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• How to wire finite state machine into component-based architecture?

  - by Pup

  State machines seem to cause harmful dependencies in component-based architectures. How, specifically, is communication handled between a state machine and the components that carry out state-related behavior? Where I'm at: I'm new to component-based architectures. I'm making a fighting game, although I don't think that should matter. I envision my state machine being used to toggle states like "crouching", "dashing", "blocking", etc. I've found this state-management technique to be the most natural system for a component-based architecture, but it conflicts with techniques I've read about: Dynamic Game Object Component System for Mutable Behavior Characters It suggests that all components activate/deactivate themselves by continually checking a condition for activation. I think that actions like "running" or "walking" make sense as states, which is in disagreement with the accepted response here: finite state machine used in mario like platform game I've found this useful, but ambiguous: How to implement behavior in a component-based game architecture? It suggests having a separate component that contains nothing but a state machine. But, this necessitates some kind of coupling between the state machine component and nearly all the other components. I don't understand how this coupling should be handled. These are some guesses: A. Components depend on state machine: Components receive reference to state machine component's getState(), which returns an enumeration constant. Components update themselves regularly and check this as needed. B. State machine depends on components: The state machine component receives references to all the components it's monitoring. It queries their getState() methods to see where they're at. C. Some abstraction between them Use an event hub? Command pattern? D. Separate state objects that reference components State Pattern is used. Separate state objects are created, which activate/deactivate a set of components. State machine switches between state objects. I'm looking at components as implementations of aspects. They do everything that's needed internally to make that aspect happen. It seems like components should function on their own, without relying on other components. I know some dependencies are necessary, but state machines seem to want to control all of my components.

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• Why is a fully transparent pixel still rendered?

  - by Mr Bell

  I am trying to make a pixel shader that achieves an effect similar to this video http://www.youtube.com/watch?v=f1uZvurrhig&feature=related My basic idea is render the scene to a temp render target then Render the previously rendered image with a slight fade on to another temp render target Draw the current scene on top of that Draw the results on to a render target that persists between draws Draw the results on to the screen But I am having problems with the fading portion. If I have my pixel shader return a color with its A component set to 0, shouldn't that basically amount to drawing nothing? (Assuming that sprite batch blend mode is set to AlphaBlend) To test this I have my pixel shader return a transparent red color. Instead of nothing being drawn, it draws a partially transparent red box. I hope that my question makes sense, but if it doesnt please ask me to clarify Here is the drawing code public override void Draw(GameTime gameTime) { GraphicsDevice.SamplerStates[1] = SamplerState.PointWrap; drawImageOnClearedRenderTarget(presentationTarget, tempRenderTarget, fadeEffect); drawImageOnRenderTarget(sceneRenderTarget, tempRenderTarget); drawImageOnClearedRenderTarget(tempRenderTarget, presentationTarget); GraphicsDevice.SetRenderTarget(null); drawImage(backgroundTexture); drawImage(presentationTarget); base.Draw(gameTime); } private void drawImage(Texture2D image, Effect effect = null) { spriteBatch.Begin(0, BlendState.AlphaBlend, SamplerState.PointWrap, null, null, effect); spriteBatch.Draw(image, new Rectangle(0, 0, width, height), Color.White); spriteBatch.End(); } private void drawImageOnRenderTarget(Texture2D image, RenderTarget2D target, Effect effect = null) { GraphicsDevice.SetRenderTarget(target); drawImage(image, effect); } private void drawImageOnClearedRenderTarget(Texture2D image, RenderTarget2D target, Effect effect = null) { GraphicsDevice.SetRenderTarget(target); GraphicsDevice.Clear(Color.Transparent); drawImage(image, effect); } Here is the fade pixel shader sampler TextureSampler : register(s0); float4 PixelShaderFunction(float2 texCoord : TEXCOORD0) : COLOR0 { float4 c = 0; c = tex2D(TextureSampler, texCoord); //c.a = clamp(c.a - 0.05, 0, 1); c.r = 1; c.g = 0; c.b = 0; c.a = 0; return c; } technique Fade { pass Pass1 { PixelShader = compile ps_2_0 PixelShaderFunction(); } }

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• What is Database Continuous Integration?

  - by SQLDev

  Although not everyone is practicing continuous integration, many have at least heard of the concept. A recent poll on www.simple-talk.com indicates that 40% of respondents are employing the technique. It is widely accepted that the earlier issues are identified in the development process, the lower the cost to the development process. The worst case scenario, of course, is for the bug to be found by the customer following the product release. A number of Agile development best practices have evolved to combat this problem early in the development process, including pair programming, code inspections and unit testing. Continuous integration is one such Agile concept that tackles the problem at the point of committing a change to source control. This can alternatively be run on a regular schedule. This triggers a sequence of events that compiles the code and performs a variety of tests. Often the continuous integration process is regarded as a build validation test, and if issues were to be identified at this stage, the testers would simply not 'waste their time ' and touch the build at all. Such a ‘broken build’ will trigger an alert and the development team’s number one priority should be to resolve the issue. How application code is compiled and tested as part of continuous integration is well understood. However, this isn’t so clear for databases. Indeed, before I cover the mechanics of implementation, we need to decide what we mean by database continuous integration. For me, database continuous integration can be implemented as one or more of the following: 1)      Your application code is being compiled and tested. You therefore need a database to be maintained at the corresponding version. 2)      Just as a valid application should compile, so should the database. It should therefore be possible to build a new database from scratch. 3)     Likewise, it should be possible to generate an upgrade script to take your already deployed databases to the latest version. I will be covering these in further detail in future blogs. In the meantime, more information can be found in the whitepaper linked off www.red-gate.com/ci If you have any questions, feel free to contact me directly or post a comment to this blog post.

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• What is Database Continuous Integration?

