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• Configuring a WCF Client to Use UserName Credentials On the Request and Check Certificate Credential

  - by AlEl

  I'm trying to use WCF to consume a web service provided by a third-party's Oracle Application Server. I pass a username and password in a UsernameToken as part of the request and as part of the response the web service returns a standard security tag in the header which includes a digest and signature. With my current setup, I successfully send a request to the server and the web service sends the expected response data back. However, when parsing the response WCF throws a MessageSecurityException, with an InnerException.Message of "Supporting token signatures not expected." My guess is that WCF wants me to configure it to handle the signature and verify it. I have a certificate from the third party that hosts the web service that I should be able to use to verify the signature, although I'm not sure if I'll need it. Here's a sample header from a response that makes WCF throw the exception: <?xml version="1.0" encoding="UTF-8"?> <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Header> <wsse:Security soap:mustUnderstand="1" xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"> <dsig:Signature xmlns="http://www.w3.org/2000/09/xmldsig#" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"> <dsig:SignedInfo> <dsig:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/> <dsig:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/> <dsig:Reference URI="#_51IUwNWRVvPOcz12pZHLNQ22"> <dsig:Transforms> <dsig:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/> </dsig:Transforms> <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/> <dsig:DigestValue> [DigestValue here] </dsig:DigestValue> </dsig:Reference> <dsig:Reference URI="#_dI5j0EqxrVsj0e62J6vd6w22"> <dsig:Transforms> <dsig:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/> </dsig:Transforms> <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/> <dsig:DigestValue> [DigestValue here] </dsig:DigestValue> </dsig:Reference> </dsig:SignedInfo> <dsig:SignatureValue> [Signature Value Here] </dsig:SignatureValue> <dsig:KeyInfo> <wsse:SecurityTokenReference xmlns="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"> <wsse:Reference URI="#BST-9nKWbrE4LRv6maqstrGuUQ22" ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509v3"/> </wsse:SecurityTokenReference> </dsig:KeyInfo> </dsig:Signature> <wsse:BinarySecurityToken ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509v3" EncodingType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary" wsu:Id="BST-9nKWbrE4LRv6maqstrGuUQ22" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"> [Security Token Here] </wsse:BinarySecurityToken> <wsu:Timestamp wsu:Id="_dI5j0EqxrVsj0e62J6vd6w22" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"> <wsu:Created>2010-05-26T18:46:30Z</wsu:Created> </wsu:Timestamp> </wsse:Security> </soap:Header> <soap:Body wsu:Id="_51IUwNWRVvPOcz12pZHLNQ22" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"> [Body content here] </soap:Body> </soap:Envelope> My binding configuration looks like: <basicHttpBinding> <binding name="myBinding" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" allowCookies="false" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" maxBufferSize="65536" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" transferMode="Buffered" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <security mode="TransportWithMessageCredential"> <transport clientCredentialType="None" proxyCredentialType="None" realm="" /> <message clientCredentialType="UserName" algorithmSuite="Default" /> </security> </binding> </basicHttpBinding> I think that basically what I have to do is configure WCF to use UserName client credentials in the request and Certificate client credentials in the response. I don't know how to do this though. I'm new at WCF, so I'm sorry if this is a bit of a dumb question. I've been trying to Google solutions, but there seem to be so many different ways to configure WCF that I'm getting overwhelmed. Thanks in advance!

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• mod_deflate Supported Encodings for Compression

  - by sparc

  It seems to me, that mod_deflate in Apache 2.2 will always return: Content-Encoding: gzip and never: Content-Encoding: deflate It was explained to me, that although there may be a deflate algorithm, mod_deflate is named after a file-format, in which the algorithm could be any of: gzip, bzip. pkzip Of those three, mod_deflate provides gzip. It seems as though gzip is the most popular and widely-supported algorithm in web browsers, but I know some web servers and proxies do return Content-Encoding: deflate. Aside from the confusion of the module's name, it true that mod_deflate will only return Content-Encoding: gzip? Thank you.

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• How to create Encryption Key for Encryption Algorithms?

