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  • Variable number of two-dimensional arrays into one big array

    - by qlb
    I have a variable number of two-dimensional arrays. The first dimension is variable, the second dimension is constant. i.e.: Object[][] array0 = { {"tim", "sanchez", 34, 175.5, "bla", "blub", "[email protected]"}, {"alice", "smith", 42, 160.0, "la", "bub", "[email protected]"}, ... }; Object[][] array1 = { {"john", "sdfs", 34, 15.5, "a", "bl", "[email protected]"}, {"joe", "smith", 42, 16.0, "a", "bub", "[email protected]"}, ... }; ... Object[][] arrayi = ... I'm generating these arrays with a for-loop: for (int i = 0; i < filter.length; i++) { MyClass c = new MyClass(filter[i]); //data = c.getData(); } Where "filter" is another array which is filled with information that tells "MyClass" how to fill the arrays. "getData()" gives back one of the i number of arrays. Now I just need to have everything in one big two dimensional array. i.e.: Object[][] arrayComplete = { {"tim", "sanchez", 34, 175.5, "bla", "blub", "[email protected]"}, {"alice", "smith", 42, 160.0, "la", "bub", "[email protected]"}, ... {"john", "sdfs", 34, 15.5, "a", "bl", "[email protected]"}, {"joe", "smith", 42, 16.0, "a", "bub", "[email protected]"}, ... ... }; In the end, I need a 2D array to feed my Swing TableModel. Any idea on how to accomplish this? It's blowing my mind right now.

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  • Selecting a multi-dimensional array in LINQ

    - by mckhendry
    I have a task where I need to translate a DataTable to a two-dimensional array. That's easy enough to do by just looping over the rows and columns (see example below). private static string[,] ToArray(DataTable table) { var array = new string[table.Rows.Count,table.Columns.Count]; for (int i = 0; i < table.Rows.Count; ++i) for (int j = 0; j < table.Columns.Count; ++j) array[i, j] = table.Rows[i][j].ToString(); return array; } What I'd really like to do is use a select statement in LINQ to generate that 2D array. Unfortunately it looks like there is no way in LINQ to select a multidimensional array. Yes, I'm aware that I can use LINQ to select a jagged array, but that's not what I want. Is my assumption correct, or is there a way to use LINQ to select a multi-dimensional array?

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  • In .NET, What Is Fastest Way to Initialize Multi-Dimensional Array to Non-Default Value

    - by AMissico
    How do I initialize a multi-dimensional array of a primitive type as fast as possible? I am stuck with using multi-dimensional arrays. My problem is performance. The following routine initializes a 100x100 array in approx. 500 ticks. Removing the int.MaxValue initialization results in approx. 180 ticks just for the looping. Approximately 100 ticks to create the array without looping and without initializing to int.MaxValue. Routines similiar to this are called a few tens-of-thousands to several million times. I am open to suggestions on how to optimize this non-default initialization of an array. One idea I had is to use a smaller primitive type when available. For instance, using byte instead of int, saves 100 ticks. I would be happy with this, but I am hoping that I don't have to change the primitive data type. public int[,] CreateArray(Size size) { int[,] array = new int[size.Width, size.Height]; for (int x = 0; x < size.Width; x++) { for (int y = 0; y < size.Height; y++) { array[x, y] = int.MaxValue; } } return array; }

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  • How do I maintain coherency between model and view-model in MVVM pattern?

    - by Mike Garrett
    Problem Statement I'm writing a very basic WPF application to alter the contents of a configuration file. The data format is an XML file with a schema. I want to use it as a learning project for MVVM, so I have duly divided the code into Model: C# classes auto-generated from xsd.exe View-Model: View-friendly representation of the Model. View: Xaml and empty code behind I understand how the View-Model can make View-binding a breeze. However, doesn't that leave the View-Model <- Model semantics very awkward? Xsd.exe generates C# classes with arrays for multiple XML elements. However, at the V-VM level you need Observable Collections. Questions: Does this really mean I have to keep two completely different collection types representing the same data in coherence? What are the best practices for maintaining coherence between the Model and the View-Model?

