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Which programming language to choose? (for a specific problem/domain, details inside)

- by Bijan

I am building a trading portfolio management system that is responsible for production, optimization, and simulation of non-high frequency trading portfolios (dealing with 1min or 3min bars of data, not tick data). I plan on employing Amazon web services to take on the entire load of the application. I have four choices that I am considering as language. a) Java b) C++ c) C# d) Python Here is the scope of the extremes of the project scope. This isn't how it will be, maybe ever, but it's within the scope of the requirements: Weekly simulation of 10,000,000 trading systems. (Each trading system is expected to have its own data mining methods, including feature selection algorithms which are extremely computationally-expensive. Imagine 500-5000 features using wrappers. These are not run often by any means, but it's still a consideration) Real-time production of portfolio w/ 100,000 trading strategies Taking in 1 min or 3 min data from every stock/futures market around the globe (approx 100,000) Portfolio optimization of portfolios with up to 100,000 strategies. (rather intensive algorithm) Speed is a concern, but I believe that Java can handle the load. I just want to make sure that Java CAN handle the above requirements comfortably. I don't want to do the project in C++, but I will if it's required. The reason C# is on there is because I thought it was a good alternative to Java, even though I don't like Windows at all and would prefer Java if all things are the same. Python - I've read somethings on PyPy and pyscho that claim python can be optimized with JIT compiling to run at near C-like speeds.... That's pretty much the only reason it is on this list, besides that fact that Python is a great language and would probably be the most enjoyable language to code in, which is not a factor at all for this project, but a perk. To sum up: - real time production - weekly simulations of a large number of systems - weekly/monthly optimizations of portfolios - large numbers of connections to collect data from There is no dealing with millisecond or even second based trades. The only consideration is if Java can possibly deal with this kind of load when spread out of a necessary amount of EC2 servers. Thank you guys so much for your wisdom.

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javascript simple object creation test: opera leaks?

- by joe

Hi, I am trying to figure out certain memory leak conditions in javascript on a few browsers. Currently I'm only testing FF 3.6, Opera 10.10, and Safari 4.0.3. I've started with a fairly simple test, and can confirm no memory leaks in Firefox and Safari. But Opera just takes memory and never gives it back. What gives? Here's the test: <html> <head> <script type="text/javascript"> window.onload = init; //window.onunload = cleanup; var a=[]; function init() { var d = document.createElement('div'); d.innerHTML = "page loading..."; document.body.appendChild(d); for (var i=0; i<400000; i++) { a[i] = new Obj("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); } d.innerHTML = "PAGE LOADED"; } function cleanup() { for (var i=0; i<400000; i++) { a[i] = null; } } function Obj(msg) { this.msg=msg; } </script> </head> <body> </body> </html> I shouldn't need the cleanup() call on window.unload, but tried that also. No luck. As you can see this is simple JS, no circular DOM links, no closures. I monitor the memory usage using 'top' on Mac 10.4.11. Memory usage spikes up on page load, as expected. In FF and Safari reloading the page does not use any further memory, and all memory is returned when the window (tab) is closed. In Opera, memory spikes on load, and seems to also spike further on each reload (but not always...). But regardless of reload, memory never goes back down below the initial load spike. I had hoped this was a no-brainer test that all browsers would pass, so I could move on to more "interesting" conditions. Am I doing something wrong here? Or is this a known Opera issue? Thanks! -joe

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how to config grails1.2 with oscache?

- by wavelet

I do this : DataSource.groovy: hibernate { cache.use_second_level_cache=true cache.use_query_cache=true cache.provider_class='com.opensymphony.oscache.hibernate.OSCacheProvider' } and in BuildConfig.groovy: inherits( "global" ) { // uncomment to disable ehcache excludes 'ehcache' } runtime ("opensymphony:oscache:2.4.1") { excludes 'jms', 'commons-logging', 'servlet-api' } but i only get this error : commons.DefaultGrailsApplication The class [com.ai.scenter.service.reschange.ResourceChangeAdapter] was not found when attempting to load Grails application. Skipping. commons.DefaultGrailsApplication The class [com.ai.scenter.service.reschange.ResourceChangeService] was not found when attempting to load Grails application. Skipping. hibernate.ConfigurableLocalSessionFactoryBean There was an error configuring the Hibernate second level cache: could not instantiate CacheProvider [com.opensymphony.oscache.hibernate.OSCacheProvide] hibernate.ConfigurableLocalSessionFactoryBean This is normally due to one of two reasons. Either you have incorrectly specified the cache provider class name in [DataSource.groovy] or you do not have the cache provider on your classpath (eg. runtime ("net.sf.ehcache:ehcache:1.6.1")) how can i do it?

