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  • Show/hide glossary page in YUI

    - by QLiu
    Hello All, I am trying to develop a toggle function like http://www.lutsr.nl/yui/toggle/ But it works a little different as them. When user enters the glossary page, he sees a full list of Alphabet with all the techical terms explaination All — A | B | C | E | G | H | M | P | Q | R | S | T | U | Z | ActiveSync® Microsoft® ActiveSync est l’ application permettant à un pocket pc d’ échanger des informations avec un ordinateur . Le Pocket PC doit utiliser Microsoft Windows Mobile™ ou Windows CE. Bluetooth® Le Bluetooth permet aux informations d’ être transmises entre les appareils électroniques qui ont le Bluetooth. Si vous utilisez le Bluetooth, vous n'avez pas besoin de connecter les périphériques à l'aide de câbles. ............................. If the user clicks B Alphabet, the rest of content will hide, except B. and B will be move to top of the section. If the user clicks All aplphabet, the whole list will be reset. What I have now, it is able to show/hide and listen to click event. Here is my source code: <a href="#A" class ="toggle" rel="A_section,fade,20"> A</a> | <a href="#B" class ="toggle" rel="B_section,fade,20"> B</a> | Script: //Load JavaScript Ready event. this.toggleLinks=YAHOO.util.Dom.getElementsByClassName("toggle"); for(var i=0; i<this.toggleLinks.length; i++) { YAHOO.util.Event.addListener(this.toggleLinks[i], "click", this.animateElements,this); } toggleElements : function(e,controlNode,refEl) { if(controlNode && refEl) { if(YAHOO.util.Dom.hasClass(refEl,"show")) { YAHOO.util.Dom.removeClass(controlNode,"selected"); YAHOO.util.Dom.removeClass(refEl,"show"); } else { YAHOO.util.Dom.addClass(controlNode,"selected"); YAHOO.util.Dom.addClass(refEl,"show"); } } // to disable control node's default behaviour return false; }, animateElements : function(e,obj) { // obj = javascript toggle object // this = link clicked YAHOO.util.Event.preventDefault(e); if(this.rel) { controlNode = this; } if(typeof(controlNode) == "string") { controlNode = YAHOO.util.Dom.get(controlNode); } // objParameters // [0] = object id // [1] = animation type (fade, slide) // [2] = animation duration (seconds) var linkClicked = this; var objParameters = controlNode.rel.split(","); var refEl = YAHOO.util.Dom.get(objParameters[0]); var objStatus = YAHOO.util.Dom.hasClass(refEl,"show"); // if true, object is shown switchClasses = function() { obj.toggleOtherElements(e,linkClicked,refEl); obj.toggleElements(e,linkClicked,refEl); } if(objParameters[1] == "fade") { if(objStatus == true) { var attributes = { opacity: {from: .999, to: 0} } var objAnim = new YAHOO.util.Anim(objParameters[0],attributes); objAnim.useSeconds = false; objAnim.duration = objParameters[2]; objAnim.onComplete.subscribe(switchClasses); objAnim.animate(); } else { YAHOO.util.Dom.setStyle(objParameters[0],"opacity",0); switchClasses(); var attributes = { opacity: {from: 0, to: .999} } var objAnim = new YAHOO.util.Anim(objParameters[0],attributes); objAnim.useSeconds = false; objAnim.duration = objParameters[2]; objAnim.animate(); } } else if (objParameters[1] == "slide") { // not implemented yet } else { // NO ANIMATION - switch classes switchClasses(); } }, toggleOtherElements : function(e,linkClicked,refEl) { // toggle selected state of other elements pointing to the same source for(var i=0; i<this.toggleLinks.length; i++) { var objParameters = this.toggleLinks[i].rel.split(","); var linkClickedParameters = linkClicked.rel.split(","); if(objParameters[0] == linkClickedParameters[0]) { if(YAHOO.util.Dom.hasClass(this.toggleLinks[i],"selected")) { YAHOO.util.Dom.removeClass(this.toggleLinks[i],"selected"); } else { YAHOO.util.Dom.addClass(this.toggleLinks[i],"selected"); } } } }

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  • Clean Code Developer & Certification in IT - MSCC 21.09.2013

    It was a very busy weekend this time, and quite some hectic to organise the second meetup on a Saturday for the Mauritius Software Craftsmanship Community (MSCC) but it was absolutely fun. Following, I'm writing a brief summary about the topics we spoke about and the new impulses I got. "What a meetup... I was positively impressed. At the beginning I thought that noone would actually show up but then by the time the room got filled. Lots of conversation, great dialogues and fantastic networking between fresh students, experienced students, experienced employees, and self-employed attendees. That's what community is all about!" Above quote was my first reaction shortly after the gathering. And despite being busy during the weekend and yesterday, I took my time to reflect a little bit on things happened and statements made before writing it here on my blog. Additionally, I was also very curious about possible reactions and blogs from other attendees. Reactions from other craftsmen Let me quickly give you some links and quotes from others first... "Like Jochen posted on facebook, that was indeed a 5+ hours marathon (maybe 4 hours for me but still) … Wohoo! We’re indeed a bunch of crazy geeks who did not realise how time flew as we dived into the myriad discussions that sprouted. Yet in the end everyone was happy (:" -- Ish on MSCC meetup - The marathon (: "And the 4hours spent @ Talking drums bore its fruit..I was doing something I never did before....reading the borrowed book while walking....and though I was not that familiar with things mentionned in the book...I was skimming,scanning & flipping...reading titles...short paragraphs...and I skipped pages till I reached home." -- Yannick on Mauritius Software Craftsmanship 1st Meet-up "Hi Developers, Just wanted to share with you the meetups i attended last Saturday - [...] - The second meetup is the one hosted by Jochen Kirstätter, the MSCC, where the attendees were Craftsman, no woman, this time - all sharing the same passion of being a developer - even though it is on different platforms(Windows - Windows Phone - Linux - Adobe(yes a designer) - .Net) - but we manage to sit at the same table - sharing developer views and experience in the corporate world - also talking about good practice when coding( where Jochen initiated a discussion on Clean Coding ) i could not stay till the end - but from what i have heard - the longer you stay the more fun you have till 1600. Developers in the Facebook grouping i invite you to stay tuned about the various developer communities popping up - where you can come to share and learn good practices, develop the entrepreneurial spirit, and learn and share your passion about technologies" -- Arnaud on Facebook More feedback has been posted on the event directly. So, should I really write more? Wouldn't that spoil the impressions? Starting the day with a surprise Indeed, I was very pleased to stumble over the existence of Mobile Monday Mauritius on LinkedIn, an association about any kind of mobile app development, mobile gadgets and latest smartphones on the market. Despite the Monday in their name they had scheduled their recent meeting on Saturday between 10:00 and 12:00hrs. Wow, what a coincidence! Let's grap the bull by its horns and pay them an introductory visit. As they chose the Ebene Accelerator at the Orange Tower in Ebene it was a no-brainer to leave home a bit earlier and stop by. It was quite an experience and fun to talk to the geeks over there. Really looking forward to organise something together.... Arriving at the venue As the children got a bit uneasy at the MoMo gathering and I didn't want to disturb them too much, we arrived early at Bagatelle. Well, no problems as we went for a decent breakfast at Food Lover's Market. Shortly afterwards we went to our venue location, Talking Drums, and prepared the room for the meeting. We only had to take off a repro-painting of the wall in order to have a decent area for the projector. All went very smooth and my two little ones were of great help. Just in time, our first craftsman Avinash arrived on the spot. And then the waiting started... Luckily, not too long. Bit by bit more and more IT people came to join our meeting. Meanwhile, I used the time to give a brief introduction about the MSCC in general, what we are (hm, maybe I am) trying to achieve and that the recent phase is completely focused on creating more awareness that a community like the MSCC is active here in Mauritius. As soon as we reached some 'critical mass' of about ten people I asked everyone for a short introduction and bio, just in case... Conversation between participants started to kick in and we were actually more networking than having a focus on our topics of the day. Quick updates on latest news and development around the MSCC Finally, Clean Code Developer No matter how the position is actually called, whether it is Software Engineer, Software Developer, Programmer, Architect, or Craftsman, anyone working in IT is facing almost the same obstacles. As for the process of writing software applications there are re-occurring patterns and principles combined with some common exercise and best practices on how to resolve them. Initiated by the must-read book 'Clean Code' by Robert C. Martin (aka Uncle Bob) the concept of the Clean Code Developer (CCD) was born already some years ago. CCD is much likely to traditional martial arts where you create awareness of certain principles and learn how to apply practices to improve your style. The CCD initiative recommends to indicate your level of knowledge and experience with coloured wrist bands - equivalent to the belt colours - for various reasons. Frankly speaking, I think that the biggest advantage here is provided by the obvious recognition of conceptual understanding. For example, take the situation of a team meeting... A member with a higher grade in CCD, say Green grade, sees that there are mainly Red grades to talk to, and adjusts her way of communication to their level of understanding. The choice of words might change as certain elements of CCD are not yet familiar to all team members. So instead of talking in an abstract way which only Green grades could follow the whole scenario comes down to Red grade level. Different story, better results... Similar to learning martial arts, we only covered two grades during this occasion - black and red. Most interestingly, there was quite some positive feedback and lots of questions about the principles and practices of the red grade. And we gathered real-world examples from various craftsman and discussed them. Following the Clean Code Developer Red Grade and some annotations from our meetup: CCD Red Grade - Principles Don't Repeat Yourself - DRY Keep It Simple, Stupid (and Short) - KISS Beware of Optimisations! Favour Composition over Inheritance - FCoI Interestingly most of the attendees already heard about those key words but couldn't really classify or categorize them. It's very similar to a situation in which you do not the particular for a thing and have to describe it to others... until someone tells you the actual name and suddenly all is very simple. CCD Red Grade - Practices Follow the Boy Scouts Rule Root Cause Analysis - RCA Use a Version Control System Apply Simple Refactoring Pattern Reflect Daily Introduction to the principles and practices of Clean Code Developer - here: Red Grade As for the various ToDo's we commonly agreed that the Boy Scout Rule clearly is not limited to software development or IT administration but applies to daily life in general. Same for the root cause analysis, btw. We really had good stories with surprisingly endings and conclusions. A quick check about who is using a version control system brought more drive into the conversation. Not only that we had people that aren't using any VCS at all, we also had the 'classic' approach of backup folders and naming conventions as well as the VCS 'junkie' that has to use multiple systems at a time. Just for the records: Git and GitHub seem to be in favour of some of the attendees. Regarding the daily reflection at the end of the day we came up with an easy solution: Wrap it up as a blog entry! Certifications in IT This is kind of a controversy in IT in general. Is it interesting to go for certifications or are they completely obsolete? What are the possibilities to get certified? What are the options we have in Mauritius? How would certificates stand compared to other educational tracks like Computer Science or Web Design. The ratio between craftsmen with certifications like MCP, MSTS, CCNA or LPI versus the ones without wasn't in favour for the first group but there was a high interest in the topic itself and some were really surprised to hear that exam preparations are completely free available online including temporarily voucher codes for either discounts or completely free exams. Furthermore, we discussed possible options on forming so-called study groups on a specific certificates and organising more frequent meetups in order to learn together. Taking into consideration that we have sponsored access to the video course material of Pluralsight (and now PeepCode as well as TrainSignal), we might give it a try by the end of the year. Current favourites are LPIC Level 1 and one of the Microsoft exams 40-78x. Feedback and ideas for the MSCC The closing conversations and discussions about how the MSCC is recently doing, what are the possibilities and what's (hopefully) going to happen in the future were really fertile and I made a couple of mental bullet points which I'm looking forward to tackle down together with orher craftsmen. Eventually, it might be a good option to elaborate on some issues during our weekly Code & Coffee sessions one Wednesday morning. Active discussion on various IT topics like certifications (LPI, MCP, CCNA, etc) and sharing experience Finally, we made it till the end of the planned time. Well, actually the talk was still on and we continued even after 16:00hrs. Unfortunately, we (the children and I) had to leave for evening activities. My resume of the day... It was great to have 15 craftsmen in one room. There are hundreds of IT geeks out there in Mauritius, and as Mauritius Software Craftsmanship Community we still have a lot of work to do to pass on the message to some more key players and companies. Currently, it seems that we are able to attract a good number of students in Computer Science... but we have a lot more to offer, even or especially for IT people on the job. I'm already looking forward to our next Saturday meetup in the near future. PS: Meetup pictures are courtesy of Nirvan Pagooah. Thanks for sharing...

