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• How can find out the device Id of my unmounted DVD?

  - by fred.bear

  When I put a DVD into the DVD drive, it appears in Nautilus Places, but is not automatically mounted. (this is by personal choice). In this unmounted state, mount (of course) reports nothing, and likewise for df.. but Nautilus is aware of the DVD hardware unit and has read the Label; which it shows in Places So it seems to me that Nautilus has already accessed the DVD devices (Did it temporarily mount it?)... The main point of my question was to determine how to find the device Id of an unmounted device .. but as I've been writing this, I now think it may not be as simple as that... This issue came up because I wanted to test this command cat iso-pieces.* | growisofs -Z /dev/dvd=/dev/stdin, but then realized that I didn't know how to get my DVD's device Id. ... and does the above command requires a mounted device, or does it write directly to the device? ... as you can see, I'm a bit vague about devices :) Come to think of it maybe Nautalus read the DVD device directly, because when all is said and done, something has to read/write directly to it. info growisofs says: Under Linux it will most likely be an ide-scsi device such as "/dev/scd0 How can I find this Id via a script?

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• Looking for an example of how a software project can be managed/deployed

  - by rguilbault

  My company is evaluating adopting off-the-shelf ALM products to aid in our development lifecycle; we currently use our own homegrown solutions to manage requirements gathering, specification documentation, testing, etc. One of the issues I am having is understanding how to move code between stages of development. We have what we call a pipeline, which consists of particular stops: [Source] - [QC] - [Production] At the first stop, the developer works out a solution to some requested change and performs individual testing. When that process is complete (and peer review has been performed), our ALM system physically moves the affected programs from the [Source] runtime environment to the [QC] runtime environment. This movement of code is triggered by advancing the status of the change request to match the stage of the pipeline. I have been searching the internet for a few days trying to find how the process is accomplished elsewhere -- I have read a bit about builds, automated testing, various ALM products, etc. but nowhere does any of this state how builds interact with initial change requests, what the triggers are, how dependencies are managed, how the various forms of testing are accommodated (e.g. unit testing, integration testing, regression testing), etc. Can anyone point me to any resources detailing specific workflows or attempt to explain (generically) how a change could/should be tracked and moved though the development lifecycle? I'd be very appreciative. Note: I've cleaned up the question to hopefully make it easier to understand. Also, I found another question (which I can't find now) that referenced this book, which sounds like it might be exactly what I am looking for -- not sure if I want to shell out the cash for it, though.

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• What is better for the overall performance and feel of the game: one setInterval performing all the work, or many of them doing individual tasks?

  - by Bane

  This question is, I suppose, not limited to Javascript, but it is the language I use to create my game, so I'll use it as an example. For now, I have structured my HTML5 game like this: var fps = 60; var game = new Game(); setInterval(game.update, 1000/fps); And game.update looks like this: this.update = function() { this.parseInput(); this.logic(); this.physics(); this.draw(); } This seems a bit inefficient, maybe I don't need to do all of those things at once. An obvious alternative would be to have more intervals performing individual tasks, but is it worth it? var fps = 60; var game = new Game(); setInterval(game.draw, 1000/fps); setInterval(game.physics, 1000/a); //where "a" is some constant, performing the same function as "fps" ... With which approach should I go and why? Is there a better alternative? Also, in case the second approach is the best, how frequently should I perform the tasks?

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• How do you plan your asynchronous code?

  - by NullOrEmpty

  I created a library that is a invoker for a web service somewhere else. The library exposes asynchronous methods, since web service calls are a good candidate for that matter. At the beginning everything was just fine, I had methods with easy to understand operations in a CRUD fashion, since the library is a kind of repository. But then business logic started to become complex, and some of the procedures involves the chaining of many of these asynchronous operations, sometimes with different paths depending on the result value, etc.. etc.. Suddenly, everything is very messy, to stop the execution in a break point it is not very helpful, to find out what is going on or where in the process timeline have you stopped become a pain... Development becomes less quick, less agile, and to catch those bugs that happens once in a 1000 times becomes a hell. From the technical point, a repository that exposes asynchronous methods looked like a good idea, because some persistence layers could have delays, and you can use the async approach to do the most of your hardware. But from the functional point of view, things became very complex, and considering those procedures where a dozen of different calls were needed... I don't know the real value of the improvement. After read about TPL for a while, it looked like a good idea for managing tasks, but in the moment you have to combine them and start to reuse existing functionality, things become very messy. I have had a good experience using it for very concrete scenarios, but bad experience using them broadly. How do you work asynchronously? Do you use it always? Or just for long running processes? Thanks.

