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• Developing Schema Compare for Oracle (Part 5): Query Snapshots

  - by Simon Cooper

  If you've emailed us about a bug you've encountered with the EAP or beta versions of Schema Compare for Oracle, we probably asked you to send us a query snapshot of your databases. Here, I explain what a query snapshot is, and how it helps us fix your bug. Problem 1: Debugging users' bug reports When we started the Schema Compare project, we knew we were going to get problems with users' databases - configurations we hadn't considered, features that weren't installed, unicode issues, wierd dependencies... With SQL Compare, users are generally happy to send us a database backup that we can restore using a single RESTORE DATABASE command on our test servers and immediately reproduce the problem. Oracle, on the other hand, would be a lot more tricky. As Oracle generally has a 1-to-1 mapping between instances and databases, any databases users sent would have to be restored to their own instance. Furthermore, the number of steps required to get a properly working database, and the size of most oracle databases, made it infeasible to ask every customer who came across a bug during our beta program to send us their databases. We also knew that there would be lots of issues with data security that would make it hard to get backups. So we needed an easier way to be able to debug customers issues and sort out what strange schema data Oracle was returning. Problem 2: Test execution time Another issue we knew we would have to solve was the execution time of the tests we would produce for the Schema Compare engine. Our initial prototype showed that querying the data dictionary for schema information was going to be slow (at least 15 seconds per database), and this is generally proportional to the size of the database. If you're running thousands of tests on the same databases, each one registering separate schemas, not only would the tests would take hours and hours to run, but the test servers would be hammered senseless. The solution To solve these, we needed to be able to populate the schema of a database without actually connecting to it. Well, the IDataReader interface is the primary way we read data from an Oracle server. The data dictionary queries we use return their data in terms of simple strings and numbers, which we then process and reconstruct into an object model, and the results of these queries are identical for identical schemas. So, we can record the raw results of the queries once, and then replay these results to construct the same object model as many times as required without needing to actually connect to the original database. This is what query snapshots do. They are binary files containing the raw unprocessed data we get back from the oracle server for all the queries we run on the data dictionary to get schema information. The core of the query snapshot generation takes the results of the IDataReader we get from running queries on Oracle, and passes the row data to a BinaryWriter that writes it straight to a file. The query snapshot can then be replayed to create the same object model; when the results of a specific query is needed by the population code, we can simply read the binary data stored in the file on disk and present it through an IDataReader wrapper. This is far faster than querying the server over the network, and allows us to run tests in a reasonable time. They also allow us to easily debug a customers problem; using a simple snapshot generation program, users can generate a query snapshot that could be sent along with a bug report that we can immediately replay on our machines to let us debug the issue, rather than having to obtain database backups and restore databases to test systems. There are also far fewer problems with data security; query snapshots only contain schema information, which is generally less sensitive than table data. Query snapshots implementation However, actually implementing such a feature did have a couple of 'gotchas' to it. My second blog post detailed the development of the dependencies algorithm we use to ensure we get all the dependencies in the database, and that algorithm uses data from both databases to find all the needed objects - what database you're comparing to affects what objects get populated from both databases. We get information on these additional objects using an appropriate WHERE clause on all the population queries. So, in order to accurately replay the results of querying the live database, the query snapshot needs to be a snapshot of a comparison of two databases, not just populating a single database. Furthermore, although the code population queries (eg querying all_tab_cols to get column information) can simply be passed straight from the IDataReader to the BinaryWriter, we need to hook into and run the live dependencies algorithm while we're creating the snapshot to ensure we get the same WHERE clauses, and the same query results, as if we were populating straight from a live system. We also need to store the results of the dependencies queries themselves, as the resulting dependency graph is stored within the OracleDatabase object that is produced, and is later used to help order actions in synchronization scripts. This is significantly helped by the dependencies algorithm being a deterministic algorithm - given the same input, it will always return the same output. Therefore, when we're replaying a query snapshot, and processing dependency information, we simply have to return the results of the queries in the order we got them from the live database, rather than trying to calculate the contents of all_dependencies on the fly. Query snapshots are a significant feature in Schema Compare that really helps us to debug problems with the tool, as well as making our testers happier. Although not really user-visible, they are very useful to the development team to help us fix bugs in the product much faster than we otherwise would be able to.

