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  • How to set buffer size in client-server app using sockets?

    - by nelly
    First of all i am new to networking so i may say dumb thing in here. Considering a client-server application using sockets(.net with c# if that matters). The client sends some data, the server process it and sends back a string. The client sends some other data, the serve process it, queries the db and sends back several hundreds of items from the database The client sends some other type of data and the server notifies some other clients . My question is how to set the buffer size correctly for reading/writing operation. Should i do something like this: byte[] buff = new byte[client.ReceiveBufferSize] ? I am thinking of something like this: Client sends data to the server(and the server will follow the same pattern) byte[] bytesToSend=new byte[2048] //2048 to be standard for any command send by the client bytes 0..1 ->command type bytes 1..2047 ->command parameters byte[] bytesToReceive=new byte[8]/byte[64]/byte[8192] //switch(command type) But..what is happening when a client is notified by the server without sending data? What is the correct way to accomplish what i am trying to do? Thanks for reading.

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  • How to get around LazyInitializationException in scheduled jobs?

    - by Shreerang
    I am working on a J2EE server application which is deployed on Tomcat. I use Spring source as MVC framework and Hibernate as ORM provider. My object model has lot of Lazy relationships (dependent objects are fetched on request). The high level design is like Service level methods call a few DAO methods to perform database operation. The service method is called either from the Flex UI or as a scheduled job. When it is called from Flex UI, the service method works fine i.e. it fetches some objects using DAO methods and even Lazy loading works. This is possible by the use of OpenSessionInViewFilter configured with the UI servlet. But when the same service method is called as scheduled Job, it gives LazyInitializationException. I can not configure OpenSessionInViewFilter because there is no servlet or UI request associated with that. I tried configuring Transaction around the scheduled job method so that service method starts a transaction and all the DAO methods participate in that same transaction, hoping that the transaction will remain active and hibernate session will be available. But it does not work. Please suggest if anyone has ever been able to get such a configuration working. If needed, I can post the Hibernate configuration and log messages. Thanks a lot for help! Shreerang

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  • T4MVC Optional Parameter Inferred From Current Context

    - by Itakou
    I have read the other post about this at T4MVC OptionalParameter values implied from current context and I am using the latest T4MVC (2.11.1) which is suppose to have the fix in. I even checked checked to make sure that it's there -- and it is. I am still getting the optional parameters filled in based on the current context. For example: Let's say I have a list that is by default ordered by a person's last name. I have the option to order by first name instead with the URL http://localhost/list/stuff?orderby=firstname When I am in that page, I want to go back to order by first name with the code: @Html.ActionLink("order by last name", MVC.List.Stuff(null)) the link I wanted was simply http://localhost/list/stuff without any parameters to keep the URL simple and short - invoking default behaviors within the action. But instead the orderby is kept and the url is still http://localhost/list/stuff?orderby=firstname Any help would be great. I know that in the most general cases, this does remove the query parameter - maybe I do have a specific case where it was not removed. I find that it only happens when I have the URL inside a page that I included with RenderPartial. My actual code is <li>@Html.ActionLink("Recently Updated", MVC.Network.Ticket.List(Model.UI.AccountId, "LastModifiedDate", null, null, null, null, null))</li> <li>@Html.ActionLink("Recently Created", MVC.Network.Ticket.List(Model.UI.AccountId, "CreatedDate", null, null, null, null, null))</li> <li>@Html.ActionLink("Most Severe", MVC.Network.Ticket.List(Model.UI.AccountId, "MostSevere", null, null, null, null, null))</li> <li>@Html.ActionLink("Previously Closed", MVC.Network.Ticket.List(Model.UI.AccountId, "LastModifiedDate", null, "Closed", null, null, null))</li> the problem happens when someone clicks Previously Closed and and go to ?status=closed. When they click Recently Updated, which I want to the ?status so that it shows the active ones, the ?status=closed stays. Any insight would be greatly appreciated.

