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• Java, Massive message processing with queue manager (trading)

  - by Ronny

  Hello, I would like to design a simple application (without j2ee and jms) that can process massive amount of messages (like in trading systems) I have created a service that can receive messages and place them in a queue to so that the system won't stuck when overloaded. Then I created a service (QueueService) that wraps the queue and has a pop method that pops out a message from the queue and if there is no messages returns null, this method is marked as "synchronized" for the next step. I have created a class that knows how process the message (MessageHandler) and another class that can "listen" for messages in a new thread (MessageListener). The thread has a "while(true)" and all the time tries to pop a message. If a message was returned, the thread calls the MessageHandler class and when it's done, he will ask for another message. Now, I have configured the application to open 10 MessageListener to allow multi message processing. I have now 10 threads that all time are in a loop. Is that a good design?? Can anyone reference me to some books or sites how to handle such scenario?? Thanks, Ronny

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• SQL Script To Generate a Database Dictionary **With Linked Fields**

  - by Albert

  I would like to generate a Data Dictionary for a SQL Server 2008 database that has one row for each field, and the following columns: table_name field_name data_type link_table (for when the field in question is a foreign key) link_field (for when the field in question is a foreign key) I can get the first 3 columns with something like the SQL script below...but I don't know how to get the last two columns of foreign key information. INFORMATION_SCHEMA.TABLE_CONSTRAINTS gets close, but doesn't have the data I'm looking for. Can someone help with this point? SELECT TABLE_NAME,COLUMN_NAME,DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS Secondarily if anyone has any suggestions on additional fields which would be helpful please post.

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• Zend Framework Application: module dependencies

  - by takeshin

  How do you handle dependencies between modules in Zend Framework to create reusable, drop-in modules? E.g. I have Newsletter module, which allows users to subscribe, providing e-mail address. Next, I plan to add Blog module, which allows to subscribe to posts by e-mail (it obviously duplicates some functionality of the newsletter, but the e-mails addresses are stored in User model). Next one is the Forum module, with the same subscribe to post functionality. But I want to have ability to use these modules independent to each one, i.e. application with newsletter alone, newsletter with blog, comibnation two or three modules at once. This is pretty common, e.g. the same story with search feature. I want to have search module, with options to search in all data, blog data or forum data if available. Is there any design pattern for this? Do I have to add some moduleExists($moduleMame), or provide some interface or abstract classes, some base controller pattern, similar for each module?

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• Getting a permission error when trying to connect to sql database

  - by Matt

  I have a sql server on a dedicated machine, running SQL 2008. I have the IP of the box, a database setup on it. I've built a small script that just does a connection test, and when I run it, I get the following error. Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. I've been told by the admin that SQL remote access has been granted for my IP address. Anybody know what's wrong?

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• How should I handle expected errors? eg. "username already exists"

  - by Pheter

  I am struggling to understand how I should design the error handling parts of my code. I recently asked a similar question about how I should go about returning server error codes to the user, eg. 404 errors. I learnt that I should handle the error from within the current part of the application; seem's simple enough. However, what should I do when I can't handle the error from the current link in the chain? For example, I may have a class that is used to manage authentication. One of it's methods could be createUser($username, $password). Within that function, I need to determine if the username already exists. If this is true, how should I alert the calling code about this? Returning null instead of a user object is one way. But how do I then know what caused the error? How should I handle errors in such a way that calling code can easily find out what caused the error? Is there a design pattern commonly used for this kind of situation?

