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  • High traffic chat - how to check if there is new message and show it for all users

    - by user2633999
    I already had question about this but obviously it was not accepted very well, apparently too long when it's actually more information so you could have given me better answer. Ok, I will be much clearer now. Best possible logic to develop scalable chat in terms of stability, storing/reading messages on chat, updating chat on new message for all users etc.? I have most of this developed, the logic I think I miss is -- check if there is new message and show it for all users. I have this implemented but it crashes the site due to its traffic of 300k-400k people, so that's my main question. The chat is PHP based and uses Pusher (www.pusher.com) for instant messaging but it lacks what I need because it's more like a websocket. I'm using hardcoded files to keep messages (want to avoid database as much as possible). It's a no extension type of file, I'm sure you know. I'm getting crash with $fp = fopen(..., "w"); // pretend ... is the path and filename fwrite($fp, $msg); //hardcode the message fclose($fp); where $msg is the message itself. I'm having 1 file per message. I show last 150 messages = 150 file accesses and reads, yeah it's too much I guess. I have better logic now which I'm pursuing and that is 1 file with last 50-100 messages at all time. Sure it should be much better. How does it crash, that's the trickiest part because everything seems ordinary, believe me it is difficult to determine what exactly crashes the site, but in like 5 minutes when I try to open the site it's gone, then I put the old content without chat and is back online again. I'm having jquery post every 1 second to check if there is new message. I'm using timestamp in a special file where I keep the time last message was sent and if ((time() - time in file) <= 2) = reload last 150 messages including the last one. Too much input/output, write/read or however to say it I think is what crashes the site.

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  • Working for Web using open-source Technologies

    - by anirudha
    As a Web Developer we all have own dream to make a great web application. a great application was built upon high discipline and best practice on the process of development then we can make modification easier in future as if we want. the user feedback also have a matter because they tell us what they want or expected with the application we make day and night. sometime they report a nice story , experience or a problem they got with our application. so that's matter because they telling about our application much more because they use our software and a part of process of future development or next version of application we make. so the Web have a good thing that they updated as soon as possible. in desktop application their is a numbers of trouble client have when they want to use our application. first thing that installation of software never goes right on every system. big company spent a big amount of money to troble these problem the user have with their software.   Web application is nice implementation of application because their is no trouble with installation all have same experience and if something goes wrong patch come soon and no waiting for new version. Chrome even a desktop application [browser] but they automatically update themselves so their is no trouble for user to get next version now hasseles.    Web application development in Microsoft way have their own rule , pattern practice to make better application in less time. the technologies i want to show you here is some great opensource example like MySQL jQuery and ASP.NET MVC a framework based on ASP.NET server side language.   For going to next step we need to show you a list of software you need to have to fully experience this tutorial.   Visual Web Developer 2010 Express Edition  MySQL [open-source RDBMS]   Query [open-source javascript library]   for getting these software you need to pay nothing.   Visual Web Developer can obtained from Microsoft.com/Express or if you are student or Web Developer you are eligible to get the Visual studio professional and many other great software from Microsoft through their Dreamspark or WebsiteSpark programmes.   MySQL is a great Relational Database management software who are freely available from MySQL.com as a database monitorting tool you can use MySQL workbrench who can be freely get from MySQL official website or many other free tool are available for begining development with MySQL   jQuery is a great library for making javascipt development easier and faster.you can obtained jQuery from jQuery.com their official website.

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  • Play Framework Plugin for NetBeans IDE

    - by Geertjan
    The start of minimal support for the Play Framework in NetBeans IDE 7.3 Beta would constitute (1) recognizing Play projects, (2) an action to run a Play project, and (3) classpath support. Well, most of that I've created already, as can be seen, e.g., below you can see logical views in the Projects window for Play projects (i.e., I can open all the samples that come with the Play distribution). Right-clicking a Play project lets you run it and, if the embedded browser is selected in the Options window, you can see the result in the IDE. Make a change to your code and refresh the browser, which immediately shows you your changes: What needs to be done, among other things: A wizard for creating new Play projects, i.e., it would use the Play command line to create the application and then open it in the IDE. Integration of everything available on the Play command line. Maybe the logical view, i.e., what is shown in the Projects window, should be changed. Right now, only the folders "app" and "test" are shown there, with everything else accessible in the Files window, as can be seen in the screenshot above. More work on the classpath, i.e., I've hardcoded a few things just to get things to work correctly. Options window extension to register the Play executable, instead of the current hardcoded solution. Scala integrations, i.e., investigate if/how the NetBeans Scala plugin is helpful and, if not, create different/additional solutions. E.g., the HTML templates are partly in Scala, i.e., need to embed Scala support into HTML. Hyperlinking in the "routes" file, as well as special support for the "application.conf" file. Anyone interested, especially if you're a Play fan (a "playboy"?), in joining me in working on this NetBeans plugin? I'll be uploading the sources to a java.net repository soon. It will be here, once it has been made publicly accessible: http://java.net/projects/nbplay/sources/nbplay Kind of cool detail is that the NetBeans plugin is based on Maven, which means that you could use any Maven-supporting IDE to work on this plugin.