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  • ASP.NET MVC 2 AJAX dilemma: Lose Models concept or create unmanageable JavaScript

    - by Slightly Frustrated
    Hi, Ok, let's assume we are working with ASP.NET MVC 2 (latest and greatest preview) and we want to create AJAX user interface with jQuery. So what are our real options here? Option 1 - Pass Json from the Controller to the view, and then the view submits Json back to the controller. This means (in the order given): User opens some View (let's say - /Invoices/January) which has to visualize a list of data (e.g. <IEnumerable<X.Y.Z.Models.Invoice>>) Controller retrieves the Model from the repository (assuming we are using repository pattern). Controller creates a new instance of a class which we will serialize to Json. The reasaon we do this, is because the model may not be serializable (circular reference ftl) Controller populates the soon-to-be-serialized class with data Controller serializes the class to Json and passes it the view. User does some change and submits the 'form' The View submits back Json to the controller The Controller now must 'manually' validate the input, because the Json passed does not bind to a Model See, if our View is communicating to the controller via Json, we lose the Model validation, which IMHO is incredible disadvantage. In this case, forget about data annotations and stuff. Option 2 - Ok, the alternative of the first approach is to pass the Models to the Views, which is the default behavior in the template when you start a new project. We pass a strong typed model to the view The view renders the appropriate html and javascript, sticking to the model property names. This is important! The user submits the form. If we stick to the model names, when we .serialize() the form and submit it to the controller it will map to a model. There is no Json mapping. The submitted form directly binds to a strongly typed model, hence, we can use the model validation. E.g. we keep the business logic where it should be. Problem with this approach is, if we refactor some of the Models (change property names, types, etc), the javascript we wrote would become invalid. We will have to manually refactor the scripting and hope we don't miss something. There is no way you can test it either. Ok, the question is - how to write an AJAX front end, which keeps the business logic validation in the model (e.g. controller passes and receives a Model type), but in the same time doesn't screw up the javascript and html when we refactor the model?

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  • asp.net mvc model binding

    - by mctayl
    Hi there Iam using asp.net mvc to do model binding, when I pass a model to a view, I am able to see the model data displayed in the form inside a label, <%= Html.Label(Model.title) % <%= Html.Label(Model.description) % however, I am not able to do the same using <%= Html.TextArea(Model.description)% is there a syntax difference between displaying in a label as oppsed tp a textbox

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  • How to show ModelState.AddModelError when the Model is Empty in MVC4

    - by kk1076
    I am displaying a shopping cart. I need to check for empty values in Shopping cart and display a message like "The Shopping Cart is empty". When I use ModelState.AddModelError in myAction, it throws an exception as there is null reference in Model. How to display the ErrorMessage. My Action public ActionResult Index() { string id = Request.QueryString["UserID"]; IList<CartModel> objshop = new List<CartModel>(); objshop = GetCartDetails(id); if (objshop.Count > 0) { return View(objshop.ToList()); } else { ModelState.AddModelError("", "Your Shopping Cart is empty!"); } return View(); } My View @{ @Html.ValidationSummary(true) } <th > @Html.DisplayNameFor(model => model.ProductName) </th> <th > @Html.DisplayNameFor(model => model.Quantity) </th> <th > @Html.DisplayNameFor(model => model.Rate) </th> <th > @Html.DisplayNameFor(model => model.Price) </th> @foreach (var item in Model) { <td> @Html.DisplayFor(modelItem => item.ProductName)</td> <td> @Html.DisplayFor(modelItem => item.Quantity)</td> <td> @Html.DisplayFor(modelItem => item.Rate) </td> <td> @Html.DisplayFor(modelItem => item.Price) </td> } Any suggestions.