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• Web service accessing client database

  - by chupinette

  Hello all! I am new to web services and i have a question: Should a web service be able to access the client database? Sorry if i am not using the proper terms. Lets say i have a web service method called : GetCarDetails(string name) which will actually return details from car table. in this method i have an sql statement like SELECT * FROM car WHERE name = ?. In the client application, i have a textbox where i can input a name and a button on which when i click, fill a gridview. So im kinda confused, should the web service normally know that the client has a table called car?Please correct me if ive used the wrong terms. Thanks

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• How to understand existing projects

  - by John

  Hi. I am a trainee developer and have been writing .NET applications for about a year now. Most of the work I have done has involved building new applications (mainly web apps) from scratch and I have been given more or less full control over the software design. This has been a great experience however, as a trainee developer my confidence about whether the approaches I have taken are the best is minimal. Ideally I would love to collaborate with more experienced developers (I find this the best was I learn) however in the company I work for developers tend to work in isolation (a great shame for me). Recently I decided that a good way to learn more about how experienced developers approach their design might be to explore some open source projects. I found myself a little overwhelmed by the projects I looked at. With my level of experience it was hard to understand the body of code I faced. My question is slight fuzzy one. How do developers approach the task of understanding a new medium to large scale project. I found myself pouring over lots of code and struggling to see the wood for the trees. At any one time I felt that I could understand a small portion of the system but not see how its all fits together. Do others get this same feeling? If so what approaches do you take to understanding the project? Do you have any other advice about how to learn design best practices? Any advice will be very much appreciated. Thank you.

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• Should frontend and backend be handled by different controllers?

  - by DR

  In my previous learning projects I always used a single controller, but now I wonder if that is good practice or even always possible. In all RESTful Rails tutorials the controllers have a show, an edit and an index view. If an authorized user is logged on, the edit view becomes available and the index view shows additional data manipulation controls, like a delete button or a link to the edit view. Now I have a Rails application which falls exactly into this pattern, but the index view is not reusable: The normal user sees a flashy index page with lots of pictures, complex layout, no Javascript requirement, ... The Admin user index has a completly different minimalistic design, jQuery table and lots of additional data, ... Now I'm not sure how to handle this case. I can think of the following: Single controller, single view: The view is split into two large blocks/partials using an if statement. Single controller, two views: index and index_admin. Two different controllers: BookController and BookAdminController None of these solutions seems perfect, but for now I'm inclined to use the 3rd option. What's the preferred way to do this?

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• Have you ever derived a programming solution from nature?

  - by Ryu

  When you step back and look at ... the nature of animals, insects, plants and the problems they have organically solved perhaps even the nature and balance of the universe Have you ever been able to solve a problem by deriving an approach from nature? I've heard of Ant Colony Algorithms being able to optimize supply chain amongst other things. Also Fractal's being the "geometry of nature" have been applied to a wide range of problems. Now that spring is here again and the world is coming back to life I'm wondering if anybody has some experiences they can share. Thanks PS I would recommend watching the "Hunting the Hidden Dimension" Nova episode on fractals.

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• Archiving Database Tables using Java

  - by HonorGod

  My application demands archiving database tables between sybase and db2 and vice-a-versa and within(db2 to db2 and sybase to sybase) using java. I am trying to understand the best strategies around in terms performance, implementation, ease of use and scalability. Here is my current process - source and destination tables with the acceptable parameters (from java) are defined within xml. the application reads the source and destination configurations and execute them sequentially. destination is sometime optional when source is just deleting data from a specific table or when the source is just calling a stored procedure. dataset between source and destination is extremely large (in millions) From top of my head, it looks like I can define dependencies between multiple source and destination combination and have them execute in parallel in multiple treads. But will this improve any performance(i hope it will)? Are there any open-source frameworks for data archiving using java? Any other thoughts on the implements side will be really helpful. Thanks

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• REST authentication S3 like hmac sha1 signature vs symetric data encryption.

  - by coulix

  Hello stackers, I was arguing about an S3 like aproach using authorization hash with a secret key as the seed and some data on the request as the message signed with hmac sha1 (Amazon S3 way) vs an other developer supporting symetric encryption of the data with a secret key known by the emiter and the server. What are the advantage of using signed data with hmac sha1 vs symetric key other than the fact that with the former, we do not need to encrypt the username or password. What would be the hardest to break ? symetric encryption or sha1 hashing at la S3 ? If all big players are using oauth and similar without symetric key it is sure that there are obvious advantages, what are those ?