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  • Practices for domain models in Javascript (with frameworks)

    - by AndyBursh
    This is a question I've to-and-fro'd with for a while, and searched for and found nothing on: what're the accepted practices surrounding duplicating domain models in Javascript for a web application, when using a framework like Backbone or Knockout? Given a web application of a non-trivial size with a set of domain models on the server side, should we duplicate these models in the web application (see the example at the bottom)? Or should we use the dynamic nature to load these models from the server? To my mind, the arguments for duplicating the models are in easing validation of fields, ensuring that fields that expected to be present are in fact present etc. My approach is to treat the client-side code like an almost separate application, doing trivial things itself and only relying on the server for data and complex operations (which require data the client-side doesn't have). I think treating the client-side code like this is akin to separation between entities from an ORM and the models used with the view in the UI layer: they may have the same fields and relate to the same domain concept, but they're distinct things. On the other hand, it seems to me that duplicating these models on the server side is a clear violation of DRY and likely to lead to differing results on the client- and server-side (where one piece gets updated but the other doesn't). To avoid this violation of DRY we can simply use Javascripts dynamism to get the field names and data from the server as and when they're neeed. So: are there any accepted guidelines around when (and when not) to repeat yourself in these situations? Or this a purely subjective thing, based on the project and developer(s)? Example Server-side model class M { int A DateTime B int C int D = (A*C) double SomeComplexCalculation = ServiceLayer.Call(); } Client-side model function M(){ this.A = ko.observable(); this.B = ko.observable(); this.C = ko.observable(); this.D = function() { return A() * C(); } this.SomeComplexCalculation = ko.observalbe(); return this; }l M.GetComplexValue = function(){ this.SomeComplexCalculation(Ajax.CallBackToServer()); }; I realise this question is quite similar to this one, but I think this is more about almost wholly untying the web application from the server, where that question is about doing this only in the case of complex calculation.

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  • Variable number of GUI Buttons

    - by Wakaka
    I have a generic HTML5 Canvas GUI Button class and a Scene class. The Scene class has a method called createButton(), which will create a new Button with onclick parameter and store it in a list of buttons. I call createButton() for all UI buttons when initializing the Scene. Because buttons can appear and disappear very often during rendering, Scene would first deactivate all buttons (temporarily remove their onclick, onmouseover etc property) before each render frame. During rendering, the renderer would then activate the required buttons for that frame. The problem is that part of the UI requires a variable number of buttons, and their onclick, onmouseover etc properties change frequently. An example is a buffs system. The UI will list all buffs as square sprites for the current unit selected, and mousing over each square will bring up a tooltip with some information on the buff. But the number of buffs is variable thus I won't know how many buttons to create at the start. What's the best way to solve this problem? P.S. My game is in Javascript, and I know I can use HTML buttons, but would like to make my game purely Canvas-based. Create buttons on-the-fly during rendering. Thus I will only have buttons when I require them. After the render frame these buttons would be useless and removed. Create a fixed set of buttons that I'm going to assume the number of buffs per unit won't exceed. During each render frame activate the buttons accordingly and set their onmouseover property. Assign a button to each Buff instance. This sounds wrong as the buff button is a part of the GUI which can only have one unit selected. Assigning a button to every single Buff in the game seems to be overkill. Also, I would need to change the button's position every render frame since its order in the unit's list of buffs matter. Any other solutions? I'm actually quite for idea (1) but am worried about the memory/time issues of creating a new Button() object every render frame. But this is in Javascript where object creation is oh-so-common ({} mainly) due to automatic garbage collection. What is your take on this? Thanks!

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  • What is a useful pattern to maintaining an object state in a one to many relationship?

    - by ahenderson
    I am looking for a design for my application, here are the players(classes) involved. struct Transform { // Uses a matrix to transform the position. // Also acts acts as the state of a Dialog. Position transform(Position p); //other methods. }; struct Dialog { // There are multiple dialog for the user to transform the output. Transform& t; void ChangeTranformation(){t.rotate(360);} } struct Algorithm { //gives us a position based on an implementation. For example this can return points on a circle or line. Transform& t; Position m_p; Dialog& d; Position GetCurrentPosition(){ return t.transform(m_p);} //other methods. } Properties I need: Each algorithms has one dialog and each dialog can have many algorithms associated with it. When the user selects an algorithm a dialog associated with that algorithm is displayed. If the user selects a different algorithm then re-selects back the state is restored in the dialog. Basically I want a good design pattern to maintain the state of the dialog given that many algorithms use it and they can be switched back and forth. Does anyone have any suggestions? Here is a use case: Dialog1 has a single edit box to control the radius. Algorithm1 generates points on a unit circle. Algorithm2 is the same as Algorithm1. The user has selected Algorithm1 and entered 2 into the edit box. This will generate points on a circle of radius 2. The user then selects Algorithm2 and enters 10 into the edit box of Dialog1. This will generate points on a circle of radius 10. Finally Algorithm1 is selected again. The edit box of Dialog1 should show 2 and points on a circle of radius 2 should be generated.

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  • Watch ON-Demand Oracle's 4th Annual Primavera Virtual Summit

    - by Melissa Centurio Lopes
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Did you miss Oracle's 4th Annual Primavera Virtual Summit? Or, maybe you attended the virtual event live, but want to re-watch some presentations or download industry-specific assets - well you can! Watch and visit here, on-demand.  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} This event is now available On-Demand for your convenience. Feel free to log-in anytime to listen again about: New cloud based PPM solutions presentations. Special Primavera Roadmap presentation- what's new and what's coming. Customer stories highlighting their successes with Primavera Unifier, Oracle Instantis and Primavera P6 Enterprise Project Portfolio Management. And don't forget to visit the Resource Library to check out all the latest product information, whitepapers, and demos which are all available to download and read at your convenience. During your visit to the Virtual Summit ON-Demand, we would appreciate you visiting the Networking Lounge and taking a few minutes to fill out the survey. We would really like to hear what you think. You can also visit the Primavera Website for more information about the newest EPPM solutions and offerings.