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  • Computing, storing, and retrieving values to and from an N-Dimensional matrix

    - by Adam S
    This question is probably quite different from what you are used to reading here - I hope it can provide a fun challenge. Essentially I have an algorithm that uses 5(or more) variables to compute a single value, called outcome. Now I have to implement this algorithm on an embedded device which has no memory limitations, but has very harsh processing constraints. Because of this, I would like to run a calculation engine which computes outcome for, say, 20 different values of each variable and stores this information in a file. You may think of this as a 5(or more)-dimensional matrix or 5(or more)-dimensional array, each dimension being 20 entries long. In any modern language, filling this array is as simple as having 5(or more) nested for loops. The tricky part is that I need to dump these values into a file that can then be placed onto the embedded device so that the device can use it as a lookup table. The questions now, are: What format(s) might be acceptable for storing the data? What programs (MATLAB, C#, etc) might be best suited to compute the data? C# must be used to import the data on the device - is this possible given your answer to #1?

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  • ASP.NET MVC 2 Model object validation

    - by Jimmy
    Hey guys, I'm trying to validate a model object outside of the context of ModelState within a controller, I currently have a parser that creates model objects from an excel file and I want to be able to report how many entries were added to the database and how many failed, is there a way to validate a model object on its data annotations outside of model binding? I'm looking for something similar to the rails model method of model.valid? or a way for me to implement that myself. My current solution is just manually checking if a few key fields are present but this duplicates requirements between my model class and its metadata, there has to be a better way to hook into the model validation checking that is done by mvc 2. Thanks

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  • CoffeeScript 2 Dimensional Array Usage

    - by Chris
    I feel like I'm missing something with CoffeeScript and 2 dimensional arrays. I'm simply attempting to make a grid of spaces (think checkers). After some searching and a discovery with the arrays.map function, I came up with this: @spaces = [0...20].map (x)-> [0...20].map (y) -> new Elements.Space() And this seems to work great, I have a nice 2 dimensional array with my Space object created in each. But now I want to send the created space constructor the x,y location. Because I'm two layers deep, I lost the x variable when I entered the map function for y. Ideally I would want to do something like: @spaces = [0...20].map (x)-> [0...20].map (y) -> new Elements.Space(x, y) or something that feels more natural to me like: for row in rows for column in row @spaces[row][column] = new Elements.Space(row, column) I'm really open to any better way of doing this. I know how I would do it in standard JavaScript, but really would like to learn how to do it in CoffeeScript.

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  • Inter Quake Model IQM render Directx9

    - by Andrew_0
    I'm trying to render an Inter Quake Model(http://lee.fov120.com/iqm/) in DirectX9 that I exported from blender. I want to display animations which IQM supports and my model format does not. The model is a cylinder. It loads fine in the iqm sdk opengl viewer but when i try to render it in directx9 using for example(this is just to render the vertices): IDirect3DDevice9 * device; HRESULT hr = S_OK; for(int i = 0; i < nummeshes; i++) { iqmmesh &m = meshes[0]; hr = device->DrawIndexedPrimitiveUP(D3DPT_TRIANGLELIST, 0, 3*m.num_triangles, m.num_triangles ,&tris[m.first_triangle] ,D3DFMT_INDEX32 ,inposition ,sizeof(unsigned int)); } It renders like this: Incorrect The light grey bit that looks like two triangles in the middle is what is rendered(ignore the other stuff). Whereas it is meant to look like this(using a custom importer which I designed which matches what is displayed in blender): Correct Anyone have any suggestions on what might be going wrong?