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How to cancel a web service call if it's not responding

- by drizzle

Hi, I have a web page (.aspx) that calls a third party web service to get some data. It usually takes couple of seconds to get the response back, and then the rest of the page will load. Occasionally the call gets stuck either due to the web service is down, or internet connection, etc., the page just hang there and will not load. My questions is: 1) Is there a way to abort/cancel the web service call after a set amount of time? 2) Is it even possible to verify the status of the web service before calling it? Thanks.

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java.lang.UnsatisfiedLinkError, mach-o but wrong architecture on Mac10.6.2

- by Yinan

I was trying to run a project in my local machine. I tried to load this jnilib file which I got from a running instance of this project on my Mac 10.6.2, System.load(lib.getAbsolutePath()); then I got this exception thrown: java.lang.UnsatisfiedLinkError, mach-o but wrong architecture I have check the jnilib with file command: libScreenMatchProxy.jnilib: Mach-O dynamically linked shared library i386 I guess this is because the jnilib file is compiled in 32bit but the Java comes with Mac10.6 is 64bit. So I go to Java Preference and set Java to use 32bit first. But it didn't work. As mentioned above, this jnilib file is copied from a running instance of the project on my Mac, so it should work. I don't understand why it working in the installed application but not in my Eclipse.

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Ninject: Abstract Class

- by Pickels

Hello, Do I need to do something different in an abstract class to get dependency injection working with Ninject? I have a base controller with the following code: public abstract class BaseController : Controller { public IAccountRepository AccountRepository { get; set; } } My module looks like this: public class WebDependencyModule : NinjectModule { public override void Load() { Bind<IAccountRepository>().To<AccountRepository>(); } } And this is my Global.asax: protected override void OnApplicationStarted() { Kernel.Load(new WebDependencyModule()); } protected override IKernel CreateKernel() { return new StandardKernel(); } It works when I decorate the IAccountRepository property with the [Inject] attribute. Thanks in advance.

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Will news ticker using overflow:hidden cause Google to see site as spam?

- by molipix

In the hope of tempting Googlebot with fresh content, I've implemented a homepage news ticker which displays the 20 most recent headlines on our site. The implementation I have chosen is a <ul> with each headline being a <li> Initially all the <li> elements have no style but Javascript kicks in on page load and gives all but one of them a display="style:none" attribute. Javascript then displays each of the other 19 headlines in a loop. So far so good. However, in order to prevent a visually unplesant page load where the 20 items display and then immediately collapse, I am using overflow:hidden on the <ul> element. Anyone got a view on what Googlebot is likely to make of this? Does the fact that I'm using overflow:hidden make the content look like spam?

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BULK INSERT with inconsitant number of columns

- by aceinthehole

I am trying to load a large amount data in SQL server from a flat file using BULK INSERT. However, my file has varying number of column, for instance the first row contains 14 and the second contains 4. That is OK, I just want to make a table with the max number of columns and load the file into it with nulls for the missing columns. I can play with it from that point. But it seems that SQL Server when reaching the end of the line and having more columns to fill for that same row in the destination table, just moves on to the next line and attempts to put the data on that line to the wrong column of the table. Is there a way to get the behavior that I am looking for? Is there a table hint that I can use the specify this? Has anyone run into this before? Here is the code BULK INSERT #t FROM '<path to file>' WITH ( DATAFILETYPE = 'char', KEEPNULLS, FIELDTERMINATOR = '#' )

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Prototype Ajax.Updater Response OK, but not showing up in FF. working in Safari!

- by koko

Hi, I've got a quite strange problem here. I'm calling some simple code via Ajax.Updater: new Ajax.Updater('load','http://myurl.com/demo.pl?key=demokey&param1=xyz&param2=abc',{ method:'get', onComplete:function(transport){ alert(transport.responseText) } }); which gets some code like this: <img id="2009_04_15_1239786246" src='../pv/100/2009_04_15_1239786246-01.jpg' border="1"> <img id="2009_04_15_1239786066" src='../pv/100/2009_04_15_1239786066-01.jpg' border="1"> ... and so on This code shows up in my firebug console as my server response, so everything should be fine. No errors here at all. Works fine in Safari. Firefox, according to Firebug, knows there is a response, but it won't show a thing in my div 'load' and the alert(transport.responseText) is also empty. I have no idea what could be the problem here.

