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  • How to create Chat application using Servlets & JSP

    - by Crazy boy
    I want to create chat application using Servlets & JSP. May I know how can I create chat application as I have never created before? How much knowledge I need to have to create chat application? Is there any need of networking API to create chat application? What's the design pattern I need to follow to create that application? Is there any need of database?

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  • error with redirect using listener JSF 2.0

    - by Ray
    I have a index.xhtml page <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:ui="http://java.sun.com/jsf/facelets"> <f:view> <ui:insert name="metadata" /> <f:event type="preRenderView" listener="#{item.show}" /> <h:body></h:body> </f:view> </html> And in bean class with scope session this method public void show() throws IOException, DAOException { ExternalContext externalContext = FacesContext.getCurrentInstance() .getExternalContext(); //smth String rootPath = externalContext.getRealPath("/"); String realPath = rootPath + "pages\\template\\body\\list.xhtml"; externalContext.redirect(realPath); } i think that I should redirect to next page but I have "browser can't show page" and list.xhtml (if I do this page as welcome-page I haven't error, it means that error connected with redirect) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:ui="http://java.sun.com/jsf/facelets"> <h:body> <ui:composition template="/pages/layouts/mainLayout.xhtml"> <ui:define name="content"> <h:form></h:form></ui:define></ui:composition> </h:body> </html> in consol i didn't have any error. in web.xml <welcome-file-list> <welcome-file>index.xhtml</welcome-file> </welcome-file-list> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.xhtml</url-pattern> </servlet-mapping> What can be the reason this problem?

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  • Creating an additional related model with Devise

    - by Tim Sullivan
    I've started to implement a new project using Devise, which is pretty fantastic for handling users. However, when a user signs up, they're not just creating a User model, but also need to create a related Account model that represents the company. Additional users will also belongs_to this Account model. I can't seem to find a hook for this in Devise, though it seems like a pretty common pattern. What's the best practice for this?

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  • ASP.NET MVC: How can I explain an invalid type violation to an end-user with Html.ValidationSummary?

    - by Terminal Frost
    Serious n00b warning here; please take mercy! So I finished the Nerd Dinner MVC Tutorial and I'm now in the process of converting a VB.NET application to ASP.NET MVC using the Nerd Dinner program as a sort of rough template. I am using the "IsValid / GetRuleViolations()" pattern to identify invalid user input or values that violate business rules. I am using LINQ to SQL and am taking advantage of the "OnValidate()" hook that allows me to run the validation and throw an application exception upon trying to save changes to the database via the CustomerRepository class. Anyway, everything works well, except that by the time the form values reach my validation method invalid types have already been converted to a default or existing value. (I have a "StreetNumber" property that is an integer, though I imagine this would be a problem for DateTime or any other non-strings as well.) Now, I am guessing that the UpdateModel() method throws an exception and then alters the value because the Html.ValidationMessage is displayed next to the StreetNumber field but my validation method never sees the original input. There are two problems with this: While the Html.ValidationMessage does signal that something is wrong, there is no corresponding entry in the Html.ValidationSummary. If I could even get the exception message to show up there indicating an invalid cast or something that would be better than nothing. My validation method which resides in my Customer partial class never sees the original user input so I do not know if the problem is a missing entry or an invalid type. I can't figure out how I can keep my validation logic nice and neat in one place and still get access to the form values. I could of course write some logic in the View that processes the user input, however that seems like the exact opposite of what I should be doing with MVC. Do I need a new validation pattern or is there some way to pass the original form values to my model class for processing? CustomerController Code // POST: /Customers/Edit/[id] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Customer customer = customerRepository.GetCustomer(id); try { UpdateModel(customer); customerRepository.Save(); return RedirectToAction("Details", new { id = customer.AccountID }); } catch { foreach (var issue in customer.GetRuleViolations()) ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(customer); }

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  • PHP OOP Design Patterns: Should I Create two seperate classes for registration and form validation?

