorizontally() { try { //C:\Users\m-takayashiki\.netbeans\6.9\config\GF3\domain1 // ================== ?????? ======================= URL templateFileUrl = this.getClass().getResource("?????????.xls"); // /C:/Users/m-takayashiki/Documents/NetBeansProjects/KogaAlpha/build/web/WEB-INF/classes/local/test/jaxrs/?????????.xls System.out.println(templateFileUrl.getPath()); String templateFilePath = URLDecoder.decode(templateFileUrl.getPath(), "UTF-8"); String outputFileDir = "MasatoExcelHorizontalOutput"; ReportProcessor reportProcessor = new ReportProcessor(); ReportBook outputBook = new ReportBook(templateFilePath, outputFileDir, ExcelExporter.FORMAT_TYPE); ReportSheet outputSheet = new ReportSheet("??????"); outputBook.addReportSheet(outputSheet); // ======================================================== // --------------- ?????? ------------------------- reportProcessor.addReportBookExporter(new OutputStreamExporter(response)); System.out.println("wtf???"); reportProcessor.process(outputBook); System.out.println("done!!"); } catch(Exception e) { System.out.println(e); } //return response; return; } }//end class class OutputStreamExporter extends ReportBookExporter { private HttpServletResponse response; public OutputStreamExporter(HttpServletResponse response) { this.response = response; } @Override public String getExtention() { return null; } @Override public String getFormatType() { return ExcelExporter.FORMAT_TYPE; } @Override public void output(Workbook book, BookData bookdata, ConvertConfiguration configuration) throws ExportException { //TODO write to stream try { response.setContentType("application/vnd.ms-excel"); response.setHeader("Content-Disposition", "attachment; filename=masatoExample.xls"); book.write(response.getOutputStream()); response.getOutputStream().close(); System.out.println("booya!!"); } catch(Exception e) { System.out.println(e); } } }//end class

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  • The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

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