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• Using design-patterns to transform web-service model classes into local model classes and vise versa

  - by Daniil Petrov

  There is a web-application built with play framework 1.2.7. It contains less than 10 model classes. The main purpose of the application is a lightweight access to a complex remote application (more than 50 model classes). The remote application has its own SOAP API and we use it for synchronization of data. There is a scheduled job in the web-app which makes requests to the remote app. It gets bunches of objects from the remote model and populates corresponding objects of the local model. Currently, there are two groups of classes - the local model and the remote model (generated from wsdl schema). It is not allowed to make any modifications to the remote model. Transformations are being made in the scheduled job class. When it gets objects from the remote app it creates local objects. Recently, it was decided to add a possibility to modify the remote objects. It requires more transformations on our side. We need to transform from remote to local model when reading objects and from local to remote when changing objects. I wonder if this would be possible to use some design-patterns to reduce a number of transformations?

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• Object oriented design importance

  - by user5507

  I started studying Object Oriented Design and Modelling using the this book by James Rumbaugh. It uses a tool called Object Modeling Technique (OMT). I have certain newbie questions. I searched the net, but couldn't get answers The book is pretty old. Don't know why the school told me to learn this. I know OMT is a predecessor of the Unified Modeling Language (UML). So its a waste? Whether the concepts change very much when we move from OMT to UML? I know OMT has Object, Dynamic and Functional Model. Wikipedia says UML is compatible with OMT and UML is a model too. As per wikipedia the UML models are Static and Dynamic and they are represented by different diagrams like class, object, activity, sequence..... I couldn't find the equivalence of this in OMT. I read that there are many object oriented development methods like OMT, Booch,.... Which one is used by Industry ? Where could I get a comparison of different Object oriented development methods?

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• Design pattern for window management in a Java Swing app

  - by Lord Torgamus

  I've just started creating my very first little Java Swing app. When the program opens, it brings up a single, simple window with a label and a couple buttons. Clicking one of those buttons is supposed to wipe out the welcome screen and replace it with a totally different panel. I'm not sure what the best way to create that functionality is. One method would be to pass my JFrame as an argument into... just about every other component, but that feels hacky to me. Or, there's making each panel double as an action listener, but that doesn't seem right, either. Is there a design pattern I should be applying here? "Replace the contents of the main — and only — window" must be a reasonably common operation. A name for the pattern would be enough; I can use Google on my own from there. (I wouldn't say no to a longer explanation, though.)

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• Android threads trouble wrapping my head around design

  - by semajhan

  I am having trouble wrapping my head around game design. On the android platform, I have an activity and set its content view with a custom surface view. The custom surface view acts as my panel and I create instances of all classes and do all the drawing and calculation in there. Question: Should I instead create the instances of other classes in my activity? Now I create a custom thread class that handles the game loop. Question: How do I use this one class in all my activities? Or do I have to create a separate instance of the extended thread class each time? In my previous game, I had multiple levels that had to create an instance of the thread class and in the thread class I had to set constructor methods for each separate level and in the loop use a switch statement to check which level it needs to render and update. Sorry if that sounds confusing. I just want to know if the method I am using is inefficient (which it probably is) and how to go about designing it the correct way. I have read many tutorials out there and I am still having lots of trouble with this particular topic. Maybe a link to a some tutorials that explain this? Thanks.

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• Which of these design patterns is superior?