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• Do cross reference database tables have a place in domain driven design?

  - by Mike Cellini

  First some background. Let's say we have a system where a customer is placing an order in a web interface. The items that customer is ordering can priced in various ways. Sometimes including the cost of delivery and sometimes not at all. That pricing effectively depends on a variety of factors including the vendor's own pricing model, that vendor's individual contracts with customers as well as that vendor's contracts with its own suppliers. Let's assume that once a customer places an order for a particular item and chooses a contract if any, the method of delivery can be determined by variables on those contracts. Those delivery methods also live in their own table in the database and have various properties consumed downstream. It makes sense that a cross reference or lookup table would store that information. That table would be loaded into the domain and could then be used to apply the appropriate delivery method while processing the order. Does this make sense in the context of domain driven design? Or is my thinking too relational? Is this logic that should be built into it's own class/method (I mean beyond apply the cross reference table data)?

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• How to refactor to cleaner version of maintaing states of the widget

  - by George

  Backstory I inherited a bunch of code that I'd like to refactor. It is a UI application written in javascript. Current state: We have main application which consist of several UI components. And each component has entry fields, textboxes, menus, etc), like "ticket", "customer information", etc. Based on input, where the application was called from, who is the user, we enable/disable, hide, show, change titles. Unfortunately, the app grew to the point where it is really hard to scale, add new features. Main the driver (application code) calls set/unset functions of the respective components. So a lot of the stuff look like this Main app unit function1() { **call_function2()** component1.setX(true); component1.setY(true); component2.setX(false); } call_function2() { // it may repeat some of the code function1 called } and we have a lot of this in the main union. I am cleaning this mess. What is the best way to maintain the state of widgets? Please let me know if you need me to clarify.

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• Do the benefits of Resin/Quercus outweigh the overhead?

  - by Craige

  Lately, I've been looking more and more into Resin + Quercus as a technology to develop an application of mine. The reason I started looking into it was that this application has high reporting needs, a lot of which cannot (or realistically, should not) be created in real-time. Java would offer a nice backend to queue and generate reports. Also, with Quercus I would be able to develop my data models in Hibernate, and use them "from PHP", thus effectively stretching these models across front and back-end. This same concept would also apply to any front/back-end common business logic, which could be developed in Java libraries. Now, the downside is that whichever front-end (PHP) MVC Framework I choose (my goal was Symfony 2), it is unlikely to work without some heavy modification, if it can work at all. Quercus is a pretty close implementation of PHP, and is supposed to be compatible with PHP5.3, so namespaces and closures SHOULDN'T be a problem, but when I tried to run an existing Symfony 1.4 app, I failed miserably. So, my question to you is, do you think the benefits of Resin + Quercus outweigh the overhead of using a not-so-perfect/stable implementation of PHP? If this were your application, and your goal was and end-product, rather than educational purposes, what would you decide?

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• Learning how to design knowledge and data flow [closed]

  - by max

  In designing software, I spend a lot of time deciding how the knowledge (algorithms / business logic) and data should be allocated between different entities; that is, which object should know what. I am asking for advice about books, articles, presentations, classes, or other resources that would help me learn how to do it better. I code primarily in Python, but my question is not really language-specific; even if some of the insights I learn don't work in Python, that's fine. I'll give a couple examples to clarify what I mean. Example 1 I want to perform some computation. As a user, I will need to provide parameters to do the computation. I can have all those parameters sent to the "main" object, which then uses them to create other objects as needed. Or I can create one "main" object, as well as several additional objects; the additional objects would then be sent to the "main" object as parameters. What factors should I consider to make this choice? Example 2 Let's say I have a few objects of type A that can perform a certain computation. The main computation often involves using an object of type B that performs some interim computation. I can either "teach" A instances what exact parameters to pass to B instances (i.e., make B "dumb"); or I can "teach" B instances to figure out what needs to be done when looking at an A instance (i.e., make B "smart"). What should I think about when I'm making this choice?