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  • nhibernate sessionfactory instance more than once on web service

    - by Manuel
    Hello, i have a web service that use nhibernate. I have a singleton pattern on the repositorry library but on each call the service, it creates a new instance of the session factory wich is very expensive. What can i do? region Atributos /// <summary> /// Session /// </summary> private ISession miSession; /// <summary> /// Session Factory /// </summary> private ISessionFactory miSessionFactory; private Configuration miConfiguration = new Configuration(); private static readonly ILog log = LogManager.GetLogger(typeof(NHibernatePersistencia).Name); private static IRepositorio Repositorio; #endregion #region Constructor private NHibernatePersistencia() { //miConfiguration.Configure("hibernate.cfg.xml"); try { miConfiguration.Configure(); this.miSessionFactory = miConfiguration.BuildSessionFactory(); this.miSession = this.SessionFactory.OpenSession(); log.Debug("Se carga NHibernate"); } catch (Exception ex) { log.Error("No se pudo cargar Nhibernate " + ex.Message); throw ex; } } public static IRepositorio Instancia { get { if (Repositorio == null) { Repositorio = new NHibernatePersistencia(); } return Repositorio; } } #endregion #region Propiedades /// <summary> /// Sesion de NHibernate /// </summary> public ISession Session { get { return miSession.SessionFactory.GetCurrentSession(); } } /// <summary> /// Sesion de NHibernate /// </summary> public ISessionFactory SessionFactory { get { return this.miSessionFactory; } } #endregion In wich way can i create a single instance for all services?

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  • OOP design issue: Polymorphism

    - by Graham Phillips
    I'm trying to solve a design issue using inheritance based polymorphism and dynamic binding. I have an abstract superclass and two subclasses. The superclass contains common behaviour. SubClassA and SubClassB define some different methods: SubClassA defines a method performTransform(), but SubClassB does not. So the following example 1 var v:SuperClass; 2 var b:SubClassB = new SubClassB(); 3 v = b; 4 v.performTransform(); would cause a compile error on line 4 as performTransform() is not defined in the superclass. We can get it to compile by casting... (v as SubClassA).performTransform(); however, this will cause a runtime exception to be thrown as v is actually an instance of SubClassB, which also does not define performTransform() So we can get around that by testing the type of an object before casting it: if( typeof v == SubClassA) { (cast v to SubClassA).performTransform(); } That will ensure that we only call performTransform() on v's that are instances of SubClassA. That's a pretty inelegant solution to my eyes, but at least its safe. I have used interface based polymorphism (interface meaning a type that can't be instantiated and defines the API of classes that implement it) in the past, but that also feels clunky. For the above case, if SubClassA and SubClassB implemented ISuperClass that defined performTransform, then they would both have to implement performTransform(). If SubClassB had no real need for a performTransform() you would have to implement an empty function. There must be a design pattern out there that addresses the issue.

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  • Error when creating an image from a UIView

    - by Raphael Pinto
    Hi, I'm creating an image from a view whith the folowing code : UIGraphicsBeginImageContext(myView.bounds.size); [myView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil); The image is created in the user album but in the consol I get this : 2010-05-11 10:17:17.974 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.014 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.077 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.087 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.091 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.095 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.111 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.115 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.120 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.124 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.129 myApp[3875:1807] sqlite error 1 [cannot commit - no transaction is active] 2010-05-11 10:17:18.133 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 I don't know where the problem come from. Can you help me?

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  • What's the proper approach for writing multi-path "story" flows?

    - by Basiclife
    Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

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  • How to append html only if the div is empty in jQuery?