  - by Akash Kava

  I want to use encryption algorithm available in .Net Security namespace, however I am trying to understand how to generate the key, for example AES algorithm needs 256 bits, that 16 bytes key, and some initialization vector, which is also few bytes. Can I use any combination of values in my Key and IV? e.g. all zeros in Key and IV are valid or not? I know the detail of algorithm which does lots of xors, so zero wont serve any good, but are there any restrictions by these algorithms? Or Do I have to generate the key using some program and save it permanently somewhere?

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• Describe the Damas-Milner type inference in a way that a CS101 student can understand

  - by user128807

  Hindley-Milner is a type system that is the basis of the type systems of many well known functional programming languages. Damas-Milner is an algorithm that infers (deduces?) types in a Hindley-Milner type system. Wikipedia gives a description of the algorithm which, as far as I can tell, amounts to a single word: "unification." Is that all there is to it? If so, that means that the interesting part is the type system itself not the type inference system. If Damas-Milner is more than unification, I would like a description of Damas-Milner that includes a simple example and, ideally, some code. Also, this algorithm is often said to do type inference. Is it really an inference system? I thought it was only deducing the types. Related questions: What is Hindley Miller? Type inference to unification problem

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• How can I read this url in Rebol ?

  - by Rebol Tutorial

  when trying to read this kind of url URL: http://v4.lscache2.c.youtube.com/videoplayback?ip=0.0.0.0&sparams=id,expire,ip,ipbits,itag,algorithm,burst,factor,oc:U0dWSlhTVF9FSkNNNl9QTVhJ&algorithm=throttle-factor&itag=34&ipbits=0&burst=40&sver=3&expire=1275886800&key=yt1&signature=89195E808CB3FBBC7BDE7298A1DC0613D7987F00.D3064112E8F479C523F8DF4FBFDF392CE48167C2&factor=1.25&id=34e01ad39b34b5c9& I get this error read/binary url connecting to: v4.lscache2.c.youtube.com ** User Error: Error. Target url: http://v4.lscache2.c.youtube.com/videoplayback?ip=0.0.0.0&sparams=id,expire,ip,ipbits, itag,algorithm... ** Near: read/binary url

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• Coordinate geometry operations in images/discrete space

  - by avd

  I have images which have line segments, rays etc. I am representing these line segments using Bresenham algorithm (means whatever coordinates I get using this algorithm between two points). Now I want to do operations such as finding intersection point between two line segments, finding the projection of one vector onto other etc... The problem is I am not working in continuous space. The line segments are being approximated using Bresenham algorithm. So I want suggestions on what are the best and most efficient ways to do this? A link to C++ library or implementation would also be good enough. Please suggest some books which deal with such problems.

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• Architectural decision : QT or Eclipse Platform ?

  - by umanga

  We are in the process of designing a tool to be used with HDEM(High Definition Electron Microscope).We get stacks of 2D images from HDEM and first step is 'detecting borders' on the sections.After detecting edges of 2D slices ,next step is construct the 3D model using these 2D slices. This 'border detecting' algorithm(s) is/are implemented by one of professor and he has used and suggests to use C.(to gain high performance and probably will parallelise in future) We have to develop comprehensive UI ,3D viewer ,2D editor...etc and use this algorithm. Application should support usual features like project save/open.Undo,Redo...etc Our technology decisions are: A) Build entire platform from the scratch using QT. B) Use Eclipse Platform Our concerns are, if we choose A) we can easily integrate the 'border detecting' algorithm(s) because the development environment is C/C++ But we have to implement the basic features from the scratch. If we choose B) we get basic features from the Eclipse platform , but integrating C libraries going to be a tedious task. Any suggestions on this?

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• st-ordering library function?

  - by chang

  I'm in the search for an implementation of an ear-decomposition algorithm (http://www.ics.uci.edu/~eppstein/junkyard/euler/ear.html). I examined networkx and didn't find one. Although the algorithm layout is vaguely in my mind, I'd like to see some reference implementation, too. Side problem: First step could be an st-ordering of a graph. Are there any implementations for st-ordering algorithms you know? Thanks for your input. I'd really like to contribute e.g. to networkx by implementing the ear-decomposition algorithm in python.

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• How can I convert arbitrary strings to CLS-Compliant names?