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• Java game design question (graphical objects)

  - by vemalsar

  Hello Guys, I'm beginner in game development, in Java and here on this site too and I have a game design question. Please comment my idea: I have a main loop which call update and draw method. I want to use an ArrayList which store graphical objects, they have coordinate and image or text to draw and my game objects extends this class. In update, I can choose which objects should be put in the array and in draw method I'll display the elements of array on the screen. I'm using a buffer and draw first there, but it is not important now I guess...Here is a simple (not full) code, only the logic: public class GamePanel extends JPanel implements KeyListener { ArrayList<graphicalObjects> graphArray = new ArrayList<graphicalObjects>(); public void update() { //change the game scene, update the graphArray, process input etc. } public void draw() { //draws every element of graphArray to a JPanel } public static main(String[] args) { while(true) { update(); draw(); } } } My questions: Should have I use interface or abstract class for graphicalObjects? graphicalObjects class and the ArrayList really needs or there is some better solution? How to draw objects? They draw themself with their own method or in the draw method I have to draw manually based on graphicalObjects variables (x,y coordinates, image etc.)? If this conception is wrong, please suggest another one! All comments are welcome and sorry if this is dumb question, thanks!

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• Preferred way for dealing with customer-defined data in enterprise application

  - by Axarydax

  Let's say that we have a small enterprise web (intranet) application for managing data for car dealers. It has screens for managing customers, inventory, orders, warranties and workshops. This application is installed at 10 customer sites for different car dealers. First version of this application was created without any way to provide for customer-specific data. For example, if dealer A wanted to be able to attach a photo to a customer, dealer B wanted to add e-mail contact to each workshop, and dealer C wanted to attach multiple PDF reports to a warranty, each and every feature like this was added to the application, so all of the customers received everything on new update. However, this will inevitably lead to conflicts as the number of customers grow as their usage patterns are unique, and if, for instance, a specific dealer requested to have an ability to attach (for some reason) a color of inventory item (and be able to search by this color) as a required item, others really wouldn't need this feature, and definitely will not want it to be a required item. Or, one dealer would like to manage e-mail contacts for their employees on a separate screen of the application. I imagine that a solution for this is to use a kind of plugin system, where we would have a core of the application that provides for standard features like customers, inventory, etc, and all of the customer's installed plugins. There would be different kinds of plugins - standalone screens like e-mail contacts for employees, with their own logic, and customer plugin which would extend or decorate inventory items (like photo or color). Inventory (customer,order,...) plugins would require to have installation procedure, hooks for plugging into the item editor, item displayer, item filtering for searching, backup hook and such. Is this the right way to solve this problem?

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• TechEd 2012: Fast SQL Server

  - by Tim Murphy

  While I spend a certain amount of my time creating databases (coding around SQL Server and setup a server when I have to) it isn’t my bread and butter.  Since I have run into a number of time that SQL Server needed to be tuned I figured I would step out of my comfort zone and see what I can learn. Brent Ozar packed a mountain of information into his session on making SQL Server faster.  I’m not sure how he found time to hit all of his points since he was allowing the audience abuse him on Twitter instead of asking questions, but he managed it.  I also questioned his sanity since he appeared to be using a fruit laptop. He had my attention though when he stated that he had given up on telling people to not use “select *”. He posited that it could be fixed with hardware by caching the data in memory.  He continued by cautioning that having too many indexes could defeat this approach.  His logic was sound if not always practical, but it was a good place to start when determining the trade-offs you need to balance.  He was moving pretty fast, but I believe he was prescribing this solution predominately for OLTP database prior to moving on to data warehouse solutions. Much of the advice he gave for data warehouses is contained in the Microsoft Fast Track guidance so I won’t rehash it here.  To summarize the solution seems to be the proper balance memory, disk access speed and the speed of the pipes that get the data from storage to the CPU.  It appears to be sound guidance and the session gave enough information that going forward we should be able to find the details needed easily.  Just what the doctor ordered. del.icio.us Tags: SQL Server,TechEd,TechEd 2012,Database,Performance Tuning

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• Access Control Service: Walkthrough Videos of Web Application, SOAP, REST and Silverlight Integration

  - by Your DisplayName here!