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  • Microsoft SQL Server 2012 Analysis Services – The BISM Tabular Model #ssas #tabular #bism

    - by Marco Russo (SQLBI)
    I, Alberto and Chris spent many months (many nights, holidays and also working days of the last months) writing the book we would have liked to read when we started working with Analysis Services Tabular. A book that explains how to use Tabular, how to model data with Tabular, how Tabular internally works and how to optimize a Tabular model. All those things you need to start on a real project in order to make an happy customer. You know, we’re all consultants after all, so customer satisfaction is really important to be paid for our job! Now the book writing is finished, we’re in the final stage of editing and reviews and we look forward to get our print copy. Its title is very long: Microsoft SQL Server 2012 Analysis Services – The BISM Tabular Model. But the important thing is that you can already (pre)order it. This is the list of chapters: 01. BISM Architecture 02. Guided Tour on Tabular 03. Loading Data Inside Tabular 04. DAX Basics 05. Understanding Evaluation Contexts 06. Querying Tabular 07. DAX Advanced 08. Understanding Time Intelligence in DAX 09. Vertipaq Engine 10. Using Tabular Hierarchies 11. Data modeling in Tabular 12. Using Advanced Tabular Relationships 13. Tabular Presentation Layer 14. Tabular and PowerPivot for Excel 15. Tabular Security 16. Interfacing with Tabular 17. Tabular Deployment 18. Optimization and Monitoring And this is the book cover – have a good read!

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  • Best Persistence choice for J2EE-App with frequently changing Data Model

    - by Ben-G
    Whenever I develop a J2EE-Application, I at some point decide to switch from my dummy Persistence (Simply Using Lists and other Data Structures) to some Sort of Database Persistence. Mostly when I hope the Data Model is more or less complete. From this point on, changes to the data model become exhausting, but unluckily they occur rather often. I've used different Object-Relational-Mappers (iBatis, Hibernate) for my projects. They definitely reduce the pain coming with Data Model changes, but they anyway let me adjust code/configuration at 3 or 4 places for every single change. To me, that's cumbersome and error prone. I made a better experience with DB4O, which simply persists Java Objects as they are, but I believe it's performance does not scale for huge applications. Is there anyway to maintain performance while letting out all the ugly configuration work? I'm seeking a performant framework which really hides persistence from my code. Wish for thinking? Or am I missing out THE technology? Hope you can help.

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  • How stoper one annimation model on XNA?

    - by Mehdi Bugnard
    I met a Difficulty for one stoper annimation. Everything works great starter for the animation. But I do not see how stoper and can continue the annimation paused. The "animationPlayer.StartClip (clip)" is used to choke the annimation but impossible to find a way to stoper Thans's a lot Here is my code to use. protected override void LoadContent() { //Model - Player model_player = Content.Load<Model>("Models\\Player\\models"); // Look up our custom skinning information. SkinningData skinningData = model_player.Tag as SkinningData; if (skinningData == null) throw new InvalidOperationException ("This model does not contain a SkinningData tag."); // Create an animation player, and start decoding an animation clip. animationPlayer = new AnimationPlayer(skinningData); AnimationClip clip = skinningData.AnimationClips["ArmLowAction_006"]; animationPlayer.StartClip(clip); } protected overide update(GameTime gameTime) { KeyboardState key = Keyboard.GetState(); // If player don't move -> stop anim if (!key.IsKeyDown(Keys.W) && !keyStateOld.IsKeyUp(Keys.S) && !keyStateOld.IsKeyUp(Keys.A) && !keyStateOld.IsKeyUp(Keys.D)) { //animation stop ? not exist ? animationPlayer.Stop(); isPlayerStop = true; } else { if(isPlayerStop == true) { isPlayerStop = false; animationPlayer.StartClip(Clip); } }

