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  • How can I share an entity framework model across website users

    - by richardmoss
    Hello, Currently my website is based around MVC and the Entity Framework running against a SQL Server 2005 database. So far, it has all been running very smoothly, and I really enjoy MVC and its slimmer more concise code (and no huge viewstates or soul destroying postbacks ;)) Recently I was working on upgrading the site to use a simple forum system, and this is where I started running into problems. When I was testing the site using two different browsers, if I created or replied to a post in one browser, the other browser couldn't see the post. At the moment, each visitor to the site gets their own copy of the entity model, which I store in their session data. Obviously this is the problem as updates to one model aren't getting carried to the other. As a test, I tried storing a single copy of the model which all visitors would access by assigning the model to a static variable. This worked, and both browsers could see each others modifications. However, it had its side effects. For example, if I fired up both browsers at the same time and the model was initialized, one browser would crash, and the other would work fine, despite me using a locking object so in theory one of them should have been delayed until the model was ready (of course I could have implemented this wrong ;)). Also, originally this site did use one model for all visitors and when it was live, it frequently shut down - killing the IIS application pool while it did. Now I'm not sure if this was related, but I don't really want to reintroduce whatever bug I had that caused this shut down. So, my question is a simple one really - what is the best way of either using the same model for all website users so they all see updates, or if they do have separate copies (which I imagine will have a performance impact in time) how can the models detect changes in the database and update themselves according. Thanks in advance for any advice! Regards; Richard Moss

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  • Design patterns for Caching Images in a MVC?

    - by Onema
    Hi, I'm designing an image cache system that will be used in an MVC CMS. The main purpose of the image cacher is to modify images: scale, crop, etc and cache them in the client site. I have created an image cache Model and Mapper that interact with the Database, to keep track of the images and know what kind of actions have been applied to them (scale, crop, etc). In addition to the Model and Mapper I have created a ImageCacher Class that is used by the API to manage the Model and image creation based on arguments passed by the client site, this class creates the images and generates the links to the images for the View. A coworker argued that I need to include the functionality of this last Class inside the Model, as the bulk of the logic should go in the model. I respectfully disagree with him since I feel the model's responsibility is to deal with the information about the images cached at the database level, and the responsibility of the ImageCacher Class is to create the url/image that we will be caching (keeping the single responsibility principle). In addition to this I believe that a model should not have Presentation-related features, like creating or showing images. Does anyone have any insight on this? is there a particular design pattern that would make this division of tasks clear and and the image cacher reusable? Should I add all the logic in the Model? Thank you.

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  • mvc design in a card game

    - by Hong
    I'm trying to make a card game. some classes I have are: CardModel, CardView; DeckModel, DeckView. The deck model has a list of card model, According to MVC, if I want to send a card to a deck, I can add the card model to the deck model, and the card view will be added to the deck view by a event handler. So I have a addCard(CardModel m) in the DeckModel class, but if I want to send a event to add the card view of that model to the deck view, I only know let the model has a reference to view. So the question is: If the card model and deck model have to have a reference to their view classes to do it? If not, how to do it better? Update, the code: public class DeckModel { private ArrayList<CardModel> cards; private ArrayList<EventHandler> actionEventHandlerList; public void addCard(CardModel card){ cards.add(card); //processEvent(event x); //must I pass a event that contain card view here? } CardModel getCards(int index){ return cards.get(index); } public synchronized void addEventHandler(EventHandler l){ if(actionEventHandlerList == null) actionEventHandlerList = new ArrayList<EventHandler>(); if(!actionEventHandlerList.contains(l)) actionEventHandlerList.add(l); } public synchronized void removeEventHandler(EventHandler l){ if(actionEventHandlerList!= null && actionEventHandlerList.contains(l)) actionEventHandlerList.remove(l); } private void processEvent(Event e){ ArrayList list; synchronized(this){ if(actionEventHandlerList!= null) list = (ArrayList)actionEventHandlerList.clone(); else return; } for(int i=0; i<actionEventHandlerList.size(); ++i){ actionEventHandlerList.get(i).handle(e); } } }

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  • Writing an ASP.Net Web based TFS Client