  Over the weekend I worked a little more on my ACS2 sample. Instead of writing it all down, I decided to quickly record four short videos that cover the relevant features and code. Have fun ;) Part 1 – Overview This video does a quick walkthrough of the solution and shows the web application part. This includes driving the sign in UI via JavaScript (thanks Matias) as well as the registration logic I wrote about here. watch Part 2 – SOAP Service and Client The sample app also exposes a WCF SOAP service. This video shows how to wire up the service to ACS and hows how to create a client that first requests a token from an IdP and then sends this token to ACS. watch Part 3 – REST Service and Client This part shows how to set up a WCF REST service that consumes SWT tokens from ACS. Unfortunately there is currently no standard WIF plumbing for REST. For the service integration I had to combine a lot of code from different sources (kzu, zulfiq) as well as the WIF SDK and OAuth CTPs together. But it is working. watch Part 4 – Silverlight and Web Identity Integration This part took by far the most time to write. The Silverlight Client shows ho to sign in to the application using a registered identity provider (including web identities) and using the resulting SWT token to call our REST service. This is designed to be a desktop (OOB) client application (thanks to Jörg for the UI magic). watch code download

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• Integrating Amazon EC2 in Java via NetBeans IDE

  - by Geertjan

  Next, having looked at Amazon Associates services and Amazon S3, let's take a look at Amazon EC2, the elastic compute cloud which provides remote computing services. I started by launching an instance of Ubuntu Server 14.04 on Amazon EC2, which looks a bit like this in the on-line AWS Management Console, though I whitened out most of the details: Now that I have at least one running instance available on Amazon EC2, it makes sense to use the services that are integrated into NetBeans IDE:  I created a new application with one class, named "AmazonEC2Demo". Then I dragged the "describeInstances" service that you see above, with the mouse, into the class. Then the IDE automatically created all the other files you see below, i.e., 4 Java classes and one properties file: In the properties file, register the access ID and secret keys. These are read by the other generated Java classes. Signing and authentication are done automatically by the code that is generated, i.e., there's nothing generic you need to do and you can immediately begin working on your domain-specific code. Finally, you're now able to rewrite the code in "AmazonEC2Demo" to connect to Amazon EC2 and obtain information about your running instance: public class AmazonEC2Demo { public static void main(String[] args) { String instanceId1 = "i-something"; RestResponse result; try { result = AmazonEC2Service.describeInstances(instanceId1); System.out.println(result.getDataAsString()); } catch (IOException ex) { Logger.getLogger(AmazonEC2Demo.class.getName()).log(Level.SEVERE, null, ex); } } } From the above, you'll receive a chunk of XML with data about the running instance, it's name, status, dates, etc. In other words, you're now ready to integrate Amazon EC2 features directly into the applications you're writing, without very much work to get started. Within about 5 minutes, you're working on your business logic, rather than on the generic code that anyone needs when integrating with Amazon EC2.

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• Call DB Stored Procedure using @NamedStoredProcedureQuery Injection