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  • Text on a model

    - by alecnash
    I am trying to put some text on a Model and I want it to be dynamic. Did some research and came up with drawing the text on the texture and then set it on the model. I use something like this: public static Texture2D SpriteFontTextToTexture(SpriteFont font, string text, Color backgroundColor, Color textColor) { Size = font.MeasureString(text); RenderTarget2D renderTarget = new RenderTarget2D(GraphicsDevice, (int)Size.X, (int)Size.Y); GraphicsDevice.SetRenderTarget(renderTarget); GraphicsDevice.Clear(Color.Transparent); Spritbatch.Begin(); //have to redo the ColorTexture Spritbatch.Draw(ColorTexture.Create(GraphicsDevice, 1024, 1024, backgroundColor), Vector2.Zero, Color.White); Spritbatch.DrawString(font, text, Vector2.Zero, textColor); Spritbatch.End(); GraphicsDevice.SetRenderTarget(null); return renderTarget; } When I was working with primitives and not models everything worked fine because I set the texture exactly where I wanted but with the model (RoundedRect 3D button). It now looks like that: Is there a way to have the text centered only on one side?

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  • Where we should put validation for domain model

    - by adisembiring
    I still looking best practice for domain model validation. Is that good to put the validation in constructor of domain model ? my domain model validation example as follows: public class Order { private readonly List<OrderLine> _lineItems; public virtual Customer Customer { get; private set; } public virtual DateTime OrderDate { get; private set; } public virtual decimal OrderTotal { get; private set; } public Order (Customer customer) { if (customer == null) throw new ArgumentException("Customer name must be defined"); Customer = customer; OrderDate = DateTime.Now; _lineItems = new List<LineItem>(); } public void AddOderLine //.... public IEnumerable<OrderLine> AddOderLine { get {return _lineItems;} } } public class OrderLine { public virtual Order Order { get; set; } public virtual Product Product { get; set; } public virtual int Quantity { get; set; } public virtual decimal UnitPrice { get; set; } public OrderLine(Order order, int quantity, Product product) { if (order == null) throw new ArgumentException("Order name must be defined"); if (quantity <= 0) throw new ArgumentException("Quantity must be greater than zero"); if (product == null) throw new ArgumentException("Product name must be defined"); Order = order; Quantity = quantity; Product = product; } } Thanks for all of your suggestion.

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  • Announcing Oracle Retail Reference Model, Version 2.4

    - by Oracle Retail Documentation Team
    The Oracle Retail Reference Model (RRM) collection of established practice business processes has been updated and re-released as RRM, Version 2.4. A permanent link to the My Oracle Support Document ID, 1145264.1, is available on the right side of this blog, in the Bookmarks section. The Oracle Retail Retail Reference Model (RRM) business process designs are intended to support an implementation of the merchandising, stores, and planning products. These designs are a guide for both the business and implementation teams. They explain some scenarios and factors that need to be considered for a successful implementation. The designs are created for a generic retailer, with some considerations made for hardlines, apparel (softlines), grocery, and telecommunications. Oracle Retail Reference Model 2.4 Doc ID 1145264.1This release includes the following: Updates for particular Oracle Retail application releases since August 2011. Updates per feedback received from process users, including Advanced Inventory Planning flow additions. Improvements in the area of standardized role names and organizational units. Please send any questions, comments, and suggestions to [email protected].

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  • String on a model

    - by alecnash
    I am trying to put a sting on a Model and I want it to be dynamic. Did some research and came up with drawing the text on the texture and then set it on the model. I use something like this: public static Texture2D SpriteFontTextToTexture(SpriteFont font, string text, Color backgroundColor, Color textColor) { Size = font.MeasureString(text); RenderTarget2D renderTarget = new RenderTarget2D(GraphicsDevice, (int)Size.X, (int)Size.Y); GraphicsDevice.SetRenderTarget(renderTarget); GraphicsDevice.Clear(Color.Transparent); Spritbatch.Begin(); //have to redo the ColorTexture Spritbatch.Draw(ColorTexture.Create(GraphicsDevice, 1024, 1024, backgroundColor), Vector2.Zero, Color.White); Spritbatch.DrawString(font, text, Vector2.Zero, textColor); Spritbatch.End(); GraphicsDevice.SetRenderTarget(null); return renderTarget; } When I was working with primitives and not models everything worked fine because I set the texture exactly where I wanted but with the model (RoundedRect 3d button) it looks like that: Is there a way to have the text centered only on one side?