  - by David Atkinson

  Although not everyone is practicing continuous integration, many have at least heard of the concept. A recent poll on www.simple-talk.com indicates that 40% of respondents are employing the technique. It is widely accepted that the earlier issues are identified in the development process, the lower the cost to the development process. The worst case scenario, of course, is for the bug to be found by the customer following the product release. A number of Agile development best practices have evolved to combat this problem early in the development process, including pair programming, code inspections and unit testing. Continuous integration is one such Agile concept that tackles the problem at the point of committing a change to source control. This can alternatively be run on a regular schedule. This triggers a sequence of events that compiles the code and performs a variety of tests. Often the continuous integration process is regarded as a build validation test, and if issues were to be identified at this stage, the testers would simply not 'waste their time ' and touch the build at all. Such a ‘broken build’ will trigger an alert and the development team’s number one priority should be to resolve the issue. How application code is compiled and tested as part of continuous integration is well understood. However, this isn’t so clear for databases. Indeed, before I cover the mechanics of implementation, we need to decide what we mean by database continuous integration. For me, database continuous integration can be implemented as one or more of the following: 1)      Your application code is being compiled and tested. You therefore need a database to be maintained at the corresponding version. 2)      Just as a valid application should compile, so should the database. It should therefore be possible to build a new database from scratch. 3)     Likewise, it should be possible to generate an upgrade script to take your already deployed databases to the latest version. I will be covering these in further detail in future blogs. In the meantime, more information can be found in the whitepaper linked off www.red-gate.com/ci If you have any questions, feel free to contact me directly or post a comment to this blog post.

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• Scan Your Thumb Drive for Viruses from the AutoPlay Dialog

  - by Mysticgeek

  It’s always a good idea to scan someone’s flash drive for viruses when you use it on your PC. Today we look at how to use Microsoft Security Essentials to scan thumb drives via the AutoPlay dialog. Editor Note: This technique was created by our friend Ramesh Srinivasan from the winhelponline tech blog. If you haven’t done so already, download and install Microsoft Security Essentials (link below), which has earned the How-To Geek official endorsement. Next download the mseautoplay.zip (link below). Unzip the file to view its contents. Then move the msescan.vbs script file into the Windows directory. Next double-click on the mseautoplay.reg file… Click Yes to the warning dialog window asking if you’re sure you want to add to the registry. After it’s added you’ll get a confirmation message…click OK. Now when you pop in a thumb drive, when AutoPlay comes up you will have the options to scan it with MSE first. MSE starts the scan of the thumb drive…   You can use this to scan any removable media. Here is an example of the ability to scan a DVD with MSE before opening any files. You can also go into Control Panel and set it as a default option of AutoPlay. Open Control Panel, View by Large icons, and click on AutoPlay. Notice that now when you go to change the default options for different types of media, Scanning with MSE is now included in the dropdown lists. Remove Settings If you want to remove the MSE AutoPlay Handler, Ramesh was kind enough to create an undo registry file. Double-click on undo.reg from the original MSE AutoPlay folder and click yes to the message to remove the setting.   Then you will need to go into the Windows directory and manually delete the msescan.vbs script file. This is an awesome trick which will allow you to scan your thumb drives and other removable media from the AutoPlay dialog. We tested it out on XP, Vista, and Windows 7 and it works perfectly on each one. Download mseautoplay.zip Download Microsoft Security Essentials Read Our Review of MSE Similar Articles Productive Geek Tips Disable AutoPlay in Windows VistaFind Your Missing USB Drive on Windows XPDisable Autoplay of Audio CDs and USB DrivesHow To Remove Antivirus Live and Other Rogue/Fake Antivirus MalwareScan Files for Viruses Before You Download With Dr.Web TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 VMware Workstation 7 Acronis Online Backup Sculptris 1.0, 3D Drawing app AceStock, a Tiny Desktop Quote Monitor Gmail Button Addon (Firefox) Hyperwords addon (Firefox) Backup Outlook 2010 Daily Motivator (Firefox)

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• SharePoint 2010 Data Retrival Techinques

  - by Jayant Sharma

  In SharePoint, we have two options to perform CRUD operation.1. using server side code2. using client side codeusing server side code, we have 1. CAML2. LINQusing client side code, we have 1. Client Object Model    1.1.      Managed Client Object Model     1.2.     Silverlight Client Object Model    1.3.     ECMA Client Object Model2. SharePoint Web Services3. ADO Data Service (based on REST Web Services)4. Using RPC Call (owssvr.dll)Which and when these options are used depend upon requirements. Every options are certain advantages and disadvantages. So, before start development of any new sharepoint project, it is important to understand the limitations of different methods.Server Object Model is used when our application is host on the same server on which sharepoint is installed. while Client Side code is used to access sharepoint from client system. In SharePoint 2010 specially Client Object Model (COM) are introduced to perform the sharepoint operations from client system. Advantage of CAML:    -  It is fast.    -  Can be use it from all kind of technology like Silverlight, or Jquery    -  You can use U2U CAML Query builder to generate CAML Query.Disadvantage Of CAML:    - Error Prone, as we can detect the error only at runtimeAdvantage of LINQ:    -  Object Oriented technique (Object Relation Model)    -  LINQ  to SharePoint provider are working with Strongly Type List Item Objects, So intellisence are present at runtime    -  No need of knowledge of CAML    -  Less Error Prone as it as it uses C# syntex.    -  You can compare two Fields of SharePoint ListDisadvantage Of LINQ:    -  List Attachment is not supported in SPMetal Tool    -  Created By, Created, Modified and Modified By Fields are not created by SPMetal Tool.    -  Custom fields are not created by SPMetal Tools    -  External Lists are not supported    -  Though at backend LINQ genenates CAML Query so it is slower than directly using CAML in Code.  Advantage of Client Object Model    -  Used to access sharepoint from client system    -  No WebServer is required at Client End    - Can use Silverlight and JavaScripts to make better and fast User experienceDisadvantage of Client Object Model    -  You cannot use RunwithEleveatedPrivilege    - Cross Site Collection query are not possible    - Lesser API's are availableADO.Net Data Services:    -  Only List based operations are possible, other type of operations are not possible.SharePoint Web Services and RPC Call:    - Previously it was used in SharePoint 2007 but after the introduction  of Client Object Model,  Microsoft recommends not to use Web Services to fetch data from SharePoint. In SharePoint 2010 it is avaliable only for backward compatibility.Ref: http://msdn.microsoft.com/en-us/library/ee539764Jayant Sharma

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• Which techniques to study?