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• MVC Forms Authentication with custom database

  - by AndrewVos

  I'm trying to get forms authentication working for an mvc site. I have a custom database with a users table, and I would like to do my own password validation. I am logging in my user like this: if (PasswordHasher.Hash(password) == dataUser.Password) { FormsAuthentication.SetAuthCookie(email, true); return true; } The problem is, when the session expires obviously the user has to login again. I am thinking I should be storing this Auth cookie in my users table? Update: I'm obviously in desperate need of more education in this area. I just noticed that the user stays authenticated even after an iisreset. I guess what I'm asking is how can I get persistent and non persistent authentication working properly. I want a user to not have to login again if they click "remember", and if they don't then their authentication should expire when the forms authentication is set to expire.

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• Question about domain models & their visibility...

  - by Another SO User

  I was involved in an interesting debate about the visibility of domain models & was wondering if people here have any good guidance. Per my understanding of MDA, we need not expose the domain model throughout the application layers & tiers The reason being that any change to the domain model has an impact in the overall application The wise thing to do would be to expose light-weight object (DTO's) which are a small sub-set of the domain model to abstract the actual model On the flip side, any change to the domain model would mean changing various DTO's throughout the application for the change to be visible, while if we do expose the domain model, then the change is in a single location Hope to see some comments & thoughts about this. Appreciate all the help!

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• Real life Java Swing Project

  - by santiagobasulto

  Hi everybody! I've been working with swing for the last 2 years, but i'm still not satisfy with my own work. The apps are "fast" enough, but the development isn't enough "clean". Can you recommend me any real world project, book, or something similar that shows me how a real world swing app work. May be a framework, something structured, etc. For example, i'm thinking i may code a "window manager" that has all the window of the app in an unified resource, may be cached, etc. I think all those good ideas must be implemented already. Thanks!

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• Sort database entries via a dropdown list

  - by Lin

  Hello! I'm curious if anyone could possibly help me, because I can't find anything exactly related to it anywhere, and it's driving me nuts. I'd like to have a dropdown list on a page, that will give the visitor the option to sort all entries by year. I have entries from i.e. 2001, 2005, 2009, 2010. The years should be displayed in the dropdown, so the visitor can easily just select all entries dated 2001 if they want. The year for each entry is located in the one database table I have. In other words, I simply want a "sort by" dropdown that you can see on pretty much any shopping site nowadays. But with set years. Thanks in advance for any replies!

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• The way cores, processes, and threads work exactly?

  - by unknownthreat

  I need a bit of an advice for understanding how this whole procedure work exactly. If I am incorrect in any part described below, please correct me. In a single core CPU, it runs each process in the OS, jumping around from one process to another to utilize the best of itself. A process can also have many threads, in which the CPU core runs through these threads when it is running on the respective process. Now, on a multiple core CPU, Do the cores run in every process together, or can the cores run separately in different processes at one particular point of time? For instance, you have program A running two threads, can a duo core CPU run both threads of this program? I think the answer should be yes if we are using something like OpenMP. But while the cores are running in this OpenMP-embedded process, can one of the core simply switch to other process? For programs that are created for single core, when running at 100%, why the CPU utilization of each core are distributed? (ex. A duo core CPU of 80% and 20%. The utilization percentage of all cores always add up to 100% for this case.) Do the cores try help each other run each thread of each process in some ways? Frankly, I'm not sure how this works exactly. Any advice is appreciated.

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• designing multi module J2EE application

  - by user728947

  Might be my question is abstract or out of context, but i am asking here since i have little idea how this happens. I am wondering how big application/ platform break down there application in to multiple module and how they able to manage modules dependencies. For example in some E-commerce application they tend to break down it in various modules like pricing,promotions,shipping.import/export and many more. when we develop those application we hardly think about the underlying modules and how they have been designed to provides functionalists. Most of those module are not web-applications but are standalone module and not deployed in the web-app as jar files. can any one help me to understand how they break up things or is there any standard way to do this.any help/resources to get insight will really be helpful

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• The one true domain model - a fallacy?