  - by durron597

  I find I tend to design class structures where several subclasses have nearly identical functionality, but one piece of it is different. So I write nearly all the code in the abstract class, and then create several subclasses to do the one different thing. Does this pattern have a name? Is this the best way for this sort of scenario? Option 1: public interface TaxCalc { String calcTaxes(); } public abstract class AbstractTaxCalc implements TaxCalc { // most constructors and fields are here public double calcTaxes(UserFinancials data) { // code double diffNumber = getNumber(data); // more code } abstract protected double getNumber(UserFinancials data); protected double initialTaxes(double grossIncome) { // code return initialNumber; } } public class SimpleTaxCalc extends AbstractCalc { protected double getNumber(UserFinancials data) { double temp = intialCalc(data.getGrossIncome()); // do other stuff return temp; } } public class FancyTaxCalc extends AbstractTaxCalc { protected double getNumber(UserFinancials data) { int temp = initialCalc(data.getGrossIncome()); // Do fancier math return temp; } } Option 2: This version is more like the Strategy pattern, and should be able to do essentially the same sorts of tasks. public class TaxCalcImpl implements TaxCalc { private final TaxMath worker; public DummyImpl(TaxMath worker) { this.worker = worker; } public double calcTaxes(UserFinancials data) { // code double analyzedDouble = initialNumber; int diffNumber = worker.getNumber(data, initialNumber); // more code } protected int initialTaxes(double grossIncome) { // code return initialNumber; } } public interface TaxMath { double getNumber(UserFinancials data, double initial); } Then I could do: TaxCalc dum = new TaxCalcImpl(new TaxMath() { @Override public double getNumber(UserFinancials data, double initial) { double temp = data.getGrossIncome(); // do math return temp; }); And I could make specific implementations of TaxMath for things I use a lot, or I could make a stateless singleton for certain kinds of workers I use a lot. So the question I'm asking is: Which of these patterns is superior, when, and why? Or, alternately, is there an even better third option?

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• Android threads trouble wrapping my head around design

  - by semajhan

  I am having trouble wrapping my head around game design. On the android platform, I have an activity and set its content view with a custom surface view. The custom surface view acts as my panel and I create instances of all classes and do all the drawing and calculation in there. Question: Should I instead create the instances of other classes in my activity? Now I create a custom thread class that handles the game loop. Question: How do I use this one class in all my activities? Or do I have to create a separate thread each time? In my previous game, I had multiple levels that had to create an instance of the thread class and in the thread class I had to set constructor methods for each separate level and in the loop use a switch statement to check which level it needs to render and update. Sorry if that sounds confusing. I just want to know if the method I am using is inefficient (which it probably is) and how to go about designing it the correct way. I have read many tutorials out there and I am still having lots of trouble with this particular topic. Maybe a link to a some tutorials that explain this? Thanks.

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• Examples of limitations in IT due to different bit length by design

  - by Alaudo

  I am teaching the course "Introduction in Programming" for the first-year students and would like to find interesting examples where the datatype size in bits, chosen by design, led to certain known restrictions or important values. Here are some examples: Due to the fact that the Bell teleprinter used 7-bit-code (later accepted as ASCII) until now have we often to encode attachments in electronic messages to contain only 7 bit data. Classical limitation of 32-bit address space leads to the 4Gb maximal RAM size available for 32-bit systems and 4Gb maximal file size in FAT32. Do you know some other interesting examples how the choice of the data type (and especially its binary length) influenced the modern IT world. Added after some discussion in comments: I am not going to teach how to overcome limitations. I just want them to know that 1 byte can hold the values from -127..0..+127 o 0..255, 2 bytes cover the range 0..65535 etc by proving examples they know from other sources, like the above-mentioned base64 encoding etc. We are just learning the basic datatypes and I am trying to find a good reference for "how large" these types are.

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• 5 Mac Applications For Web And Graphic Design

  - by Jyoti

  In this article free applications useful and effective for the development and creation of websites with your Mac computer. Without further ado, here are 5 Excellent Mac Application for Web and Graphic Design. Fotoflexer : Fotoflexer claims to be “The world’s most advanced online image editor”. It offers completely free access to numerous features such as photo effects, graphics, shapes, morphing, and the creation of collages. You can also integrate and share your art with social sites like MySpace, Flickr, Facebook, and more. This can be an important app if the site you are creating is going to use applications. Simple CSS : With Simple CSS you can create Cascading Style Sheets from scratch or edit them right from the comfort of your desktop. Update styles on multiple pages all at once and reduce the data transfer usage on your page for faster loads. Blender : Blender is an open source software that allows you to create 3D animation with interactive playback leaves you with the option to optimize the style of your site with a few graphics. You can create animations with shades of colors, glossy features, soft shadows and advanced rendering features. JAlbum : Jalbum is a very useful app that allows you to create stylish photo galleries to publish on the web. All you have to do is simply drag selected folders into a pane where any images contained within the folder will automatically be arranged into a photo gallery. You can add several different themes and templates to enhance the appearance of your gallery, later then gain the HTML code and publish the complete gallery onto the web. Colorate : With Colorate you can create harmonized color palettes along with color schemes. Generate these palettes for images, photographs and more.