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  • Unable to boot into 11.10 in normal (get a black screen) OR recovery (get just a flashing cursor, no cli)

    - by user1092284
    Okay, so I had a dual boot of Tango Studio (based on Ubuntu 10.04) and Windows XP. Yesterday I downloaded the .iso for Ubuntu 11.10 and attempted to install from a USB (my BIOS won't normally boot from USB but I had PLOP boot manager on a CD). I booted up Ubuntu from the USB and then from there formatted the partition with Tango on and installed Ubuntu 11.10. On booting up I came into Grub rescue mode. So I booted up from the USB again and used boot-repair to reinstall Grub. After this I would see the normal Grub menu, but on choosing Ubuntu I would come to a black screen. On choosing recovery mode it would begin starting normally with no obvious errors but instead of coming to a cli I would just get a blank screen with a flashing cursor on the top left, not accepting any input. I have since reformatted and reinstalled from a CD rather than USB and had the exact same problem. I used boot-repair again and the result is the same. Output of the most recent boot-repair is at http://paste.ubuntu.com/869805/ I have also tried editing the ubuntu grub entry and replacing quiet with text nomodeset as I saw in an answer to another question. This got me a bit further - I saw the purple ubuntu loading screen but still came to a blank screen after that. Anyway, in most of the other questions in which that is brought up the user is still able to boot into recovery, while I am not. Can anyone help? Thanks in advance, let me know if there's any more info I need to provide! EDIT FOR MORE INFO: I read something saying it's quiet splash that should be replaced with nomodeset. Earlier I had left splash in the line. So i tried it this way and it froze after displaying the following text: fsck from util-linux 2.19.1 mountall: Plymouth command failed mountall: Disconnected from Plymouth /dev/sda5:clean, 139359/1741488 files, 745830/6961125 blocks From a bit of googling it doesn't look like plymouth is essential, but I've checked and I do have the most current versions of mountall and plymouth installed so I don't know why there's a problem EDIT FOR MORE INFO AGAIN: I used dkpg --reconfigure plymouth cause I saw it mentioned in another forum and it still says plymouth command failed on boot

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  • SSMS Tools Pack 3.0 is out. Full SSMS 2014 support and improved features.

    - by Mladen Prajdic
    With version 3.0 the SSMS 2014 is fully supported. Since this is a new major version you'll eventually need a new license. Please check the EULA to see when. As a thank you for your patience with this release, everyone that bought the SSMS Tools Pack after April 1st, the release date of SQL Server 2014, will receive a free upgrade. You won't have to do anything for this to take effect. First thing you'll notice is that the UI has been completely changed. It's more in line with SSMS and looks less web-like. Also the core has been updated and rewritten in some places to be better suited for future features. Major improvements for this release are: Window Connection Coloring Something a lot of people have asked me over the last 2 years is if there's a way to color the tab of the window itself. I'm very glad to say that now it is. In SSMS 2012 and higher the actual query window tab is also colored at the top border with the same color as the already existing strip making it much easier to see to which server your query window is connected to even when a window is not focused. To make it even better, you can not also specify the desired color based on the database name and not just the server name. This makes is useful for production environments where you need to be careful in which database you run your queries in. Format SQL The format SQL core was rewritten so it'll be easier to improve it in future versions. New improvement is the ability to terminate SQL statements with semicolons. This is available only in SSMS 2012 and up. Execution Plan Analyzer A big request was to implement the Problems and Solutions tooltip as a window that you can copy the text from. This is now available. You can move the window around and copy text from it. It's a small improvement but better stuff will come. SQL History Current Window History has been improved with faster search and now also shows the color of the server/database it was ran against. This is very helpful if you change your connection in the same query window making it clear which server/database you ran query on. The option to Force Save the history has been added. This is a menu item that flushes the execution and tab content history save buffers to disk. SQL Snippets Added an option to generate snippet from selected SQL text on right click menu. Run script on multiple databases Configurable database groups that you can save and reuse were added. You can create groups of preselected databases to choose from for each server. This makes repetitive tasks much easier New small team licensing option A lot of requests came in for 1 computer, Unlimited VMs option so now it's here. Hope it serves you well.

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  • ADF Mobile Released!!

    - by Denis T
    ADFmfAnnounce We are pleased to announce the general availability of the newest version of Oracle’s ADF Mobile framework. This new framework provides the much anticipated on-device capabilities that the latest mobile applications require.  Feature Highlights Java - Oracle brings a Java VM embedded with each application so you can develop all your business logic in the platform neutral language you know and love! (Yes, even iOS!) JDBC - Since we give you Java, we also provide JDBC along with a SQLite driver and engine that also supports encryption out of the box. Multi-Platform - Truly develop your application only once and deploy to multiple platforms. iOS and Android platforms are supported for both phone and tablet. Flexible - You can decide how to implement the UI: (a) Use existing server-based UI framework like JSF. (b) Use your own favorite HTML5 framework like JQuery. (c) Use our declarative HTML5 component set provided with the framework. ADF Mobile XML or AMX for short, provides all the normal input and layout controls you expect and we also add charts/maps/gauges along with it to provide a very comprehensive UI controls. You can also mix and match any of the three for ultimate flexibility! Device Feature Access - You can get access to device features from either Java or JavaScript to invoke features like camera, GPS, email, SMS, contacts, etc. Secure - ADF Mobile provides integrated security that works with your server back-end as well. Whether you’re using remote URLs, local HTML or AMX, you can secure any/all of your features with a single consistent login page. Since we also give you SQLite encryption, we are assured that your data is safe. Rapid - Using the same development techniques that ADF developers are already used to, you can quickly create mobile applications without ever learning another language! Architecture ADF Mobile is a “hybrid” architecture that employs a natively built “container” on each platform that hosts a number of browser windows that are used to display the application content. We add the Java VM as a natively built library to the container for business logic.   How To Get Started ADF Mobile is an extension to the recently released JDeveloper version 11.1.2.3.0. Simple get the latest JDeveloper from Oracle Technology Network and use the Check for Updates feature to get the ADF Mobile extension. Note: ADF Mobile does not require developers to learn any other languages or frameworks but to build/deploy to iOS, you must be on an Apple MacintoshTM and have Xcode installed. To build/deploy to Android™ you must have the Android SDK installed.