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• MVVM - how to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Why does my application hang in interruptible state?

  - by Greg

  Hello, I am running on Ubuntu 10.04 LTS Server an GTK application that used to work fine. It suddenly started to hang in interruptible state (Sl+) without any apparent reason. Here is a snippet of the strace: poll([{fd=3, events=POLLIN}, {fd=5, events=POLLIN}], 2, 0) = 0 (Timeout) poll([{fd=5, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=5, revents=POLLOUT}]) writev(5, [{"\2\30\4\0\224\4\240\0\0@\0\0\37\0\240\0\2\4\4\0\224\4\240\0\0@\0\0\37\0\240\0"..., 192}, {NULL, 0}, {"", 0}], 3) = 192 read(5, 0x2ba9ac4, 4096) = -1 EAGAIN (Resource temporarily unavailable) I googled that line read(5, 0x2ba9ac4, 4096), which seems to be more significant, and it seems that many other applications tend to have the same problem. I tried to restart my X server, but it didn't help. Do you have an idea how to solve this problem?

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• The entire content of my Wordpress page has disappeared

  - by John Catterfeld

  I have a blog installed on my site using Wordpress. Last week I upgraded Wordpress from 2.6 to 3.0.4 (I had to do this manually). All went well, or so I thought, but I have just noticed that the content of an existing page has vanished. The page URL still works, but all content has disappeared - doctype, html tags, body tags, everything. Please note, this is specific to pages - posts are still displaying fine. I have since created a brand new page which does not display the content either. Things I have tried include Switching to a freshly installed theme Deactivating all plugins Setting the problem page to draft, and back again Deleting the .htaccess file I suspect it's a database problem and have contacted my hosting company who have said the only thing they can do is restore the DB from a backup, but that I should consider it a last resort. Does anyone have any further ideas what to try?

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• Networkmanager in systray gone and sound not working after update 13.10

  - by rubo77

  After upgrading my Xubuntu 13.04 to 13.10 I have no sound. I still have sound if I start VLC with sudo mpg123 test.mp3 So it seemd there is a right problem EDIT after adding myself to the group audio with adduser myself audio I could play sounds again from the desktop with VLC But one problem remaining: The systray, usually looking like this: is not working anymore. No audio-settings and no network-manager in the taskbar in XFCE: there is just one small box with nothing in it. When I install stalonetray, There I see the status of wicd and all the other statuses, so the systray seems to be broken.

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• Programmatically adding metatags to Masterpages in Web Forms and MVC [migrated]

  - by Mike Clarke

  Has anyone got any ideas on where we should be adding our SEO metadata in a Web Forms project? Why I ask is that currently I have two main Masterpages, one is the home page and the other one is every other page, they both have the same metadata that’s just a generic description and set of key words about my site. The problem with that is search engines are only picking up my home page and my own search engine displays the same title and description for all results. The other problem is the site is predominantly dynamic so if you type in a search for beach which is a major categories on the site you get 10000 results that all go to different information but all look like a link to the same page to the user. edit It's live here www.themorningtonpeninsula.com

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• Examples of Liskov Substitution

  - by james lewis

  I'm facilitating a session next week on the Liskov Substitution Principle and I was wondering if anyone had any examples of violations 'from the trenches'? I'm looking for something other than uncle Bob's rectangle - square problem and the persistent set problem he talks about in A-PPP (although that is a great example). So far I'm using the example of a (very simple) List and an IndexedList as the 'correct' use of inheritance. And the addition of a Set to this hierarchy as a violation (as a Set is distinct; strengthening the pre condition of the Add method). I've also taken this great example and it's solution from this question Both those examples are great but I'm looking for something more subtle and harder to spot. So far I've come up with nothing so if you've got a great, subtle example post it up. Also, any metaphors you've come across that helped you understand LSP would be really useful too.

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• How can I simulate objects floating on water without a physics engine?