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  • Solaris: What comes next?

    - by alanc
    As you probably know by now, a few months ago, we released Solaris 11 after years of development. That of course means we now need to figure out what comes next - if Solaris 11 is “The First Cloud OS”, then what do we need to make future releases of Solaris be, to be modern and competitive when they're released? So we've been having planning and brainstorming meetings, and I've captured some notes here from just one of those we held a couple weeks ago with a number of the Silicon Valley based engineers. Now before someone sees an idea here and calls their product rep wanting to know what's up, please be warned what follows are rough ideas, and as I'll discuss later, none of them have any committment, schedule, working code, or even plan for integration in any possible future product at this time. (Please don't make me force you to read the full Oracle future product disclaimer here, you should know it by heart already from the front of every Oracle product slide deck.) To start with, we did some background research, looking at ideas from other Oracle groups, and competitive OS'es. We examined what was hot in the technology arena and where the interesting startups were heading. We then looked at Solaris to see where we could apply those ideas. Making Network Admins into Socially Networking Admins We all know an admin who has grumbled about being the only one stuck late at work to fix a problem on the server, or having to work the weekend alone to do scheduled maintenance. But admins are humans (at least most are), and crave companionship and community with their fellow humans. And even when they're alone in the server room, they're never far from a network connection, allowing access to the wide world of wonders on the Internet. Our solution here is not building a new social network - there's enough of those already, and Oracle even has its own Oracle Mix social network already. What we proposed is integrating Solaris features to help engage our system admins with these social networks, building community and bringing them recognition in the workplace, using achievement recognition systems as found in many popular gaming platforms. For instance, if you had a Facebook account, and a group of admin friends there, you could register it with our Social Network Utility For Facebook, and then your friends might see: Alan earned the achievement Critically Patched (April 2012) for patching all his servers. Matt is only at 50% - encourage him to complete this achievement today! To avoid any undue risk of advertising who has unpatched servers that are easier targets for hackers to break into, this information would be tightly protected via Facebook's world-renowned privacy settings to avoid it falling into the wrong hands. A related form of gamification we considered was replacing simple certfications with role-playing-game-style Experience Levels. Instead of just knowing an admin passed a test establishing a given level of competency, these would provide recruiters with a more detailed level of how much real-world experience an admin has. Achievements such as the one above would feed into it, but larger numbers of experience points would be gained by tougher or more critical tasks - such as recovering a down system, or migrating a service to a new platform. (As long as it was an Oracle platform of course - migrating to an HP or IBM platform would cause the admin to lose points with us.) Unfortunately, we couldn't figure out a good way to prevent (if you will) “gaming” the system. For instance, a disgruntled admin might decide to start ignoring warnings from FMA that a part is beginning to fail or skip preventative maintenance, in the hopes that they'd cause a catastrophic failure to earn more points for bolstering their resume as they look for a job elsewhere, and not worrying about the effect on your business of a mission critical server going down. More Z's for ZFS Our suggested new feature for ZFS was inspired by the worlds most successful Z-startup of all time: Zynga. Using the Social Network Utility For Facebook described above, we'd tie it in with ZFS monitoring to help you out when you find yourself in a jam needing more disk space than you have, and can't wait a month to get a purchase order through channels to buy more. Instead with the click of a button you could post to your group: Alan can't find any space in his server farm! Can you help? Friends could loan you some space on their connected servers for a few weeks, knowing that you'd return the favor when needed. ZFS would create a new filesystem for your use on their system, and securely share it with your system using Kerberized NFS. If none of your friends have space, then you could buy temporary use space in small increments at affordable rates right there in Facebook, using your Facebook credits, and then file an expense report later, after the urgent need has passed. Universal Single Sign On One thing all the engineers agreed on was that we still had far too many "Single" sign ons to deal with in our daily work. On the web, every web site used to have its own password database, forcing us to hope we could remember what login name was still available on each site when we signed up, and which unique password we came up with to avoid having to disclose our other passwords to a new site. In recent years, the web services world has finally been reducing the number of logins we have to manage, with many services allowing you to login using your identity from Google, Twitter or Facebook. So we proposed following their lead, introducing PAM modules for web services - no more would you have to type in whatever login name IT assigned and try to remember the password you chose the last time password aging forced you to change it - you'd simply choose which web service you wanted to authenticate against, and would login to your Solaris account upon reciept of a cookie from their identity service. Pinning notes to the cloud We also all noted that we all have our own pile of notes we keep in our daily work - in text files in our home directory, in notebooks we carry around, on white boards in offices and common areas, on sticky notes on our monitors, or on scraps of paper pinned to our bulletin boards. The contents of the notes vary, some are things just for us, some are useful for our groups, some we would share with the world. For instance, when our group moved to a new building a couple years ago, we had a white board in the hallway listing all the NIS & DNS servers, subnets, and other network configuration information we needed to set up our Solaris machines after the move. Similarly, as Solaris 11 was finishing and we were all learning the new network configuration commands, we shared notes in wikis and e-mails with our fellow engineers. Users may also remember one of the popular features of Sun's old BigAdmin site was a section for sharing scripts and tips such as these. Meanwhile, the online "pin board" at Pinterest is taking the web by storm. So we thought, why not mash those up to solve this problem? We proposed a new BigAddPin site where users could “pin” notes, command snippets, configuration information, and so on. For instance, once they had worked out the ideal Automated Installation manifest for their app server, they could pin it up to share with the rest of their group, or choose to make it public as an example for the world. Localized data, such as our group's notes on the servers for our subnet, could be shared only to users connecting from that subnet. And notes that they didn't want others to see at all could be marked private, such as the list of phone numbers to call for late night pizza delivery to the machine room, the birthdays and anniversaries they can never remember but would be sleeping on the couch if they forgot, or the list of automatically generated completely random, impossible to remember root passwords to all their servers. For greater integration with Solaris, we'd put support right into the command shells — redirect output to a pinned note, set your path to include pinned notes as scripts you can run, or bring up your recent shell history and pin a set of commands to save for the next time you need to remember how to do that operation. Location service for Solaris servers A longer term plan would involve convincing the hardware design groups to put GPS locators with wireless transmitters in future server designs. This would help both admins and service personnel trying to find servers in todays massive data centers, and could feed into location presence apps to help show potential customers that while they may not see many Solaris machines on the desktop any more, they are all around. For instance, while walking down Wall Street it might show “There are over 2000 Solaris computers in this block.” [Note: this proposal was made before the recent media coverage of a location service aggregrator app with less noble intentions, and in hindsight, we failed to consider what happens when such data similarly falls into the wrong hands. We certainly wouldn't want our app to be misinterpreted as “There are over $20 million dollars of SPARC servers in this building, waiting for you to steal them.” so it's probably best it was rejected.] Harnessing the power of the GPU for Security Most modern OS'es make use of the widespread availability of high powered GPU hardware in today's computers, with desktop environments requiring 3-D graphics acceleration, whether in Ubuntu Unity, GNOME Shell on Fedora, or Aero Glass on Windows, but we haven't yet made Solaris fully take advantage of this, beyond our basic offering of Compiz on the desktop. Meanwhile, more businesses are interested in increasing security by using biometric authentication, but must also comply with laws in many countries preventing discrimination against employees with physical limations such as missing eyes or fingers, not to mention the lost productivity when employees can't login due to tinted contacts throwing off a retina scan or a paper cut changing their fingerprint appearance until it heals. Fortunately, the two groups considering these problems put their heads together and found a common solution, using 3D technology to enable authentication using the one body part all users are guaranteed to have - pam_phrenology.so, a new PAM module that uses an array USB attached web cams (or just one if the user is willing to spin their chair during login) to take pictures of the users head from all angles, create a 3D model and compare it to the one in the authentication database. While Mythbusters has shown how easy it can be to fool common fingerprint scanners, we have not yet seen any evidence that people can impersonate the shape of another user's cranium, no matter how long they spend beating their head against the wall to reshape it. This could possibly be extended to group users, using modern versions of some of the older phrenological studies, such as giving all users with long grey beards access to the System Architect role, or automatically placing users with pointy spikes in their hair into an easy use mode. Unfortunately, there are still some unsolved technical challenges we haven't figured out how to overcome. Currently, a visit to the hair salon causes your existing authentication to expire, and some users have found that shaving their heads is the only way to avoid bad hair days becoming bad login days. Reaction to these ideas After gathering all our notes on these ideas from the engineering brainstorming meeting, we took them in to present to our management. Unfortunately, most of their reaction cannot be printed here, and they chose not to accept any of these ideas as they were, but they did have some feedback for us to consider as they sent us back to the drawing board. They strongly suggested our ideas would be better presented if we weren't trying to decipher ink blotches that had been smeared by the condensation when we put our pint glasses on the napkins we were taking notes on, and to that end let us know they would not be approving any more engineering offsites in Irish themed pubs on the Friday of a Saint Patrick's Day weekend. (Hopefully they mean that situation specifically and aren't going to deny the funding for travel to this year's X.Org Developer's Conference just because it happens to be in Bavaria and ending on the Friday of the weekend Oktoberfest starts.) They recommended our research techniques could be improved over just sitting around reading blogs and checking our Facebook, Twitter, and Pinterest accounts, such as considering input from alternate viewpoints on topics such as gamification. They also mentioned that Oracle hadn't fully adopted some of Sun's common practices and we might have to try harder to get those to be accepted now that we are one unified company. So as I said at the beginning, don't pester your sales rep just yet for any of these, since they didn't get approved, but if you have better ideas, pass them on and maybe they'll get into our next batch of planning.

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  • jQuery / jqGrids / Submitting form data troubles...