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  • "Expecting A Different Result?" (2 of 3 in 'No Customer Left Behind' Series)

    - by Kathryn Perry
    A guest post by David Vap, Group Vice President, Oracle Applications Product Development Many companies already have some type of customer experience initiative in process or one that could be framed as such. The challenge is that the initiatives too often are started in a department silo, don't have the right level of executive sponsorship, or have been initiated without the necessary insight and strategic business alignment. You can't keep doing the same things, give it a customer experience name, and expect a different result. You can't continue to just compete on price or features - that is not sustainable in commoditized markets. And ultimately, investing in technology alone doesn't solve customer experience problems; it just adds to the complexity of them. You need a customer experience strategy and approach on how to execute a customer-centric worldview within your business. To develop this, you must take an outside in journey on how your customers are interacting with your business to establish a benchmark of your customers' experiences. Then you must get cross-functional alignment on what you are trying to achieve, near, mid, and long term. Your execution of that strategy should be based on a customer experience approach: Understand your customer: You need to capture the insights across interactions, channels (including social), and personas to better understand whom to serve, how to serve them, and when to serve them. Not all experiences or customers are equal, so leverage this insight to understand the strategic business objectives you need to address. Then determine which experiences can be improved immediately and which over time to get the result you need. Empower your ecosystem: You need to align your front-line employees with your strategy and give them the power, insight, and tools that allow them to cultivate a culture around strengthening the relationships with your customers. You also need to provide the transparency, access, and collaboration that enable your customers and partners to self serve and self solve and to share with ease. Adapt your business: You need to enable the discipline of agility within your organization and infrastructure so that you can innovate, tailor, and personalize experiences. This needs to be done both reactively from insight and proactively in real time so you can stay ahead of shifting market trends and evolving consumer behaviors. No longer will the old approaches provide the same returns. To compete, differentiate, and win in a world where the customer has the power, you must execute a strategy that is sure to deliver a better brand experience for your customers. Note: This is Part 2 in a three-part series. Part 1 is here. Stop back for Part 3 on November 28.

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 13

    - by MarkPearl
    Learning Outcomes Explain the advantages of using a large number of registers Discuss the way in which compilers optimize register usage Discuss the evolution of CISC machines Describe the characteristics of RISC architecture Discuss the RISC vs. CISC controversy Describe the way in which RISC and CISC design principles can be combined Instruction Execution Characteristics To understand the the line of reasoning of RISC advocates, we need a brief overview of instruction execution characteristics. These include… Operations Operands Procedure Calls These three sections can be studied in depth in the textbook at pages 503 - 505 A number of groups have come up with the conclusion that the attempt to make the instruction set architecture closer to HLLs (High Level Languages) is not the most effective design strategy. Rather HLL’s can be best supported by optimizing performance of the most time-consuming features of typical HLL programs. Generally 3 main characteristics came up to improve performance… Use a large number of registers or use a compiler to optimize register usage Careful attention needs to be paid to the design of instruction pipelines A simplified (reduced) instruction set is indicated The use of a large register optimization One of the most important design principles of RISC machines is the use of a large number of registers. The concept of register windows and the use of a large register file versus the use of cache memory are discussed. On the face of it, the use of a large set of registers should decrease the need to access memory. The design task is to organize the registers in such a fashion that this goal is realized. Read page 507 – 510 for a detailed explanation. Compiler-based register optimization   Reduced Instructions Set Architecture There are two advantages to smaller programs… Because the program takes up less memory, there is a savings in that resource (this was more compelling when memory was more expensive) Smaller programs should improve performance, and this will happen in two ways – fewer instructions means fewer instruction bytes to be fetched and in a paging environment smaller programs occupy fewer pages, reducing page faults. Certain characteristics are common to RISC processors… One instruction per cycle Register-to-register operations Simple addressing modes Simple instruction formats RISC vs. CISC After initial enthusiasm for RISC machines, there has been a growing realization that RISC designs may benefit from the inclusion of some CISC features CISC designs may benefit from the inclusion of some RISC features

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  • How to run WordPress and Java web app running on Tomcat on the same server?

    - by Chantz
    I have to run a WordPress site served via Apache2 & Java-based webapp using Tomcat on the same server. When users come to example.com or example.com/public-pages they need to served from WordPress but when they come to example.com/private-pages they need to be served from the Tomcat. I have asked this question on serverfault where they suggested using different port, different IP & sub-domain. I want to go for different port solution since it will mean I need to buy only one SSL certificate. I tried doing the reverse proxy method by having the following in my default-ssl.conf <VirtualHost _default_:443> ServerAdmin webmaster@localhost ServerName localhost:443 DocumentRoot /var/www <Directory /var/www> #For Wordpress Options FollowSymLinks AllowOverride All </Directory> <Proxy *> Order deny,allow Allow from all </Proxy> ProxyRequests Off ProxyPass /private-pages ajp://localhost:8009/ ProxyPassReverse /private-pages ajp://localhost:8009/ SSLEngine on SSLProxyEngine On SSLCertificateFile /etc/apache2/ssl/apache.crt SSLCertificateKeyFile /etc/apache2/ssl/apache.key </VirtualHost> As you have noticed I am using mod_proxy_ajp in Apache2 for this. And that my Tomcat is listening to port 8009 and then serving content. So now when I go to example.com/private-pages I am seeing the content from my Tomcat. But 2 issues are happening. All my static resources are getting 404-ed, so none of my images, CSS, js are getting loaded. I see that the browser is requesting for the resources using URL example.com/css/* This will clearly not work because it translates to example.com:80/css/* instead of example.com:8009/css/* & there are no such resources in the WordPress directory. If I go to example.com/private-pages/abcd I am somehow kicked to the WordPress site (which obviously displays a 404 page). I can understand why #1 is happening but have no clue why the #2 is happening. Regardless, if there is another clean solution for resolving this, I would appreciate y'alls help.