  - by user1075940

  In my game the water movement is done in a shader using Gerstner equations. The water movement looks realistic enough for a school project but I encounter serious problem when I wanted to do sailing on waves (similar to this). I managed to do collision with land by calculating quad's vertices and normals beneath ship, however same method can not be applied to water because XZ are displaced and Y is calculated in a shader :( How to approach this problem ? Is it possible to retrieve transformed grid from shader? Unfortunately no external physics libraries can be used.

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• How do I efficiently code both the client and server at the same time?

  - by liamzebedee

  I'm coding my game using a client-server model. When playing on singleplayer, the game starts a local server, and interacts with it just like a remote server (multiplayer). I have done this to avoid coding separate singleplayer and multiplayer code. I have just started coding and have encountered a major problem. Currently I'm developing the game in Eclipse, having all the game classes organized into packages. Then, in my server code, I just use all the classes in the client packages. The problem is, these client classes have variables that are specific to rendering, which obviously wouldn't be performed on a server. Should I create modified versions of the client classes to use in the server? Or should I just modify the client classes with a boolean, to indicate if its the client/server using it. Are there any other options I have? I just had a thought about maybe using the server class as the core class, then extending it with rendering stuff?

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• Modularity through HTTP

  - by Michael Williamson

  As programmers, we strive for modularity in the code we write. We hope that splitting the problem up makes it easier to solve, and allows us to reuse parts of our code in other applications. Object-orientation is the most obvious of many attempts to get us closer to this ideal, and yet one of the most successful approaches is almost accidental: the web. Programming languages provide us with functions and classes, and plenty of other ways to modularize our code. This allows us to take our large problem, split it into small parts, and solve those small parts without having to worry about the whole. It also makes it easier to reason about our code. So far, so good, but now that we’ve written our small, independent module, for example to send out e-mails to my customers, we’d like to reuse it in another application. By creating DLLs, JARs or our platform’s package container of choice, we can do just that – provided our new application is on the same platform. Want to use a Java library from C#? Well, good luck – it might be possible, but it’s not going to be smooth sailing. Even if a library exists, it doesn’t mean that using it going to be a pleasant experience. Say I want to use Java to write out an XML document to an output stream. You’d imagine this would be a simple one-liner. You’d be wrong: import org.w3c.dom.*; import java.io.*; import javax.xml.transform.*; import javax.xml.transform.dom.*; import javax.xml.transform.stream.*; private static final void writeDoc(Document doc, OutputStream out) throws IOException { try { Transformer t = TransformerFactory.newInstance().newTransformer(); t.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, doc.getDoctype().getSystemId()); t.transform(new DOMSource(doc), new StreamResult(out)); } catch (TransformerException e) { throw new AssertionError(e); // Can't happen! } } Most of the time, there is a good chance somebody else has written the code before, but if nobody can understand the interface to that code, nobody’s going to use it. The result is that most of the code we write is just a variation on a theme. Despite our best efforts, we’ve fallen a little short of our ideal, but the web brings us closer. If we want to send e-mails to our customers, we could write an e-mail-sending library. More likely, we’d use an existing one for our language. Even then, we probably wouldn’t have niceties like A/B testing or DKIM signing. Alternatively, we could just fire some HTTP requests at MailChimp, and get a whole slew of features without getting anywhere near the code that implements them. The web is inherently language agnostic. So long as your language can send and receive text over HTTP, and probably parse some JSON, you’re about as well equipped as anybody. Instead of building libraries for a specific language, we can build a service that almost every language can reuse. The text-based nature of HTTP also helps to limit the complexity of the API. As SOAP will attest, you can still make a horrible mess using HTTP, but at least it is an obvious horrible mess. Complex data structures are tedious to marshal to and from text, providing a strong incentive to keep things simple. By contrast, spotting the complexities in a class hierarchy is often not as easy. HTTP doesn’t solve every problem. It probably isn’t such a good idea to use it inside an inner loop that’s executed thousands of times per second. What’s more, the HTTP approach might introduce some new problems. We often need to add a thin shim to each application that we wish to communicate over HTTP. For instance, we might need to write a small plugin in PHP if we want to integrate WordPress into our system. Suddenly, instead of a system written in one language, we’re maintaining a system with several distinct languages and platforms. Even then, we should strive to avoid re-implementing the same old thing. As programmers, we consistently underestimate both the cost of building a system and the ongoing maintenance. If we allow ourselves to integrate existing applications, even if they’re in unfamiliar languages, we save ourselves those development and maintenance costs, as well as being able to pick the best solution for our problem. Thanks to the web, HTTP is often the easiest way to get there.