    - by Kelso
    Ive been messing with jqgrids alot of the last couple days, and I have nearly everything the way I want it from the display, tabs with different grids, etc. Im wanting to make use of Modal for adding and editing elements on my grid. My problem that Im running into is this. I have my editurl:"editsu.php" set, if that file is renamed, on edit, i get a 404 in the modal.. great! However, with that file in place, nothing at all seems to happen. I even put a die("testing"); line at the top, so it sees the file, it just doesnt do anything with it. Below is the content. ........ the index page jQuery("#landings").jqGrid({ url:'server.php?tid=1', datatype: "json", colNames:['ID','Tower','Sector', 'Client', 'VLAN','IP','DLink','ULink','Service','Lines','Freq','Radio','Serial','Mac'], colModel:[ {name:'id', index:'id', width : 50, align: 'center', sortable:true,editable:true,editoptions:{size:10}}, {name:'tower', index:'tower', width : 85, align: 'center', sortable:true,editable:false,editoptions:{readonly:true,size:30}}, {name:'sector', index:'sector', width : 50, align: 'center',sortable:true,editable:true,editoptions:{readonly:true,size:20}}, {name:'customer',index:'customer', width : 175, align: 'left', editable:true,editoptions:{readonly:true,size:35}}, {name:'vlan', index:'vlan', width : 35, align: 'left',editable:true,editoptions:{size:10}}, {name:'suip', index:'suip', width : 65, align: 'left',editable:true,editoptions:{size:20}}, {name:'datadl',index:'datadl', width:55, editable: true,edittype:"select",editoptions:{value:"<? $qr = qquery("select * from datatypes"); while ($q = ffetch($qr)) {echo "$q[id]:$q[name];";}?>"}}, {name:'dataul', index:'dataul', width : 55, editable: true,edittype:"select",editoptions:{value:"<? $qr = qquery("select * from datatypes"); while ($q = ffetch($qr)) {echo "$q[id]:$q[name];";}?>"}}, {name:'servicetype', index:'servicetype', width : 85, editable: true,edittype:"select",editoptions:{value:"<? $qr = qquery("select * from servicetype"); while ($q = ffetch($qr)) {echo "$q[id]:$q[name];";}?>"}}, {name:'voicelines', index:'voicelines', width : 35, align: 'center',editable:true,editoptions:{size:30}}, {name:'freqname', index:'freqname', width : 35, editable: true,edittype:"select",editoptions:{value:"<? $qr = qquery("select * from freqband"); while ($q = ffetch($qr)) {echo "$q[id]:$q[name];";}?>"}}, {name:'radioname', index:'radioname', width : 120, editable: true,edittype:"select",editoptions:{value:"<? $qr = qquery("select * from radiotype"); while ($q = ffetch($qr)) {echo "$q[id]:$q[name];";}?>"}}, {name:'serial', index:'serial', width : 100, align: 'right',editable:true,editoptions:{size:20}}, {name:'mac', index:'mac', width : 120, align: 'right',editable:true,editoptions:{size:20}} ], rowNum:20, rowList:[30,50,70], pager: '#pagerl', sortname: 'sid', mtype: "GET", viewrecords: true, sortorder: "asc", altRows: true, caption:"Landings", editurl:"editsu.php", height:420 }); jQuery("#landings").jqGrid('navGrid','#pagerl',{edit:true,add:true,del:false,search:false},{height:400,reloadAfterSubmit:false},{height:400,reloadAfterSubmit:false},{reloadAfterSubmit:false},{}); now for the editsu.php file.. $operation = $_REQUEST['oper']; if ($operation == "edit") { qquery("UPDATE customers SET vlan = '".$_POST['vlan']."', datadl = '".$_POST['datadl']."', dataul = '".$_POST['dataul']."', servicetype = '".$_POST['servicetype']."', voicelines = '".$_POST['voicelines']."', freqname = '".$_POST['freqname']."', radioname = '".$_POST['radioname']."', serial = '".$_POST['serial']."', mac = '".$_POST['mac']."' WHERE id = '".$_POST['id']."'") or die(mysql_error()); } Im just having a hard time troubleshooting this to figure out where its getting hung up at. My next question after this would be to see if its possible to make it so when you click "add", that it auto inserts a row into the db with a couple variable predtermined and then bring up the modal window, but ill work on the first problem first. thanks!

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  • SDL side-scroller scrolls inconsistantly

    - by SDLFunTimes
    So I'm working on an upgrade from my previous project (that I posted here for code review) this time implementing a repeating background (like what is used on cartoons) so that SDL doesn't have to load really big images for a level. There's a strange inconsistency in the program, however: the first time the user scrolls all the way to the right 2 less panels are shown than is specified. Going backwards (left) the correct number of panels is shown (that is the panels repeat the number of times specified in the code). After that it appears that going right again (once all the way at the left) the correct number of panels is shown and same going backwards. Here's some selected code and here's a .zip of all my code constructor: Game::Game(SDL_Event* event, SDL_Surface* scr, int level_w, int w, int h, int bpp) { this->event = event; this->bpp = bpp; level_width = level_w; screen = scr; w_width = w; w_height = h; //load images and set rects background = format_surface("background.jpg"); person = format_surface("person.png"); background_rect_left = background->clip_rect; background_rect_right = background->clip_rect; current_background_piece = 1; //we are displaying the first clip rect_in_view = &background_rect_right; other_rect = &background_rect_left; person_rect = person->clip_rect; background_rect_left.x = 0; background_rect_left.y = 0; background_rect_right.x = background->w; background_rect_right.y = 0; person_rect.y = background_rect_left.h - person_rect.h; person_rect.x = 0; } and here's the move method which is probably causing all the trouble: void Game::move(SDLKey direction) { if(direction == SDLK_RIGHT) { if(move_screen(direction)) { if(!background_reached_right()) { //move background right background_rect_left.x += movement_increment; background_rect_right.x += movement_increment; if(rect_in_view->x >= 0) { //move the other rect in to fill the empty space SDL_Rect* temp; other_rect->x = -w_width + rect_in_view->x; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece++; std::cout << current_background_piece << std::endl; } if(background_overshoots_right()) { //sees if this next blit is past the surface //this is used only for re-aligning the rects when //the end of the screen is reached background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x += movement_increment; if(get_person_right_side() > w_width) { //person went too far right person_rect.x = w_width - person_rect.w; } } } else if(direction == SDLK_LEFT) { if(move_screen(direction)) { if(!background_reached_left()) { //moves background left background_rect_left.x -= movement_increment; background_rect_right.x -= movement_increment; if(rect_in_view->x <= -w_width) { //swap the rect in view SDL_Rect* temp; rect_in_view->x = w_width; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece--; std::cout << current_background_piece << std::endl; } if(background_overshoots_left()) { background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x -= movement_increment; if(person_rect.x < 0) { //person went too far left person_rect.x = 0; } } } } without the rest of the code this doesn't make too much sense. Since there is too much of it I'll upload it here for testing. Anyway does anyone know how I could fix this inconsistency?

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  • WCF Stream.Read always returns 0 in client

    - by G_M
    I've spent most of my day trying to figure out why this isn't working. I have a WCF service that streams an object to the client. The client is then supposed to write the file to its disk. But when I call stream.Read(buffer, 0, bufferLength) it always returns 0. Here's my code: namespace StreamServiceNS { [ServiceContract] public interface IStreamService { [OperationContract] Stream downloadStreamFile(); } } class StreamService : IStreamService { public Stream downloadStreamFile() { ISSSteamFile sFile = getStreamFile(); BinaryFormatter bf = new BinaryFormatter(); MemoryStream stream = new MemoryStream(); bf.Serialize(stream, sFile); return stream; } } Service config file: <system.serviceModel> <services> <service name="StreamServiceNS.StreamService"> <endpoint address="stream" binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IStreamService" name="BasicHttpEndpoint_IStreamService" contract="SWUpdaterService.ISWUService" /> </service> </services> <bindings> <basicHttpBinding> <binding name="BasicHttpBinding_IStreamService" transferMode="StreamedResponse" maxReceivedMessageSize="209715200"></binding> </basicHttpBinding> </bindings> <behaviors> <serviceBehaviors> <behavior> <serviceThrottling maxConcurrentCalls ="100" maxConcurrentSessions="400"/> <serviceMetadata httpGetEnabled="true"/> <serviceDebug includeExceptionDetailInFaults="false"/> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> </system.serviceModel> Client: TestApp.StreamServiceRef.StreamServiceClient client = new StreamServiceRef.StreamServiceClient(); try { Stream stream = client.downloadStreamFile(); int bufferLength = 8 * 1024; byte[] buffer = new byte[bufferLength]; FileStream fs = new FileStream(@"C:\test\testFile.exe", FileMode.Create, FileAccess.Write); int bytesRead; while ((bytesRead = stream.Read(buffer, 0, bufferLength)) > 0) { fs.Write(buffer, 0, bytesRead); } stream.Close(); fs.Close(); } catch (Exception e) { Console.WriteLine("Error: " + e.Message); } Client app.config: <system.serviceModel> <bindings> <basicHttpBinding> <binding name="BasicHttpEndpoint_IStreamService" maxReceivedMessageSize="209715200" transferMode="StreamedResponse"> </binding> </basicHttpBinding> </bindings> <client> <endpoint address="http://[server]/StreamServices/streamservice.svc/stream" binding="basicHttpBinding" bindingConfiguration="BasicHttpEndpoint_IStreamService" contract="StreamServiceRef.IStreamService" name="BasicHttpEndpoint_IStreamService" /> </client> </system.serviceModel> (some code clipped for brevity) I've read everything I can find on making WCF streaming services, and my code looks no different than theirs. I can replace the streaming with buffering and send an object that way fine, but when I try to stream, the client always sees the stream as "empty". The testFile.exe gets created, but its size is 0KB. What am I missing?

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  • If 'Architect' is a dirty word - what's the alternative; when not everyone can actually design a goo

    - by Andras Zoltan
    Now - I'm a developer first and foremost; but whenever I sit down to work on a big project with lots of interlinking components and areas, I will forward-plan my interfaces, base classes etc as best I can - putting on my Architect hat. For a few weeks I've been doing this for a huge project - designing whole swathes of interfaces etc for a business-wide platform that we're developing. The basic structure is a couple of big projects that consists of service and data interfaces, with some basic implementations of all of these. On their own, these assemblies are useless though, as they are simply intended intended as a scaffold on which to build a business-specific implementation (we have a lot of businesses). Therefore, the design of the core platform is absolutely crucial, since consumers of the system are not intended to know which implementation they are actually using. In the past it's not worked so well, but after a few proof-of-concepts and R&D projects this new platform is now growing nicely and is already proving itself. Then somebody else gets involved in the project - he's a TDD man who sees code-level architecture as an irrelevance and is definitely from the camp that 'architect' is a dirty word - I should add that our working relationship is very good despite this :) He's open about the fact that he can't architect in advance and obviously TDD really helps him because it allows him to evolve his systems over time. That I get, and totally understand; but it means that his coding style, basically, doesn't seem to be able to honour the architecture that I've been putting in place. Now don't get me wrong - he's an awesome coder; but the other day he needed to extend one of his components (an implementation of a core interface) to bring in an extra implementation-specific dependency; and in doing so he extended the core interface as well as his implementation (he uses ReSharper), thus breaking the independence of the whole interface. When I pointed out his error to him, he was dismayed. Being test-first, all that mattered to him was that he'd made his tests pass, and just said 'well, I need that dependency, so can't we put it in?'. Of course we could put it in, but I was frustrated that he couldn't see that refactoring the generic interface to incorporate an implementation-specific feature was just wrong! But it is all very Charlie Brown to him (you know the sound the adults make when they're talking to the children) - as far as he's concerned we don't need to worry about it because we can always refactor. The problem is, the culture of test-write-refactor is all very well and good - but not when you're dealing with a platform that is going to be shared out among so many projects that you could never get them all in one place to make the refactorings work. In my opinion, sometimes you actually have to think about what you're doing, and not just let nature take its course. Am I simply fulfilling the role of Architect as a dirty word here? I believe that architecture is important and should be thought about before code gets written; unless it's a particularly small project. But when you're working in a team of people who don't think that way, or even can't think that way how can you actually get this across? Is it a case of simply making the architecture off-limits to changes by other people? I don't want to start having bloody committees just to be able to grow the system; but equally I don't want to be the only one responsible for it all. Do you think the architect role is a waste of time? Is it at odds with TDD and other practises? Can this mix of different practises be made to work, or should I just be a lot less precious (and in so doing allow a generic platform become useless!)? Or do I just lay down the law? Any ideas/experiences/views gratefully received.