    - by johnnyb3000
    I have this code for displaying content for login and registration in my PHP file: <?php // LOGIN PART ?> <div class="login-part"></div> <?php // REGISTRATION PART ?> <div class="registration-part"></div> And this in my js file: $(document).ready( function() { // FOR REGISTRATION $('span.logreg.reg').click(function () { $('div.registration-part').append('<p>Registration</p>'); }); // FOR LOGIN $('span.logreg.log').click(function () { // insert html $('div.login-part').append('<p>Login</p>'); }); }); Now, everytime I click on a span it shows the text login or registration, according to which of the span was clicked. Thats OK, however I need to add it only once, so when the user click more times on the span it will be not adding more text. Remove() or empty() is not an option, as far as I know, because I need the information inside input boxes (there will be input boxes later for inserting user info) to stay there and not be deleted if the user click accidentally on the span again. It can however delete the html inside the div, if he clicks on another span. E.g. if span.log is active, after clicking on span.log nothing happens, but if he clicks on span.reg the html inside div.login-part will be removed and registration text will appear. How to do something like this?

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  • Cost of logic in a query

    - by FrustratedWithFormsDesigner
    I have a query that looks something like this: select xmlelement("rootNode", (case when XH.ID is not null then xmlelement("xhID", XH.ID) else xmlelement("xhID", xmlattributes('true' AS "xsi:nil"), XH.ID) end), (case when XH.SER_NUM is not null then xmlelement("serialNumber", XH.SER_NUM) else xmlelement("serialNumber", xmlattributes('true' AS "xsi:nil"), XH.SER_NUM) end), /*repeat this pattern for many more columns from the same table...*/ FROM XH WHERE XH.ID = 'SOMETHINGOROTHER' It's ugly and I don't like it, and it is also the slowest executing query (there are others of similar form, but much smaller and they aren't causing any major problems - yet). Maintenance is relatively easy as this is mostly a generated query, but my concern now is for performance. I am wondering how much of an overhead there is for all of these case expressions. To see if there was any difference, I wrote another version of this query as: select xmlelement("rootNode", xmlforest(XH.ID, XH.SER_NUM,... (I know that this query does not produce exactly the same, thing, my plan was to move the logic to PL/SQL or XSL) I tried to get execution plans for both versions, but they are the same. I'm guessing that the logic does not get factored into the execution plan. My gut tells me the second version should execute faster, but I'd like some way to prove that (other than writing a PL/SQL test function with timing statements before and after the query and running that code over and over again to get a test sample). Is it possible to get a good idea of how much the case-when will cost? Also, I could write the case-when using the decode function instead. Would that perform better (than case-statements)?

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  • Efficient database access when dealing with multiple abstracted repositories

    - by Nathan Ridley
    I want to know how most people are dealing with the repository pattern when it involves hitting the same database multiple times (sometimes transactionally) and trying to do so efficiently while maintaining database agnosticism and using multiple repositories together. Let's say we have repositories for three different entities; Widget, Thing and Whatsit. Each repository is abstracted via a base interface as per normal decoupling design processes. The base interfaces would then be IWidgetRepository, IThingRepository and IWhatsitRepository. Now we have our business layer or equivalent (whatever you want to call it). In this layer we have classes that access the various repositories. Often the methods in these classes need to do batch/combined operations where multiple repositories are involved. Sometimes one method may make use of another method internally, while that method can still be called independently. What about, in this scenario, when the operation needs to be transactional? Example: class Bob { private IWidgetRepository _widgetRepo; private IThingRepository _thingRepo; private IWhatsitRepository _whatsitRepo; public Bob(IWidgetRepository widgetRepo, IThingRepository thingRepo, IWhatsitRepository whatsitRepo) { _widgetRepo = widgetRepo; _thingRepo= thingRepo; _whatsitRepo= whatsitRepo; } public void DoStuff() { _widgetRepo.StoreSomeStuff(); _thingRepo.ReadSomeStuff(); _whatsitRepo.SaveSomething(); } public void DoOtherThing() { _widgetRepo.UpdateSomething(); DoStuff(); } } How do I keep my access to that database efficient and not have a constant stream of open-close-open-close on connections and inadvertent invocation of MSDTS and whatnot? If my database is something like SQLite, standard mechanisms like creating nested transactions are going to inherently fail, yet the business layer should not have to be concerning itself with such things. How do you handle such issues? Does ADO.Net provide simple mechanisms to handle this or do most people end up wrapping their own custom bits of code around ADO.Net to solve these types of problems?