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  • Testing my model for hybrid scheduling in Embedded Systems

    - by markusian
    I am working on a project for school, where I have to analyze the performances of a few fixed-priority servers algorithms (polling server, deferrable server, priority exchange) using a simulator in the case of hybrid scheduling, where we have both hard periodic tasks and soft aperiodic tasks. In my model I consider that: the hard tasks have a period equal to their deadline, with a known worst case execution time (wcet). The actual execution time could be smaller than the wcet. the soft tasks have a known wcet and random interarrival times. The actual execution time could be smaller than the wcet. In order to test those algorithms I need realistic case studies. For this reason I'm digging in the scientific literature but I am facing different problems: Sometimes I find a list of hard tasks with wcet, but it is not specified how the soft tasks parameters are found. Given the wcet of a task, how can I model its actual execution time? This means, what random distribution should I use considering the wcet? How can I model the random interarrival times of soft aperiodic tasks?

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  • Should a domain expert make class diagrams?

    - by Matthieu
    The domain expert in our team uses UML class diagrams to model the domain model. As a result, the class diagrams are more of technical models rather than domain models (it serves of some sort of technical specifications for developpers because they don't have to do any conception, they just have to implement the model). In the end, the domain expert ends up doing the job of the architect/technical expert right? Is it normal for a domain expert (not a developer or technical profile) to do class diagrams? If not, what kind of modeling should he be using?

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  • What is the best approach for creating a Common Information Model?

    - by Kaiser Advisor
    Hi, I would like to know the best approach to create a Common Information Model. Just to be clear, I've also heard it referred to as a canonical information model, semantic information model, and master data model - As far as I can tell, they are all referring to the same concept. I've heard in the past that a combined "top-down" and "bottom-up" approach is best. This has the advantage of incorporating "Ivory tower" architects and developers - The work will meet somewhere in the middle and usually be both logical and practical. However, this involves bringing in a lot of people with different skill sets. I've also seen a couple of references to the Distributed Management Task Force, but I can't glean much on best practices in terms of CIM development. This is something I'm quite interested in getting some feedback on since having a strong CIM is a prerequisite to SOA. Thanks for your help! KA Update I've heard another strategy goes along with overall SOA implementation: Get the business involved, and seek executive sponsorship. This would be part of the "Top-down" effort.

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  • Asp.Net MVC - Binding of parameter to model value!

    - by Pino
    This seems like the model binding is causing me issues. Essentially I have a model called ProductOption and for the purpose of this question it has 2 fields ID (Int) PK ProductID (Int) FK I have a standard route set-up context.MapRoute( "Product_default", "Product/{controller}/{action}/{id}", new { controller = "Product", action = "Index", id = UrlParameter.Optional } ); and if the user wants to add an option the URL is, /Product/Options/Add/1 in the above URL 1 is the ProductID, I have the following code to return a blank model the the view, [HttpGet] public ActionResult Add(int id) { return View("Manage", new ProductOptionModel() { ProductID = id }); } Now in my view I keep a hidden field <%= Html.HiddenFor(x=>x.ID) %> This is used to determine (on submit) if we are editing or adding a new option. However the Model binder in .net seems to replace .ID (Which was 0 when leaving the above get actionresult) with 1 (or the value of the id parameter in the URL) How can I stop or work around this? ViewModel public class ProductExtraModel { //Database public int ID { get; set; } public string Name { get; set; } public int ProductID { get; set; } public ProductModel Product { get; set; } }

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  • What are the benefits and risks of moving to a Model Driven Architecture approach?