  - by Brian Hinchey

  Does anyone know of an algorithm (or external library) that I could call to convert an arbitrary string (i.e. outside my control) to be CLS compliant? I am generating a dynamic RDLC (Client Report Definition) for an ASP.Net Report Viewer control and some of the field names need to be based on strings entered by the user. Unfortunately I have little control over the entry of the field names by the client (through a 3rd party CMS). But I am quite flexible around substitutions required to create the compliant string. I have a reactive hack algorithm for now along the lines of: public static string FormatForDynamicRdlc(this string s) { //We need to change this string to be CLS compliant. return s.Replace(Environment.NewLine, string.Empty) .Replace("\t", string.Empty) .Replace(",", string.Empty) .Replace("-", "_") .Replace(" ", "_"); } But I would love something more comprehensive. Any ideas? NOTE: If it is of any help, the algorithm I am using to create the dynamic RDLC is based on the BuildRDLC method found here: http://csharpshooter.blogspot.com/2007/08/revised-dynamic-rdlc-generation.html

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• Compression Array of Bytes

  - by Pedro Magalhaes

  Hi, My problem is: I want to store a array of bytes in compressed file, and then I want to read it with a good performance. So I create a array of bytes then pass to a ZLIB algorithm then store it in the file. For my surprise the algorithm doesn't work well., probably because the array is a random sample. Using this approach, it will will be ber easy to read. Just copy the stream to memory, decompress them and copy it to a array of bytes. But i need to compress the file. Do I have to use a algorithm, like RLE, for compresse the byte array? I think that I can store the byte array like a string and then compress it. But i think I am going to have a poor performance on reading data. Sorry for my poor english. Thanks

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• How to convert string "0671" or "0x45" into integer form with 0 and 0x in the beginning.

  - by Harshit Sharma

  I wanted to make my own encryption algorithm and decryption algorithm , encryption algorithm works fine and converts ascii value of the characters into alternate hexadecimal and octal representations. But when I tried decryption, problem occured as it return int('0671') = 671, as 0671 is string type in the following code. Is there a method to convert "ox56" into integer form?????? NOTE: Following string is alternate octal and hexa of ascii value of char. ///////////////DECRYPTION/////// l="01630x7401620x6901560x67" f=len(l) k=0 d=0 x=[] for i in range(0,f,4): g=l[i:i+4] print g k=k+1 if(k%2==0): p=g print p else: p=int(g) print p

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• What technologies to use for a particle system with enormous calculation demand?

  - by Amir Rezaei

  I have a particle system with X particles. Each particle tests for collision with other particles. This gives X*X = X^2 collision tests per frame. For 60f/s, this corresponds to 60*X^2 collision detection per second. What is the best technological approach for these intensive calculations? Should I use F#, C, C++ or C#, or something else? The following are constraints The code is written in C# with the latest XNA Multi-threaded may be considered No special algorithm that tests the collision with the nearest neighbors or that reduces the problem The last constraint may be strange, so let me explain. Regardless constraint 3, given a problem with enormous computational requirement what would be the best approach to solve the problem. An algorithm reduces the problem; still the same algorithm may behave different depending on technology. Consider pros and cons of CLR vs native C.

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• How to tell MATLAB to open and save specific files in the same directory

  - by its-me

  I have to run an image processing algorithm on numerous images in a directory. An image is saved as name_typeX.tif, so there are X different type of images for a given name. The image processing algorithm takes an input image and outputs an image result. I need to save this result as name_typeX_number.tif, where 'number' is also an output from the algorithm for a given image. Now.. How do I tell MATLAB to open a specific 'typeX' file? Also note that there are other non-tif files in the same directory. How to save the result as name_typeX_number.tif? The results have to be saved in the same directory where the input images are present. How do I tell MATLAB NOT to treat the results that have been saved as an input images? I have to run this as background code on a server... so no user inputs allowed Thanks

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• How do I remove a repository of yum

  - by sunil

  When I search for a package in yum(centos 6), it tries to search in a repro named 'c6-media' And it gives a bunch of errors as follows file:///media/CentOS/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/CentOS/repodata/repomd.xml Trying other mirror. file:///media/cdrecorder/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrecorder/repodata/repomd.xml Trying other mirror. file:///media/cdrom/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrom/repodata/repomd.xml Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: c6-media. Please verify its path and try again Obviously the error seems to say that yum is trying to search for the CD/DVD which installed the OS. I do not have it now. All I want to do now is to delete this repository from yum. I went to the package manager graphical tool and removed this from the sources. Seems yum and the graphical tool do not use the same config. This is just my guess.