  - by anwilson

  Oracle Database Stored Procedure can be called from EJB business layer to perform complex DB specific operations. This approach will avoid overhead from frequent network hits which could impact end-user result. DB Stored Procedure can be invoked from EJB Session Bean business logic using org.eclipse.persistence.queries.StoredProcedureCall API. Using this approach requires more coding to handle the Session and Arguments of the Stored Procedure, thereby increasing effort on maintenance. EJB 3.0 introduces @NamedStoredProcedureQuery Injection to call Database Stored Procedure as NamedQueries. This blog will take you through the steps to call Oracle Database Stored Procedure using @NamedStoredProcedureQuery.EMP_SAL_INCREMENT procedure available in HR schema will be used in this sample.Create Entity from EMPLOYEES table.Add @NamedStoredProcedureQuery above @NamedQueries to Employees.java with definition as given below - @NamedStoredProcedureQuery(name="Employees.increaseEmpSal", procedureName = "EMP_SAL_INCREMENT", resultClass=void.class, resultSetMapping = "", returnsResultSet = false, parameters = { @StoredProcedureParameter(name = "EMP_ID", queryParameter = "EMPID"), @StoredProcedureParameter(name = "SAL_INCR", queryParameter = "SALINCR")} ) Observe how Stored Procedure's arguments are handled easily in  @NamedStoredProcedureQuery using @StoredProcedureParameter.Expose Entity Bean by creating a Session Facade.Business method need to be added to Session Bean to access the Stored Procedure exposed as NamedQuery. public void salaryRaise(Long empId, Long salIncrease) throws Exception { try{ Query query = em.createNamedQuery("Employees.increaseEmpSal"); query.setParameter("EMPID", empId); query.setParameter("SALINCR", salIncrease); query.executeUpdate(); } catch(Exception ex){ throw ex; } } Expose business method through Session Bean Remote Interface. void salaryRaise(Long empId, Long salIncrease) throws Exception; Session Bean Client is required to invoke the method exposed through remote interface.Call exposed method in Session Bean Client main method. final Context context = getInitialContext(); SessionEJB sessionEJB = (SessionEJB)context.lookup("Your-JNDI-lookup"); sessionEJB.salaryRaise(new Long(200), new Long(1000)); Deploy Session BeanRun Session Bean Client.Salary of Employee with Id 200 will be increased by 1000.

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• How to rotate a group of objects around a common center?

  - by user1662292

  I've made a model in 3D Studio Max 9. It consists of a variety of cubes, clyinders etc. In XNA I've imported the model okay and it shows correctly. However, when I apply rotation, each component in the model rotates around it's own centre. I want the model to rotate as a single unit. I've linked the components in 3D Max and they rotate as I want in Max. protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); model = Content.Load<Model>("Models/Alien1"); } protected override void Update(GameTime gameTime) { camera.Update(1f, new Vector3(), graphics.GraphicsDevice.Viewport.AspectRatio); rotation += 0.1f; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); Matrix[] transforms = new Matrix[model.Bones.Count]; model.CopyAbsoluteBoneTransformsTo(transforms); Matrix worldMatrix = Matrix.Identity; Matrix rotationYMatrix = Matrix.CreateRotationY(rotation); Matrix translateMatrix = Matrix.CreateTranslation(location); worldMatrix = rotationYMatrix * translateMatrix; foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = worldMatrix * transforms[mesh.ParentBone.Index]; effect.View = camera.viewMatrix; effect.Projection = camera.projectionMatrix; effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; } mesh.Draw(); } base.Draw(gameTime); } More Info: Rotating the object via it's properties works fine so I'm guessing there's something up with the code rather than with the object itself. Translating the object also causes the objects to get moved independently of each other rather than as a single model and each piece becomes spread around the scene. The model is in .X format.

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• PyQt application architecture

  - by L. De Leo

  I'm trying to give a sound structure to a PyQt application that implements a card game. So far I have the following classes: Ui_Game: this describes the ui of course and is responsible of reacting to the events emitted by my CardWidget instances MainController: this is responsible for managing the whole application: setup and all the subsequent states of the application (like starting a new hand, displaying the notification of state changes on the ui or ending the game) GameEngine: this is a set of classes that implement the whole game logic Now, the way I concretely coded this in Python is the following: class CardWidget(QtGui.QLabel): def __init__(self, filename, *args, **kwargs): QtGui.QLabel.__init__(self, *args, **kwargs) self.setPixmap(QtGui.QPixmap(':/res/res/' + filename)) def mouseReleaseEvent(self, ev): self.emit(QtCore.SIGNAL('card_clicked'), self) class Ui_Game(QtGui.QWidget): def __init__(self, window, *args, **kwargs): QtGui.QWidget.__init__(self, *args, **kwargs) self.setupUi(window) self.controller = None def place_card(self, card): cards_on_table = self.played_cards.count() + 1 print cards_on_table if cards_on_table <= 2: self.played_cards.addWidget(card) if cards_on_table == 2: self.controller.play_hand() class MainController(object): def __init__(self): self.app = QtGui.QApplication(sys.argv) self.window = QtGui.QMainWindow() self.ui = Ui_Game(self.window) self.ui.controller = self self.game_setup() Is there a better way other than injecting the controller into the Ui_Game class in the Ui_Game.controller? Or am I totally off-road?