    - by Tone
    I work for a company with about 350 employees and we are in the process of growing. Our current codebase is not structured very well and we are looking both at how to improve it immediately (by organizing objects into namespaces, separating concerns, etc.) and moving to a model driven architecture approach, where we model and design everything first with uml, then generate code from that model. We have been looking heavily at Sparx Systems Enterprise Architect (EA) (which is UML 2.0 capable) and we are also considering the tools in VS 2010. I know there are other tools out there (Rational XDE being one) but I really do not think we can spend $1500+ per license at this point. I'm not looking for answers on which tool is better than another but more for experiences moving from a cowboy coding environment (that is, little planning and design, just jump in and start coding) to a model driven architecture. Looking back was it helpful to your organization? What are the pain points? What are the risks? What are the benefits?

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  • Does the Java Memory Model (JSR-133) imply that entering a monitor flushes the CPU data cache(s)?

    - by Durandal
    There is something that bugs me with the Java memory model (if i even understand everything correctly). If there are two threads A and B, there are no guarantees that B will ever see a value written by A, unless both A and B synchronize on the same monitor. For any system architecture that guarantees cache coherency between threads, there is no problem. But if the architecture does not support cache coherency in hardware, this essentially means that whenever a thread enters a monitor, all memory changes made before must be commited to main memory, and the cache must be invalidated. And it needs to be the entire data cache, not just a few lines, since the monitor has no information which variables in memory it guards. But that would surely impact performance of any application that needs to synchronize frequently (especially things like job queues with short running jobs). So can Java work reasonably well on architectures without hardware cache-coherency? If not, why doesn't the memory model make stronger guarantees about visibility? Wouldn't it be more efficient if the language would require information what is guarded by a monitor? As i see it the memory model gives us the worst of both worlds, the absolute need to synchronize, even if cache coherency is guaranteed in hardware, and on the other hand bad performance on incoherent architectures (full cache flushes). So shouldn't it be more strict (require information what is guarded by a monitor) or more lose and restrict potential platforms to cache-coherent architectures? As it is now, it doesn't make too much sense to me. Can somebody clear up why this specific memory model was choosen? EDIT: My use of strict and lose was a bad choice in retrospect. I used "strict" for the case where less guarantees are made and "lose" for the opposite. To avoid confusion, its probably better to speak in terms of stronger or weaker guarantees.

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  • OSI Model

    - by kaleidoscope
    The Open System Interconnection Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it. Description of OSI layers: Layer 1: Physical Layer ·         Defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. ·         Establishment and termination of a connection to a communications medium. ·         Participation in the process whereby the communication resources are effectively shared among multiple users. ·         Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. Layer 2: Data Link Layer ·         Provides the functional and procedural means to transfer data between network entities. ·         Detect and possibly correct errors that may occur in the Physical Layer. The error check is performed using Frame Check Sequence (FCS). ·         Addresses is then sought to see if it needs to process the rest of the frame itself or whether to pass it on to another host. ·         The Layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. ·         MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. ·         LLC layer controls frame synchronization, flow control and error checking.   Layer 3: Network Layer ·         Provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks. ·         Performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. ·         Network Layer Routers operate at this layer—sending data throughout the extended network and making the Internet possible.   Layer 4: Transport Layer ·         Provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. ·         Controls the reliability of a given link through flow control, segmentation/de-segmentation, and error control. ·         Transport Layer can keep track of the segments and retransmit those that fail. Layer 5: Session Layer ·         Controls the dialogues (connections) between computers. ·         Establishes, manages and terminates the connections between the local and remote application. ·         Provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. ·         Implemented explicitly in application environments that use remote procedure calls. Layer 6: Presentation Layer ·         Establishes a context between Application Layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the presentation service understands both and the mapping between them. The presentation service data units are then encapsulated into Session Protocol data units, and moved down the stack. ·         Provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. Layer 7: Application Layer ·         This layer interacts with software applications that implement a communicating component. ·         Identifies communication partners, determines resource availability, and synchronizes communication. o       When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. o       When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists. o       In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Technorati Tags: Kunal,OSI,Networking

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