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  • EF Doesn't Like Same Named Tables

    - by Anthony Trudeau
    Originally posted on: http://geekswithblogs.net/tonyt/archive/2013/07/02/153327.aspxIt's another week and another restriction imposed by the Entity Framework (EF). Don't get me wrong. I like EF, but I don't like how it restricts you in different ways. At this point you may be asking yourself the question: how can you have more than one table with the same name?The answer is to have tables in different schemas. I do this to partition the data based on the area of concern. It allows security to be assigned conveniently. A lot of people don't use schemas. I love them. But this article isn't about schemas.In the situation I have two tables:Contact.PersonEmployee.PersonThe first contains the basic, more public information such as the name. The second contains mostly HR specific information. I then mapped these tables to two classes. I stuck to a Table per Class (TPC) mapping, because of problems I've had in the past implementing inheritance with EF. The following code gives you the basic contents of the classes.[Table("Person", Schema = "Employee")]public class Employee {   ...   public int PersonId { get; set; }   [ForeignKey("PersonId")]   public virtual Person Person { get; set; }}[Table("Person", Schema = "Contact")]public class Person {   [Key]   public int Id { get; set; }   ...}This seemingly simple scenario just doesn't work. The problem occurs when you try to add a Person to the DbContext. You get an InvalidOperationException with the following text:The entity types 'Employee' and 'Person' cannot share table 'People' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them..This is interesting for a couple of reasons. First, there is no People table in my database. Second, I have used the SetInitializer method to stop a database from being created, so it shouldn't be thinking about new tables.The solution to my problem was to change the name of my Employee.Person table. I decided to name it Employee.Employee. It's not ideal, but it gets me past the EF limitation. I hope that this article will help someone else that has the same problem.

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  • Let&rsquo;s keep informed with &ldquo;Data Explorer&rdquo;

    - by Luca Zavarella
    At Pass Summit 2011 a new project was announced. It’s a Microsoft SQL Azure Lab and its codename is Microsoft “Data Explorer”. According to the official blog (http://blogs.msdn.com/b/dataexplorer/), this new tool provides an innovative way to acquire new knowledge from the data that interest you. In a nutshell, Data Explorer allows you to combine data from multiple sources, to publish and share the result. In addition, you can generate data streams in the RESTful open format (Open Data Protocol), and they can then be used by other applications. Nonetheless we can still use Excel or PowerPivot to analyze the results. Sources can be varied: Excel spreadsheets, text files, databases, Windows Azure Marketplace, etc.. For those who are not familiar with this resource, I strongly suggest you to keep an eye on the data services available to the Marketplace: https://datamarket.azure.com/browse/Data To tell the truth, as I read the above blog post, I was tempted to think of the Data Explorer as a "SSIS on Azure" addressed to the Power User. In fact, reading the response from Tim Mallalieu (Group Program Manager of Data Explorer) to the comment made to his post, I had a positive response to my first impression: “…we originally thinking of ourselves as Self-Service ETL. As we talked to more folks and started partnering with other teams we realized that would be an area that we can add value but that there were more opportunities emerging.” The typical operations of the ETL phase ( processing and organization of data in different formats) can be obtained thanks to Data Explorer Mashup. This is an image of the tool: The flexibility in the manipulation of information is given by Data Explorer Formula Language. This is a formula-based Excel-style specific language: Anyone wishing to know more can check the project page in addition to aforementioned blog: http://www.microsoft.com/en-us/sqlazurelabs/labs/dataexplorer.aspx In light of this new project, there is no doubt about the intention of Microsoft to get closer and closer to the Power User, providing him flexible and very easy to use tools for data analysis. The prime example of this is PowerPivot. The question that remains is always the same: having in a company more Power User will implicitly mean having different data models representing the same reality. But this would inevitably lead to anarchical data management... What do you think about that?

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  • 2d, Top-down map with different levels

    - by Ktash
    So, I'm creating a 2d, top down, sprite based (tiled) game, and right now I'm working on maps (well, a map editor at the moment, but it will be creating my maps, so basically the same thing). The scenario So, I'm thinking about efficiency and creating a map in pieces. In each piece, I plan on having 'layers'. Basically, I plan on rendering it down to a 'below hero' level, and an 'above hero' level, with the hero rendered in between obviously. There will likely also be a 'on level with hero' layer, but I'm not quite there yet. Not even worrying about events or interaction yet. Just looking to get a hero on the screen. Now for movement, I obviously need to know what tiles can be moved and in what direction. My plan at the moment is each tile getting 8 bits (4 'can enter in direction' bits, 4 'can leave in direction'). This will allow me to limit movement and even allow one way directional movement. The dilemma This works great for a lot of scenarios. It will allow me to store a map in essentially 3 layers, a string, and gives me flexibility going forward. However, I can't create maps that themselves have layers. A good example is a bridge where the user can go under or over the bridge without invalid moves being allowed. I can't create a platform and allow movement underneath. These are things I would like to be able to include in my game. My idea In theory, I could allow multiple hero layers and then allow multiple sets of 'below' and 'above' layers (or sandwich layers). But this complicates my system, and makes movement between maps potentially tricky (If the hero is on the third layer at the edge of a map, but that corresponds to the second layer on the other map, how can I allow or disallow movement). My question Is there a better way to manage multiple maps with multiple levels like this where a users level may be 'connected' on different levels on different maps? Or even... Am I doing this the hard way? Is there a more standard way to handle top-down 2d tiled maps that I am just not aware of? Things to note or that might be helpful This will be done in Javascript (transferred around in JSON) State will need to be transferred quickly, so a map-id and x/y/direction should be enough to get me a boolean 'can move' value Maps will not be standard sized (though they will be in a certain number of tiles) Making an editor tool so that I can have others help, so something that I can create in a tool would be helpful 'Teleportation' locations will likely need to exist to get into building maps and to and from different map sets (which will not necessarily be connected), but have not been created yet (lumping in with events at the moment).