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• iOS chat application design, sending/relaying the message over to the end user

  - by AyBayBay

  I have a design question. Let us say you were tasked with building a chat application, specifically for iOS (iOS Chat Application). For simplicity let us say you can only chat with one person at a time (no group chat functionality). How then can you achieve sending a message directly to an end user from phone A to phone B? Obviously there is a web service layer with some API calls. One of the API calls available will be startChat(). After starting a chat, when you send a message, you make another async call, let us call it sendMessage() and pass in a string with your message. Once it goes to the web service layer, the message gets stored in a database. Here is where I am currently stuck. After the message gets sent to the web service layer, how do we then achieve sending/relaying the message over to the end user? Should the web server send out a message to the end user and notify them, or should each client call a receiveMessage() method periodically, and if the server side has some info for them it can then respond with that info? Finally, how can we handle the case in which the user you are trying to send a message to is offline? How can we make sure the end user gets the packet when he moves back to an area with signal?

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• Office design and layout for agile development

  - by Adam Eberbach

  (moved from stackoverflow) I have found lot of discussions here on about which keyboard, desk, light or colored background is best - but I can't find one addressing the layout of the whole office. We are a company with about 20 employees moving to a new place, something larger. There are two main development practices going on here with regular combination, the back end people often needing to work with the mobile people to arrange web services. There are about twice as many back end people as mobile people. About half of the back end developers are working on-site at any time and while they are almost never all in the office at once at least 5-10 spaces need to be provided - so most of the time the two groups are about equal. We have the chance to arrange desks, partitions and possibly even walls to make the space good. There won't be cash for dot-com frills like catering or massages but now's the time to be planning to avoid ending up with a bunch of desks in a long line. Joel on Software's Bionic Office is an article I've remembered from way back and it has some good ideas but I* (and more importantly the company's owners) are not completely sold on the privacy idea in an environment where we are supposed to be collaborating. This is another great link - The Ultimate Software Development Office Layout - I hadn't even remembered enclosed meeting rooms until reading this. Does the private office stand in the way of agile development? Is the scrum enough forced contact and if you need to bug someone you should need to get up and knock on their door? What design layouts can you point to and why would you recommend them? *I'm not against closed offices at all but would be happy if some other solution can do just as well. If it can't... well, that's what this question is all about.

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• Question about a simple design problem

  - by Uri

  At work I stumbled uppon a method. It made a query, and returned a String based on the result of the query, such as de ID of a customer. If the query didn't return a single customer, it'd return a null. Otherwise, it'd return a String with the ID's of them. It looked like this: String error = getOwners(); if (error != null) { throw new Exception("Can't delete, the flat is owned by: " + error); } ... Ignoring the fact that getCustomers() returns a null when it should instead return an empty String, two things are happening here. It checks if the flat is owned by someone, and then returns them. I think a more readable logic would be to do this: if (isOwned) { throw new Exception("Can't delete, the flat is owned by: " + getOwners()); } ... The problem is that the first way does with one query what I do with two queries to the database. What would be a good solution involving good design and efficiency for this?

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• Best design for a "Command Executer" class

  - by Justin984

  Sorry for the vague title, I couldn't think of a way to condense the question. I am building an application that will run as a background service and intermittently collect data about the system its running on. A second Android controller application will query the system over tcp/ip for statistics about the system. Currently, the background service has a tcp listener class that reads/writes bytes from a socket. When data is received, it raises an event to notify the service. The service takes the bytes, feeds them into a command parser to figure out what is being requested, and then passes the parsed command to a command executer class. When the service receives a "query statistics" command, it should return statistics over the tcp/ip connection. Currently, all of these classes are fully decoupled from each other. But in order for the command executer to return statistics, it will obviously need access to the socket somehow. For reasons I can't completely articulate, it feels wrong for the command executer to have a direct reference to the socket. I'm looking for strategies and/or design patterns I can use to return data over the socket while keeping the classes decoupled, if this is possible. Hopefully this makes sense, please let me know if I can include any info that would make the question easier to understand.