  - by Djentleman

  Just to give you some background info, I'm studying a programming major at a tertiary level and am in my third year, so I'm not a newbie off the street. However, I am still quite new to game programming as a subset of programming. One of my personal projects for next semester is to design and create a 2D platformer game with emphasis on procedural generation and "neato" effects (think metroidvania). I've written up a list of some techniques to help me improve my personal skills (using XNA for the time being). The list is as follows: QuadTrees: Build a basic program in XNA that moves basic 2D sprites (circles and squares) around a set path and speed and changes their colour when they collide. Add functionality to add and delete objects of different sizes (select a direction and speed when adding and just drag and drop them in). Particles: Build a basic program in XNA in which you can select different colours and create particle effects of those colours on screen by clicking and dragging the mouse around (simple particles emerging from where the mouse is clicked). Add functionality where you can change the amount of particles to be drawn and the speed at which they travel and when they expire. Possibly implement gravity and wind after part 3 is complete. Physics: Build a basic program in XNA where you have a ball in a set 2D environment, a wind slider, and a gravity slider (can go to negative for reverse gravity). You can click to drag the ball around and release to throw it and, depending on what you do, the ball interacts with the environment. Implement other shapes afterwards. Random 2D terrain generation: Build a basic program in XNA that randomly generates terrain (including hills, caves, etc) created from 2D tiles. Add functionality that draws the tiles from a tileset and places different tiles depending on where they lie on the y-axis (dirt on top, then rock, then lava, etc). Randomised objects: Build a basic program in XNA that, when a button is clicked, displays a randomised item sprite based on parameters (type, colour, etc) with the images pulled from tilesets. Add the ability to save the item as an object, which stores it in a side-pane where it can be selected for viewing. Movement: Build a basic program in XNA where you can move an object around in an environment (tile-based) with a camera that pans with it. No gravity. Implement gravity and wind, allow the character to jump and fall with some basic platforms. So my question is this: Are there any other commonly used techniques that I should research, and can I get some suggestions as to the effectiveness of the techniques I've chosen to work on (e.g., don't do QuadTree stuff because [insert reason here], or, do [insert technique here] before you start working on particles because [insert reason here])? I hope this is clear enough and please let me know if I can further clarify anything!

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• Bay Area Coherence Special Interest Group Next Meeting July 21, 2011

  - by csoto

  Date: Thursday, July 21, 2011 Time: 4:30pm - 8:15pm ET (note that Parking at 475 Sansome Closes at 8:30pm) Where: Oracle Office, 475 Sansome Street, San Francisco, CA Google Map We will be providing snacks and beverages. Register! - Registration is required for building security. Presentation Line Up:? 5:10pm - Batch Processing Using Coherence in Oracle Group Policy Administration - Paul Cleary, Oracle Oracle Insurance Policy Administration (OIPA) is a flexible, rules-based policy administration solution that provides full record keeping for all policy lifecycle transactions. One component of OIPA is Cycle processing, which is the batch processing of pending insurance transactions. This presentation introduces OIPA and Cycle processing, describing the unique challenges of processing a high volume of transactions within strict time windows. It then reviews how OIPA uses Oracle Coherence and the Processing Pattern to meet these challenges, describing implementation specifics that highlight the simplicity and robustness of the Processing Pattern. 6:10pm - Secure, Optimize, and Load Balance Coherence with F5 - Chris Akker, F5 F5 Networks, Inc., the global leader in Application Delivery Networking, helps the world’s largest enterprises and service providers realize the full value of virtualization, cloud computing, and on-demand IT. Recently, F5 and Oracle partnered to deliver a novel solution that integrates Oracle Coherence 3.7 with F5 BIG-IP Local Traffic Manager (LTM). This session will introduce F5 and how you can leverage BIG-IP LTM to secure, optimize, and load balance application traffic generated from Coherence*Extend clients across any number of servers in a cluster and to hardware-accelerate CPU-intensive SSL encryption. 7:10pm - Using Oracle Coherence to Enable Database Partitioning and DC Level Fault Tolerance - Alexei Ragozin, Independent Consultant and Brian Oliver, Oracle Partitioning is a very powerful technique for scaling database centric applications. One tricky part of partitioned architecture is routing of requests to the right database. The routing layer (routing table) should know the right database instance for each attribute which may be used for routing (e.g. account id, login, email, etc): it should be fast, it should fault tolerant and it should scale. All the above makes Oracle Coherence a natural choice for implementing such routing tables in partitioned architectures. This presentation will cover synchronization of the grid with multiple databases, conflict resolution, cross cluster replication and other aspects related to implementing robust partitioned architecture. Additional Info:?? - Download Past Presentations: The presentations from the previous meetings of the BACSIG are available for download here. Click on the presentation titles to download the PDF files. - Join the Coherence online community on our Oracle Coherence Users Group on LinkedIn. - Contact BACSIG with any comments, questions, presentation proposals and content suggestions.

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• PCF shadow shader math causing artifacts

  - by user2971069

  For a while now I used PCSS for my shadow technique of choice until I discovered a type of percentage closer filtering. This method creates really smooth shadows and with hopes of improving performance, with only a fraction of texture samples, I tried to implement PCF into my shader. This is the relevant code: float c0, c1, c2, c3; float f = blurFactor; float2 coord = ProjectedTexCoords; if (receiverDistance - tex2D(lightSampler, coord + float2(0, 0)).x > 0.0007) c0 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, 0)).x > 0.0007) c1 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(0, f)).x > 0.0007) c2 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, f)).x > 0.0007) c3 = 1; coord = (coord % f) / f; return 1 - (c0 * (1 - coord.x) * (1 - coord.y) + c1 * coord.x * (1 - coord.y) + c2 * (1 - coord.x) * coord.y + c3 * coord.x * coord.y); This is a very basic implementation. blurFactor is initialized with 1 / LightTextureSize. So the if statements fetch the occlusion values for the four adjacent texels. I now want to weight each value based on the actual position of the texture coordinate. If it's near the bottom-right pixel, that occlusion value should be preferred. The weighting itself is done with a simple bilinear interpolation function, however this function takes a 2d vector in the range [0..1] so I have to convert my texture coordinate to get the distance from my first pixel to the second one in range [0..1]. For that I used the mod operator to get it into [0..f] range and then divided by f. This code makes sense to me, and for specific blurFactors it works, producing really smooth one pixel wide shadows, but not for all blurFactors. Initially blurFactor is (1 / LightTextureSize) to sample the 4 adjacent texels. I now want to increase the blurFactor by factor x to get a smooth interpolation across maybe 4 or so pixels. But that is when weird artifacts show up. Here is an image: Using a 1x on blurFactor produces a good result, 0.5 is as expected not so smooth. 2x however doesn't work at all. I found that only a factor of 1/2^n produces an good result, every other factor produces artifacts. I'm pretty sure the error lies here: coord = (coord % f) / f; Maybe the modulo is not calculated correctly? I have no idea how to fix that. Is it even possible for pixel that are further than 1 pixel away?