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  • How can I tweak this A* search pathfinding algorithm to handle different terrain movement values?

    - by user422318
    I'm creating a 2D map-based action game with similar interaction design as Diablo II. In other words, the player clicks around a map to move their player. I just finished player movement and am moving on to pathfinding. In the game, enemies should charge the player's character. There are also five different terrain types that give different movement bonuses. I want the AI to take advantage of these terrain bonuses as they try to reach the player. I was told to check out the A* search algorithm (http://en.wikipedia.org/wiki/A*_search_algorithm). I'm doing this game in HTML5 and JavaScript, and found a version in JavaScript: http://www.briangrinstead.com/blog/astar-search-algorithm-in-javascript I'm trying to figure out how to tweak it though. Below are my ideas about what I need to change. What else do I need to worry about? When I create a graph, I will need to initialize the 2D array I pass in passed on with a traversal of a map that corresponds to the different terrain types. in graph.js: "GraphNodeType" definition needs to be modified to handle the 5 terrain types. There will be no walls. in astar.js: The g and h scoring will need to be modified. How should I do this? in astar.js: isWall() should probably be removed. My game doesn't have walls. in astar.js: I'm not sure what this is. I think it indicates a node that isn't valid to be processed. When would this happen, though? At a high level, how do I change this algorithm from "oh, is there a wall there?" to "will this terrain get me to the player faster than the terrain around me?" Because of time, I'm also debating reusing my Bresenham algorithm for the enemies. Unfortunately, the different terrain movement bonuses won't be used by the AI, which will make the game suck. :/ I'd really like to have this in for the prototype, but I'm not a developer by trade nor am I a computer scientist. :D If you know of any code that does what I'm looking for, please share! Sanity check tips for this are also appreciated.

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  • Building Enterprise Smartphone App &ndash; Part 3: Key Concerns

    - by Tim Murphy
    This is part 3 in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Keys Concerns Of Smartphones In The Enterprise These are the factors that you need to be aware of and address in order to build successful enterprise smartphone applications.  Most of them have nothing to do with the application itself as you will see here. Managing Devices Managing devices is a factor that is going to effect how much your company will have to spend outside of developing the applications.  How will you track the devices within the corporation?  How often will you have to replace phones and as a consequence have to upgrade your applications to support new phones?  The devices can represent a significant investment of capital.  If these questions are not addressed you will find a number of hidden costs throughout the life of your solution. Purchase or BYOD We have seen the trend of Bring Your Own Device (BYOD) lately within the enterprise.  How many meetings have you been in where someone is on their personal iPad, iPhone, Android phone or Windows Phone?  The issue is if you can afford to support everyone's choice in device? That is a lot to take on even if you only support the current release of each platform. Do you go with the most popular device or do you pick a platform that best matches your current ecosystem and distribute company owned devices?  There is no easy answer here, but you should be able give some dollar value to both hardware and development costs related to platform coverage. Asset Tracking/Insurance Smartphones are devices that are easier to lose or have stolen than laptops and desktops. Not only do you have your normal asset management concerns but also assignment of financial responsibility. You also will need to insure them against damage and theft and add legal documents that spell out the responsibilities of the employees that use these devices. Personal vs. Corporate Data What happens when you terminate an employee?  How do you recover the device?  What happens when they have put personal data on the device?  These are all situation that can cause possible loss of corporate intellectual property or legal repercussions of reclaiming a device with personal data on it.  Policies need to be put in place that protect the company from being exposed to type of loss.  This can mean significant legal and procedural cost that you need to consider. Coming Up In the last installment of this series I will cover application development considerations. del.icio.us Tags: Smartphones,Enterprise Smartphone Apps,Architecture

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  • Developing web sites that imitate desktop apps. How to fight that paradigm? [closed]

    - by user1598390
    Supposse there's a company where web sites/apps are designed to resemble desktop apps. They struggle to add: Splash screens Drop-down menus Tab-pages Pages that don't grow downward with content, context is inside scrollable area so page is of a fixed size, as if resembling the one-screen limitation of desktop apps. Modal windows, pop-ups, etc. Tree views Absolutely no access to content unless you login-first, even with non-sensitive content. After splash screen desapears, you are presented with a login screen. No links - just simulated buttons. Fixed page-size. Cannot open a linked in other tab Print button that prints directly ( not showing printable page so the user can't print via the browser's print command ) Progress bars for loading content even when the browser indicates it with its own animation Fonts and color amulate a desktop app made with Visual Basic, PowerBuilder etc. Every app seems almost as if were made in Visual Basic. They reject this elements: Breadcrumbs Good old underlined links Generated/dynamic navigation, usage-based suggestions Ability to open links in multiple tabs Pagination Printable pages Ability to produce a URL you can save or share that links to an item, like when you send someone the link to an especific StackExchange question. The only URL is the main one. Back button To achieve this, tons of javascript code is needed. Lots and lots of Javascript and Ajax code for things not related with the business but with the necessity to hide/show that button, refresh this listbox, grey-out that label, etc. The coplexity generated by forcing one paradigm into another means most lines of code are dedicated to maintain the illusion of a desktop app. What is the best way to change this mindset, and make them embrace the web, and start producing modern, web apps instead of desktop imitations ? EDIT: These sites are intranet sites. Users hate these apps. They constantly whine about them, but they have to use them to do their daily work. These sites are in-house solutions, the end-users have no choice but to use them. They are a "captive audience". Also, substitution will not happen because of high costs. But at least if that mindset is changed, new developments would be more web-like.