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• Design help with parallel process

  - by brazc0re

  I am re-factoring some code and an having an issue with retrieving data from two parallel processes. I have an application that sends packets back and forth via different mediums (ex: RS232, TCP/IP, etc). The jist if of this question is that there are two parallel processes going on. I hope the picture below displays what is going on better than I can word it: SetupRS232() class creates a new instance of the SerialPort by: SerialPort serialPort = new SerialPort(); My question is, what is the best way that the Communicator() class, which sends out the packet via the respective medium, get access to the SerialPort object from the SetupRS232 class? I can do it with a Singleton but have heard that they are generally not the best design to go by. I am trying to follow SRP but I do feel like I am doing something wrong here. Communicator() will need to go out of it's way to get access to SetupRS232() to get access to the SerialPort class. I actually haven't found a way to even get access to it. Would designing each medium class, for example, SetupRS232(), SetupTCPIP, as a singleton be the best way to approach this problem?

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• Help with design structure choice: Using classes or library of functions

  - by roverred

  So I have GUI Class that will call another class called ImageProcessor that contains a bunch functions that will perform image processing algorithms like edgeDetection, gaussianblur, contourfinding, contour map generations, etc. The GUI passes an image to ImageProcessor, which performs one of those algorithm on it and it returns the image back to the GUI to display. So essentially ImageProcessor is a library of independent image processing functions right now. It is called in the GUI like so Image image = ImageProcessor.EdgeDetection(oldImage); Some of the algorithms procedures require many functions, and some can be done in a single function or even one line. All these functions for the algorithms jam packed into ImageProcessor can be pretty messy, and ImageProcessor doesn't sound it should be a library. So I was thinking about making every algorithm be a class with a shared interface say IAlgorithm. Then I pass the IAlgorithm interface from the GUI to the ImageProcessor. public interface IAlgorithm{ public Image Process(); } public class ImageProcessor{ public Image Process(IAlgorithm TheAlgorithm){ return IAlgorithm.Process(); } } Calling in the GUI like so Image image = ImageProcessor.Process(new EdgeDetection(oldImage)); I think it makes sense in an object point of view, but the problem is I'll end up with some classes that are just one function. What do you think is a better design, or are they both crap and you have a much better idea? Thanks!

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• OOP Design: relationship between entity classes

  - by beginner_

  I have at first sight a simple issue but can't wrap my head around on how to solve. I have an abstract class Compound. A Compound is made up of Structures. Then there is also a Container which holds 1 Compound. A "special" implementation of Compound has Versions. For that type of Compound I want the Container to hold the Versionof the Compound and not the Compound itself. You could say "just create an interface Containable" and a Container holds 1 Containable. However that won't work. The reason is I'm creating a framework and the main part of that framework is to simplify storing and especially searching for special data type held by Structure objects. Hence to search for Containers which contain a Compound made up of a specific Structure requires that the "Path" from Containerto Structure is well defined (Number of relationships or joins). I hope this was understandable. My question is how to design the classes and relationships to be able to do what I outlined.

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• SQL SERVER – World Shapefile Download and Upload to Database – Spatial Database