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• Windows screen shots via command-line SSH session

  - by Geoff Fritz

  I've browsed the handful of "screen capture" queries here, but I was unable to find anything which addressed my specific need. I'm looking for a command-line tool that I can run via remote SSH connection (by way of the cygwin sshd daemon). There are several to choose from, but the few I've tried (ImageMagick, nircmd, and MiniCap) all result in a blank screen. I assume that this is due to the remotely logged in user not having a proper graphical console session running. The goal here is automate screen capture and retrieval of the main system console (what one would see if they were looking at the physical monitor) through the use of ssh script from a Unix host: ssh user@windowshost "screencap --output /tmp/console.jpg" scp user@windowshost:/tmp/console.jpg /some/destdir Note that these must be done on demand, so polling a remote directory that has snapshots dumped periodically will not work. Bonus points for programs that are open source and have a portable install (so I don't need to RDP/VNC into the machine to run a graphical installer).

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• Ultra-lightweight web browser?

  - by zildjohn01

  Are there any good super-lightweight graphical web browsers out there? I'd like to be able to browse the web on an old PC, but the mainstream crop of browsers is just too heavy, and I don't want to resort to something like Lynx. There must be something decent out there that'll fit in 16 or 32MB of RAM comfortably. 100% standards compliance isn't necessary, but I'd like something that supports the most widely used parts of CSS and JavaScript. The goal is to get 98% of sites usable in a nice, graphical format.

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• Ultra-lightweight web browser?

  - by zildjohn01

  Are there any good super-lightweight graphical web browsers out there? I'd like to be able to browse the web on an old PC, but the mainstream crop of browsers is just too heavy, and I don't want to resort to something like Lynx. There must be something decent out there that'll fit in 16 or 32MB of RAM comfortably. 100% standards compliance isn't necessary, but I'd like something that supports the most widely used parts of CSS and JavaScript. The goal is to get 98% of sites usable in a nice, graphical format.

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• Is it bad practice to apply class-based design to JavaScript programs?

  - by helixed

  JavaScript is a prototyped-based language, and yet it has the ability to mimic some of the features of class-based object-oriented languages. For example, JavaScript does not have a concept of public and private members, but through the magic of closures, it's still possible to provide the same functionality. Similarly, method overloading, interfaces, namespaces and abstract classes can all be added in one way or another. Lately, as I've been programming in JavaScript, I've felt like I'm trying to turn it into a class-based language instead of using it in the way it's meant to be used. It seems like I'm trying to force the language to conform to what I'm used to. The following is some JavaScript code I've written recently. It's purpose is to abstract away some of the effort involved in drawing to the HTML5 canvas element. /* Defines the Drawing namespace. */ var Drawing = {}; /* Abstract base which represents an element to be drawn on the screen. @param The graphical context in which this Node is drawn. @param position The position of the center of this Node. */ Drawing.Node = function(context, position) { return { /* The method which performs the actual drawing code for this Node. This method must be overridden in any subclasses of Node. */ draw: function() { throw Exception.MethodNotOverridden; }, /* Returns the graphical context for this Node. @return The graphical context for this Node. */ getContext: function() { return context; }, /* Returns the position of this Node. @return The position of this Node. */ getPosition: function() { return position; }, /* Sets the position of this Node. @param thePosition The position of this Node. */ setPosition: function(thePosition) { position = thePosition; } }; } /* Define the shape namespace. */ var Shape = {}; /* A circle shape implementation of Drawing.Node. @param context The graphical context in which this Circle is drawn. @param position The center of this Circle. @param radius The radius of this circle. @praram color The color of this circle. */ Shape.Circle = function(context, position, radius, color) { //check the parameters if (radius < 0) throw Exception.InvalidArgument; var node = Drawing.Node(context, position); //overload the node drawing method node.draw = function() { var context = this.getContext(); var position = this.getPosition(); context.fillStyle = color; context.beginPath(); context.arc(position.x, position.y, radius, 0, Math.PI*2, true); context.closePath(); context.fill(); } /* Returns the radius of this Circle. @return The radius of this Circle. */ node.getRadius = function() { return radius; }; /* Sets the radius of this Circle. @param theRadius The new radius of this circle. */ node.setRadius = function(theRadius) { radius = theRadius; }; /* Returns the color of this Circle. @return The color of this Circle. */ node.getColor = function() { return color; }; /* Sets the color of this Circle. @param theColor The new color of this Circle. */ node.setColor = function(theColor) { color = theColor; }; //return the node return node; }; The code works exactly like it should for a user of Shape.Circle, but it feels like it's held together with Duct Tape. Can somebody provide some insight on this?