  - by James L

  I've just finished working for a client which has burnt millions on a project to come up with the 'one true domain model' for their business. This was the project's sole deliverable. What are your thoughts on this? Is a single version of the truth realistic?

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• Updating my database

  - by Malcolm

  I am new with the subsonic, and I have a problem when trying to update the database from the sql server. I have created a gridview by still is not returning the updates results. can you please help me? its getting an error code on dc.AddMostaHse(); (Cannot implicity convert type 'void to 'object') Here is the code being done of DataAccess.cs page public void AddMostaHse() { Mosta.MostaHSE1 xx = new MostaHSE1(); xx.ID = 94; xx.FunctionLocation = "lza94"; xx.acno = 12; xx.Save(); } Binding it with the gridview. { DataAccess dc = new DataAccess(); gvtest.DataSource = dc.AddMostaHse(); gvtest.DataBind(); }

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• Turn database result into array

  - by Industrial

  Hi everyone, I have just made the update/add/delete part for the "Closure table" way of organizing query hierarchical data that are shown on page 70 in this slideshare: http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back My database looks like this: Table Categories: ID Name 1 Top value 2 Sub value1 Table CategoryTree: child parent 1 1 2 2 2 1 However, I have a bit of an issue getting the full tree back as an multidimensional array from a single query. Here's what I would like to get back: array ( 'topvalue' = array ( 'Subvalue', 'Subvalue2', 'Subvalue3' = array ('Subvalue 1', 'Subvalue 2', 'Subvalue 3' ) ); ); Update: Found this link, but I still have a hard time to convert it into an array: http://karwin.blogspot.com/2010/03/rendering-trees-with-closure-tables.html

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• What are the best ways to scale small business applications ?

  - by Rachel

  I have one small online sale business but I want to make it scalable at limited expense and so am looking out at various services which can help me make my business scalable. I was looking into Amazon Web Services and it seems to be a viable option. Are there any other ways for adding scalability to small online businesses ?

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• What's the benefits of SOA over OO?

  - by ghedas

  I want to know the differences between SOA and OO, and why SOA is going to popular?

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• Replace singletons with what?

  - by fig-gnuton

  Singletons are so often said to be a bad design choice, so how should you design an application when you want to avoid them?

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• Update database in asp.net not working

  - by Badescu Alexandru

  Hello ! i have in asp.net a few textboxes and i wish to update my database with the values that they encapsulate . The problem is that it doesn't work and although it doesn't work, the syntax seems correct and there are no errors present . Here is my linkbutton : <asp:linkbutton id="clickOnSave" runat="server" onclick="Save_Click" Text="Save Profile" /> and my update function protected void Save_Click(object sender, EventArgs e) { SqlConnection con = new System.Data.SqlClient.SqlConnection(); con.ConnectionString = "DataSource=.\\SQLEXPRESS;AttachDbFilename=C:\\Users\\alex\\Documents\\seeubook_db.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"; con.Open(); String commandString = "UPDATE users SET last_name='" + Text4.Text.Trim() + "' , first_name='" + Textbox1.Text.Trim() + "' , about_me='" + Textbox5.Text.Trim() + "' , where_i_live='" + Textbox2.Text.Trim() + "' , where_i_was_born='" + Textbox3.Text.Trim() + "' , work_place='" + Textbox4.Text.Trim() + "' WHERE email='" + Session["user"] + "'"; SqlCommand sqlCmd = new SqlCommand(commandString, con); sqlCmd.ExecuteNonQuery(); con.Close(); }

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• Is there some way to test your code on Solaris through the web?

  - by eSKay

  Both Ideone and Codepad have Little endian architechtures. I want to test my code on some machine with big-endian architechture (for example - Solaris - which I don't have). Is there some way that you know about?

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