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• Preventing Users From Copying Text From and Pasting It Into TextBoxes

  Many websites that support user accounts require users to enter an email address as part of the registration process. This email address is then used as the primary communication channel with the user. For instance, if the user forgets her password a new one can be generated and emailed to the address on file. But what if, when registering, a user enters an incorrect email address? Perhaps the user meant to enter [email protected], but accidentally transposed the first two letters, entering [email protected]. How can such typos be prevented? The only foolproof way to ensure that the user's entered email address is valid is to send them a validation email upon registering that includes a link that, when visited, activates their account. (This technique is discussed in detail in Examining ASP.NET's Membership, Roles, and Profile - Part 11.) The downside to using a validation email is that it adds one more step to the registration process, which will cause some people to bail out on the registration process. A simpler approach to lessening email entry errors is to have the user enter their email address twice, just like how most registration forms prompt users to enter their password twice. In fact, you may have seen registration pages that do just this. However, when I encounter such a registration page I usually avoid entering the email address twice, but instead enter it once and then copy and paste it from the first textbox into the second. This behavior circumvents the purpose of the two textboxes - any typo entered into the first textbox will be copied into the second. Using a bit of JavaScript it is possible to prevent most users from copying text from one textbox and pasting it into another, thereby requiring the user to type their email address into both textboxes. This article shows how to disable cut and paste between textboxes on a web page using the free jQuery library. Read on to learn more! Read More >Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Simplifying C++11 optimal parameter passing when a copy is needed

  - by Mr.C64

  It seems to me that in C++11 lots of attention was made to simplify returning values from functions and methods, i.e.: with move semantics it's possible to simply return heavy-to-copy but cheap-to-move values (while in C++98/03 the general guideline was to use output parameters via non-const references or pointers), e.g.: // C++11 style vector<string> MakeAVeryBigStringList(); // C++98/03 style void MakeAVeryBigStringList(vector<string>& result); On the other side, it seems to me that more work should be done on input parameter passing, in particular when a copy of an input parameter is needed, e.g. in constructors and setters. My understanding is that the best technique in this case is to use templates and std::forward<>, e.g. (following the pattern of this answer on C++11 optimal parameter passing): class Person { std::string m_name; public: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> explicit Person(T&& name) : m_name(std::forward<T>(name)) { } ... }; A similar code could be written for setters. Frankly, this code seems boilerplate and complex, and doesn't scale up well when there are more parameters (e.g. if a surname attribute is added to the above class). Would it be possible to add a new feature to C++11 to simplify code like this (just like lambdas simplify C++98/03 code with functors in several cases)? I was thinking of a syntax with some special character, like @ (since introducing a &&& in addition to && would be too much typing :) e.g.: class Person { std::string m_name; public: /* Simplified syntax to produce boilerplate code like this: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> */ explicit Person(std::string@ name) : m_name(name) // implicit std::forward as well { } ... }; This would be very convenient also for more complex cases involving more parameters, e.g. Person(std::string@ name, std::string@ surname) : m_name(name), m_surname(surname) { } Would it be possible to add a simplified convenient syntax like this in C++? What would be the downsides of such a syntax?

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• Mise à jour Partner Enablement Oracle University (novembre)

  - by swalker

  Executive overview of Oracle Fusion Applications in 1-day from your desktop Designed from the ground up using the latest technology advances and incorporating the best practices gathered from Oracle's thousands of customers, Oracle Fusion Applications are 100% open-standards-based business applications that set a new standard for the way we innovate, work, and adopt technology. Learn more about them: Oracle University has scheduled a 1–day executive overview as a Live Virtual Class on the following dates: 1 December 2 December Your OPN discount applies to the standard price shown on the website. New In Class and Online dates will be shared on education.oracle.com. Book online or contact your local Oracle University representative for scheduling requests and more information. Deux nouvelles formations intensives OPN Only Boot Camps Les formations OPN Only Boot Camps suivantes viennent d'être mises à disposition : Formation technique intensive de 3 jours Oracle Exadata 11g  : Vous prépare à devenir un Spécialiste certifié de l’implémentation Oracle Exadata 11g Actuellement prévue en Allemagne, au Royaume-Uni Possibilité d'organisation dans tous les pays Dates des classes virtuelles en direct : 15-17 fév. 2012 & 16-18 mai 2012 Formation intensive de 5 jours Oracle BI Enterprise Edition 11g Implementation Actuellement prévue en Suède Possibilité d'organisation dans tous les pays Consulter le calendrier complet des formations OPN Only Boot Camp. Nouveautés du côté des certifications : Java SE 7 Soyez parmi les premiers à obtenir la certification Java SE 7 . Les examens suivants sont depuis peu disponibles en bêta test : Code et intitulé de l'examen Filière de certification 1Z1-805 Upgrade to Java SE 7 Programmer (Bêta jusqu'au 17 déc. 2011) Professionnel certifié Oracle (Certified Professional), Programmeur Java SE 7 1Z1-803 Java SE 7 Programmer I (Bêta jusqu'au 17 déc. 2011) Associé certifié Oracle (Certified Associate), Programmeur Java SE 7 Un examen bêta vous confère deux avantages distincts : vous serez parmi les premiers à obtenir la certification, vous bénéficiez d'un tarif réduit. Les examens bêta peuvent être passés dans n'importe quel Centre de test Pearson VUE. Nouveaux cours Parmi les nouveautés d’Oracle Université de ce mois-ci, vous trouverez : Nouveaux cours - Cliquez ici pour en savoir plus. Vos partenaires souhaitent-ils obtenir le point de vue des experts de l'Oracle University ? Conseillez-leur de consulter les newsletters suivantes de l'Oracle University " href="http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=289&p_nl=tech" target="_blank">Newsletters Technologie Newsletters Applications Restez connecté à Oracle University : OracleMix Twitter LinkedIn Facebook