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  • Why does my token return NULL and how can I fix it?(c++)

    - by Van
    I've created a program to get a string input from a user and parse it into tokens and move a robot according to the input. The program is supposed to recognize these inputs(where x is an integer): "forward x" "back x" "turn left x" "turn right x" and "stop". The program does what it's supposed to for all commands except for "stop". When I type "stop" the program prints out "whats happening?" because I've written a line which states: if(token == NULL) { cout << "whats happening?" << endl; } Why does token get NULL, and how can I fix this so it will read "stop" properly? here is the code: bool stopper = 0; void Navigator::manualDrive() { VideoStream video(&myRobot, 0);//allows user to see what robot sees video.startStream(); const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; while(stopper == 0) { cout << "Enter your directions below: " << endl; cin.getline(uinput,bufSize); Navigator::parseInstruction(uinput); } } /* parseInstruction(char *c) -- parses cstring instructions received * and moves robot accordingly */ void Navigator::parseInstruction(char * uinput) { char delim[] = " "; char *token; // cout << "Enter your directions below: " << endl; // cin.getline (uinput, bufSize); token=strtok(uinput, delim); if(token == NULL) { cout << "whats happening?" << endl; } if(strcmp("forward", token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); double value = fabs(0.0735 * fabs(inches) - 0.0550); myRobot.forward(1, value); } else if(strcmp("back",token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); double value = fabs(0.0735 * fabs(inches) - 0.0550); myRobot.backward(1/*speed*/, value/*time*/); } else if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("left",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.00467 * degrees - 0.04); myRobot.turnLeft(1/*speed*/, value/*time*/); } else if(strcmp("right",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.00467 * degrees - 0.04); myRobot.turnRight(1/*speed*/, value/*time*/); } } else if(strcmp("stop",token) == 0) { stopper = 1; } else { std::cerr << "Unknown command '" << token << "'\n"; } } /* autoDrive() -- reads in file from ifstream, parses * and moves robot according to instructions in file */ void Navigator::autoDrive(string filename) { const int bufSize = 42; char fLine[bufSize]; ifstream infile; infile.open("autodrive.txt", fstream::in); while (!infile.eof()) { infile.getline(fLine, bufSize); Navigator::parseInstruction(fLine); } infile.close(); } I need this to break out of the while loop and end manualDrive because in my driver program the next function called is autoDrive.

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  • Parallel Classloading Revisited: Fully Concurrent Loading

    - by davidholmes
    Java 7 introduced support for parallel classloading. A description of that project and its goals can be found here: http://openjdk.java.net/groups/core-libs/ClassLoaderProposal.html The solution for parallel classloading was to add to each class loader a ConcurrentHashMap, referenced through a new field, parallelLockMap. This contains a mapping from class names to Objects to use as a classloading lock for that class name. This was then used in the following way: protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException { synchronized (getClassLoadingLock(name)) { // First, check if the class has already been loaded Class c = findLoadedClass(name); if (c == null) { long t0 = System.nanoTime(); try { if (parent != null) { c = parent.loadClass(name, false); } else { c = findBootstrapClassOrNull(name); } } catch (ClassNotFoundException e) { // ClassNotFoundException thrown if class not found // from the non-null parent class loader } if (c == null) { // If still not found, then invoke findClass in order // to find the class. long t1 = System.nanoTime(); c = findClass(name); // this is the defining class loader; record the stats sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0); sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); sun.misc.PerfCounter.getFindClasses().increment(); } } if (resolve) { resolveClass(c); } return c; } } Where getClassLoadingLock simply does: protected Object getClassLoadingLock(String className) { Object lock = this; if (parallelLockMap != null) { Object newLock = new Object(); lock = parallelLockMap.putIfAbsent(className, newLock); if (lock == null) { lock = newLock; } } return lock; } This approach is very inefficient in terms of the space used per map and the number of maps. First, there is a map per-classloader. As per the code above under normal delegation the current classloader creates and acquires a lock for the given class, checks if it is already loaded, then asks its parent to load it; the parent in turn creates another lock in its own map, checks if the class is already loaded and then delegates to its parent and so on till the boot loader is invoked for which there is no map and no lock. So even in the simplest of applications, you will have two maps (in the system and extensions loaders) for every class that has to be loaded transitively from the application's main class. If you knew before hand which loader would actually load the class the locking would only need to be performed in that loader. As it stands the locking is completely unnecessary for all classes loaded by the boot loader. Secondly, once loading has completed and findClass will return the class, the lock and the map entry is completely unnecessary. But as it stands, the lock objects and their associated entries are never removed from the map. It is worth understanding exactly what the locking is intended to achieve, as this will help us understand potential remedies to the above inefficiencies. Given this is the support for parallel classloading, the class loader itself is unlikely to need to guard against concurrent load attempts - and if that were not the case it is likely that the classloader would need a different means to protect itself rather than a lock per class. Ultimately when a class file is located and the class has to be loaded, defineClass is called which calls into the VM - the VM does not require any locking at the Java level and uses its own mutexes for guarding its internal data structures (such as the system dictionary). The classloader locking is primarily needed to address the following situation: if two threads attempt to load the same class, one will initiate the request through the appropriate loader and eventually cause defineClass to be invoked. Meanwhile the second attempt will block trying to acquire the lock. Once the class is loaded the first thread will release the lock, allowing the second to acquire it. The second thread then sees that the class has now been loaded and will return that class. Neither thread can tell which did the loading and they both continue successfully. Consider if no lock was acquired in the classloader. Both threads will eventually locate the file for the class, read in the bytecodes and call defineClass to actually load the class. In this case the first to call defineClass will succeed, while the second will encounter an exception due to an attempted redefinition of an existing class. It is solely for this error condition that the lock has to be used. (Note that parallel capable classloaders should not need to be doing old deadlock-avoidance tricks like doing a wait() on the lock object\!). There are a number of obvious things we can try to solve this problem and they basically take three forms: Remove the need for locking. This might be achieved by having a new version of defineClass which acts like defineClassIfNotPresent - simply returning an existing Class rather than triggering an exception. Increase the coarseness of locking to reduce the number of lock objects and/or maps. For example, using a single shared lockMap instead of a per-loader lockMap. Reduce the lifetime of lock objects so that entries are removed from the map when no longer needed (eg remove after loading, use weak references to the lock objects and cleanup the map periodically). There are pros and cons to each of these approaches. Unfortunately a significant "con" is that the API introduced in Java 7 to support parallel classloading has essentially mandated that these locks do in fact exist, and they are accessible to the application code (indirectly through the classloader if it exposes them - which a custom loader might do - and regardless they are accessible to custom classloaders). So while we can reason that we could do parallel classloading with no locking, we can not implement this without breaking the specification for parallel classloading that was put in place for Java 7. Similarly we might reason that we can remove a mapping (and the lock object) because the class is already loaded, but this would again violate the specification because it can be reasoned that the following assertion should hold true: Object lock1 = loader.getClassLoadingLock(name); loader.loadClass(name); Object lock2 = loader.getClassLoadingLock(name); assert lock1 == lock2; Without modifying the specification, or at least doing some creative wordsmithing on it, options 1 and 3 are precluded. Even then there are caveats, for example if findLoadedClass is not atomic with respect to defineClass, then you can have concurrent calls to findLoadedClass from different threads and that could be expensive (this is also an argument against moving findLoadedClass outside the locked region - it may speed up the common case where the class is already loaded, but the cost of re-executing after acquiring the lock could be prohibitive. Even option 2 might need some wordsmithing on the specification because the specification for getClassLoadingLock states "returns a dedicated object associated with the specified class name". The question is, what does "dedicated" mean here? Does it mean unique in the sense that the returned object is only associated with the given class in the current loader? Or can the object actually guard loading of multiple classes, possibly across different class loaders? So it seems that changing the specification will be inevitable if we wish to do something here. In which case lets go for something that more cleanly defines what we want to be doing: fully concurrent class-loading. Note: defineClassIfNotPresent is already implemented in the VM as find_or_define_class. It is only used if the AllowParallelDefineClass flag is set. This gives us an easy hook into existing VM mechanics. Proposal: Fully Concurrent ClassLoaders The proposal is that we expand on the notion of a parallel capable class loader and define a "fully concurrent parallel capable class loader" or fully concurrent loader, for short. A fully concurrent loader uses no synchronization in loadClass and the VM uses the "parallel define class" mechanism. For a fully concurrent loader getClassLoadingLock() can return null (or perhaps not - it doesn't matter as we won't use the result anyway). At present we have not made any changes to this method. All the parallel capable JDK classloaders become fully concurrent loaders. This doesn't require any code re-design as none of the mechanisms implemented rely on the per-name locking provided by the parallelLockMap. This seems to give us a path to remove all locking at the Java level during classloading, while retaining full compatibility with Java 7 parallel capable loaders. Fully concurrent loaders will still encounter the performance penalty associated with concurrent attempts to find and prepare a class's bytecode for definition by the VM. What this penalty is depends on the number of concurrent load attempts possible (a function of the number of threads and the application logic, and dependent on the number of processors), and the costs associated with finding and preparing the bytecodes. This obviously has to be measured across a range of applications. Preliminary webrevs: http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.hotspot/ http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.jdk/ Please direct all comments to the mailing list [email protected].

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  • UVA Online Judge 3n+1 : Right answer is Wrong answer

    - by Samuraisoulification
    Ive been toying with this problem for more than a week now, I have optimized it a lot, I seem to be getting the right answer, since it's the same as when I compare it to other's answers that got accepted, but I keep getting wrong answer. Im not sure what's going on! Anyone have any advice? I think it's a problem with the input or the output, cause Im not exactly sure how this judge thing works. So if anyone could pinpoint the problem, and also give me any advice on my code, Id be very appreciative!!! #include <iostream> #include <cstdlib> #include <stdio.h> #include <vector> using namespace std; class Node{ // node for each number that has teh cycles and number private: int number; int cycles; bool cycleset; // so it knows whether to re-set the cycle public: Node(int num){ number = num; cycles = 0; cycleset = false; } int getnumber(){ return number; } int getcycles(){ return cycles; } void setnumber(int num){ number = num; } void setcycles(int num){ cycles = num; cycleset = true; } bool cycled(){ return cycleset; } }; class Cycler{ private: vector<Node> cycleArray; int biggest; int cycleReal(unsigned int number){ // actually cycles through the number int cycles = 1; if (number != 1) { if (number < 1000000) { // makes sure it's in vector bounds if (!cycleArray[number].cycled()) { // sees if it's been cycled if (number % 2 == 0) { cycles += this->cycleReal((number / 2)); } else { cycles += this->cycleReal((3 * number) + 1); } } else { // if cycled get the number of cycles and don't re-calculate, ends recursion cycles = cycleArray[number].getcycles(); } } else { // continues recursing if it's too big for the vector if (number % 2 == 0) { cycles += this->cycleReal((number / 2)); } else { cycles += this->cycleReal((3 * number) + 1); } } } if(number < 1000000){ // sets cycles table for the number in the vector if (!cycleArray[number].cycled()) { cycleArray[number].setcycles(cycles); } } return cycles; } public: Cycler(){ biggest = 0; for(int i = 0; i < 1000000; i++){ // initialize the vector, set the numbers Node temp(i); cycleArray.push_back(temp); } } int cycle(int start, int end){ // cycles thorugh the inputted numbers. int size = 0; for(int i = start; i < end ; i++){ size = this->cycleReal(i); if(size > biggest){ biggest = size; } } int temp = biggest; biggest = 0; return temp; } int getBiggest(){ return biggest; } }; int main() { Cycler testCycler; int i, j; while(cin>>i>>j){ //read in untill \n int biggest = 0; if(i > j){ biggest = testCycler.cycle(j, i); }else{ biggest = testCycler.cycle(i, j); } cout << i << " " << j << " " << biggest << endl; } return 0; }

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  • Of transactions and Mongo

    - by Nuri Halperin
    Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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  • Future of VB.NET? [closed]

    - by Alex Yeung
    Hi all, I worked with C# for years. Last year, I changed my job and the company use VB.NET. Of course, theoretically C# and VB.NET are very similar and I easily adapted. However, I have worked for VB.NET for 1 year. I cannot see any future of VB.NET. As a programming language, it is so foo. Here is a list of what C# can do but VB.NET cannot Case insensitive variables how to think a new variable name? If I have a property called FolderPath, i need to establish another private variable called _folderPath or m_folderPath. In C#, FolderPath and folderPath are two variables. Moreover, it gets compile error if variable name is same as a class name. For example Dim guid = Guid.NewGuid(). (What the...) Again, I need to think a new variable name. Adhoc scope In C#, we could use {...} to create a adhoc scope and all resource in {...} will not affect the code outside. However there is not such syntax in VB.NET. I could only use If True Then and End If to make a local scope which is so unclear. In-Method Region Sometime, it is unavoidable to have a long long method. VB.NET does not support in-method region. I always need to scroll down for 1000 lines. It wastes my time. No multi-line string definition In C#, we could var s = @"..." to define a multi-line string. In VB.NET there is no direct method to do that. The indirect way is use XML-literal string. Dim s = <![CDATA[...]]>.Value. However it is unclear. No block comment In C#, we have line comment // and block comment /* ... */. However in VB.NET we only have line comment which is a very big trouble for me. No statement end symbol Statements are separated by line break in VB.NET; while statements are separated by ; in C#. Underscore I think many people know underscore _ is continue statement symbol. I really disagree with that. I know MS VB.NET language team is going to remove the underscore syntax from VB.NET. However what can we do now? Although underscore is removed in the future, what's the advantage of that? I cannot see any advantage! With scope With scope is an evil scope. Although it allows shorter statement, it is hard to trace. Default Namesapce in project level It is a nightmare for me. The only advantage of VB.NET is property initialization. I think C# cannot do that (correct me if I am wrong.) Public Property ThisIsMyProperty As String = "MyValue" Remarks: I don't think optional method parameters is an advantage of OOP. By those disadvantages, I cannot see the future of VB.NET. Anyone sees the future of VB.NET?