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• Ubuntu 12.04 Can't Login-Tty Console said: -bash: /usr/bin/byobu/-launch: no such file or directory

  - by zuhudfm

  I face problem in login to Ubuntu 12.04. I think it's caused by accessing super user (if not wrong). I type sudo nautilus to put a background to burg, but i fail x_x. After reboot, i can't login to desktop. But i can login as guest. I had 'googling' for problem solving. Most of it is login to screen like terminal (maybe tty console) by pressing ctrl+alt+F1. But after i login system says: -bash: /usr/bin/byobu/-launch: no such file or directory help help help :(

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• Mts mblaze doesn't connect to internet

  - by Chetan

  I've sony vaio vpceb24en laptop, I'm using dual boot system with windows 7 and ubuntu. Firstly I installed ubuntu 10.04 LTS then upgraded to 12.04 & 12.04.1 afterwards. I have mts mblaze dongle. I have set up the mts connection profile under the mobile broadband. My problem is : Sometimes my connection is easily made & I use it, sometime it never connects. So I have to restart my system then it connects to internet sometimes. But now it's not connecting even I restarted my system many times, just it shows trying to connect icon once, then never tries to connect. while in windows it's working fine. Please someone help me out how to resolve this problem as I'm very new to linux. Thanks, Chetan

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• Getting Black screen after installing 12.04 on new Mac Pro

  - by Matteo

  I installed Ubuntu 12.04 on my new Mac Pro. I had some problems because bootcamp did not allow me to partition the hd without a Windows cd. I inserted a Windows cd and did the partition and then I stopped the installation. I completed the installation of Ubuntu that now works. The problem is that Grub can't start Mac OS. It sees the Mac OS X in the menu but if I try to start it I have a black screen or sometime just the boot manager. Has anyone else experienced this problem?

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• Copy hangs in local network

  - by umpirsky

  I want to copy files from one Ubuntu system to another.They are both in local wireless network. I shared entire home dir on one, and tried to copy some files to another. It works for some time and then it just hangs at some point. I use Nautilus to copy files. Here is the example screenshot, it just hangs like this: After I cancel, Nautilus icon in lauchbar keeps progress bar, so I guess there is some problem. What can be the problem?

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• Jquery website is not opening in UBUNTU but in XP, Everything is fine

  - by Raman Sethi

  I know it is weird, But I just discovered this, jquery.com is not opening in my ubuntu firefox or other KDE browser and hence many sites that copy codes from code.jquery.com also hanged. Is there any solution to this problem. I have found the problem It is actually with the DNS servers I am using, Google DNS, 8.8.8.8 and 8.8.4.4, whenever I use these DNS in ubuntu my system stop responding to some sites, actually they are connected nicely, but the request end up in waiting.. I dont understand why...??? I checked my DNS with cat /etc/resolv.conf Even after using Google DNS, it is showing DNS servers I received automatically after connecting to the service provider. I am connecting using Network Manager, not using DNS I provided but using the default one. Any Solution??