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• OpenGL position from depth is wrong

  - by CoffeeandCode

  My engine is currently implemented using a deferred rendering technique, and today I decided to change it up a bit. First I was storing 5 textures as so: DEPTH24_STENCIL8 - Depth and stencil RGBA32F - Position RGBA10_A2 - Normals RGBA8 x 2 - Specular & Diffuse I decided to minimize it and reconstruct positions from the depth buffer. Trying to figure out what is wrong with my method currently has not been fun :/ Currently I get this: which changes whenever I move the camera... weird Vertex shader really simple #version 150 layout(location = 0) in vec3 position; layout(location = 1) in vec2 uv; out vec2 uv_f; void main(){ uv_f = uv; gl_Position = vec4(position, 1.0); } Fragment shader Where the fun (and not so fun) stuff happens #version 150 uniform sampler2D depth_tex; uniform sampler2D normal_tex; uniform sampler2D diffuse_tex; uniform sampler2D specular_tex; uniform mat4 inv_proj_mat; uniform vec2 nearz_farz; in vec2 uv_f; ... other uniforms and such ... layout(location = 3) out vec4 PostProcess; vec3 reconstruct_pos(){ float z = texture(depth_tex, uv_f).x; vec4 sPos = vec4(uv_f * 2.0 - 1.0, z, 1.0); sPos = inv_proj_mat * sPos; return (sPos.xyz / sPos.w); } void main(){ vec3 pos = reconstruct_pos(); vec3 normal = texture(normal_tex, uv_f).rgb; vec3 diffuse = texture(diffuse_tex, uv_f).rgb; vec4 specular = texture(specular_tex, uv_f); ... do lighting ... PostProcess = vec4(pos, 1.0); // Just for testing } Rendering code probably nothing wrong here, seeing as though it always worked before this->gbuffer->bind(); gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT); gl::Enable(gl::DEPTH_TEST); gl::Enable(gl::CULL_FACE); ... bind geometry shader and draw models and shiz ... gl::Disable(gl::DEPTH_TEST); gl::Disable(gl::CULL_FACE); gl::Enable(gl::BLEND); ... bind textures and lighting shaders shown above then draw each light ... gl::BindFramebuffer(gl::FRAMEBUFFER, 0); gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT); gl::Disable(gl::BLEND); ... bind screen shaders and draw quad with PostProcess texture ... Rinse_and_repeat(); // not actually a function ;) Why are my positions being output like they are?

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• JavaScript Class Patterns &ndash; In CoffeeScript

  - by Liam McLennan

  Recently I wrote about JavaScript class patterns, and in particular, my favourite class pattern that uses closure to provide encapsulation. A class to represent a person, with a name and an age, looks like this: var Person = (function() { // private variables go here var name,age; function constructor(n, a) { name = n; age = a; } constructor.prototype = { toString: function() { return name + " is " + age + " years old."; } }; return constructor; })(); var john = new Person("John Galt", 50); console.log(john.toString()); Today I have been experimenting with coding for node.js in CoffeeScript. One of the first things I wanted to do was to try and implement my class pattern in CoffeeScript and then see how it compared to CoffeeScript’s built-in class keyword. The above Person class, implemented in CoffeeScript, looks like this: # JavaScript style class using closure to provide private methods Person = (() -> [name,age] = [{},{}] constructor = (n, a) -> [name,age] = [n,a] null constructor.prototype = toString: () -> "name is #{name} age is #{age} years old" constructor )() I am satisfied with how this came out, but there are a few nasty bits. To declare the two private variables in javascript is as simple as var name,age; but in CoffeeScript I have to assign a value, hence [name,age] = [{},{}]. The other major issue occurred because of CoffeeScript’s implicit function returns. The last statement in any function is returned, so I had to add null to the end of the constructor to get it to work. The great thing about the technique just presented is that it provides encapsulation ie the name and age variables are not visible outside of the Person class. CoffeeScript classes do not provide encapsulation, but they do provide nicer syntax. The Person class using native CoffeeScript classes is: # CoffeeScript style class using the class keyword class CoffeePerson constructor: (@name, @age) -> toString: () -> "name is #{@name} age is #{@age} years old" felix = new CoffeePerson "Felix Hoenikker", 63 console.log felix.toString() So now I have a trade-off: nice syntax against encapsulation. I think I will experiment with both strategies in my project and see which works out better.

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• The most dangerous SQL Script in the world!

  - by DrJohn

  In my last blog entry, I outlined how to automate SQL Server database builds from concatenated SQL Scripts. However, I did not mention how I ensure the database is clean before I rebuild it. Clearly a simple DROP/CREATE DATABASE command would suffice; but you may not have permission to execute such commands, especially in a corporate environment controlled by a centralised DBA team. However, you should at least have database owner permissions on the development database so you can actually do your job! Then you can employ my universal "drop all" script which will clear down your database before you run your SQL Scripts to rebuild all the database objects. Why start with a clean database? During the development process, it is all too easy to leave old objects hanging around in the database which can have unforeseen consequences. For example, when you rename a table you may forget to delete the old table and change all the related views to use the new table. Clearly this will mean an end-user querying the views will get the wrong data and your reputation will take a nose dive as a result! Starting with a clean, empty database and then building all your database objects using SQL Scripts using the technique outlined in my previous blog means you know exactly what you have in your database. The database can then be repopulated using SSIS and bingo; you have a data mart "to go". My universal "drop all" SQL Script To ensure you start with a clean database run my universal "drop all" script which you can download from here: 100_drop_all.zip By using the database catalog views, the script finds and drops all of the following database objects: Foreign key relationships Stored procedures Triggers Database triggers Views Tables Functions Partition schemes Partition functions XML Schema Collections Schemas Types Service broker services Service broker queues Service broker contracts Service broker message types SQLCLR assemblies There are two optional sections to the script: drop users and drop roles. You may use these at your peril, particularly as you may well remove your own permissions! Note that the script has a verbose mode which displays the SQL commands it is executing. This can be switched on by setting @debug=1. Running this script against one of the system databases is certainly not recommended! So I advise you to keep a USE database statement at the top of the file. Good luck and be careful!!