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  • Writing a synchronized thread-safety wrapper for NavigableMap

    - by polygenelubricants
    java.util.Collections currently provide the following utility methods for creating synchronized wrapper for various collection interfaces: synchronizedCollection(Collection<T> c) synchronizedList(List<T> list) synchronizedMap(Map<K,V> m) synchronizedSet(Set<T> s) synchronizedSortedMap(SortedMap<K,V> m) synchronizedSortedSet(SortedSet<T> s) Analogously, it also has 6 unmodifiedXXX overloads. The glaring omission here are the utility methods for NavigableMap<K,V>. It's true that it extends SortedMap, but so does SortedSet extends Set, and Set extends Collection, and Collections have dedicated utility methods for SortedSet and Set. Presumably NavigableMap is a useful abstraction, or else it wouldn't have been there in the first place, and yet there are no utility methods for it. So the questions are: Is there a specific reason why Collections doesn't provide utility methods for NavigableMap? How would you write your own synchronized wrapper for NavigableMap? Glancing at the source code for OpenJDK version of Collections.java seems to suggest that this is just a "mechanical" process Is it true that in general you can add synchronized thread-safetiness feature like this? If it's such a mechanical process, can it be automated? (Eclipse plug-in, etc) Is this code repetition necessary, or could it have been avoided by a different OOP design pattern?

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  • Is locking on the requested object a bad idea?

    - by Quick Joe Smith
    Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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  • JavaScript Keycode 46 is DEL Function key or (.) period sign?

    - by Omar
    Im writing some logic in JavaScript using jquery, where i must check the input content against a REGEX pattern ex: "^[a-zA-Z0-9_]*$" //Alpha-numeric and _ The logic is almost done, i just have a little problem filtering the function key DEL, my logic goes like this: var FunctionsKey = new Array(8, 9, 13, 16, 35, 36, 37, 39, 46); function keypressValidation(key) { if (config.regexExp != null) { if ($.inArray(key, FunctionsKey) != -1) { return true; } else { var keyChar = String.fromCharCode(key); return RegexCheck(keyChar); } } return true; } If the KeyCode is one of those in the array, i let it pass, if not i get the char and compare it against the REGEX. The problem is: in some Browsers the DEL and '.' (period sign) have the same key Code 46. So is there a better logic to filter the function keys or must i write a condition for that case, maybe removing the 46 from the array and try to convert it to char and if is (.) let it go to the Regex function if not let it pass? The other question will be are there more shared Key Codes in some browsers? EDIT: My suggested solution wont work because it doesn't matter which key the user pressed (DEL or period) i always get (.) as CHAR at least on OPERA and FF =(.

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  • Dimension Reduction in Categorical Data with missing values

    - by user227290
    I have a regression model in which the dependent variable is continuous but ninety percent of the independent variables are categorical(both ordered and unordered) and around thirty percent of the records have missing values(to make matters worse they are missing randomly without any pattern, that is, more that forty five percent of the data hava at least one missing value). There is no a priori theory to choose the specification of the model so one of the key tasks is dimension reduction before running the regression. While I am aware of several methods for dimension reduction for continuous variables I am not aware of a similar statical literature for categorical data (except, perhaps, as a part of correspondence analysis which is basically a variation of principal component analysis on frequency table). Let me also add that the dataset is of moderate size 500000 observations with 200 variables. I have two questions. Is there a good statistical reference out there for dimension reduction for categorical data along with robust imputation (I think the first issue is imputation and then dimension reduction)? This is linked to implementation of above problem. I have used R extensively earlier and tend to use transcan and impute function heavily for continuous variables and use a variation of tree method to impute categorical values. I have a working knowledge of Python so if something is nice out there for this purpose then I will use it. Any implementation pointers in python or R will be of great help. Thank you.

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  • Mono Develop 2.4.1 + linq error.