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• 12.04 boots fine, with graphical splash screen, but then Monitor "out of range"

  - by Jim Bednar

  I see dozens of posts from people whose monitors are saying "out of range" under Ubuntu; seems like there are some serious problems in Ubuntu with autodetection of monitor capabilities. :-( But none of the many, many suggestions I found have solved my problem, and right now I can't use anything graphical on this machine! History: I installed Ubuntu 12.04 on my HP Proliant Microserver N40L, which worked reasonably at the default resolution across several reboots. At some point I noticed that the proprietary video driver was not in use, and tried to install one to get better window-drawing speeds, but it failed with some sort of error, and I gave up on that. A few weeks later when I next rebooted, it showed the usual BIOS screen and various boot loading screens (including GRUB), and then the usual purple Ubuntu splash screen with the dots showing that things were loading, but when it finished booting the monitor went black and eventually showed "Out of range" (with no other information). Given that there were several weeks between reboots (it's a server, after all), I've no idea if it was some system update, trying to install the proprietary drivers, or something else that caused the problem. Anyway, the system has booted fine, as I can do Ctrl-Alt-F1 to get a text prompt and can log in there. But Ctrl-Alt-F7 goes back to the out of range error. Some posters said to try Ctrl-Alt-- (minus) to cycle through resolutions until one works, but that didn't have any visible effect. Many, many others said it was a grub problem, which seems unlikely given that grub's screen looks fine, but I tried editing /etc/default/grub to set a particular resolution (trying many of them) and running update-grub, with no apparent effect. Rebooting into failsafe mode works the same as regular mode. Replacing xorg.conf with xorg.conf.failsafe works the same too. I'm at my wits' end! Isn't there anything I can do to convince Ubuntu to choose a mode that the monitor supports? E.g. the one that it is using for the splash screen? I don't need great resolution on this machine, just anything that works!!!!! Help!!!!!! Please!!!!

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• Ubuntu software centre, update manager fail to open

  - by Pradeep

  On my Ubuntu 12.04 LTS system the Software Centre and Update Manager do not open. I am unable to install any updates. And the message given below pops up. I am looking for a step-by-step process to fix this, and as a newbie, I don't know how to use the command line. Could not initialize the package information An unresolvable problem occurred while initializing the package information. Please report this bug against the 'update-manager' package and include the following error message: 'E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/extras.ubuntu.com_ubuntu_dists_precise_main_binary-i386_Packages, E:The package lists or status file could not be parsed or opened

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• Date calculation algorithm

  - by Julian Cuevas

  I'm working on a project to schedule a machine shop, basically I've got everything covered BUT date calculations, I've got a method called schedule (working on PHP here): public function schedule($start_date, $duration_in_minutes) Now my problem is, currently I'm calculating end time manually because time calculations have the following rules: During weekdays, work with business hours (7:00 AM to 5:00 PM) Work on Saturdays from 7:00 AM to 2:00 PM Ignore holidays (in Colombia we have A LOT of holidays) I already have a lookup table for holidays, I also have a Java version of this algorithm that I wrote for a previous version of the project, but that one's also manual. Is there any way to calculate an end time from a start time given duration?, my problem is that I have to consider the above rules, I'm looking for a (maybe?) math based solution, however I currently don't have the mind to devise such a solution myself. I'll be happy to provide code samples if necessary.

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• Grub Won't Boot WIndows 7

  - by STavros P.

  I have a problem with Grub 2. when i hit the Windows 7 (loader) option on the Grub boot screen Windows won't boot. i get a black screen with a white cursor blinking... Here is a log of my Boot options. I just want to delete all the other partitions which i don't know how they 've been made and stay just with the Ubuntu ext4 partition, the swap partition and the WIndows 7 partition. Can someoune help me with my problem? Here is the log: http://paste.ubuntu.com/1014619/ ps: I can only boot Windows with Hiren's Boot CD with the first option, Boot form first hard drive (win7, xp, vista).

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• Keyboard shortcut: Win key doesn't work for custom commands

  - by Xiè Jìléi

  It's all ok before upgraded from 10.04 to 12.04. It seems all right. In keyboard shortcut window, if I pressed Win+V, it can capture the key combination as Super+V, no problem. I've checked the output from xev utility, the left and right Win keys are translated to Super_L and Super_R correctly. I have found a workaround, though. Using gconf-editor, edit the entries /desktop/gnome/keybindings/*/binding and replace <Super> with <Mod4> for the problem bindings. However Super+... keys do work for most built-in actions such as "switch workspace", they just don't work for custom commands.