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• Issue 56 - Super Stylesheets Skinning in DotNetNuke 5

  May 2010 Welcome to Issue 56 of DNN Creative Magazine In this issue we show you how to use the powerful new Super Stylesheets skinning feature in DotNetNuke 5. Super Stylesheets are ideal for both beginner and experienced skin designers, they provide skin layouts using CSS. The advantage of Super Stylesheets is that you can easily create a skin layout which works in all browsers without the need to learn complex CSS techniques. They are also very quick to build and you can change a skin layout in a matter of minutes rather than hours. We show you how to build a skin from the very beginning using Super Stylesheets, we show you how to create various skin layouts, as well as multi-layouts. We also show you how to style the skin, how to add tokens such as the logo, menu, login links etc. and walk you through how to create a fully working skin from scratch. Following this we continue the Open Web Studio tutorials, this month we demonstrate how to create an installable DotNetNuke PA module using OWS. This is an essential technique which allows you to package up the OWS applications that you have created and build them into an installable zip package. The zip file is then installable as a standard DotNetNuke module which means you can easily install your OWS applications on other DotNetNuke installations by simply installing them as a standard DotNetNuke module. To finish, we have part six of the "How to Build a News Application with DotNetMushroom Rapid Application Developer (RAD)" article, where we demonstrate how to create a News Carousel using RAD, JQuery and the JCarousel plugin. This issue comes complete with 15 videos. Skinning: Super Stylesheets Skinning in DotNetNuke 5 - DNN Layouts (12 videos - 98mins) Module Development Series: How to Create an Installable DotNetNuke PA Module Using OWS (3 videos - 23mins) How to Implement a News Carousel Using DotNetMushroom RAD and JQuery View issue 56 to download all of the videos in one zip file DNN Creative Magazine for DotNetNuke Web Designers Covering DotNetNuke module video reviews, video tutorials, mp3 interviews, resources and web design tips for working with DotNetNuke. In 56 issues we have created 578 videos!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• What are the drawbacks of sending XML to browsers and let them apply XSLT?

  - by MainMa

  Context Working as a freelance developer, I often made websites completely based on XSLT. In other words, on every request, an XML file is generated, containing everything we need to know about the page content: the name of the user currently logged in, the top menu entries, if this menu is dynamic/configurable, the text to display in a specific area of the page, etc. Then XSL process (caches, etc.) it to HTML/XHTML page to send to the browser. It has a good point to make it easier to create small-scale websites, especially with PHP. It is a sort of template engine, but which I prefer to other template engines because it's much more powerful than most of template engines, and because I know it better and like it. It is also possible, when need, to give an access to raw XML data on demand for an automated access, without the need to create separate APIs. Of course, it will fail completely on any medium-scale or large-scale website, since, even with good caching techniques, XSL still degrades overall website performance and requires more CPU serverside. Question Modern browsers have the ability to take an XML file and to transform it with an associated XSL file declared in XML like <?xml-stylesheet href="demo.xslt" type="text/xsl"?>. Firefox 3 can do it. Internet Explorer 8 can do it too. It means that it is possible to migrate XSL processing from the server to the client side for 50% of users (according on browser statistics on several websites where I may want to implement this). It means that those 50% of users will receive only the XML file at each request, thus reducing their and server's bandwidth (XML file being much shorter than its processed HTML analog), and reducing server's CPU usage. What are the drawbacks of this technique? I thought about several ones, but it doesn't apply in this situation: Difficult implementation and the need to choose, based on the browser request, when to send raw XML and when to transform it to HTML instead. Obviously, the system will not be much more difficult then the actual one. The only change to make is to add XSL file link to every XML, and to add a browser check. More IO and bandwidth usage, since the XSLT file will be downloaded by the browsers, instead of being cached by the server. I don't think it will be a problem, since XSLT file will be cached by the browsers (like images, or CSS, or JavaScript files are cached actually). Possibly some problems on client side, like maybe problems when saving a page in some browsers. Difficulty to debug code: it is impossible to obtain an HTML source the browser is actually using, since the only displayed source is the downloaded XML. On the other hand, I rarely go look at HTML code on client side, and in most cases, it is unusable directly (whitespace being removed).

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• How to deal with malicious domain redirections?

  - by user359650

  It is possible for anybody to buy a domain name containing negative terms and point it to someone's website in order to damage their reputation. For instance someone could buy the domain child-pornography.com and point it to the address 64.34.119.12 which is the address behind stackoverflow.com and people navigating to the domain in question would end up visualizing content from StackExchange which would be detrimental to StackExchange's image. To illustrate this, I added the entry 64.34.119.12 child-pornography.com to my /etc/hosts file and tested. Here is what I obtained: I personally found this user experience terrible as someone could think that Stack Exchange are in favor of child pornography and awaiting support from the community to create a Q&A site about it. I tested with other websites and experienced other behaviors that I would categorize as follows: 1 - Useful 404 page (happens with stackoverflow.com): For me the worst way of handling this as the image of the targeted website is directly associated with the offending domain. The more useful the 404 page, the bigger the impression that the targeted website would be willing to help with child pornography. 2 - Redirection (happens with microsoft.com): For instance when accessing child-pornography.com you get redirected to www.microsoft.com. It isn't as bad as above as the offending domain name never appears alongside the targeted website's content, but still bad in my opinion as it gives the impression the targeted website bought the offending domain and redirected it to their website to get more traffic. 3 - Server error (happens with lemonde.fr): You get an error from the webserver which page doesn't contain any content that can be associated with the targeted website (e.g. default Apache 404 page, completely blank page). I believe that is good as the identify of the targeted website isn't revealed. Above are the various behaviors I experienced, but I also thought about a fourth way of dealing with this which is described below. 4 - Disclaimer page (haven't found any website implementing that technique): Display a message such as : "You ended here because someone bought and linked the child-pornography.com domain to our website. We do not own this domain and do not associate ourselves with it. This request has been logged by our servers and we will raise this issue with the competent authorities to have this domain taken down. If you want to access our website, please click here." The good thing about this method is that it can be implemented at application layer (good if you don't have control over web server which happens with some hosting solutions), allows you to protect yourself from any liability, and offer the visitor to be redirected to your own website. Which of the above options would you implement to deal with malicious domain linking (IMO only options 3 and 4 are worth considering) ?