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• Reflection velocity

  - by MindSeeker

  I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't find a tutorial that tackles this problem and includes the nitty gritty math/code to verify what I'm doing). If it is right, is there a better/faster/more elegant way to do this? Note that the object (this) is the moving circle, and the EntPointer object is the immovable circle. //take vector separating the two centers <x, y>, and then get unit vector of the result: MathVector2d unitnormal = MathVector2d(this -> Retxpos() - EntPointer -> Retxpos(), this -> Retypos() - EntPointer -> Retypos()).UnitVector(); //take tangent <-y, x> of the unitnormal: MathVector2d unittangent = MathVector2d(-unitnormal.ycomp, unitnormal.xcomp); MathVector2d V1 = MathVector2d(this -> Retxvel(), this -> Retyvel()); //Calculate the normal and tangent vector lengths of the velocity: (the normal changes, the tangent stays the same) double LengthNormal = DotProduct(unitnormal, V1); double LengthTangent = DotProduct(unittangent, V1); MathVector2d VelVecNewNormal = unitnormal.ScalarMultiplication(-LengthNormal); //the negative of what it was before MathVector2d VelVecNewTangent = unittangent.ScalarMultiplication(LengthTangent); //this stays the same MathVector2d NewVel = VectorAddition(VelVecNewNormal, VelVecNewTangent); //combine them xvel = NewVel.xcomp; //and then apply them yvel = NewVel.ycomp; Note also that this question is just about velocity, the position code is handled elsewhere (in other words, assume that this code is implemented at the exact moment that the circles begin to overlap). Thanks in advance for your help and time!

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• Translating an object along its heading

  - by Kuros

  I am working on a simulation that requires me to have several objects moving around in 3D space (text output of their current position on the grid and heading is fine, I do not need graphics), and I am having some trouble getting objects to move along their relative headings. I have a basic understanding of vectors and matrices. I am using a vector to represent their position, and I am also using Euler Angles. I can translate one of my entities with a matrix along whatever axis, and I can alter their heading. For example, if I have an entity at (order is XYZ) 1, 1, 1, with a heading of 0, I can apply a translation matrix to get them to talk to 1, 1, 2 fine. However, if I change their heading to 270, they still walk to 1, 1, 3, instead of 2, 1, 2 as I desire. I have a feeling that my problem lies in not translating my matrix from world space to object space, but I am not sure how to go about that. How can I do this? Addition: I am using 3D vectors to represent their current position and their heading (using the three euler angles). For now, all I want to do is have an entity walk in a square, reporting their current position at each step. So, assuming it starts at 10, 10, 10 I want it to walk as follows: 10,10,10 -> 10, 10, 15 10, 10, 15 -> 5, 10, 15 5, 10, 15 -> 5, 10, 10 5, 10, 10 -> 10, 10, 10 My 1 Z unit translation matrix is as follows: [1 0 0 0] [0 1 0 0] [0 0 1 1] [0 0 0 1] My rotation matrix is as follows: [0 0 1 0] [0 1 0 0] [-1 0 0 0] [0 0 0 1]

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• How to choose between using a Domain Event, or letting the application layer orchestrate everything

  - by Mr Happy

  I'm setting my first steps into domain driven design, bought the blue book and all, and I find myself seeing three ways to implement a certain solution. For the record: I'm not using CQRS or Event Sourcing. Let's say a user request comes into the application service layer. The business logic for that request is (for whatever reason) separated into a method on an entity, and a method on a domain service. How should I go about calling those methods? The options I have gathered so far are: Let the application service call both methods Use method injection/double dispatch to inject the domain service into the entity, letting the entity do it's thing and then let it call the method of the domain service (or the other way around, letting the domain service call the method on the entity) Raise a domain event in the entity method, a handler of which calls the domain service. (The kind of domain events I'm talking about are: http://www.udidahan.com/2009/06/14/domain-events-salvation/) I think these are all viable, but I'm unable to choose between them. I've been thinking about this a long time and I've come to a point where I no longer see the semantic differences between the three. Do you know of some guidelines when to use what?