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• New SSIS tool on Codeplex – SSIS Log Analyzer

  I stumbled across a new SSIS tool on Codeplex today, the SSIS Log Analyzer which was only released a few days ago. Whilst it is a beta release and currently only supports 2005 (2008 is promised) it looks quite interesting. It seems to be a fancy log viewer, but with some clever features and a nice looking front-end. I’ve only read the documentation so far, but it has graphs and a debug view that shows your package with the colour animations similar to when debugging in BIDS, and everyone knows, the way the pretty colours and numbers change is the best bit! I’ll quote some of the features for you here and then let you make your own mind up, is it useful in the real world? Option to analyze the logs manually by applying row and column filters over the log data or by using queries to specify more complex criterions. Automated Performance Analysis which provides a quick graphical look on which tasks spent most time during package execution. Rerun (debug) the entire sequence of events which happened during package execution showing the flow of control in graphical form, changes in runtime values for each task like execution duration etc. Support for Auto Analyzers to automatically find out issues and provide suggestions for problems which can be figured out with the help of SSIS logs and/or package. Option to analyze just log file or log and package together. Provides a lightweight environment to have a quick look at the package. Opening it in BIDS takes some time as being an authoring environment it does all sorts of validations resulting in some delay. See http://ssisloganalyzer.codeplex.com/  for more details.

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• New SSIS tool on Codeplex – SSIS Log Analyzer

  I stumbled across a new SSIS tool on Codeplex today, the SSIS Log Analyzer which was only released a few days ago. Whilst it is a beta release and currently only supports 2005 (2008 is promised) it looks quite interesting. It seems to be a fancy log viewer, but with some clever features and a nice looking front-end. I’ve only read the documentation so far, but it has graphs and a debug view that shows your package with the colour animations similar to when debugging in BIDS, and everyone knows, the way the pretty colours and numbers change is the best bit! I’ll quote some of the features for you here and then let you make your own mind up, is it useful in the real world? Option to analyze the logs manually by applying row and column filters over the log data or by using queries to specify more complex criterions. Automated Performance Analysis which provides a quick graphical look on which tasks spent most time during package execution. Rerun (debug) the entire sequence of events which happened during package execution showing the flow of control in graphical form, changes in runtime values for each task like execution duration etc. Support for Auto Analyzers to automatically find out issues and provide suggestions for problems which can be figured out with the help of SSIS logs and/or package. Option to analyze just log file or log and package together. Provides a lightweight environment to have a quick look at the package. Opening it in BIDS takes some time as being an authoring environment it does all sorts of validations resulting in some delay. See http://ssisloganalyzer.codeplex.com/  for more details.

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• AdSense Mobile Interface – I’m Loving It!

  - by Gopinath

  I love checking AdSense earnings every day on my mobile. All these days my mobile browser, opera, rendered the heavy desktop version of AdSense interface and it was tough to navigate around and see the earnings. To solve the problems of me as well as millions of other AdSense users, Google yesterday released a mobile version of AdSense user interface that works on almost all the mobile platforms – iOS, Android, Windows Phone 7, Symbian and many others. If you have opted for the new beta user interface of AdSense, you will be presented with the mobile version when you https://www.google.com/adsense on your mobile. Here is a screen grab of how looks like on iPhone and Android device.It looks similar on my Nokia mobile too. The Adsense interface for mobile is very nice – on the home page I can quickly have a look at today’s earnings, recent payment amount, last month finalized amount and the total unpaid balances. The quick reports option available the bottom of the screen lets me access a graphical view of useful earnings reports like – Last 7 days, Last 30 days, This Month and Last Month. You can also create your own reports and save them to this list for quick viewing. To view the graphical reports, you don’t need FLASH on your mobile. For more details check out the official post on Google Adsense blog. This article titled,AdSense Mobile Interface – I’m Loving It!, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• So…is it a Seek or a Scan?