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• 2D Animation Smoothness - Delta time vs. Kinematics

  - by viperld002

  I'm animating a sprite in 2D with key frames of rotation and xy-positions. I've recently had a discussion with someone saying that when the device (happens to be an iPad using cocos2D) hits a performance bump due to whatever else the user may be doing, lag will arise and that the best way to fight it is to not use actual positions, but velocities, accelerations and torques with kinematics. His message is to evaluate the positions and rotations from these speeds at the current point in time. I've never experienced a situation where I've heard of using kinematics to stem lag in 2D animations and am not sure of how effective it could be. Also, it seems to be overkill. The application is not networked so it's all running on a local device. The desired effect is that the animation always plays as closely as it can to the target frame rate. Wouldn't the technique suffer the same problems as just using the time since the last frame or a fixed time step since the kinematics would also require some time value to perform the calculation? What techniques could you suggest to best achieve the desired effect? EDIT 1 Thank you for your responses, they are very illuminating. I want to clarify my question before choosing an answer however, to make sure that this post really serves it's purpose. I have a sprite of a ball, and a text file with 3 arrays worth of information (rotation,translations x, translations y) with each unit of information existing as a key frame to be stepped through (0 to 49 and back to 0 to replay it again). I have this playing by interpolating from the current key frame to the next, every n-units of time. The animation is visibly correct when compared to a video I was given of it, and it is smooth because of the interpolations between the key frames. This is the existing state of the project. There are no physics simulated, only a static animation of a ball moving in a way an artist specifically designed. Should I, instead of rotation in degrees and translations by positions in space, derive velocities, accelerations and torques to express this static animation as a function of time? As in, position now = foo(time now), where foo uses kinematics.

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• Software Tuned to Humanity

  - by Phil Factor

  I learned a great deal from a cynical old programmer who once told me that the ideal length of time for a compiler to do its work was the same time it took to roll a cigarette. For development work, this is oh so true. After intently looking at the editing window for an hour or so, it was a relief to look up, stretch, focus the eyes on something else, and roll the possibly-metaphorical cigarette. This was software tuned to humanity. Likewise, a user’s perception of the “ideal” time that an application will take to move from frame to frame, to retrieve information, or to process their input has remained remarkably static for about thirty years, at around 200 ms. Anything else appears, and always has, to be either fast or slow. This could explain why commercial applications, unlike games, simulations and communications, aren’t noticeably faster now than they were when I started programming in the Seventies. Sure, they do a great deal more, but the SLAs that I negotiated in the 1980s for application performance are very similar to what they are nowadays. To prove to myself that this wasn’t just some rose-tinted misperception on my part, I cranked up a Z80-based Jonos CP/M machine (1985) in the roof-space. Within 20 seconds from cold, it had loaded Wordstar and I was ready to write. OK, I got it wrong: some things were faster 30 years ago. Sure, I’d now have had all sorts of animations, wizzy graphics, and other comforting features, but it seems a pity that we have used all that extra CPU and memory to increase the scope of what we develop, and the graphical prettiness, but not to speed the processes needed to complete a business procedure. Never mind the weight, the response time’s great! To achieve 200 ms response times on a Z80, or similar, performance considerations influenced everything one did as a developer. If it meant writing an entire application in assembly code, applying every smart algorithm, and shortcut imaginable to get the application to perform to spec, then so be it. As a result, I’m a dyed-in-the-wool performance freak and find it difficult to change my habits. Conversely, many developers now seem to feel quite differently. While all will acknowledge that performance is important, it’s no longer the virtue is once was, and other factors such as user-experience now take precedence. Am I wrong? If not, then perhaps we need a new school of development technique to rival Agile, dedicated once again to producing applications that smoke the rear wheels rather than pootle elegantly to the shops; that forgo skeuomorphism, cute animation, or architectural elegance in favor of the smell of hot rubber. I struggle to name an application I use that is truly notable for its blistering performance, and would dearly love one to do my everyday work – just as long as it doesn’t go faster than my brain.

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• Self-Executing Anonymous Function vs Prototype

  - by Robotsushi

  In Javascript there are a few clearly prominent techniques for create and manage classes/namespaces in javascript. I am curious what situations warrant using one technique vs. the other. I want to pick one and stick with it moving forward. I write enterprise code that is maintained and shared across multiple teams, and I want to know what is the best practice when writing maintainable javascript ? I tend to prefer Self-Executing Anonymous Functions however I am curious what the community vote is on these techniques. Prototype : function obj() { } obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test(); Self-Closing Anonymous Function : //Self-Executing Anonymous Function (function( skillet, $, undefined ) { //Private Property var isHot = true; //Public Property skillet.ingredient = "Bacon Strips"; //Public Method skillet.fry = function() { var oliveOil; addItem( "\t\n Butter \n\t" ); addItem( oliveOil ); console.log( "Frying " + skillet.ingredient ); }; //Private Method function addItem( item ) { if ( item !== undefined ) { console.log( "Adding " + $.trim(item) ); } } }( window.skillet = window.skillet || {}, jQuery )); //Public Properties console.log( skillet.ingredient ); //Bacon Strips //Public Methods skillet.fry(); //Adding Butter & Fraying Bacon Strips //Adding a Public Property skillet.quantity = "12"; console.log( skillet.quantity ); //12 //Adding New Functionality to the Skillet (function( skillet, $, undefined ) { //Private Property var amountOfGrease = "1 Cup"; //Public Method skillet.toString = function() { console.log( skillet.quantity + " " + skillet.ingredient + " & " + amountOfGrease + " of Grease" ); console.log( isHot ? "Hot" : "Cold" ); }; }( window.skillet = window.skillet || {}, jQuery )); //end of skillet definition try { //12 Bacon Strips & 1 Cup of Grease skillet.toString(); //Throws Exception } catch( e ) { console.log( e.message ); //isHot is not defined } I feel that I should mention that the Self-Executing Anonymous Function is the pattern used by the jQuery team. Update When I asked this question I didn't truly see the importance of what I was trying to understand. The real issue at hand is whether or not to use new to create instances of your objects or to use patterns which do not require constructors of the use of the new keyword. I added my own answer, because in my opinion we should make use of patterns which don't use the new keyword. For more information please see my answer.