    - by Joshua Poshua
    So here's my problem: I have two types of registration, registration A and registration B, each will have some of the same fields and some different fields. I was going to create abstract class registration and both A and B would have their own classes that extend from registration. My question is, should I create a seperate Validation class with seperate A and B validation classes that extend? or is there a better pattern to use for something like this? Thanks

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  • Guide need to build a JSP based webapplication

    - by Nick
    I want do a web-application that consists of the following pages: Main, Inventory, Shopping, Login, and Report. All will be JSPs and all will be called using the MVC pattern where one of two servlets uses the RequestDispatcher to call the appropriate JSP. This uses server-side forwarding and not redirection. I have ER diagram: http://tinypic.com/r/155oxlt/5 if u can guide I can do it successfully.

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  • How significant are JPA lazy loading performance benefits?

    - by Robert
    I understand that this is highly specific to the concrete application, but I'm just wondering what's the general opinion, or at least some personal experiences on the issue. I have an aversion towards the 'open session in view' pattern, so to avoid it, I'm thinking about simply fetching everything small eagerly, and using queries in the service layer to fetch larger stuff. Has anyone used this and regretted it? And is there maybe some elegant solution to lazy loading in the view layer that I'm not aware of?

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  • jQuery question

    - by Fuxi
    hi all, i'm having the following string <img alt="over 40 world famous brandedWATCHES BRANDs to choose from " src="http://www.fastblings.com/images/logo.jpg"></strong></a><br> i want to define a regex pattern like <img alt="(.+?)" src="http://(.+?).(jpg|gif)"> but as u can see the target strings has a linebreak in the alt attribute - so how can i incorporate this? the rule should be like "anything in the alt-attribute including linebreaks" thx

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  • What is so bad about Singletons

    - by Ewan Makepeace
    The Singleton pattern is a fully paid up member of the GoF Patterns Book but lately seems rather orphaned by the developer world. I still use quite a lot of singletons, especially for Factory classes, and while you have to be a bit careful about multithreading issues (like any class actually) fail to see why they are so awful. This site especially seems to assume that everyone agrees that Singletons are evil. Why?

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  • With MVVM, does each UI window have its own ViewModel?

    - by j0rd4n
    When I'm designing multiple views under the MVVM pattern, does each view get its own ViewModel or do they all share the same one? I understand that this is ultimately a flexible decision, but what is the best practice? My gut tells me to have a ViewModel for each view (i.e. each separate UI window). All of the blog examples of MVVM show a single view but not much beyond that.

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  • git status shows a file that I have listed explicitly in my .gitignore file

    - by metaperl
    I have the following line in my .gitignore file: var/www/docs/.backroom/billing_info/inv.pl but when I type 'git status' I am told the following: # modified: var/www/docs/.backroom/billing_info/inv.pl I dont understand how a file which is explicitly listed as an ignore pattern could be listed as modified when I want git to ignore it. There are no lines starting with a ! in my .gitignore file Here is my entire .gitignore file for reference: http://pastebin.com/Jw445Qd7

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  • c++ class member functions instatiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (vc++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Does anyone have experience simultaneously running a Drupal and Wordpress site and redirecting some

    - by DKinzer
    This is a really weird question and I apologize: I've been asked if it's possible not to import our blog from Wordpress to Drupal but just keep it in Wordpress as an archive and re-direct our users say from hostname/blog/... to hostname/wordpress/... when a URL matches the Wordpress URL pattern. I've never heard of anyone trying this and I'm wondering about pitfalls and whether or not it's even possible. Thanks! D

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  • Succinct But Complete Example of WPF App?

    - by Eric J.
    Is there a succinct but complete example project or tutorial that brings together the pieces of the Microsoft stack for a complete application? WPF MVVM Business Objects EF Database I find plenty for WPF and plenty for EF, but am having trouble fully understanding how the EF generated classes relate to business objects, and how those business objects in turn fit into the MVVM pattern.