  - by pinaldave

  During my recent, training I was asked by a student if I know a place where he can download spatial files for all the countries around the world, as well as if there is a way to upload shape files to a database. Here is a quick tutorial for it. VDS Technologies has all the spatial files for every location for free. You can download the spatial file from here. If you cannot find the spatial file you are looking for, please leave a comment here, and I will send you the necessary details. Unzip the file to a folder and it will have the following content. Then, download Shape2SQL tool from SharpGIS. This is one of the best tools available to convert shapefiles to SQL tables. Afterwards, run the .exe file. When the file is run for the first time, it will ask for the database properties. Provide your database details. Select the appropriate shape files and the tool will fill up the essential details automatically. If you do not want to create the index on the column, uncheck the box beside it. The screenshot below is simply explains the procedure. You also have to be careful regarding your data, whether that is GEOMETRY or GEOGRAPHY. In this example,  it is GEOMETRY data. Click “Upload to Database”. It will show you the uploading process. Once the shape file is uploaded, close the application and open SQL Server Management Studio (SSMS). Run the following code in SSMS Query Editor. USE Spatial GO SELECT * FROM dbo.world GO This will show the complete map of world after you click on Spatial Results in Spatial Tab. In Spatial Results Set, the Zoom feature is available. From the Select label column, choose the country name in order to show the country name overlaying the country borders. Let me know if this tutorial is helpful enough. I am planning to write a few more posts about this later. Note: Please note that the images displayed here do not reflect the original political boundaries. These data are pretty old and can probably draw incorrect maps as well. I have personally spotted several parts of the map where some countries are located a little bit inaccurately. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Spatial, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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• Distributed database technologies to share data between database systems

  This article is intended to illustrate the main concepts of distributed database technologies supporting the replication principles in order to share data among different database systems.

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• The Road to Professional Database Development: Database Normalization

  Not only is the process of normalization valuable for increasing data quality and simplifying the process of modifying data, but it actually makes the database perform much faster. To prove the point, Peter Larsson takes a large unnormalised database and subjects it to successive stages of normalisation. Get smart with SQL Backup ProGet faster, smaller backups with integrated verification.Quickly and easily DBCC CHECKDB your backups. Learn more.

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• ?????????????!??Oracle Exadata??????

  - by Yusuke.Yamamoto

  ????? ??:2010/11/24 ??:?????? ?? Oracle Exadata????????????????????!??????????????? Oracle Exadata ????????!??1??????????????????????????Oracle Exadata Database Machine???????? Oracle Exadata Database Machine ???Oracle Exadata Database Machine ??????????????????????/ For DWH?For OLTPOracle Exadata Database Machine X2 ????/ ?????????????Oracle Exadata Database Machine ????????? ????????? ????????????????? http://www.oracle.com/technology/global/jp/ondemand/otn-seminar/pdf/ord_exadata_public.pdf

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• Domain-Driven-Design question

  - by Michael

  Hello everyone, I have a question about DDD. I'm building a application to learn DDD and I have a question about layering. I have an application that works like this: UI layer calls = Application Layer - Domain Layer - Database Here is a small example of how the code looks: //****************UI LAYER************************ //Uses Ioc to get the service from the factory. //This factory would be in the MyApp.Infrastructure.dll IImplementationFactory factory = new ImplementationFactory(); //Interface and implementation for Shopping Cart service would be in MyApp.ApplicationLayer.dll IShoppingCartService service = factory.GetImplementationFactory<IShoppingCartService>(); //This is the UI layer, //Calling into Application Layer //to get the shopping cart for a user. //Interface for IShoppingCart would be in MyApp.ApplicationLayer.dll //and implementation for IShoppingCart would be in MyApp.Model. IShoppingCart shoppingCart = service.GetShoppingCartByUserName(userName); //Show shopping cart information. //For example, items bought, price, taxes..etc ... //Pressed Purchase button, so even for when //button is pressed. //Uses Ioc to get the service from the factory again. IImplementationFactory factory = new ImplementationFactory(); IShoppingCartService service = factory.GetImplementationFactory<IShoppingCartService>(); service.Purchase(shoppingCart); //**********************Application Layer********************** public class ShoppingCartService : IShoppingCartService { public IShoppingCart GetShoppingCartByUserName(string userName) { //Uses Ioc to get the service from the factory. //This factory would be in the MyApp.Infrastructure.dll IImplementationFactory factory = new ImplementationFactory(); //Interface for repository would be in MyApp.Infrastructure.dll //but implementation would by in MyApp.Model.dll IShoppingCartRepository repository = factory.GetImplementationFactory<IShoppingCartRepository>(); IShoppingCart shoppingCart = repository.GetShoppingCartByUserName(username); //Do shopping cart logic like calculating taxes and stuff //I would put these in services but not sure? ... return shoppingCart; } public void Purchase(IShoppingCart shoppingCart) { //Do Purchase logic and calling out to repository ... } } I've seem to put most of my business rules in services rather than the models and I'm not sure if this is correct? Also, i'm not completely sure if I have the laying correct? Do I have the right pieces in the correct place? Also should my models leave my domain model? In general I'm I doing this correct according DDD? Thanks!