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• I don't understand how TDD helps me get a good design if I need a design to start testing it

  - by Michael Stum

  I'm trying to wrap my head around TDD, specifically the development part. I've looked at some books, but the ones I found mainly tackle the testing part - the History of NUnit, why testing is good, Red/Green/Refactor and how to create a String Calculator. Good stuff, but that's "just" Unit Testing, not TDD. Specifically, I don't understand how TDD helps me get a good design if I need a Design to start testing it. To illustrate, imagine these 3 requirements: A catalog needs to have a list of products The catalog should remember which products a user viewed Users should be able to search for a product At this points, many books pull a magic rabbit out of a hat and just dive into "Testing the ProductService", but they don't explain how they came to the conclusion that there is a ProductService in the first place. That is the "Development" part in TDD that I'm trying to understand. There needs to be an existing design, but stuff outside of entity-services (that is: There is a Product, so there should be a ProductService) is nowhere to be found (e.g., the second requirement requires me to have some concept of a User, but where would I put the functionality to remind? And is Search a feature of the ProductService or a separate SearchService? How would I know which I should choose?) According to SOLID, I would need a UserService, but if I design a system without TDD, I might end up with a whole bunch of Single-Method Services. Isn't TDD intended to make me discover my design in the first place? I'm a .net developer, but Java resources would also work. I feel that there doesn't seem to be a real sample application or book that deals with a real line of business application. Can someone provide a clear example that illustrates the process of creating a design using TDD?

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• Information I need to know as a Java Developer [on hold]

  - by Woy

  I'm a java developer. I'm trying to get more knowledge to become a better programmer. I've listed a number of technologies to learn. Instead of what I've listed, what technologies would you suggest to learn as well for a Junior Java Developer? I realize, there's a lot of things to study. Java: - how a garbage collector works - resource management - network programming - TCP/IP HTTP - transactions, - consistency: interfaces, classes collections, hash codes, algorithms, comp. complexity concurrent programming: synchronizing, semafores steam management metability: thread-safety byte code manipulations, reflections, Aspect-Oriented Programming as base to understand frameworks such as Spring etc. Web stack: servlets, filters, socket programming Libraries: JDK, GWT, Apache Commons, Joda-Time, Dependency Injections: Spring, Nano Tools: IDE: very good knowledge - debugger - profiler - web analyzers: Wireshark, firebugs - unit testing SQL/Databases: Basics SELECTing columns from a table Aggregates Part 1: COUNT, SUM, MAX/MIN Aggregates Part 2: DISTINCT, GROUP BY, HAVING + Intermediate JOINs, ANSI-89 and ANSI-92 syntax + UNION vs UNION ALL x NULL handling: COALESCE & Native NULL handling Subqueries: IN, EXISTS, and inline views Subqueries: Correlated ITH syntax: Subquery Factoring/CTE Views Advanced Topics Functions, Stored Procedures, Packages Pivoting data: CASE & PIVOT syntax Hierarchical Queries Cursors: Implicit and Explicit Triggers Dynamic SQL Materialized Views Query Optimization: Indexes Query Optimization: Explain Plans Query Optimization: Profiling Data Modelling: Normal Forms, 1 through 3 Data Modelling: Primary & Foreign Keys Data Modelling: Table Constraints Data Modelling: Link/Corrollary Tables Full Text Searching XML Isolation Levels Entity Relationship Diagrams (ERDs), Logical and Physical Transactions: COMMIT, ROLLBACK, Error Handling

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• what's a good approach to working with multiple databases?