  - by Paul White

  You’re probably most familiar with the terms ‘Seek’ and ‘Scan’ from the graphical plans produced by SQL Server Management Studio (SSMS).  The image to the left shows the most common ones, with the three types of scan at the top, followed by four types of seek.  You might look to the SSMS tool-tip descriptions to explain the differences between them: Not hugely helpful are they?  Both mention scans and ranges (nothing about seeks) and the Index Seek description implies that it will not scan the index entirely (which isn’t necessarily true). Recall also yesterday’s post where we saw two Clustered Index Seek operations doing very different things.  The first Seek performed 63 single-row seeking operations; and the second performed a ‘Range Scan’ (more on those later in this post).  I hope you agree that those were two very different operations, and perhaps you are wondering why there aren’t different graphical plan icons for Range Scans and Seeks?  I have often wondered about that, and the first person to mention it after yesterday’s post was Erin Stellato (twitter | blog): Before we go on to make sense of all this, let’s look at another example of how SQL Server confusingly mixes the terms ‘Scan’ and ‘Seek’ in different contexts.  The diagram below shows a very simple heap table with two columns, one of which is the non-clustered Primary Key, and the other has a non-unique non-clustered index defined on it.  The right hand side of the diagram shows a simple query, it’s associated query plan, and a couple of extracts from the SSMS tool-tip and Properties windows. Notice the ‘scan direction’ entry in the Properties window snippet.  Is this a seek or a scan?  The different references to Scans and Seeks are even more pronounced in the XML plan output that the graphical plan is based on.  This fragment is what lies behind the single Index Seek icon shown above: You’ll find the same confusing references to Seeks and Scans throughout the product and its documentation. Making Sense of Seeks Let’s forget all about scans for a moment, and think purely about seeks.  Loosely speaking, a seek is the process of navigating an index B-tree to find a particular index record, most often at the leaf level.  A seek starts at the root and navigates down through the levels of the index to find the point of interest: Singleton Lookups The simplest sort of seek predicate performs this traversal to find (at most) a single record.  This is the case when we search for a single value using a unique index and an equality predicate.  It should be readily apparent that this type of search will either find one record, or none at all.  This operation is known as a singleton lookup.  Given the example table from before, the following query is an example of a singleton lookup seek: Sadly, there’s nothing in the graphical plan or XML output to show that this is a singleton lookup – you have to infer it from the fact that this is a single-value equality seek on a unique index.  The other common examples of a singleton lookup are bookmark lookups – both the RID and Key Lookup forms are singleton lookups (an RID lookup finds a single record in a heap from the unique row locator, and a Key Lookup does much the same thing on a clustered table).  If you happen to run your query with STATISTICS IO ON, you will notice that ‘Scan Count’ is always zero for a singleton lookup. Range Scans The other type of seek predicate is a ‘seek plus range scan’, which I will refer to simply as a range scan.  The seek operation makes an initial descent into the index structure to find the first leaf row that qualifies, and then performs a range scan (either backwards or forwards in the index) until it reaches the end of the scan range. The ability of a range scan to proceed in either direction comes about because index pages at the same level are connected by a doubly-linked list – each page has a pointer to the previous page (in logical key order) as well as a pointer to the following page.  The doubly-linked list is represented by the green and red dotted arrows in the index diagram presented earlier.  One subtle (but important) point is that the notion of a ‘forward’ or ‘backward’ scan applies to the logical key order defined when the index was built.  In the present case, the non-clustered primary key index was created as follows: CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col ASC) ) ; Notice that the primary key index specifies an ascending sort order for the single key column.  This means that a forward scan of the index will retrieve keys in ascending order, while a backward scan would retrieve keys in descending key order.  If the index had been created instead on key_col DESC, a forward scan would retrieve keys in descending order, and a backward scan would return keys in ascending order. A range scan seek predicate may have a Start condition, an End condition, or both.  