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  • StreamInsight 2.1, meet LINQ

    - by Roman Schindlauer
    Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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  • IRC-Bot in Ruby: PRIVMSG sends only last word of string

    - by Marius Schuller
    I'm on learning ruby and I took a already done IRC-Bot from the web which just connects to a given serven and not much more. Then I added some features (in my case I try to implement a voting where to eat lunch). Now these work fine so far but I don't know if the ruby script does something wrong or there is something wrong with the IRC-server. On the one I tested the Bot it worked well, giving an output like this: 09:14 < Wayne> !EssNA 09:14 < EssNABot> [-=EssNA-Vote=-] 09:14 < EssNABot> Options are: 09:14 < EssNABot> McDonalds. 0 09:14 < EssNABot> Currywurst 0 09:14 < EssNABot> Hendl..... 0 09:14 < EssNABot> Salatbar.. 0 09:14 < EssNABot> Griechr... 0 09:14 < EssNABot> Metzger... 0 09:14 < EssNABot> Merowinger 0 09:14 < EssNABot> Lidl...... 0 09:14 < EssNABot> Voting time is 600 seconds. The bot itself sees that like this: --> PRIVMSG #test [-=EssNA-Vote=-] --> PRIVMSG #test Options are: --> PRIVMSG #test McDonalds. 0 --> PRIVMSG #test Currywurst 0 --> PRIVMSG #test Hendl..... 0 --> PRIVMSG #test Salatbar.. 0 --> PRIVMSG #test Griechr... 0 --> PRIVMSG #test Metzger... 0 --> PRIVMSG #test Merowinger 0 --> PRIVMSG #test Lidl...... 0 --> PRIVMSG #test Voting time is 600 seconds. But on the irc which it should run on if its done the output users will see looks like this: 09:14 < Wayne> !EssNA 09:14 < EssNABot> [-=EssNA-Vote=-] 09:14 < EssNABot> are: 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> 0 09:14 < EssNABot> seconds. The output the bot gives is the same as on the server on which the output for users works. Seems to me that the problem is the IRC-server, maybe someone can point me in the right direction? Yours, Marius

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  • How to handle recurring dates (dates only) in .NET?

    - by Wayne M
    I am trying to figure out a good way to handle recurring events in .NET, specifically for an ASP.NET MVC application. The idea is that a user can create an event and specify that the event can occur repeatedly after a specific interval (e.g. "every two weeks", "once a month" and so on). What would be the best way to tackle this? My brainstorming right now is to have two tables: Job and RecurringJob. Job is the "master" record and has the description of the job as well a key to what customer it's for, while RecurringJob links back to Job and has additional info on what the occurrence frequency is (e.g. 1 for "once a month") as well as the timespan (e.g. "Weekly", "Monthly"). The issue is how to determine and set the next occurrence of the job since this will have to be something that's done regularly. I've seen two trains of thought with this: This logic should either be stored in a database column and periodically updated, or calculated on the fly in the code. Any thoughts or suggestions on tackling this? Edit: this is for a subscription based web app I'm creating to let service businesses schedule their common recurring jobs easily and track their customers. So a typical use might be to create a "Cut lawn" job for Mr Smith that occurs every month The exact date isn't important - it's the ability for the customer to see that Mr Smith gets his lawn cut every month and followup with him about it. Let me rephrase the above to better convey my idea. A sample use case for the application might be as follows: User pulls up the customer record for John Smith and clicks the Add Job link. The user fills out the form to create a job with a name of "Cut lawn", a start date of 11/15/2009, and selects a checkbox indicating that this job continually occurs. The user is presented with a secondary screen asking for the job frequency. The user indicates (haven't decided how at this point - let's assume select lists) that the job occurs once a month. User clicks save. Now, when the user views the record for John Smith, they can see that he has a job, "Cut lawn", that occurs every month starting from 11/15/2009. On the main dashboard when it's one week prior to the assumed start date, the user sees the job displayed with an indicator such as "12/15/2009 - Cut lawn (John Smith)". A week before the due date someone from the company calls him up to schedule and he says he's going to be out of town until 1/1/2010, so he wants his appointment rescheduled for that date. Our user can change the date for the job to be 1/1/2010, and now the recurrence will start one month from that date (e.g. next time will be 2/1/2010). The idea behind this is that the app is targeting businesses like lawn care, plumbers, carpet cleaners and the like where the exact date isn't as important (because it can and will change as people are busy), the key thing is to give the business an indicator that Mr. Smith's monthly service is coming up, and someone should give him a call to determine when exactly it can be scheduled for. In effect give these businesses a way to track repeat business and know when it's time to followup with a customer.

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  • Navigation in Win8 Metro Style applications

    - by Dennis Vroegop
    In Windows 8, Touch is, as they say, a first class citizen. Now, to be honest: they also said that in Windows 7. However in Win8 this is actually true. Applications are meant to be used by touch. Yes, you can still use mouse, keyboard and pen and your apps should take that into account but touch is where you should focus on initially. Will all users have touch enabled devices? No, not in the first place. I don’t think touchscreens will be on every device sold next year. But in 5 years? Who knows? Don’t forget: if your app is successful it will be around for a long time and by that time touchscreens will be everywhere. Another reason to embrace touch is that it’s easier to develop a touch-oriented app and then to make sure that keyboard, nouse and pen work as doing it the other way around. Porting a mouse-based application to a touch based application almost never works. The reverse gives you much more chances for success. That being said, there are some things that you need to think about. Most people have more than one finger, while most users only use one mouse at the time. Still, most touch-developers translate their mouse-knowledge to the touch and think they did a good job. Martin Tirion from Microsoft said that since Touch is a new language people face the same challenges they do when learning a new real spoken language. The first thing people try when learning a new language is simply replace the words in their native language to the newly learned words. At first they don’t care about grammar. To a native speaker of that other language this sounds all wrong but they still will be able to understand what the intention was. If you don’t believe me: try Google translate to translate something for you from your language to another and then back and see what happens. The same thing happens with Touch. Most developers translate a mouse-click into a tap-event and think they’re done. Well matey, you’re not done. Not by far. There are things you can do with a mouse that you cannot do with touch. Think hover. A mouse has the ability to ‘slide’ over UI elements. Touch doesn’t (I know: with Pen you can do this but I’m talking about actual fingers here). A touch is either there or it isn’t. And right-click? Forget about it. A click is a click.  Yes, you have more than one finger but the machine doesn’t know which finger you use… The other way around is also true. Like I said: most users only have one mouse but they are likely to have more than one finger. So how do we take that into account? Thinking about this is really worth the time: you might come up with some surprisingly good ideas! Still: don’t forget that not every user has touch-enabled hardware so make sure your app is useable for both groups. Keep this in mind: we’re going to need it later on! Now. Apps should be easy to use. You don’t want your user to read through pages and pages of documentation before they can use the app. Imagine that spotter next to an airfield suddenly seeing a prototype of a Concorde 2 landing on the nearby runway. He probably wants to enter that information in our app NOW and not after he’s taken a 3 day course. Even if he still has to download the app, install it for the first time and then run it he should be on his way immediately. At least, fast enough to note down the details of that unique, rare and possibly exciting sighting he just did. So.. How do we do this? Well, I am not talking about games here. Games are in a league of their own. They fall outside the scope of the apps I am describing. But all the others can roughly be characterized as being one of two flavors: the navigation is either flat or hierarchical. That’s it. And if it’s hierarchical it’s no more than three levels deep. Not more. Your users will get lost otherwise and we don’t want that. Flat is simple. Just imagine we have one screen that is as high as our physical screen is and as wide as you need it to be. Don’t worry if it doesn’t fit on the screen: people can scroll to the right and left. Don’t combine up/down and left/right scrolling: it’s confusing. Next to that, since most users will hold their device in landscape mode it’s very natural to scroll horizontal. So let’s use that when we have a flat model. The same applies to the hierarchical model. Try to have at most three levels. If you need more space, find a way to group the items in such a way that you can fit it in three, very wide lanes. At the highest level we have the so called hub level. This is the entry point of the app and as such it should give the user an immediate feeling of what the app is all about. If your app has categories if items then you might show these categories here. And while you’re at it: also show 2 or 3 of the items itself here to give the user a taste of what lies beneath. If the user selects a category you go to the section part. Here you show several sections (again, go as wide as you need) with again some detail examples. After that: the details layer shows each item. By giving some samples of the underlaying layer you achieve several things: you make the layer attractive by showing several different things, you show some highlights so the user sees actual content and you provide a shortcut to the layers underneath. The image below is borrowed from the http://design.windows.com website which has tons and tons of examples: For our app we’ll use this layout. So what will we show? Well, let’s see what sorts of features our app has to offer. I’ll repeat them here: Note planes Add pictures of that plane Notify friends of new spots Share new spots on social media Write down arrival times Write down departure times Write down the runway they take I am sure you can think of some more items but for now we'll use these. In the hub we’ll show something that represents “Spots”, “Friends”, “Social”. Apparently we have an inner list of spotter-friends that are in the app, while we also have to whole world in social. In the layer below we show something else, depending on what the user choose. When they choose “Spots” we’ll display the last spots, last spots by our friends (so we can actually jump from this category to the one next to it) and so on. When they choose a “spot” (or press the + icon in the App bar, which I’ll talk about next time) they go to the lowest and final level that shows details about that spot, including a picture, date and time and the notes belonging to that entry. You’d be amazed at how easy it is to organize your app this way. If you don’t have enough room in these three layers you probably could easily get away with grouping items. Take a look at our hub: we have three completely different things in one place. If you still can’t fit it all in in a logical and consistent way, chances are you are trying to do too much in this app. Go back to your mission statement, determine if it is specific enough and if your feature list helps that statement or makes it unclear. Go ahead. Give it a go! Next time we’ll talk about the look and feel, the charms and the app-bar….

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  • Roguelike FOV problem

    - by Manderin87
    I am working on a college compsci project and I would like some help with a field of view algorithm. I works mostly, but in some situations the algorithm sees through walls and hilights walls the player should not be able to see. void cMap::los(int x0, int y0, int radius) { //Does line of sight from any particular tile for(int x = 0; x < m_Height; x++) { for(int y = 0; y < m_Width; y++) { getTile(x,y)->setVisible(false); } } double xdif = 0; double ydif = 0; bool visible = false; float dist = 0; for (int x = MAX(x0 - radius,0); x < MIN(x0 + radius, m_Height); x++) { //Loops through x values within view radius for (int y = MAX(y0 - radius,0); y < MIN(y0 + radius, m_Width); y++) { //Loops through y values within view radius xdif = pow( (double) x - x0, 2); ydif = pow( (double) y - y0, 2); dist = (float) sqrt(xdif + ydif); //Gets the distance between the two points if (dist <= radius) { //If the tile is within view distance, visible = line(x0, y0, x, y); //check if it can be seen. if (visible) { //If it can be seen, getTile(x,y)->setVisible(true); //Mark that tile as viewable } } } } } bool cMap::line(int x0,int y0,int x1,int y1) { bool steep = abs(y1-y0) > abs(x1-x0); if (steep) { swap(x0, y0); swap(x1, y1); } if (x0 > x1) { swap(x0,x1); swap(y0,y1); } int deltax = x1-x0; int deltay = abs(y1-y0); int error = deltax/2; int ystep; int y = y0; if (y0 < y1) ystep = 1; else ystep = -1; for (int x = x0; x < x1; x++) { if ( steep && getTile(y,x)->isBlocked()) { getTile(y,x)->setVisible(true); getTile(y,x)->setDiscovered(true); return false; } else if (!steep && getTile(x,y)->isBlocked()) { getTile(x,y)->setVisible(true); getTile(x,y)->setDiscovered(true); return false; } error -= deltay; if (error < 0) { y = y + ystep; error = error + deltax; } } return true; } If anyone could help me make the first blocked tiles visible but stops the rest, I would appreciate it. thanks, Manderin87

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  • How can I modify my Shunting-Yard Algorithm so it accepts unary operators?