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  • Why C++ people loves multithreading when it comes to performances?

    - by user1849534
    I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approach here: an async approach basically based on signals, or just an async approach as called by many papers and languages like the new C# 5.0 for example, and a "companion thread" that maanges the policy of your pipeline a concurrent approach or multi-threading approach I will just say that I'm thinking about the hardware here and the worst case scenario, and I have tested this 2 paradigms myself, the async paradigm is a winner at the point that I don't get why people 90% of the time talk about concurrency when they wont to speed up things or make a good use of their resources. I have tested multi-threaded programs and async program on an old machine with an Intel quad-core that doesn't offer a memory controller inside the CPU, the memory is managed entirely by the motherboard, well in this case performances are horrible with a multi-threaded application, even a relatively low number of threads like 3-4-5 can be a problem, the application is unresponsive and is just slow and unpleasant. A good async approach is, on the other hand, probably not faster but it's not worst either, my application just waits for the result and doesn't hangs, it's responsive and there is a much better scaling going on. I have also discovered that a context change in the threading world it's not that cheap in real world scenario, it's infact quite expensive especially when you have more than 2 threads that need to cycle and swap among each other to be computed. On modern CPUs the situation it's not really that different, the memory controller it's integrated but my point is that an x86 CPUs is basically a serial machine and the memory controller works the same way as with the old machine with an external memory controller on the motherboard. The context switch is still a relevant cost in my application and the fact that the memory controller it's integrated or that the newer CPU have more than 2 core it's not bargain for me. For what i have experienced the concurrent approach is good in theory but not that good in practice, with the memory model imposed by the hardware, it's hard to make a good use of this paradigm, also it introduces a lot of issues ranging from the use of my data structures to the join of multiple threads. Also both paradigms do not offer any security abut when the task or the job will be done in a certain point in time, making them really similar from a functional point of view. According to the X86 memory model, why the majority of people suggest to use concurrency with C++ and not just an async aproach ? Also why not considering the worst case scenario of a computer where the context switch is probably more expensive than the computation itself ?

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  • High-Powered Sites for low Cost

    - by HighAltitudeCoder
    Ahh, I am experiencing the intimidation of my very first post - visible by the whole world. Ok, here goes.   This first post is nothing exceptional.  It is simply a recommendation based (fittingly, I suppose) upon the job search you may be gearing up for.  I find myself in this very situation right now.  And, I will take my own recommendation after posting this entry. Job-Seekers: To the left you will notice two links under "Recommended Learning".  I have found these links to be invaluable when it comes to re-tooling, re-familiarizing, or otherwise resharping my skills when looking for that next job. Often, you will find job-postings with the text, usually posted after a laborious list of qualifications indicating the company's desire to hire candidates who know what they are doing: "...Looking for a candidate who can hit the ground running...".  The interesting thing about this post to me is I've encountered many individuals who, after speaking and working with them for some time, I've realized are perfectly capable of hitting the ground running - and FAST.  But what if they speed off in the wrong direction? The next time you spearhead a major task in your job, ask yourself: Am I headed in the wrong direction?  There are many ways to do this.  In fact, I've found in this new field there are more tempting ways to steer your project in the wrong direction than there are good ones.  I don't want to suggest that every one of my posts will fall into the "right direction" category, however I do think a healthy dose of introspection of the pros and cons will always be beneficial before you set off. That said, allow me to expound on the previously mentioned links. These web sites are invaluable.  They demonstrate the capabilities of existing as well as new and upcoming tools available in several IDE's.  I've viewed many tutorials in LearnVisualStudio.NET, and only one or two so far in TrainingSpot, however I've been delighted in their simplicity and straightforward approach to proper usage of the particular tool or concept being discussed.  They have not (so far in my experience) demonstrated ways in which to use the tools that become cumbersome, impractical, or error-prone. Each website has step-by-step videos that can be paused, replayed, and most importantly, they are done in real time.  As the author is typing, the viewer gets to experience the coding experience from a first-person perspective, including syntax errors, unexpected behaviors, IDE setup idiosyncracies, everything.  A subtle value I've gained from these videos is that a certain degree of confusion and introspection is normal when working with new tools and exploring new paths.  They (as well as your own experience) are not to be feared, but enjoyed.  I highly recommend them. Good work, guys!

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  • IPv6, isn't it just a few extra bits?

    - by rclewis
    It's always an interesting task, to try and explain what you do to family and friends. I have described IPv6 as the "Next Generation Internet"  or "Second Internet" but the hollow expressions on my kids faces scream for the instant relief of the latest video game.  Never one to give up easily, I have formulated a new example - the Post Office... Similar to the Post Office the Internet delivers mail and packages based on addresses. As the number of residences, businesses, and delivery locations increased, the 5 digit ZIP Code (Washington, DC 20005) was expanded to ZIP+4  allowing for more precise delivery points (Postmaster General, Washington, DC 20260-3100). Ah, if only computers were as simple.  IPv6 isn't an add-on or expansion of the existing IPv4 Addressing, it is a new addressing model which will allow the internet to grow from a single computer in the basement of a university or your parents kitchen table, to support the multitude of smart phones, smart TV's, tablets, dvr's, and disk players, all clambering to connect for information. Unfortunetly there are only a finite number of IPv4 public addresses left, and those are being consumed at an ever increasing rate. Few people could have predicted the explosive growth of the internet or the shortage of IPv4 addresses we now face - but there is a "Plan B" and that is the vastly larger address space of IPv6.  Many in the industry have labeled this a "business continuity" problem,  when in fact most companies will be able to continue conducting business once they run out of existing IPv4 Addresses. The problem is really a Customer Continuity problem, how will businesses communicate with existing customers and reach new customers online who's only option is to adopt IPv6 when IPv4 is depleted? Perhaps a first step is publishing a blog that is also accessible via IPv6, it's just a few extra bits. Join us for the Oracle OpenWorld 2012 Session:   Navigating IPv6 @ Oracle Thursday, Oct. 4th 2:15PM - 3:15PM  Palace Hotel - Concert   Learn more about IPv6 Technologies at Oracle