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• Need suggestion for Mutiple Windows application design

  - by King Chan

  This was previously posted in StackOverflow, I just moved to here... I am using VS2008, MVVM, WPF, Prism to make a mutiple window CRM Application. I am using MidWinow in my MainWindow, I want Any ViewModel would able to make request to MainWindow to create/add/close MidChildWindow, ChildWindow(from WPF Toolkit), Window (the Window type). ViewModel can get the DialogResult from the ChildWindow its excutes. MainWindow have control on all opened window types. Here is my current approach: I made Dictionary of each of the windows type and stores them into MainWindow class. For 1, i.e in a CustomerInformationView, its CustomerInformationViewModel can execute EditCommand and use EventAggregator to tell MainWindow to open a new ChildWindow. CustomerInformationViewModel: CustomerEditView ceView = new CustomerEditView (); CustomerEditViewModel ceViewModel = CustomerEditViewModel (); ceView.DataContext = ceViewModel; ChildWindow cWindow = new ChildWindow(); cWindow.Content = ceView; MainWindow.EvntAggregator.GetEvent<NewWindowEvent>().Publish(new WindowEventArgs(ceViewModel.ViewModeGUID, cWindow )); cWindow.Show(); Notice that all my ViewModel will generates a Guid for help identifies the ChildWindow from MainWindow's dictionary. Since I will only be using 1 View 1 ViewModel for every Window. For 2. In CustomerInformationViewModel I can get DialogResult by OnClosing event from ChildWindow, in CustomerEditViewModel can use Guid to tell MainWindow to close the ChildWindow. Here is little question and problems: Is it good idea to use Guid here? Or should I use HashKey from ChildWindow? My MainWindows contains windows reference collections. So whenever window close, it will get notifies to remove from the collection by OnClosing event. But all the Windows itself doesn't know about its associated Guid, so when I remove it, I have to search for every KeyValuePair to compares... I still kind of feel wrong associate ViewModel's Guid for ChildWindow, it would make more sense if ChildWindow has it own ID then ViewModel associate with it... But most important, is there any better approach on this design? How can I improve this better?

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• How Would You Design This Table?

  - by sooprise

  I have to create a table where each row needs to store 50 number values. Each row will always need to store 50 number values. If this was a smaller number of values, I would just make fields for each of the values, but because there are 50, this approach seems a bit cumbersome (but since it will always be 50 values, maybe this is the correct approach?). Is there a way to store an array of values in a field? This seems like a nice solution, but the concept is almost identical to creating a relational database.

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• How can I design multi-threaded application for larger user base

  - by rokonoid

  Here's my scenario, I need to develop a scalable application. My user base may be over 100K, every user has 10 or more small tasks. Tasks check every minute with a third party application through web services, retrieving data which is written in the database, then the data is forwarded to it's original destination. So here's the processing of a small task: while(true){ Boolean isNewInformationAvailable = checkWhetherInformationIsAvailableOrNot(); If(isNewInformationAvailable ==true){ fetchTheData(); writeToDatabase(); findTheDestination(); deliverTheData(); isAvailable =false; } } As the application is large, how should I approach designing this? I'm going to use Java to write it. Should I use concurrency, and how would you manage the concurrency?

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• Good place to look for example Database Designs - Best practices

  - by Younes

  I have been given the task to design a database to store a lot of information for our company. Because the task is rather big and contains multiple modules where users should be able to do stuff, I'm worried about designing a good data model for this. I just don't want to end up with a badly designed database. I want to have some decent examples of database structures for contracts / billing / orders etc to combine those in one nice relational database. Are there any resources out there that can help me with some examples regarding this?

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• char take 1 byte in database?

  - by 5YrsLaterDBA

  does a char take 1 byte in database?

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