    - by Nev_Rahd
    I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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  • ctrl+click or shift+click not always firing the onclick event

    - by Erik
    Hi, I recently discovered that different browsers handle the onclick event differently when the control of shift key is pressed. Same thing for following links with the middle mouse button. <a href="http://www.example.com/" onclick="alert('onclick');">go to example.com</a> Onclick browser support table Mouse Keyboard Chrome Firefox Safari Opera IE5.5 IE6 IE7 IE8 IE9 Left None yes yes yes yes yes yes yes yes yes Left Ctrl yes yes yes yes ? yes no no ? Left Shift yes yes yes yes ? yes yes yes ? Middle None yes no yes no ? N/A no no ? Can someone please fill in the question marks for me? Also; I'm wondering if the behaviour differs for each version of Chrome, Firefox, Safari and Opera. Finding a logical pattern in this behaviour would be even nicer, but I don't think there is :). Thanks a lot.

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  • How to control access to third party HTML pages

    - by Wylie
    Hello, We have a Learning Management System (LMS) that runs on its own server (IIS/Server 2003). Students must login with Forms authentication to gain access to the content. We want to offer access to third party flash and audio that is embedded in HTML pages hosted on the third party server (IIS/Server 2003). Currently we use a frame in a pop-up window that is populated via a simple URL to the third party HTML pages. How can the third party control access to their content, so that only students who launch the pop-up windows from our site can access their content? Since the content is mostly video and flash, we would prefer not to stream all of their content through our server to the Student. We have a programming staff, so we could maybe... - either post or get for our HTTP request to the third party server - we could use SSL - we could programmatically assign a global NT user account to all of our users and then do some kind of Active Directory login from the LMS server to the third party server - could the third party content be hosted at Amazon S3? Would this allow for secure access/download? These are just ideas. We really have no idea. Any suggestions would be greatly appreciated. TIA, Wylie

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  • Who needs singletons?

    - by sexyprout
    Imagine you access your MySQL database via PDO. You got some functions, and in these functions, you need to access the database. The first thing I thought of is global, like: $db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'root', 'pwd'); function some_function() { global $db; $db->query('...'); } But it's considered as a bad practice. So, after a little search, I ended up with the Singleton pattern, which "applies to situations in which there needs to be a single instance of a class." According to the example of the manual, we should do this: class Database { private static $instance, $db; private function __construct(){} static function singleton() { if(!isset(self::$instance)) self::$instance = new __CLASS__; return self:$instance; } function get() { if(!isset(self::$db)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd') return self::$db; } } function some_function() { $db = Database::singleton(); $db->get()->query('...'); } some_function(); But I just can't understand why you need that big class when you can do it merely with: class Database { private static $db; private function __construct(){} static function get() { if(!isset(self::$rand)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd'); return self::$db; } } function some_function() { Database::get()->query('...'); } some_function(); This last one works perfectly and I don't need to worry about $db anymore. But maybe I'm forgetting something. So, who's wrong, who's right?

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  • Localisable Resources: how can (should one?!) wrap a UI layer source as a BL layer service?

    - by Ciel
    A service that returns localised strings could be wrapped in a service, so that it could be used both locally (eg in an MVC app) and remotely (eg possibly Silverlight). But...if sticking with the standard practice of creating resources in the UI assembly, that would in effect make a lower layer (BL/Services) have to have a ref on a higher layer (UI)...a definite no-no. And whereas a lot of AppWide resources (eg: AppName, OK, Cancel, etc.) could be defined in a Common cross-cutting assembly, and the BL/ResourceSerouce could ref and wrap those, that doesn't work in a a Modular App, where the Core app should have no binding to/knowledge of any Module. One solution could be to have each module, once mounted in mem, 'register' their Resource files with the service, who would then return it to the service (rather a long round trip, but at least consistent as a service, and potentially resources/images could be shared with other resources). Secondly, that may work in a web app...but not sure how that pattern could be extended to a Silverlight modular app (the round tripping becomes prohibitive). ie...what are best practices for allowing Resources to be to be defined by the UI designer, in a higher level, but served from the lower BL layer, as a Service? Or is there a better way of understanding/solving the problem?