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Background-image won't change using jquery in IE6

- by slav

There is a panel on my page with no default background-image css. On load it is set with jquery to an initial image, waits for 10 seconds then loads a random image out of some predetermined images. There are previous and next buttons which allow you to cycle through the images. In ie6 the initial image loads and then a random image also loads after 10 seconds, however pressing prev/next causes the background to become white and the images aren't loaded. With alerts I was able to find that it's still keeping track of the position and url of the image it's supposed to load, but just won't load it. Here is the code below. <script type="text/javascript"> var facts = new Array(); var position; $(document).ready(function() { <xsl:for-each select="$currentPage/ancestor-or-self::node[@level=1]/../node[@nodeName='Fun Fact Folder']/node"> facts[<xsl:value-of select="position()" />] = '<xsl:value-of select="." />'; </xsl:for-each> if(window.location.pathname == "/homepage.aspx" || window.location.pathname == "/") { $(".fun_facts_bg").css("background-image", "url(images/fun_fact_homepage.JPG)"); setTimeout("randomFact()",10000); } else { randomFact(); } }); function randomFact() { $("a.previous_button").css("display", "block"); $("a.next_button").css("display", "block"); position = Math.ceil(Math.random() * (facts.length - 1)); changeFact(0); } function changeFact(increment) { position = checkPosition(position, increment); $(".fun_facts_bg").css("background-image", "url(" + facts[position] + ")"); } <xsl:text disable-output-escaping="yes"><![CDATA[//><!]]></xsl:text> </script> <a class="previous_button" href="javascript:void(0);" onclick="changeFact(-1);"> <a class="next_button" href="javascript:void(0);" onclick="changeFact(1);">

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problem in jquery notify bar on submit form using php or zf

- by user1400

hi guys in my application on zend framework i use of 'jQuery Notify Bar' plugin for display messages, i'd like to show message when my form submit ,the other page is opened and notify bar be open until the other page is completely load and even some second more but the problem is that notify bar show for short Moment and when the other page begin to load , notify bar is closed, and the delay property is not effect to that $('#myForm').submit(function(){ $.notifyBar({ html: "Thank you, your settings were updated!", **delay: 20000,** animationSpeed: "normal" }); how to show notify bar in the other page too? thanks

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Loading tables dynamically with NHibernate

- by Trevor Goertzen

I'm working on a project that requires me to load tables based on table names stored in another table. More tables will be added to the DB (and by someone else), so creating NHibernate mapping files for each table isn't an option. Does anyone know if it is possible to load tables dynamically using NHibernate? Edit: I should add that I'm on .NET 2.0, so I can't use Fluent NHibernate. Thanks for the suggestion though guys. I will use that as evidence in convincing my associates to upgrade.

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Tomcat Clustering and HTTPS Issue

- by Angelo

Hi I have two instances of Tomcat 6 with content accessible via HTTP and HTTPS for other pages. I have configured the instances this way: 1) Instance one to listen on port 8080(Http) and 8443(Https) 2) Instance two to listen on port 7080(Http) and 7443(Https) I have mod_proxy configured with Apache 2.2 to do clustering. The requests are coming in properly and all works well for HTTP traffic but when you are in the app and it becomes HTTPS then i get the page cannot be found when tomcat tries to serve the page. Now if I access the two tomcat instances directly bypassing the load balancer then everything is fine. So http/https is configured properly on tomcat but not on Apache. I have a feeling i must configure Apache to handle this(or mod_proxy). Thanks,

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How Do I Pull Info from String

- by Russ Bradberry

I am trying to pull dynamics from a load that I run using bash. I have gotten to a point where I get the string I want, now from this I want to pull certain information that can vary. The string that gets returned is as follows: Records: 2910 Deleted: 0 Skipped: 0 Warnings: 0 Each of the number can and will vary in length, but the overall structure will remain the same. What I want to do is be able to get these numbers and load them into some bash variables ie: RECORDS=?? DELETED=?? SKIPPED=?? WARNING=?? In regex I would do it like this: Records: (\d*?) Deleted: (\d*?) Skipped (\d*?) Warnings (\d*?) and use the 4 groups in my variables.

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Hanging Forms When I Drag And Move My Forms

- by hosseinsinohe

I Write a Windows Application By C Sharp. I Use a Picture in Background of my Form (MainForm) And I Use Many Picture in Buttons in This Form,And also I Use Some Panel And Label with Transparent Background Color. My Forms,Panels And Buttons has flicker. I solve this problem by a method in this thread. But Still when other Forms Start over this Form,my Forms hangs when I Drag and Move my Forms over this Form.How can I Solve this Problem to Move And Drags my Forms easily And Speed? Edit:: My Forms Load Data From Access 2007 DataBase file.I Use Datasets,DataGridViews And Other Components to Load And show Data in My Forms.