    - by KingNestor
    I've been working on implementing the Shunting-Yard Algorithm in JavaScript for class. Here is my work so far: var userInput = prompt("Enter in a mathematical expression:"); var postFix = InfixToPostfix(userInput); var result = EvaluateExpression(postFix); document.write("Infix: " + userInput + "<br/>"); document.write("Postfix (RPN): " + postFix + "<br/>"); document.write("Result: " + result + "<br/>"); function EvaluateExpression(expression) { var tokens = expression.split(/([0-9]+|[*+-\/()])/); var evalStack = []; while (tokens.length != 0) { var currentToken = tokens.shift(); if (isNumber(currentToken)) { evalStack.push(currentToken); } else if (isOperator(currentToken)) { var operand1 = evalStack.pop(); var operand2 = evalStack.pop(); var result = PerformOperation(parseInt(operand1), parseInt(operand2), currentToken); evalStack.push(result); } } return evalStack.pop(); } function PerformOperation(operand1, operand2, operator) { switch(operator) { case '+': return operand1 + operand2; case '-': return operand1 - operand2; case '*': return operand1 * operand2; case '/': return operand1 / operand2; default: return; } } function InfixToPostfix(expression) { var tokens = expression.split(/([0-9]+|[*+-\/()])/); var outputQueue = []; var operatorStack = []; while (tokens.length != 0) { var currentToken = tokens.shift(); if (isNumber(currentToken)) { outputQueue.push(currentToken); } else if (isOperator(currentToken)) { while ((getAssociativity(currentToken) == 'left' && getPrecedence(currentToken) <= getPrecedence(operatorStack[operatorStack.length-1])) || (getAssociativity(currentToken) == 'right' && getPrecedence(currentToken) < getPrecedence(operatorStack[operatorStack.length-1]))) { outputQueue.push(operatorStack.pop()) } operatorStack.push(currentToken); } else if (currentToken == '(') { operatorStack.push(currentToken); } else if (currentToken == ')') { while (operatorStack[operatorStack.length-1] != '(') { if (operatorStack.length == 0) throw("Parenthesis balancing error! Shame on you!"); outputQueue.push(operatorStack.pop()); } operatorStack.pop(); } } while (operatorStack.length != 0) { if (!operatorStack[operatorStack.length-1].match(/([()])/)) outputQueue.push(operatorStack.pop()); else throw("Parenthesis balancing error! Shame on you!"); } return outputQueue.join(" "); } function isOperator(token) { if (!token.match(/([*+-\/])/)) return false; else return true; } function isNumber(token) { if (!token.match(/([0-9]+)/)) return false; else return true; } function getPrecedence(token) { switch (token) { case '^': return 9; case '*': case '/': case '%': return 8; case '+': case '-': return 6; default: return -1; } } function getAssociativity(token) { switch(token) { case '+': case '-': case '*': case '/': return 'left'; case '^': return 'right'; } } It works fine so far. If I give it: ((5+3) * 8) It will output: Infix: ((5+3) * 8) Postfix (RPN): 5 3 + 8 * Result: 64 However, I'm struggling with implementing the unary operators so I could do something like: ((-5+3) * 8) What would be the best way to implement unary operators (negation, etc)? Also, does anyone have any suggestions for handling floating point numbers as well? One last thing, if anyone sees me doing anything weird in JavaScript let me know. This is my first JavaScript program and I'm not used to it yet.

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  • Adjust parameters of serial port reading

    - by clinisbut
    Hello. I'm facing a particular issue that regards serial communication under win32. I'm communicating with a device can only accept frames when it is not already communicating. So I must find a valid frame and then inmediatelly send my request. I developed a class named Serial that handles basic operations on serial port (open, close, read, write) and then a Thread calls inside a loop read and write functions. Thread loop //Device is an object of class Serial while( device->isOpen() && !terminate ) { unsigned int readed = 0; unsigned long error = ERROR_SUCCESS; unsigned char* data = device->read( &readed, &error ); if( error==ERROR_SUCCESS ) { //If data received, deliver to upper level if( readed>0 ) { QByteArray output( (const char*)data, (signed int)readed ); emit dataArrived( output, readed ); } } else { //unrelated stuff } //Here I manage the writting issue //Only when nothing is received, and Upper layer wants to send a frame //(Upper layer only will mark as something to send when it detects a valid frame) if( readed==0 ) { out_lock.lock(); //If something to send... if( something_to_send > 0 ) { if( device->write( output_buffer, output_size, &error ) ) { //things... } } } } The Thread basically keeps reading, and when nothing is received, sees if somebody has signaled to send a frame (this means that a valid frame is just received). When this happens, it writes the frame through serial port. Here comes my problem. Inside the Serial::read() function: I use the overlapped way of reading: ::ClearCommError( handle, &dwErrors, &stat); if( stat.cbInQue ) { //If there's something to read, read it, please note the bytes to read parameter, here 1. bool ok = ::ReadFile( handle, buffer_in, 1, &bytes_read, &ov_reader ); if( !ok ) { DWORD _error = ::GetLastError(); if( _error == ERROR_IO_PENDING ) { DWORD result = ::WaitForMultipleObjects( 2, waiters, FALSE,INFINITE ); switch( result ) { //Eventshutdown case WAIT_OBJECT_0: /*code omitted*/break; case WAIT_OBJECT_0+1: ok = ::GetOverlappedResult( handle, &ov_reader, &bytes_read, true ); //check ok value omitted break; } } } } if( bytes_read>0 ) { *size = bytes_read; } Here starts my problem. When device sends me small frames (around 30 bytes) everything works fine, but when larger frames are sent, the code is not able to find any free time between frames causing the thread to never be able send any frame because readed is never 0. If I increase the number of bytes to read inside the read() function, lose the ability to detect when the device "listens": bool ok = ::ReadFile(handle, buffer_in, 50, &bytes_read, &ov_reader ); This happens because my app can receive the end of a frame together with the start of the next one. This behaviour is very common. In the other hand, if I change the INFINITE argument by a valid timeout in the WaitForMultipleObjects function, I lose data. So my question basically is... what I'm doing wrong? Why when reading 1 byte each time I don't find any free time to send my own frames? Thank you

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  • std::basic_string full specialization (g++ conflict)

    - by SoapBox
    I am trying to define a full specialization of std::basic_string< char, char_traits<char>, allocator<char> > which is typedef'd (in g++) by the <string> header. The problem is, if I include <string> first, g++ sees the typedef as an instantiation of basic_string and gives me errors. If I do my specialization first then I have no issues. I should be able to define my specialization after <string> is included. What do I have to do to be able to do that? My Code: #include <bits/localefwd.h> //#include <string> // <- uncommenting this line causes compilation to fail namespace std { template<> class basic_string< char, char_traits<char>, allocator<char> > { public: int blah() { return 42; } size_t size() { return 0; } const char *c_str() { return ""; } void reserve(int) {} void clear() {} }; } #include <string> #include <iostream> int main() { std::cout << std::string().blah() << std::endl; } The above code works fine. But, if I uncomment the first #include <string> line, I get the following compiler errors: blah.cpp:7: error: specialization of ‘std::basic_string<char, std::char_traits<char>, std::allocator<char> >’ after instantiation blah.cpp:7: error: redefinition of ‘class std::basic_string<char, std::char_traits<char>, std::allocator<char> >’ /usr/include/c++/4.4/bits/stringfwd.h:52: error: previous definition of ‘class std::basic_string<char, std::char_traits<char>, std::allocator<char> >’ blah.cpp: In function ‘int main()’: blah.cpp:22: error: ‘class std::string’ has no member named ‘blah’ Line 52 of /usr/include/c++/4.4/bits/stringfwd.h: template<typename _CharT, typename _Traits = char_traits<_CharT>, typename _Alloc = allocator<_CharT> > class basic_string; As far as I know this is just a forward delcaration of the template, NOT an instantiation as g++ claims. Line 56 of /usr/include/c++/4.4/bits/stringfwd.h: typedef basic_string<char> string; As far as I know this is just a typedef, NOT an instantiation either. So why are these lines conflicting with my code? What can I do to fix this other than ensuring that my code is always included before <string>?

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  • XForms and multiple inputs for same model tag

    - by iHeartGreek
    Hi! I apologize ahead of time if I am not asking this properly.. it is hard to put into words what I am asking.. I have XForms model such as: <file> <criteria> <criterion></criterion> </criteria> </file> I want to have multiple input text boxes that create a new criterion tag. user interface such as: <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> And I would like the XML output to look like this (once user has entered in info): <file> <criteria> <criterion>AAA</criterion> <criterion>BBB</criterion> <criterion>CCC</criterion> </criteria> </file> The way I have it doesn't work, as it sees the 3 input fields to be referring all to the same criterion tag. How do I differentiate? Thanks! I hope that made some sense! BEGIN FIRST EDIT Thanks for the responses for the basic text box! However, I now need to do this with a listbox. But for the life of me, I can't figure out how. I read somewhere to use with the xforms:select and deselect events.. but I didn't know where to place them, and the places I tried gave me very weird behaviour. I am currently implementing the following: <xf:select ref="instance('criteria_data')/criteria/criterion" selection="" appearance="compact" > <xf:label>Choose criteria</xf:label> <xf:itemset nodeset="instance('criteria_choices')/choice"> <xf:label ref="@label"></xf:label> <xf:value ref="."></xf:value> </xf:itemset> </xf:select> However when multiple choices are submitted, all selection values are inserted into the same node, separated by spaces. For example: If AAA and BBB and FFF were selected from listbox, it would result in the following XML: <criterion>AAA BBB FFF</criterion> How do I change my code to have each selection be in a separate node? i.e. I want it to look like this: <criterion>AAA</criterion> <criterion>BBB</criterion> <criterion>FFF</criterion> Thanks! END FIRST EDIT BEGIN SECOND EDIT: For the listboxes (ie xf:select appearance="compact") I ended up allowing the spaces to occur in the same node and then just transformed that xml using xsl to generate a properly formatted new xml doc (with separate individual nodes). Unfortunately, I did not find a less cumbersome solution by inserting them originally into separate nodes. The selected answer works very well for text boxes however, hence why I selected it as the answer. END SECOND EDIT

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  • A view interface for large object/array dumps

    - by user685107
    I want to embed in a page a detailed structure report of my model objects, like print_r() or var_export() produce (now I’m doing this with running var_export() on get_object_vars()). But what I actually want to see is only some properties (in most cases), but at this moment I have to use Ctrl+F and seek the variable I want, instead of just staring at it right after the page completes loading. So I’m embedding buttons to show/hide large arrays etc. but thought: ‘What if there already is the thing I do right now?’ So is there? Update: What would your ideal interface look like? First of all, dumped models fit in the first screen. All the properties can be seen at the first look at the screen (there are not many of them, around 10 per each, three models total, so it is possible). Small arrays can be shown unrolled too. Let the size of the array to count it as ‘small’ be definable. Ideally, the user can see values of the properties without doing any click, scrolling the screen or typing something. There must be some improvements to representing the values, say, if an array is empty, show array ‘My_big_array’ is empty and if a boolean variable starting with is_, has_, had_ has a false as the value, make the variable (let us take is_available for example) shown as is_NOT_available in red, and if it has true as the value, show is_available in green. Without any value shown. The same goes for defined constants. That would be ideal. I want to make focus on this kind of switches. Krumo seems useful, but since it always closes up the variable without making difference of how large it is, I cannot use it as is, but there might appear something similar on github soon :) Second update starts here: Any programmer who sees is_available = false will know what it means, no need to do more Bringing in color indication I forgot about one thing: the ‘switches’ let’s call them so, may me important or not. So I have right now some of them that will show in green or red, this is for something global, like caching, which is shown as Caching is… ON with ‘ON’ written in green, (and ‘OFF’ in red when disabled) while the words about what it is, i.e. ‘Caching is… ’ are written in black. And some which are not so important, for example I haven’t defined REVEAL_TIES is… not set with ‘not set’ written in gray, while the words describing what it is stay in black. And if it would be set the whole phrase would be in black since there is nothing important: if this small utility for showing some undercover things is working, I will see some messages after it, if it isn’t — site will be working independently of its state. Dividing switches into important ones and not with corresponding color match should improve readability, especially for those users who are not programmers and just enabled debug mode because some guy from bugzilla said do that — for them it would help to understand what is important and what is not.