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  • I want to prevent ASP.NET GridView from reacting to the enter button

    - by StephaneT
    I have an ASP.NET page with a gridview control on it with a CommandButton column with delete and select commands active. Pressing the enter key causes the first command button in the gridview to fire, which deletes a row. I don't want this to happen. Can I change the gridview control in a way that it does not react anymore to pressing the enter key? There is a textbox and button on the screen as well. They don't need to be responsive to hitting enter, but you must be able to fill in the textbox. Currently we popup a confirmation dialog to prevent accidental deletes, but we need something better than this. This is the markup for the gridview, as you can see it's inside an asp.net updatepanel (i forgot to mention that, sorry): (I left out most columns and the formatting) <asp:UpdatePanel ID="upContent" runat="server" UpdateMode="Conditional"> <Triggers> <asp:AsyncPostBackTrigger ControlID="btnFilter" /> <asp:AsyncPostBackTrigger ControlID="btnEdit" EventName="Click" /> </Triggers> <ContentTemplate> <div id="CodeGrid" class="Grid"> <asp:GridView ID="dgCode" runat="server"> <Columns> <asp:CommandField SelectImageUrl="~/Images/Select.GIF" ShowSelectButton="True" ButtonType="Image" CancelText="" EditText="" InsertText="" NewText="" UpdateText="" DeleteImageUrl="~/Images/Delete.GIF" ShowDeleteButton="True" /> <asp:BoundField DataField="Id" HeaderText="ID" Visible="False" /> </Columns> </asp:GridView> </div> </ContentTemplate> </asp:UpdatePanel>

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  • Lite-Javascript Gallery - Can I position the img absolutely in relationship to the lis?

    - by blackessej
    I have a lite-javascript run image gallery. The javascript grabs each element in the list and places it as a background in the parent element. Then the CSS styles the thumbnails as small blocks with a defined height/width. A click-event for each object toggles it’s child’s element’s visibility and adds an “active” class name to the . Using CSS, I'm trying to place the absolutely to make it appear at the same position for each thumb, but it's moving in relation to the thumbs. Here's the CSS: #jgal li { background-position:50% 50%; background-repeat:no-repeat; border:solid #999 4px; cursor:pointer; display:block; float:left; height:60px; width:60px; margin-bottom:14px; margin-right:14px; opacity:0.5; } #jgal li img { position:absolute; top:0px; left:210px; display:none; } And the site: http://www.erisdesigns.net Thanks in advance for any help!

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  • Can FFT length affect filtering accuracy?

    - by Charles
    Hi, I am designing a fractional delay filter, and my lagrange coefficient of order 5 h(n) have 6 taps in time domain. I have tested to convolute the h(n) with x(n) which is 5000 sampled signal using matlab, and the result seems ok. When I tried to use FFT and IFFT method, the output is totally wrong. Actually my FFT is computed with 8192 data in frequency domain, which is the nearest power of 2 for 5000 signal sample. For the IFFT portion, I convert back the 8192 frequency domain data back to 5000 length data in time domain. So, the problem is, why this thing works in convolution, but not in FFT multiplication. Does converting my 6 taps h(n) to 8192 taps in frequency domain causes this problem? Actually I have tried using overlap-save method, which perform the FFT and multiplication with smaller chunks of x(n) and doing it 5 times separately. The result seems slight better than the previous, and at least I can see the waveform pattern, but still slightly distorted. So, any idea where goes wrong, and what is the solution. Thank you.