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Reading and writing C++ vector to a file

- by JB

For some graphics work I need to read in a large amount of data as quickly as possible and would ideally like to directly read and write the data structures to disk. Basically I have a load of 3d models in various file formats which take too long to load so I want to write them out in their "prepared" format as a cache that will load much faster on subsequent runs of the program. Is it safe to do it like this? My worries are around directly reading into the data of the vector? I've removed error checking, hard coded 4 as the size of the int and so on so that i can give a short working example, I know it's bad code, my question really is if it is safe in c++ to read a whole array of structures directly into a vector like this? I believe it to be so, but c++ has so many traps and undefined behavour when you start going low level and dealing directly with raw memory like this. I realise that number formats and sizes may change across platforms and compilers but this will only even be read and written by the same compiler program to cache data that may be needed on a later run of the same program. #include <fstream> #include <vector> using namespace std; struct Vertex { float x, y, z; }; typedef vector<Vertex> VertexList; int main() { // Create a list for testing VertexList list; Vertex v1 = {1.0f, 2.0f, 3.0f}; list.push_back(v1); Vertex v2 = {2.0f, 100.0f, 3.0f}; list.push_back(v2); Vertex v3 = {3.0f, 200.0f, 3.0f}; list.push_back(v3); Vertex v4 = {4.0f, 300.0f, 3.0f}; list.push_back(v4); // Write out a list to a disk file ofstream os ("data.dat", ios::binary); int size1 = list.size(); os.write((const char*)&size1, 4); os.write((const char*)&list[0], size1 * sizeof(Vertex)); os.close(); // Read it back in VertexList list2; ifstream is("data.dat", ios::binary); int size2; is.read((char*)&size2, 4); list2.resize(size2); // Is it safe to read a whole array of structures directly into the vector? is.read((char*)&list2[0], size2 * sizeof(Vertex)); }

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JQuery post not working when moving web-app to a win server 2003

- by karl

I have build a webapplication using ASP.NET MVC and JQuery. On my local machine this works fine,but when moving it to a Windows server 2003 the JQuery method post stops working. I'm also using the load method and this works fine. function methodOne(id) { alert("debug1: <%= Url.Action( "MethodOne", "controller" ) + "/" %>" + id); $.post <%= Url.Action( "MethodOne", "controller" ) + "/" %>" + id, function(data) { alert("debug2"); ... } else { alert("Debugg: Add presentation to user failed"); } }); } The debug2 is never outputed. $('#panel').load("<%= Url.Action( "Method", "Controller" ) %"); Works fine.

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iframe for ad loading good or bad?

- by Cedar Jensen

According to Yahoo's "Best Practices for Speeding Up your Site", the pros for using iframes: Helps with slow third-party content like badges and ads Download scripts in parallel but the cons are: Costly even if blank Blocks page onload I want to use an iframe to load ads using the technique mentioned on this site: http://meanderingpassage.com/2007/08/15/keeping-javascript-widgets-from-controlling-your-blog/ Does using this technique mean that as soon as the html contents requested by the iframe are returned to the client, it will load the ad script, potentially blocking the rest of the page's rendering and downloading? Or will the iframe request get processed concurrently while rest of the document is downloaded and rendered?

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Why does dojo parsing time depend on css and images availability?

- by Kniganapolke

I have been profiling javascript on my page that uses dojo widgets. I don't use explicit parsing - the parser runs on page load. What I noticed is that if I clear browser cache before refreshing the page, dojo parsing takes much more time than if all the files are already cached. Note that we build all the required dojo modules into a layer (a single file), so we don't lazy-load any js files. I wonder if dojo parsing process depends on images and css resources, as far as I know it only instantiates widgets and injects dom nodes. Do you have any ideas why dojo parser runs longer (2-3 times longer in my case) when the cache is cleared?

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Hosting Javascript/CSS file on CDN similar to Google hosting jQuery

- by Alec Smart

Hello, I am wondering if there are any hosts or if I can host my file (JS & CSS) on Google so that they are cached and load real quick (due to CDN and gzip). A number of my customers use these files and I would prefer if they could somehow include this to file to receive the JS file. Ideally with filename.js?publickey=sdfgsdfg (which will be tied to a particular domain name). The problem is that my hosting needs are very small- only about 100kb. Any suggestions. My problem is that the customers using the JS & CSS file, have no clue about gzipping content or caching (as their shared hosts do not support it), as a result causes the JS/CSS to take forever to load. Am wondering if I can leverage an existing free service, or I do not mind paying either. Thank you for your time.