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  • How Expedia Made My New Bride Cry

    - by Lance Robinson
    Tweet this? Email Expedia and ask them to give me and my new wife our honeymoon? When Expedia followed up their failure with our honeymoon trip with a complete and total lack of acknowledgement of any responsibility for the problem and endless loops of explaining the issue over and over again - I swore that they would make it right. When they brought my new bride to tears, I got an immediate and endless supply of motivation. I hope you will help me make them make it right by posting our story on Twitter, Facebook, your blog, on Expedia itself, and when talking to your friends in person about their own travel plans.   If you are considering using them now for an important trip - reconsider. Short summary: We arrived early for a flight - but Expedia had made a mistake with the data they supplied to JetBlue and Emirates, which resulted in us not being able to check in (one leg of our trip was missing)!  At the time of this post, three people (myself, my wife, and an exceptionally patient JetBlue employee named Mary) each spent hours on the phone with Expedia.  I myself spent right at 3 hours (according to iPhone records), Lauren spent an hour and a half or so, and poor Mary was probably on the phone for a good 3.5 hours.  This is after 5 hours total at the airport.  If you add up our phone time, that is nearly 8 hours of phone time over a 5 hour period with little or no help, stall tactics (?), run-around, denial, shifting of blame, and holding. Details below (times are approximate): First, my wife and I were married yesterday - June 18th, the 3 year anniversary of our first date. She is awesome. She is the nicest person I have ever known, a ton of fun, absolutely beautiful in every way. Ok enough mushy - here are the dirty details. 2:30 AM - Early Check-in Attempt - we attempted to check-in for our flight online. Some sort of technology error on website, instructed to checkin at desk. 4:30 AM - Arrive at airport. Try to check-in at kiosk, get the same error. We got to the JetBlue desk at RDU International Airport, where Mary helped us. Mary discovered that the Expedia provided itinerary does not match the Expedia provided tickets. We are informed that when that happens American, JetBlue, and others that use the same software cannot check you in for the flight because. Why? Because the itinerary was missing a leg of our flight! Basically we were not shown in the system as definitely being able to make it home. Mary called Expedia and was put on hold by their automated system. 4:55 AM - Mary, myself, and my brand new bride all waited for about 25 minutes when finally I decided I would make a call myself on my iPhone while Mary was on the airport phone. In their automated system, I chose "make a new reservation", thinking they might answer a little more quickly than "customer service". Not surprisingly I was connected to an Expedia person within 1 minute. They informed me that they would have to forward me to a customer service specialist. I explained to them that we were already on hold for that and had been for nearly half an hour, that we were going on our honeymoon and that our flight would be leaving soon - could they please help us. "Yes, I will help you". I hand the phone to JetBlue Mary who explains the situation 3 or 4 times. Obviously I couldn't hear both ends of the conversation at this point, but the Expedia person explained what the problem was by stating exactly what Mary had just spent 15 minutes explaining. Mary calmly confirms that this is the problem, and asks Expedia to re-issue the itinerary. Expedia tells Mary that they'll have to transfer her to customer service. Mary asks for someone specific so that we get an answer this time, and goes on hold. Mary get's connected, explains the situation, and then Mary's connection gets terminated. 5:10 AM - Mary calls back to the Expedia automated system again, and we wait for about 5 minutes on hold this time before I pick up my iPhone and call Expedia again myself. Again I go to sales, a person picks up the phone in less than a minute. I explain the situation and let them know that we are now very close to missing our flight for our honeymoon, could they please help us. "Yes, I will help you". Again I give the phone to Mary who provides them with a call back number in case we get disconnected again and explains the situation again. More back and forth with Expedia doing nothing but repeating the same questions, Mary answering the questions with the same information she provided in the original explanation, and Expedia simply restating the problem. Mary again asks them to re-issue the itinerary, and explains that doing so will fix the problem. Expedia again repeats the problem instead of fixing it, and Mary's connection gets terminated. 5:20 AM - Mary again calls back to Expedia. My beautiful bride also calls on her own phone. At this point she is struggling to hold back her tears, stumbling through an explanation of all that has happened and that we are about to miss our flight. Please help us. "Yes, I will help". My beautiful bride's connection gets terminated. Ok, maybe this disconnection isn't an accident. We've now been disconnected 3 times on two different phones. 5:45 AM - I walk away and pleadingly beg a person to help me. They "escalate" the issue to "Rosy" (sp?) at Expedia. I go through the whole song and dance again with Rosy, who gives me the same treatment Mary was given. Rosy blames JetBlue for now having the correct data. Meanwhile Mary is on the phone with Emirates Air (the airline for the second leg of our trip), who agrees with JetBlue that Expedia's data isn't up to date. We are informed by two airport employees that issues like this with Expedia are not uncommon, and that the fix is simple. On the phone iwth Rosy, I ask her to re-issue the itinerary because we are about to miss our flight. She again explains the problem to me. At this point, I am standing at the window, pleading with Rosy to help us get to our honeymoon, watching our airplane. Then our airplane leaves without us. 6:03 AM - At this point we have missed our flight. Re-issuing the itinerary is no longer a solution. I ask Rosy to start from the beginning and work us up a new trip. She says that she cannot do that. She says that she needs to talk to JetBlue and Emirates and find out why we cannot check-in for our flight. I remind Rosy that our flight has already left - I just watched it taxi away - it no longer matters why (not to mention the fact that we already knew why, and have known why since 4:30 AM), and have known the solution since 4:30 AM. Rosy, can you please book a new trip? Yes, but it will cost $400. Excuse me? Now you can, but it will cost ME to fix your mistake? Rosy says that she can escalate the situation to her supervisor but that will take 1.5 hours. 6:15 AM - I told Rosy that if they had re-issued the itinerary as JetBlue asked (at 4:30 AM), my new wife and I might be on the airplane now instead of dealing with this on the phone and missing the beginning (and how much more?) of our honeymoon. Rosy said that it was not necessary to re-issue the itinerary. Out of curiosity, i asked Rosy if there was some financial burden on them to re-issue the itinerary. "No", said Rosy. I asked her if it was a large time burden on Expedia to re-issue the itinerary. "No", said Rosy. I directly asked Rosy: Why wouldn't Expedia have re-issued the itinerary when JetBlue asked? No answer. I asked Rosy: If you had re-issued the itinerary at 4:30, isn't it possible that I would be on that flight right now? She actually surprised me by answering "Yes" to that question. So I pointed out that it followed that Expedia was responsible for the fact that we missed out flight, and she immediately went into more about how the problem was with JetBlue - but now it was ALSO an Emirates Air problem as well. I tell Rosy to go ahead and escalate the issue again, and please call me back in that 1.5 hours (which how is about 1 hour and 10 minutes away). 6:30 AM - I start tweeting my frustration with iPhone. It's now pretty much impossible for us to make it to The Maldives by 3pm, which is the time at which we would need to arrive in order to be allowed service to the actual island where we are staying. Expedia has now given me the run-around for 2 hours, caused me to miss my flight, and worst of all caused my amazing new wife Lauren to miss our honeymoon. You think I was mad? No. Furious. Its ok to make mistakes - but to refuse to fix them and to ruin our honeymoon? No, not ok, Expedia. I swore right then that Expedia would make this right. 7:45 AM - JetBlue mary is still talking her tail off to other people in JetBlue and Emirates Air. Mary works it out so that if Expedia simply books a new trip, JetBlue and Emirates will both waive all the fees. Now we just have to convince Expedia to fix their mistake and get us on our way! Around this time Expedia Rosy calls me back! I inform her of the excellent work of JetBlue Mary - that JetBlue and Emirates both will waive the fees so Expedia can fix their mistake and get us going on our way. She says that she sees documentation of this in her system and that she needs to put me on hold "for 1 to 10 minutes" to talk to Emirates Air (why I'm not exactly sure). I say ok. 8:45 AM - After an hour on hold, Rosy comes on the line and asks me to hold more. I ask her to call me back. 9:35 AM - I put down the iPhone Twitter app and picks up the laptop. You think I made some noise with my iPhone? Heh 11:25 AM - Expedia follows me and sends a canned "We're sorry, DM us the details".  If you look at their Twitter feed, 16 out of the most recent 20 tweets are exactly the same canned response.  The other 4?  Ads.  Um - #MultiFAIL? To Expedia:  You now have had (as explained above) 8 hours of 3 different people explaining our situation, you know the email address of our Expedia account, you know my web blog, you know my Twitter address, you know my phone number.  You also know how upset you have made both me and my new bride by treating us with such a ... non caring, scripted, uncooperative, argumentative, and possibly even deceitful manner.  In the wise words of the great Kenan Thompson of SNL: "FIX IT!".  And no, I'm NOT going away until you make this right. Period. 11:45 AM - Expedia corporate office called.  The woman I spoke to was very nice and apologetic.  She listened to me tell the story again, she says she understands the problem and she is going to work to resolve it.  I don't have any details on what exactly that resolution might me, she said she will call me back in 20 minutes.  She found out about the problem via Twitter.  Thank you Twitter, and all of you who helped.  Hopefully social media will win my wife and I our honeymoon, and hopefully Expedia will encourage their customer service teams treat their customers properly. 12:22 PM - Spoke to Fran again from Expedia corporate office.  She has a flight for us tonight.  She is booking it now.  We will arrive at our honeymoon destination of beautiful Veligandu Island Resort only 1 day late.  She cannot confirm today, but she expects that Expedia will pay for the lost honeymoon night.  Thank you everyone for your help.  I will reflect more on this whole situation and confirm its resolution after our flight is 100% confirmed.  For now, I'm going to take a breather and go kiss my wonderful wife! 1:50 PM - Have not yet received the promised phone call.  We did receive an email with a new itinerary for a flight but the booking is not for specific seats, so there is no guarantee that my wife and I will be able to sit together.  With the original booking I carefully selected our seats for every segment of our trip.  I decided to call into the phone number that Fran from the Expedia corporate office gave me.  Its automated voice system identified itself as "Tier 3 Support".  I am currently still on hold with them, I have not gotten through to a human yet. 1:55 PM - Fran from Expedia called me back.  She confirmed us as booked.  She called the airlines to confirm.  Unfortunately, Expedia was unwilling or unable to allow us any type of seat selection.  It is possible that i won't get to sit next to the woman I married less than a day ago on our 40 total hours of flight time (there and back).  In addition, our seats could be the worst seats on the planes, with no reclining seat back or right next to the restroom.  Despite this fact (which in my opinion is huge), the horrible inconvenience, the hours at the airport, and the negative Internet publicity that Expedia is receiving, Expedia declined to offer us any kind of upgrade or to mark us as SFU (suitable for upgrade).  Since they didn't offer - I asked, and was rejected.  I am grateful to finally be heading in the right direction, but not only did Expedia horribly botch this job from the very beginning, they followed that botch job with near zero customer service, followed by a verbally apologetic but otherwise half-hearted resolution.  If this works out favorably for us, great.  If not - I'm not done making noise, Expedia.  You owe us, and I expect you to make it right.  You haven't quite done that yet. Thanks - Thank you to Twitter.  Thanks to all those who sympathize with us and helped us get the attention of Expedia, since three people (one of them an airline employee) using Expedia's normal channels of communication for many hours didn't help.  Thanks especially to my PowerShell and Sharepoint friends, my local friends, and those connectors who encouraged me and spread my story. 5:15 PM - Love Wins - After all this, Lauren and I are exhausted.  We both took a short nap, and when we woke up we talked about the last 24 hours.  It was a big, amazing, story-filled 24 hours.  I said that Expedia won, but Lauren said no.  She pointed out how lucky we are.  We are in love and married.  We have wonderful family and friends.  We are both hard-working successful people who love what they do.  We get to go to an amazing exotic destination for our honeymoon like Veligandu in The Maldives...  That's a lot of good.  Expedia didn't win.  This was (is) a big loss for Expedia.  It is a public blemish for all to see.  But Lauren and I did win, big time.  Expedia may not have made things right - but things are right for us.  Post in progress... I will relay any further comments (or lack of) from Expedia soon, as well as an update on confirmation of their repayment of our lost resort room rates.  I'll also post a picture of us on our honeymoon as soon as I can!