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  • I have a performance problem

    - by Alan
    (copied from my wordpress blog). So start 95% of the performance calls that I receive. They usually continue something like: I have gathered some *stat data for you (eg the guds tool from Document 1285485.1), can you please root cause our problem? So, do you think you could? Neither can I, based on this my answer inevitably has to be "No". Given this kind of problem statement, I have no idea about the expectations, the boundary conditions, or even the application. The answer may as well be "Performance problems? Consult your local Doctor for Viagra". It's really not a lot to go on. So, What kind of problem description is going to allow me to start work on the issue that is being seen? I don't doubt that there really is an issue, it just needs to be pinned down somewhat. What behavior exactly are you expecting to see? Be specific and use business metrics. For example "run-time", "response-time" and "throughput". This helps us define exit criterea. Now, let's look at the system that is having problems. How is what you are seeing different? Use the same type of metrics. The answers to these two questions take us a long way towards being able to work a call. Even more helpful are answers to questions like Has this system ever worked to expectation? If so, when did it start exhibiting this behavior? Is the problem always present, or does it sometimes work to expectation? If it sometimes works to expectation, when are you seeing the problem? Is there any discernible pattern? Is the impact of the problem getting better, worse, or remaining constant? What kind of differences are there between when the system was performing to expectation and when it is not? Are there other machines where we could expect to see the same issue (eg similar usage and load), but are not? Again, differences? Once we start to gather information like this we start to build up a much clearer picture of exactly what we need to investigate, and what we need to achieve so that both you and me agree that the problem has been solved. Please help get that figure of poorly defined problem statements down from it's current 95% value.

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  • Are we queueing and serializing properly?

    - by insta
    We process messages through a variety of services (one message will touch probably 9 services before it's done, each doing a specific IO-related function). Right now we have a combination of the worst-case (XML data contract serialization) and best-case (in-memory MSMQ) for performance. The nature of the message means that our serialized data ends up about 12-15 kilobytes, and we process about 4 million messages per week. Persistent messages in MSMQ were too slow for us, and as the data grows we are feeling the pressure from MSMQ's memory-mapped files. The server is at 16GB of memory usage and growing, just for queueing. Performance also suffers when the memory usage is high, as the machine starts swapping. We're already doing the MSMQ self-cleanup behavior. I feel like there's a part we're doing wrong here. I tried using RavenDB to persist the messages and just queueing an identifier, but the performance there was very slow (1000 messages per minute, at best). I'm not sure if that's a result of using the development version or what, but we definitely need a higher throughput[1]. The concept worked very well in theory but performance was not up to the task. The usage pattern has one service acting as a router, which does all reads. The other services will attach information based on their 3rd party hook, and forward back to the router. Most objects are touched 9-12 times, although about 10% are forced to loop around in this system for awhile until the 3rd parties respond appropriately. The services right now account for this and have appropriate sleeping behaviors, as we utilize the priority field of the message for this reason. So, my question, is what is an ideal stack for message passing between discrete-but-LAN'ed machines in a C#/Windows environment? I would normally start with BinaryFormatter instead of XML serialization, but that's a rabbit hole if a better way is to offload serialization to a document store. Hence, my question. [1]: The nature of our business means the sooner we process messages, the more money we make. We've empirically proven that processing a message later in the week means we are less likely to make that money. While performance of "1000 per minute" sounds plenty fast, we really need that number upwards of 10k/minute. Just because I'm giving numbers in messages per week doesn't mean we have a whole week to process those messages.

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  • Protobuf design patterns

    - by Monster Truck
    I am evaluating Google Protocol Buffers for a Java based service (but am expecting language agnostic patterns). I have two questions: The first is a broad general question: What patterns are we seeing people use? Said patterns being related to class organization (e.g., messages per .proto file, packaging, and distribution) and message definition (e.g., repeated fields vs. repeated encapsulated fields*) etc. There is very little information of this sort on the Google Protobuf Help pages and public blogs while there is a ton of information for established protocols such as XML. I also have specific questions over the following two different patterns: Represent messages in .proto files, package them as a separate jar, and ship it to target consumers of the service --which is basically the default approach I guess. Do the same but also include hand crafted wrappers (not sub-classes!) around each message that implement a contract supporting at least these two methods (T is the wrapper class, V is the message class (using generics but simplified syntax for brevity): public V toProtobufMessage() { V.Builder builder = V.newBuilder(); for (Item item : getItemList()) { builder.addItem(item); } return builder.setAmountPayable(getAmountPayable()). setShippingAddress(getShippingAddress()). build(); } public static T fromProtobufMessage(V message_) { return new T(message_.getShippingAddress(), message_.getItemList(), message_.getAmountPayable()); } One advantage I see with (2) is that I can hide away the complexities introduced by V.newBuilder().addField().build() and add some meaningful methods such as isOpenForTrade() or isAddressInFreeDeliveryZone() etc. in my wrappers. The second advantage I see with (2) is that my clients deal with immutable objects (something I can enforce in the wrapper class). One disadvantage I see with (2) is that I duplicate code and have to sync up my wrapper classes with .proto files. Does anyone have better techniques or further critiques on any of the two approaches? *By encapsulating a repeated field I mean messages such as this one: message ItemList { repeated item = 1; } message CustomerInvoice { required ShippingAddress address = 1; required ItemList = 2; required double amountPayable = 3; } instead of messages such as this one: message CustomerInvoice { required ShippingAddress address = 1; repeated Item item = 2; required double amountPayable = 3; } I like the latter but am happy to hear arguments against it.

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