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How to implement a lazy loaded Silverlight data grid without using paging

- by Marc Wittke

Using the Business Application template from the brand new released RIA Services, you can see lots of examples using the data grid on top of a DomainDataSource in combination with a DataPager. The properties PageSize and LoadSize can be used to adjust the amount of data to be displayed in one page and the data that is prefetched in the background. Now I'd like to have a data grid with a scrollbar and no pager. The underlying DomainDataSource should load only the data that is diplayed in the grid. It should trigger another load, when the user scrolls down to items that are not yet in the data context. Is there any sample implementation how to do this?

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Handling OPTIONS request in nginx

- by ctmiller

We're using HAProxy as a load balancer at the moment, and it regularly makes requests to the downstream boxes to make sure they're alive using an OPTIONS request: OPTIONS /index.html HTTP/1.0 I'm working with getting nginx set up as a reverse proxy with caching (using ncache). For some reason, nginx is returning a 405 when an OPTIONS request comes in: 192.168.1.10 - - [22/Oct/2008:16:36:21 -0700] "OPTIONS /index.html HTTP/1.0" 405 325 "-" "-" 192.168.1.10 When hitting the downstream webserver directly, I get a proper 200 response. My question is: how to you make nginx pass that response along to HAProxy, or, how can I set the response in the nginx.conf? Thanks!

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Application error with MyFaces 1.2: java.lang.IllegalStateException: No Factories configured for this Application.

- by IgorB

For my app I'm using Tomcat 6.0.x and Mojarra 1.2_04 JSF implementation. It works fine, just I would like to switch now to MyFaces 1.2_10 impl of JSF. During the deployment of my app a get the following error: ERROR [org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/myApp]] StandardWrapper.Throwable java.lang.IllegalStateException: No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions! If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml. A typical config looks like this; <listener> <listener-class>org.apache.myfaces.webapp.StartupServletContextListener</listener-class> </listener> at javax.faces.FactoryFinder.getFactory(FactoryFinder.java:106) at javax.faces.webapp.FacesServlet.init(FacesServlet.java:137) at org.apache.myfaces.webapp.MyFacesServlet.init(MyFacesServlet.java:113) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371) ... Here is part of my web.xml configuration: <servlet> <servlet-name>Faces Servlet</servlet-name>  <servlet-class>org.apache.myfaces.webapp.MyFacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> ... <listener> <listener- class>org.apache.myfaces.webapp.StartupServletContextListener</listener-class> </listener> Has anyone experienced similar error, and what should I do i order to fix it? Thanx!

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whats faster, more efficient, loading a js file with arrays or populating arrays from tables

- by Leigh

I am rebuilding an ecom site where the product data is stored in a multidimensional JS array that gets loaded on page load. This data is constantly being accessed with JS due to the nature of the site, to update prices based on user selections. There are many options that affect final price. From a programming standpoint, a DB table is much easier to maintain and update than are JS arrays, and since I am porting the site over to PHP and MYSQL, I have been considering moving these arrays into tables. So, would it be better to populate an array from the DB on load so that the pricing data is always available to the JS, or stay with hard coded JS files? I considered getting data via ajax as needed, but since this site has to constantly update pricing with user interaction, I have pretty much ruled that out. How would you handle it?

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Convert jpg Byte[] to Texture2D

- by Damien Sawyer

I need to import jpeg images into a WP7/XNA app with associated metadata. The program which manages these images exports to an XML file with an encoded byte[] of the jpg files. I've written a custom importer/processor which successfully imports the reserialized objects into my XNA project. My question is, given the byte[] of the jpg, what is the best way to convert it back to Texture2D. // 'Standard' method for importing image Texture2D texture1 = Content.Load<Texture2D>("artwork"); // Uses the standard Content processor "Texture - XNA Framework" to import an image. // 'Custom' method var myCustomObject = Content.Load<CompiledBNBImage>("gamedata"); // Uses my custom content Processor to return POCO "CompiledBNBImage" byte[] myJPEGByteArray = myCustomObject.Image; // byte[] of jpeg Texture2D texture2 = ???? // What is the best way to convert myJPEGByteArray to a Texture2D? Thanks very much for your help. :-) DS

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