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• EntSSO stopped working

  - by blomqvist

  My EntSSO (Enterprise Single Sign-On Server, part of BizTalk) did not start today, with the message: The SSO service failed to start. Error Code: 0x80131700 Could not create SSOSQL. To fix the problem, reinstall SSO or try 'regasm SSOSQL.dll' from a Visual Studio command prompt. Error Code: 0x80131700   The only reason for this that I can think of is that I have just installed the .net framework 4.0 RC but I have not verified this. The solution suggest in the error message works like a charm! Open a Visual Studio command prompt and run this command: regasm  ‘C:\Program Files\Common Files\Enterprise Single Sign-On\SSOSQL.dll’ Problem solved!

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• What if I can't make my unit test fail in "Red, Green, Refactor" of TDD?

  - by Joshua Harris

  So let's say that I have a test: @Test public void MoveY_MoveZero_DoesNotMove() { Point p = new Point(50.0, 50.0); p.MoveY(0.0); Assert.assertAreEqual(50.0, p.Y); } This test then causes me to create the class Point: public class Point { double X; double Y; public void MoveY(double yDisplace) { throw new NotYetImplementedException(); } } Ok. It fails. Good. Then I remove the exception and I get green. Great, but of course I need to test if it changes value. So I write a test that calls p.MoveY(10.0) and checks if p.Y is equal to 60.0. It fails, so then I change the function to look like so: public void MoveY(double yDisplace) { Y += yDisplace; } Great, now I have green again and I can move on. I've tested not moving and moving in the positive direction, so naturally I should test a negative value. The only problem with this test is that if I wrote the test correctly, then it doesn't fail at first. That means that I didn't fit the principle of "Red, Green, Refactor." Of course, This is a first-world problem of TDD, but getting a fail at first is helpful in that it shows that your test can fail. Otherwise this seemingly innocent test that is just passing for incorrect reasons could fail later because it was written wrong. That might not be a problem if it happened 5 minutes later, but what if it happens to the poor-sap that inheirited your code two years later. What he knows is that MoveY does not work with negative values because that is what the test is telling him. But, it really could work and just be a bug in the test. I don't think that would happen in this particular case because the code sample is so simple, but if it were a large complicated system that might not be the case. It seems crazy to say that I want to fail my tests, but that is an important step in TDD, for good reasons.

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• Radiosity using a hemisphere

  - by P. Avery

  I'm working on a radiosity processor. I'm projecting scene geometry onto a hemisphere at a high order of tessellation during a visibility pass onto a 1024x1024 render target. The problem is that the edges of certain triangles are not being rendered to the item buffer( render target )...so when I test certain edges( or pixels during pixel shader ) for visibility during a reconstruction pass, visible edges are not identified and as a result the pixel for that edge is discarded. One solution was to increase the resolution of the item buffer( up to 4096x4096 )...this helped and more edges were visible, however, this was not fullproof. How do I increase visibility? Here is a screenshot of a scene after radiosity is applied: the seams are edges along a triangle face that were not visible due to the resolution of the item buffer... fixed the problem by sampling the item buffer w/8 points:

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• CSV files not being written

  - by Kamalpreet

  I worked on a small project in which the data entered in HTML forms was saved in a CSV file which was used subsequently. The files were run on Apache2. It worked fine. After about 25 days, when I reopened the project, the data entered in forms was not saved in CSV file. I checked all the permissions. I even sent a zip file of my files to one of m friends. It worked well on his system. So should I figure it out there's some problem in the system. I am using Ubuntu 13.04. Kindly suggest me something so that I am able to figure out the problem.

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• Installing Ubuntu

  - by Mister AR

  i got a problem when I wanted to installing ubuntu 12.04 on a VMWare system on my Windows 7 x64 system ... in the end of installing after retrieving Files it stopped and didn't move forward... additionally i got a another problem there where i wanted to installing packages i updated. and gave me error below : installArchives() failed: Error in function: Setting up libssl1.0.0 (1.0.1-4ubuntu5.2) ... locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing libssl1.0.0 (--configure): subprocess installed post-installation script returned error exit status 1 PLz help me soon ! tY all...

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