  - by Riz

  I'm working on a project that has its own database call it InternalDb, but also it queries two other databases, call them ExternalDb1 and ExternalDb2. Both ExternalDb1 and ExternalDb2 are actually required by a few other projects. I'm wondering what the best approach for dealing with this is? Currently, I've just created a project for each of these external databases and then generated Edmx and entities using the entity-framework approach. My thought was that I could then include these projects in any of my solutions that require access to these databases. Also, I don't have any separate business layers. I just have a solution like below: Project.Domain ExternalDb1Project.Domain ExternalDb2Project.Domain Project.Web So my Domain projects contain the data access as well as the POCOs generated by Entity Framework and any business logic. But I'm not sure if this is a good approach. For example if I want to do Validation in my Project.Domain on the entities in the InternalDb, it's fine. But if I want to do Validation for entities from either of the ExternalDbs, then I wonder where it should go? To be more specific, I retrieve Employees from ExternalDb1Project.Domain. However, I want to make sure they are Active. Where should this Validation go? How to architect a project like this at a high level? Also, I want to make sure that I use IoC for my data contexts so I can create Fakes when writing tests. I wonder where the interfaces for these various data contexts would reside?

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• Guidelines for creating referentially transparent callables

  - by max

  In some cases, I want to use referentially transparent callables while coding in Python. My goals are to help with handling concurrency, memoization, unit testing, and verification of code correctness. I want to write down clear rules for myself and other developers to follow that would ensure referential transparency. I don't mind that Python won't enforce any rules - we trust ourselves to follow them. Note that we never modify functions or methods in place (i.e., by hacking into the bytecode). Would the following make sense? A callable object c of class C will be referentially transparent if: Whenever the returned value of c(...) depends on any instance attributes, global variables, or disk files, such attributes, variables, and files must not change for the duration of the program execution; the only exception is that instance attributes may be changed during instance initialization. When c(...) is executed, no modifications to the program state occur that may affect the behavior of any object accessed through its "public interface" (as defined by us). If we don't put any restrictions on what "public interface" includes, then rule #2 becomes: When c(...) is executed, no objects are modified that are visible outside the scope of c.__call__. Note: I unsuccessfully tried to ask this question on SO, but I'm hoping it's more appropriate to this site.

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• Motivation for service layer (instead of just copying dlls)?

  - by BornToCode

  I'm creating an application which has 2 different UIs so I'm making it with a service layer which I understood is appropriate for such case. However I found myself just creating web methods for every single method I have in the BL layer, so the services basically built from methods that looks like this: return customers_bl.Get_Customer_Prices(customer_id); I understood that a main point of the service layer is to prevent duplication of code so I asked myself - well, why not just import the BL.dll (and the DAL.dll) to the other UI, and whenever making a change re-copy the dll files, it might not be so 'neat', but is the all purpose of the service layer to prevent this? {I know something is wrong in my approach, I'm probably missing the importance of service layer, I'd like to get more motivation to create another layer, especially because as it is I found that many of my BL functions ALREADY looks like: return customers_dal.Get_Customer_Prices(cust_id) which led me to ask: was it really necessary to create the BL just because on several functions I actually have LOGIC inside the BL?} so I'm looking for more motivation to creating ONE MORE layer, I'm sure it's not just to make it more convenient that I won't have to re-copy the dlls on changes? Am I grasping it wrong? Any simple guidelines on how to design service layer (corresponding to all the BL layer functions or not? any simple example?) any enlightenment on the subject?

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• What are most demanded web-development languages today for startups?

  - by Liston Catch

  What technologies are in demand nowaydas for web-development for web-startups? For frontend its all clear: HTML5, JS, AJAX, JQuery. But what about backend? What languages (and frameworks) should I consider using? I am not asking "which language is best", I just need a list of modern languages and frameworks (and not Pascal, Delphi or Basic) which are demanded and well-payed. UPD: I totally decline the "it's all about logic, not about language. language is just a tool" concept. While THEORETICALLY it's true, in reality the time you need to study required frameworks is counted by months, so language DOES matter indeed. That's why I made this topic UPD 2: Mason Wheeler, so you seriously advice me to go for Delphi? You think its DEMANDED nowadays? Or you just tell me an exception which only confirms the rule? It's like "one guy won 100,000,000$ in lottery. Just for you to know that lottery is not a bad way to earn money."

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