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  • LINQ to XML: suppressing redundant namespace attribute in child nodes

    - by GSerg
    If a node belongs to a namespace, it's children by default belong to the same namespace. So there's no need to provide an xmlns attribute on each child, which is good. However. If I create two nodes like this: Dim parent = <parent xmlns="http://my.namespace.org"/> Dim child = <child xmlns="http://my.namespace.org">value</child> parent.Add(child) Console.WriteLine(parent.ToString) The result is this: <parent xmlns="http://my.namespace.org"> <child xmlns="http://my.namespace.org">value</child> </parent> But, if create them in a less convenient way: Dim parent = <parent xmlns="http://my.namespace.org"/> Dim child As New XElement(XName.Get("child", "http://my.namespace.org")) With {.Value = "value"} parent.Add(child) Console.WriteLine(parent.ToString) The result is more desirable: <parent xmlns="http://my.namespace.org"> <child>value</child> </parent> Obviously, I'd prefer to use the first way because it is so much more intuitive and easy to code. There's also another reason to not use method 2 -- sometimes I need to create nodes with XElement.Parse, parsing a string that contains an xmlns attribute, which produces exactly same results as method 1. So the question is -- how do I get the pretty output of method 2, creating nodes as in method 1? The only option I see is to create a method that would clone given XElement, effectively recreating it according to method 2 pattern, but that seems ugly. I'm looking for a more obvious solution I overlooked for some reason.

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  • ForEach loop in Mathematica.

    - by dreeves
    I'd like something like this: ForEach[i_, {1,2,3}, Print[i] ] Or, more generally, to destructure arbitrary stuff in the list you're looping over, like: ForEach[{i_, j_}, {{1,10}, {2,20}, {3,30}}, Print[i*j] ] (Meta-question: is that a good way to call a ForEach loop, with the first argument a pattern like that?) ADDED: Some answerers have rightly pointed out that usually you want to use Map or other purely functional constructs and eschew a non-functional programming style where you use side effects. I agree! But here's an example where I think this ForEach construct is supremely useful: Say I have a list of options (rules) that pair symbols with expressions, like attrVals = {a -> 7, b -> 8, c -> 9} Now I want to make a hash table where I do the obvious mapping of those symbols to those numbers. I don't think there's a cleaner way to do that than ForEach[a_ -> v_, attrVals, h[a] = v] ADDED: I just realized that to do ForEach properly, it should support Break[] and Continue[]. I'm not sure how to implement that. Perhaps it will need to somehow be implemented in terms of For, While, or Do since those are the only loop constructs that support Break[] and Continue[]. If anyone interested in this wants to ask about that as a separate question, please do!

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  • How to best manage multi-frame MovieClips with classes?

    - by Arms
    After switching to AS3, I've been having a hell of a time figuring out the best way to manage MovieClips that have UI elements spread across multiple frames with a single class. An example that I am working on now is a simple email form. I have a MovieClip with two frames: the 1st frame has the form elements (text inputs, submit button) the 2nd frame has a "thank you" message and a button to go back to the first frame (to send another email) In the library I have linked the MovieClip to a custom class (Emailer). My immediate problem is how do I assign a MouseEvent.CLICK event to the button on the 2nd frame? I should note at this point that I am trying to avoid putting code on the timeline (except for stop() calls). This is how I am 'solving' the problem now: Emailer registers an event listener for a frame change ( addEventListener("frame 2", onFrameChange) ) On the 2nd frame of the MovieClip I am calling dispatchEvent(new Event("frame 2")); (I would prefer to not have this code on the frame, but I don't know what else to do) My two complaints with this method are that, first I have calls to addEventListener spread out across different class methods (I would rather have all UI event listeners registered in one method), and second that I have to dispatch those custom "onFrameChange" events. The second complaint grows exponentially for MovieClips that have more than just 2 frames. My so called solution feels makes me feel dirty and makes my brain hurt. I am looking for any advice on what to do differently. Perhaps there's a design pattern I should be looking at? Should I swallow my pride and write timeline code even though the rest of my application is written in class files (and I abhor the Flash IDE code editor)? I absolutely LOVE the event system, and have no problem coding applications with it, but I feel like I'm stuck thinking in terms of AS2 when working with mutl-frame movieclips and code. Any and all help would be greatly appreciated.

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