Where one is missing, the scan starts (or ends) at one extreme end of the index, depending on the scan direction.  Some examples might help clarify that: the following diagram shows four queries, each of which performs a single seek against a column holding every integer from 1 to 100 inclusive.  The results from each query are shown in the blue columns, and relevant attributes from the Properties window appear on the right: Query 1 specifies that all key_col values less than 5 should be returned in ascending order.  The query plan achieves this by seeking to the start of the index leaf (there is no explicit starting value) and scanning forward until the End condition (key_col < 5) is no longer satisfied (SQL Server knows it can stop looking as soon as it finds a key_col value that isn’t less than 5 because all later index entries are guaranteed to sort higher). Query 2 asks for key_col values greater than 95, in descending order.  SQL Server returns these results by seeking to the end of the index, and scanning backwards (in descending key order) until it comes across a row that isn’t greater than 95.  Sharp-eyed readers may notice that the end-of-scan condition is shown as a Start range value.  This is a bug in the XML show plan which bubbles up to the Properties window – when a backward scan is performed, the roles of the Start and End values are reversed, but the plan does not reflect that.  Oh well. Query 3 looks for key_col values that are greater than or equal to 10, and less than 15, in ascending order.  This time, SQL Server seeks to the first index record that matches the Start condition (key_col >= 10) and then scans forward through the leaf pages until the End condition (key_col < 15) is no longer met. Query 4 performs much the same sort of operation as Query 3, but requests the output in descending order.  Again, we have to mentally reverse the Start and End conditions because of the bug, but otherwise the process is the same as always: SQL Server finds the highest-sorting record that meets the condition ‘key_col < 25’ and scans backward until ‘key_col >= 20’ is no longer true. One final point to note: seek operations always have the Ordered: True attribute.  This means that the operator always produces rows in a sorted order, either ascending or descending depending on how the index was defined, and whether the scan part of the operation is forward or backward.  You cannot rely on this sort order in your queries of course (you must always specify an ORDER BY clause if order is important) but SQL Server can make use of the sort order internally.  In the four queries above, the query optimizer was able to avoid an explicit Sort operator to honour the ORDER BY clause, for example. Multiple Seek Predicates As we saw yesterday, a single index seek plan operator can contain one or more seek predicates.  These seek predicates can either be all singleton seeks or all range scans – SQL Server does not mix them.  For example, you might expect the following query to contain two seek predicates, a singleton seek to find the single record in the unique index where key_col = 10, and a range scan to find the key_col values between 15 and 20: SELECT key_col FROM dbo.Example WHERE key_col = 10 OR key_col BETWEEN 15 AND 20 ORDER BY key_col ASC ; In fact, SQL Server transforms the singleton seek (key_col = 10) to the equivalent range scan, Start:[key_col >= 10], End:[key_col <= 10].  This allows both range scans to be evaluated by a single seek operator.  To be clear, this query results in two range scans: one from 10 to 10, and one from 15 to 20. Final Thoughts That’s it for today – tomorrow we’ll look at monitoring singleton lookups and range scans, and I’ll show you a seek on a heap table. Yes, a seek.  On a heap.  Not an index! If you would like to run the queries in this post for yourself, there’s a script below.  Thanks for reading! IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; -- ================ -- Singleton lookup -- ================ ; -- Single value equality seek in a unique index -- Scan count = 0 when STATISTIS IO is ON -- Check the XML SHOWPLAN SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 32 ; -- =========== -- Range Scans -- =========== ; -- Query 1 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col <= 5 ORDER BY E.key_col ASC ; -- Query 2 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col > 95 ORDER BY E.key_col DESC ; -- Query 3 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 10 AND E.key_col < 15 ORDER BY E.key_col ASC ; -- Query 4 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 20 AND E.key_col < 25 ORDER BY E.key_col DESC ; -- Final query (singleton + range = 2 range scans) SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 10 OR E.key_col BETWEEN 15 AND 20 ORDER BY E.key_col ASC ; -- === TIDY UP === DROP TABLE dbo.Example; © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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• 2.5D game development