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  • text replace with regex in sqlserver

    - by Thiyaneshwaran S
    Currently i have sql-server nvarchar(max) column which has text that starts with """ The only thing that varies in the pattern is the < in the class name. The common part is "" Some sample values are "" "" "" All the These span text are present only at the beginning of the column. Any such matching span in the middle should not be removed or matched. Whats the sql server query with regex to remove all these occurance of span?

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  • Do we need seperate file path for window and linux in java

    - by Kishor Sharma
    I have a file on linux ubuntu server hosted with path name /home/kishor/project/detail/. When I made a web app in window to upload and download file from specified location i used path "c:\kishor\projects\detail\" for saving in window. For my surprise when i used window file path name in my server i am still able to get files and upload them, i.e, "c:\kishor\projects\detail\". Can anyone explain why it is working (as window and linux both use different file path pattern).

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  • Stored procedure performance randomly plummets; trivial ALTER fixes it. Why?

    - by gWiz
    I have a couple of stored procedures on SQL Server 2005 that I've noticed will suddenly take a significantly long time to complete when invoked from my ASP.NET MVC app running in an IIS6 web farm of four servers. Normal, expected completion time is less than a second; unexpected anomalous completion time is 25-45 seconds. The problem doesn't seem to ever correct itself. However, if I ALTER the stored procedure (even if I don't change anything in the procedure, except to perhaps add a space to the script created by SSMS Modify command), the completion time reverts to expected completion time. IIS and SQL Server are running on separate boxes, both running Windows Server 2003 R2 Enterprise Edition. SQL Server is Standard Edition. All machines have dual Xeon E5450 3GHz CPUs and 4GB RAM. SQL Server is accessed using its TCP/IP protocol over gigabit ethernet (not sure what physical medium). The problem is present from all web servers in the web farm. When I invoke the procedure from a query window in SSMS on my development machine, the procedure completes in normal time. This is strange because I was under the impression that SSMS used the same SqlClient driver as in .NET. When I point my development instance of the web app to the production database, I again get the anomalous long completion time. If my SqlCommand Timeout is too short, I get System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Question: Why would performing ALTER on the stored procedure, without actually changing anything in it, restore the completion time to less than a second, as expected? Edit: To clarify, when the procedure is running slow for the app, it simultaneously runs fine in SSMS with the same parameters. The only difference I can discern is login credentials (next time I notice the behavior, I'll be checking from SSMS with the same creds). The ultimate goal is to get the procs to sustainably run with expected speed without requiring occasional intervention. Resolution: I wanted to to update this question in case others are experiencing this issue. Following the leads of the answers below, I was able to consistently reproduce this behavior. In order to test, I utilize sp_recompile and pass it one of the susceptible sprocs. I then initiate a website request from my browser that will invoke the sproc with atypical parameters. Lastly, I initiate a website request to a page that invokes the sproc with typical parameters, and observe that the request does not complete because of a SQL timeout on the sproc invocation. To resolve this on SQL Server 2005, I've added OPTIMIZE FOR hints to my SELECT. The sprocs that were vulnerable all have the "all-in-one" pattern described in this article. This pattern is certainly not ideal but was a necessary trade-off given the timeframe for the project.

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  • Undo/Redo using Memento: Stack, Queue or just LinkedList?

    - by serhio
    What is the best having when implementing Memento pattern (for Undo/Redo) in witch collection to Keep Mementos? Basically, I need this(c = change, u = undo, r = redo): 0 *c -1 0 *c -2 -1 0 *c -3 -2 -1 0 <u -2 -1 0 1 *c -3 -2 -1 0 Variants: LinkedList - possible in principle, maybe not optimized. Queue - not adapted for this task, IMO. Stack - not adapted for undo AND redo; Double Stack - maybe optimal, but can't control the undo maximum size.

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