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• Part 5: Choose the right tool - or - why

  - by volker.eckardt(at)oracle.com

  Consider the following client request “Please create a report for us to list expenses”. Which Oracle EBS tool would you choose? There are plenty of options available: Oracle Reports, or BI Publisher with PDF or Excel layout, or Discoverer, or BI Publisher Stand Alone, or PDF online generation, or Oracle WebADI, or Plain SQL*Plus as Concurrent Program, or Online review option … Assuming, you as development lead have to decide, you may decide by available skill set in your development team. However, is this a good decision? An important question to influence the decision is the “Why” question: why do you need this report, what process is behind, what exactly you like to achieve? We see often data created or printed, although it would be much better to get the data in Excel, and upload changes via WebADI directly. There are more points that should drive your decision: How many of such requirements you have got? Has this technique been used in the project already? Are there related reusable’s you may gain from? How difficult is it to maintain your solution? Can you merge this report with another one, to reduce test and maintenance work? In addition, also your own development standards should guide you a bit to come to a good decision. In one of my own projects, we discussed such topics in our weekly team meeting. By utilizing the team knowledge best, you may come to a better decision, and additionally, your team supports your decision. Unfortunately, I have rarely seen dedicated team trainings or planned knowledge transfer to support such processes. Often the pressure to deliver on time is too high to have discussion and decision time left. But exactly this can help keeping maintenance costs low by limiting the number of alternative solutions for similar requirements. Lastly, design decisions should be documented to allow another person taking this over easily. Decisions shall be reviewed and updated regularly, to reflect related procedures or Oracle products respective product versions. Summary: Oracle EBS offers plenty of alternatives to implement customizations. Create and maintain a decision tree to support the design process. Do not leave the decision just on developer side. Limit the number of alternative solutions as best as possible; choose one which is the most appropriate also from future maintenance perspective.

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• What You Said: Staying Productive While Working from home

  - by Jason Fitzpatrick

  Earlier this week we asked you to share your telecommuting/work-from-home productivity tips. Now we’re back with a tips and tricks roundup; read on to see how your fellow readers stay focused at home. By far and away the most common technique deployed as carefully isolating work from home life. Carol writes: I love working from home and have done so for 6 years now. I have a routine just as if I was going to an office, except my commute is 12 steps. I get ready for work, grab my purse and smart phone and go to up the steps to my office. I maintain a separate phone line and voice mail for work that I cannot answer from anywhere but my work desk. I use call forwarding when I travel so only my office phone number is published. I have VOIP phone service so I can forward calls from the internet if I forget, or need to change where the phone is forwarded. I do have a wired and wireless head set so I can go get a cold drink if on one of those long boring conference calls. I plan my ‘get off from work’ time and try to stick to it, as with any job some days I am late getting off, but it all works out. I make sure my office is for work only, any other computer play time is in a different part of the house on different computer. My office has laptop, dock, couple of monitors, multipurpose printer, fax, scanner, file cabinets – just like the office at a company. I just also happen to have a couple of golden retrievers that come to work with me and usually lay quietly until 5, and yes they know it is 5pm sometimes before I do. For me, one of the biggest concerns when working from home is not being unproductive, but the danger of never stopping work. You could keep going and going because let’s face it – the company will let you do it, so I set myself up to prevent that and maintain a separateness. HTG Explains: Does Your Android Phone Need an Antivirus? How To Use USB Drives With the Nexus 7 and Other Android Devices Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder?

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• Sampling SQL server batch activity

  - by extended_events

  Recently I was troubleshooting a performance issue on an internal tracking workload and needed to collect some very low level events over a period of 3-4 hours.  During analysis of the data I found that a common pattern I was using was to find a batch with a duration that was longer than average and follow all the events it produced.  This pattern got me thinking that I was discarding a substantial amount of event data that had been collected, and that it would be great to be able to reduce the collection overhead on the server if I could still get all activity from some batches. In the past I’ve used a sampling technique based on the counter predicate to build a baseline of overall activity (see Mikes post here).  This isn’t exactly what I want though as there would certainly be events from a particular batch that wouldn’t pass the predicate.  What I need is a way to identify streams of work and select say one in ten of them to watch, and sql server provides just such a mechanism: session_id.  Session_id is a server assigned integer that is bound to a connection at login and lasts until logout.  So by combining the session_id predicate source and the divides_by_uint64 predicate comparator we can limit collection, and still get all the events in batches for investigation. CREATE EVENT SESSION session_10_percent ON SERVER ADD EVENT sqlserver.sql_statement_starting(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info_external (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlserver.sql_statement_completed(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))) ADD TARGET ring_buffer WITH (MAX_DISPATCH_LATENCY=30 SECONDS,TRACK_CAUSALITY=ON) GO   There we go; event collection is reduced while still providing enough information to find the root of the problem.  By the way the performance issue turned out to be an IO issue, and the session definition above was more than enough to show long waits on PAGEIOLATCH*.        

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• Lazy Processing of Streams

  - by Giorgio

  I have the following problem scenario: I have a text file and I have to read it and split it into lines. Some lines might need to be dropped (according to criteria that are not fixed). The lines that are not dropped must be parsed into some predefined records. Records that are not valid must be dropped. Duplicate records may exist and, in such a case, they are consecutive. If duplicate / multiple records exist, only one item should be kept. The remaining records should be grouped according to the value contained in one field; all records belonging to the same group appear one after another (e.g. AAAABBBBCCDEEEFF and so on). The records of each group should be numbered (1, 2, 3, 4, ...). For each group the numbering starts from 1. The records must then be saved somewhere / consumed in the same order as they were produced. I have to implement this in Java or C++. My first idea was to define functions / methods like: One method to get all the lines from the file. One method to filter out the unwanted lines. One method to parse the filtered lines into valid records. One method to remove duplicate records. One method to group records and number them. The problem is that the data I am going to read can be too big and might not fit into main memory: so I cannot just construct all these lists and apply my functions one after the other. On the other hand, I think I do not need to fit all the data in main memory at once because once a record has been consumed all its underlying data (basically the lines of text between the previous record and the current record, and the record itself) can be disposed of. With the little knowledge I have of Haskell I have immediately thought about some kind of lazy evaluation, in which instead of applying functions to lists that have been completely computed, I have different streams of data that are built on top of each other and, at each moment, only the needed portion of each stream is materialized in main memory. But I have to implement this in Java or C++. So my question is which design pattern or other technique can allow me to implement this lazy processing of streams in one of these languages.

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