  - by ne5tebiu

  2.5D ("two-and-a-half-dimensional"), 3/4 perspective and pseudo-3D are terms used to describe either: graphical projections and techniques which cause a series of images or scenes to fake or appear to be three-dimensional (3D) when in fact they are not, or gameplay in an otherwise three-dimensional video game that is restricted to a two-dimensional plane. (Information taken from Wikipedia.org) I have a question based on 2.5D game development. As stated before, 2.5D uses graphical projections and techniques to make fake 3d or a gameplay restricted to a two-dimensional plane. A good example is a TQ Digital made game: Zero Online (screenshot) the whole map is made of 2d images and only NPCs and players are 3d. The maps were drawn manually by hand without any 3d software rendering. As I'm playing the game I feel like I'm going from a lower part of the map (ground) to a higher one (some metal platform) and it feels like I'm moving in 3 dimensions. But when I look closely, I see that the player size didn't change and the shadow too but I'm still feeling like I'm somehow higher then before (I had rendered a simple map myself that I made in 3dmax but it didn't quite give the result I wanted). How to accomplish such an effect?

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• Unity 3D (with Nvidia driver) becomes very slow and laggy

  - by Graham

  How can I prevent my Unity 3D desktop from becoming slow after a while, given that I have an Nvidia Quadro NVS 290 graphics in TwinView mode? The desktop starts out fast on login, but becomes slow / lagging / hesitant / high latency after a while, symptoms being spikes in CPU usage by /usr/bin/X whenever I cause any graphical activity with the mouse or keyboard (e.g. typing, changing tabs, dragging windows). The desktop remains slow even with all windows (except htop in Terminal) and extraneous processes killed. Detail: Changing tabs in Terminal takes about a second, and X spikes to 76% CPU. As I type into Firefox, X spikes to 95% CPU. Dragging Termiinal window, X goes to 70% CPU. Basically, every graphical action sends CPU usage of X through the roof. Device: Nvidia Quadro NVS 290 Driver package: binary driver nvidia-current-updates (280.13-0ubuntu5) Dual Monitors: Pair of DELL UltraSharp 1908FP in TwinView (X screen 2560x1024) OS: Fresh install of Ubuntu 11.10 amd64 Desktop with all updates. Hardware: Dell Precision T5400 Workstation Pastebin of Xorg.0.log Pastebin of xorg.conf Pastebin of nvidia-xconfig -t output (easier to read than xorg.conf) Output of /usr/lib/nux/unity_support_test -p: To obtain the following htop screenshow I typed "asdf" several times in in this text box, alt-tabbed to Terminal and took a screenshot of the high X CPU usage. This also happens when firefox is not running: Quadro NVS 290 has "No" thermal sensor according to sensors-detect: Next adapter: NVIDIA i2c adapter 0 at 2:00.0 (i2c-0) Do you want to scan it? (YES/no/selectively): Client found at address 0x50 Probing for `Analog Devices ADM1033'... No Probing for `Analog Devices ADM1034'... No P robing for `SPD EEPROM'... No Probing for `EDID EEPROM'... Yes (confidence 8, not a hardware monitoring chip) I tried the nouveau driver by disabling the nvidia-current-updates under Additional Drivers, but Ubuntu and xrandr -q fail to detect the second monitor. This may be issue 737349. Funniest thing is that Nouveau wiki says that XRandR 1.2 dual-monitor is supported so it should work with a second monitor.

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• Grub options are not visible on booting on Samsung ATIV Book 9 Lite running Ubuntu 14.04

  - by mjwittering

  I've managed to install Ubuntu 14.04 on my new Samsung ATIV Book 9 Lite ultrabook. After updating some configuratiosn in the UEFI installation was very easy. The only questions and issue I believe I'm still experience is when booting. I believe when the laptop would be displaying the grub boot options I see the following. There is a black screen with a purple border of 10px around the screen. I'd like to know how I can update my system so that I see the grub boot manager. I've run these commands: sudo cat /etc/default/grub # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: # info -f grub -n 'Simple configuration' GRUB_DEFAULT=0 GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX="" # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef" # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480 # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true" # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1" The command was not possible, sudo efibootmgr.

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