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  • Ops Center 12c - Provisioning Solaris Using a Card-Based NIC

    - by scottdickson
    It's been a long time since last I added something here, but having some conversations this last week, I got inspired to update things. I've been spending a lot of time with Ops Center for managing and installing systems these days.  So, I suspect a number of my upcoming posts will be in that area. Today, I want to look at how to provision Solaris using Ops Center when your network is not connected to one of the built-in NICs.  We'll talk about how this can work for both Solaris 10 and Solaris 11, since they are pretty similar.  In both cases, WANboot is a key piece of the story. Here's what I want to do:  I have a Sun Fire T2000 server with a Quad-GbE nxge card installed.  The only network is connected to port 2 on that card rather than the built-in network interfaces.  I want to install Solaris on it across the network, either Solaris 10 or Solaris 11.  I have met with a lot of customers lately who have a similar architecture.  Usually, they have T4-4 servers with the network connected via 10GbE connections. Add to this mix the fact that I use Ops Center to manage the systems in my lab, so I really would like to add this to Ops Center.  If possible, I would like this to be completely hands free.  I can't quite do that yet. Close, but not quite. WANBoot or Old-Style NetBoot? When a system is installed from the network, it needs some help getting the process rolling.  It has to figure out what its network configuration (IP address, gateway, etc.) ought to be.  It needs to figure out what server is going to help it boot and install, and it needs the instructions for the installation.  There are two different ways to bootstrap an installation of Solaris on SPARC across the network.   The old way uses a broadcast of RARP or more recently DHCP to obtain the IP configuration and the rest of the information needed.  The second is to explicitly configure this information in the OBP and use WANBoot for installation WANBoot has a number of benefits over broadcast-based installation: it is not restricted to a single subnet; it does not require special DHCP configuration or DHCP helpers; it uses standard HTTP and HTTPS protocols which traverse firewalls much more easily than NFS-based package installation.  But, WANBoot is not available on really old hardware and WANBoot requires the use o Flash Archives in Solaris 10.  Still, for many people, this is a great approach. As it turns out, WANBoot is necessary if you plan to install using a NIC on a card rather than a built-in NIC. Identifying Which Network Interface to Use One of the trickiest aspects to this process, and the one that actually requires manual intervention to set up, is identifying how the OBP and Solaris refer to the NIC that we want to use to boot.  The OBP already has device aliases configured for the built-in NICs called net, net0, net1, net2, net3.  The device alias net typically points to net0 so that when you issue the command  "boot net -v install", it uses net0 for the boot.  Our task is to figure out the network instance for the NIC we want to use.  We will need to get to the OBP console of the system we want to install in order to figure out what the network should be called.  I will presume you know how to get to the ok prompt.  Once there, we have to see what networks the OBP sees and identify which one is associated with our NIC using the OBP command show-nets. SunOS Release 5.11 Version 11.0 64-bit Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. {4} ok banner Sun Fire T200, No Keyboard Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548. Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c. {4} ok show-nets a) /pci@7c0/pci@0/pci@2/network@0,1 b) /pci@7c0/pci@0/pci@2/network@0 c) /pci@780/pci@0/pci@8/network@0,3 d) /pci@780/pci@0/pci@8/network@0,2 e) /pci@780/pci@0/pci@8/network@0,1 f) /pci@780/pci@0/pci@8/network@0 g) /pci@780/pci@0/pci@1/network@0,1 h) /pci@780/pci@0/pci@1/network@0 q) NO SELECTION Enter Selection, q to quit: d /pci@780/pci@0/pci@8/network@0,2 has been selected. Type ^Y ( Control-Y ) to insert it in the command line. e.g. ok nvalias mydev ^Y for creating devalias mydev for /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias ... net3 /pci@7c0/pci@0/pci@2/network@0,1 net2 /pci@7c0/pci@0/pci@2/network@0 net1 /pci@780/pci@0/pci@1/network@0,1 net0 /pci@780/pci@0/pci@1/network@0 net /pci@780/pci@0/pci@1/network@0 ... name aliases By looking at the devalias and the show-nets output, we can see that our Quad-GbE card must be the device nodes starting with  /pci@780/pci@0/pci@8/network@0.  The cable for our network is plugged into the 3rd slot, so the device address for our network must be /pci@780/pci@0/pci@8/network@0,2. With that, we can create a device alias for our network interface.  Naming the device alias may take a little bit of trial and error, especially in Solaris 11 where the device alias seems to matter more with the new virtualized network stack. So far in my testing, since this is the "next" network interface to be used, I have found success in naming it net4, even though it's a NIC in the middle of a card that might, by rights, be called net6 (assuming the 0th interface on the card is the next interface identified by Solaris and this is the 3rd interface on the card).  So, we will call it net4.  We need to assign a device alias to it: {4} ok nvalias net4 /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias net4 /pci@780/pci@0/pci@8/network@0,2 ... We also may need to have the MAC for this particular interface, so let's get it, too.  To do this, we go to the device and interrogate its properties. {4} ok cd /pci@780/pci@0/pci@8/network@0,2 {4} ok .properties assigned-addresses 82060210 00000000 03000000 00000000 01000000 82060218 00000000 00320000 00000000 00008000 82060220 00000000 00328000 00000000 00008000 82060230 00000000 00600000 00000000 00100000 local-mac-address 00 21 28 20 42 92 phy-type mif ... From this, we can see that the MAC for this interface is  00:21:28:20:42:92.  We will need this later. This is all we need to do at the OBP.  Now, we can configure Ops Center to use this interface. Network Boot in Solaris 10 Solaris 10 turns out to be a little simpler than Solaris 11 for this sort of a network boot.  Since WANBoot in Solaris 10 fetches a specified In order to install the system using Ops Center, it is necessary to create a OS Provisioning profile and its corresponding plan.  I am going to presume that you already know how to do this within Ops Center 12c and I will just cover the differences between a regular profile and a profile that can use an alternate interface. Create a OS Provisioning profile for Solaris 10 as usual.  However, when you specify the network resources for the primary network, click on the name of the NIC, probably GB_0, and rename it to GB_N/netN, where N is the instance number you used previously in creating the device alias.  This is where the trial and error may come into play.  You may need to try a few instance numbers before you, the OBP, and Solaris all agree on the instance number.  Mark this as the boot network. For Solaris 10, you ought to be able to then apply the OS Provisioning profile to the server and it should install using that interface.  And if you put your cards in the same slots and plug the networks into the same NICs, this profile is reusable across multiple servers. Why This Works If you watch the console as Solaris boots during the OSP process, Ops Center is going to look for the device alias netN.  Since WANBoot requires a device alias called just net, Ops Center uses the value of your netN device alias and assigns that device to the net alias.  That means that boot net will automatically use this device.  Very cool!  Here's a trace from the console as Ops Center provisions a server: Sun Sun Fire T200, No KeyboardCopyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548.Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c.auto-boot? =            false{0} ok  {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2 See what happened?  Ops Center looked for the network device alias called net4 that we specified in the profile, took the value from it, and made it the net device alias for the boot.  Pretty cool! WANBoot and Solaris 11 Solaris 11 requires an additional step since the Automated Installer in Solaris 11 uses the MAC address of the network to figure out which manifest to use for system installation.  In order to make sure this is available, we have to take an extra step to associate the MAC of the NIC on the card with the host.  So, in addition to creating the device alias like we did above, we also have to declare to Ops Center that the host has this new MAC. Declaring the NIC Start out by discovering the hardware as usual.  Once you have discovered it, take a look under the Connectivity tab to see what networks it has discovered.  In the case of this system, it shows the 4 built-in networks, but not the networks on the additional cards.  These are not directly visible to the system controller.  In order to add the additional network interface to the hardware asset, it is necessary to Declare it.  We will declare that we have a server with this additional NIC, but we will also  specify the existing GB_0 network so that Ops Center can associate the right resources together.  The GB_0 acts as sort of a key to tie our new declaration to the old system already discovered.  Go to the Assets tab, select All Assets, and then in the Actions tab, select Add Asset.  Rather than going through a discovery this time, we will manually declare a new asset. When we declare it, we will give the hostname, IP address, system model that match those that have already been discovered.  Then, we will declare both GB_0 with its existing MAC and the new GB_4 with its MAC.  Remember that we collected the MAC for GB_4 when we created its device alias. After you declare the asset, you will see the new NIC in the connectivity tab for the asset.  You will notice that only the NICs you listed when you declared it are seen now.  If you want Ops Center to see all of the existing NICs as well as the additional one, declare them as well.  Add the other GB_1, GB_2, GB_3 links and their MACs just as you did GB_0 and GB_4.  Installing the OS  Once you have declared the asset, you can create an OS Provisioning profile for Solaris 11 in the same way that you did for Solaris 10.  The only difference from any other provisioning profile you might have created already is the network to use for installation.  Again, use GB_N/netN where N is the interface number you used for your device alias and in your declaration.  And away you go.  When the system boots from the network, the automated installer (AI) is able to see which system manifest to use, based on the new MAC that was associated, and the system gets installed. {0} ok {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2...SunOS Release 5.11 Version 11.0 64-bitCopyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved.Remounting root read/writeProbing for device nodes ...Preparing network image for useDownloading solaris.zlib--2012-02-17 15:10:17--  http://10.140.204.22:5555/var/js/AI/sparc//solaris.zlibConnecting to 10.140.204.22:5555... connected.HTTP request sent, awaiting response... 200 OKLength: 126752256 (121M) [text/plain]Saving to: `/tmp/solaris.zlib'100%[======================================>] 126,752,256 28.6M/s   in 4.4s    2012-02-17 15:10:21 (27.3 MB/s) - `/tmp/solaris.zlib' saved [126752256/126752256] Conclusion So, why go to all of this trouble?  More and more, I find that customers are wiring their data center to only use higher speed networks - 10GbE only to the hosts.  Some customers are moving aggressively toward consolidated networks combining storage and network on CNA NICs.  All of this means that network-based provisioning cannot rely exclusively on the built-in network interfaces.  So, it's important to be able to provision a system using other than the built-in networks.  Turns out, that this is pretty straight-forward for both Solaris 10 and Solaris 11 and fits into the Ops Center deployment process quite nicely. Hopefully, you will be able to use this as you build out your own private cloud solutions with Ops Center.

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  • Beware Sneaky Reads with Unique Indexes

    - by Paul White NZ
    A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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