    - by Glav
    So one of the things I needed to do was write an ASP.Net MVC based application for our senior execs to manage a set of arbitrary attributes against stories, bugs etc to be able to attribute whether the item was related to Research and Development, and if so, what kind. We are using TFS Azure and don’t have the option of custom templates. I have decided on using a string based field within the template that is not very visible and which we don’t use to write a small set of custom which will determine the research and development association. However, this string munging on the field is not very user friendly so we need a simple tool that can display attributes against items in a simple dropdown list or something similar. Enter a custom web app that accesses our TFS items in Azure (Note: We are also using Visual Studio 2012) Now TFS Azure uses your Live ID and it is not really possible to easily do this in a server based app where no interaction is available. Even if you capture the Live ID credentials yourself and try to submit them to TFS Azure, it wont work. Bottom line is that it is not straightforward nor obvious what you have to do. In fact, it is a real pain to find and there are some answers out there which don’t appear to be answers at all given they didn’t work in my scenario. So for anyone else who wants to do this, here is a simple breakdown on what you have to do: Go here and get the “TFS Service Credential Viewer”. Install it, run it and connect to your TFS instance in azure and create a service account. Note the username and password exactly as it presents it to you. This is the magic identity that will allow unattended, programmatic access. Without this step, don’t bother trying to do anything else. In your MVC app, reference the following assemblies from “C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\ReferenceAssemblies\v2.0”: Microsoft.TeamFoundation.Client.dll Microsoft.TeamFoundation.Common.dll Microsoft.TeamFoundation.VersionControl.Client.dll Microsoft.TeamFoundation.VersionControl.Common.dll Microsoft.TeamFoundation.WorkItemTracking.Client.DataStoreLoader.dll Microsoft.TeamFoundation.WorkItemTracking.Client.dll Microsoft.TeamFoundation.WorkItemTracking.Common.dll If hosting this in Internet Information Server, for the application pool this app runs under, you will need to enable 32 Bit support. You also have to allow the TFS client assemblies to store a cache of files on your system. If you don’t do this, you will authenticate fine, but then get an exception saying that it is unable to access the cache at some directory path when you query work items. You can set this up by adding the following to your web.config, in the <appSettings> element as shown below: <appSettings> <!-- Add reference to TFS Client Cache --> <add key="WorkItemTrackingCacheRoot" value="C:\windows\temp" /> </appSettings> With all that in place, you can write the following code: var token = new Microsoft.TeamFoundation.Client.SimpleWebTokenCredential("{you-service-account-name", "{your-service-acct-password}"); var clientCreds = new Microsoft.TeamFoundation.Client.TfsClientCredentials(token); var currentCollection = new TfsTeamProjectCollection(new Uri(“https://{yourdomain}.visualstudio.com/defaultcollection”), clientCreds); TfsConfigurationServercurrentCollection.EnsureAuthenticated(); In the above code, not the URL contains the “defaultcollection” at the end of the URL. Obviously replace {yourdomain} with whatever is defined for your TFS in Azure instance. In addition, make sure the service user account and password that was generated in the first step is substituted in here. Note: If something is not right, the “EnsureAuthenticated()” call will throw an exception with the message being you are not authorised. If you forget the “defaultcollection” on the URL, it will still fail but with a message saying you are not authorised. That is, a similar but different exception message. And that is it. You can then query the collection using something like: var service = currentCollection.GetService<WorkItemStore>(); var proj = service.Projects[0]; var allQueries = proj.StoredQueries; for (int qcnt = 0; qcnt < allQueries.Count; qcnt++) {     var query = allQueries[qcnt];     var queryDesc = string.format(“Query found named: {0}”,query.Name); } You get the idea. If you search around, you will find references to the ServiceIdentityCredentialProvider which is referenced in this article. I had no luck with this method and it all looked too hard since it required an extra KB article and other magic sauce. So I hope that helps. This article certainly would have helped me save a boat load of time and frustration.

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  • Grid pathfinding with a lot of entities

    - by Vee
    I'd like to explain this problem with a screenshot from a released game, DROD: Gunthro's Epic Blunder, by Caravel Games. The game is turn-based and tile-based. I'm trying to create something very similar (a clone of the game), and I've got most of the fundamentals done, but I'm having trouble implementing pathfinding. Look at the screenshot. The guys in yellow are friendly, and want to kill the roaches. Every turn, every guy in yellow pathfinds to the closest roach, and every roach pathfinds to the closest guy in yellow. By closest I mean the target with the shortest path, not a simple distance calculation. All of this without any kind of slowdown when loading the level or when passing turns. And all of the entities change position every turn. Also (not shown in screenshot), there can be doors that open and close and change the level's layout. Impressive. I've tried implementing pathfinding in my clone. First attempt was making every roach find a path to a yellow guy every turn, using a breadth-first search algorithm. Obviously incredibly slow with more than a single roach, and would get exponentially slower with more than a single yellow guy. Second attempt was mas making every yellow guy generate a pathmap (still breadth-first search) every time he moved. Worked perfectly with multiple roaches and a single yellow guy, but adding more yellow guys made the game slow and unplayable. Last attempt was implementing JPS (jump point search). Every entity would individually calculate a path to its target. Fast, but with a limited number of entities. Having less than half the entities in the screenshot would make the game slow. And also, I had to get the "closest" enemy by calculating distance, not shortest path. I've asked on the DROD forums how they did it, and a user replied that it was breadth-first search. The game is open source, and I took a look at the source code, but it's C++ (I'm using C#) and I found it confusing. I don't know how to do it. Every approach I tried isn't good enough. And I believe that DROD generates global pathmaps, somehow, but I can't understand how every entity find the best individual path to other entities that move every turn. What's the trick? This is a reply I just got on the DROD forums: Without having looked at the code I'd wager it's two (or so) pathmaps for the whole room: One to the nearest enemy, and one to the nearest friendly for every tile. There's no need to make a separate pathmap for every entity when the overall goal is "move towards nearest enemy/friendly"... just mark every tile with the number of moves it takes to the nearest target and have the entity chose the move that takes it to the tile with the lowest number. To be honest, I don't understand it that well.

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  • A Patent for Workload Management Based on Service Level Objectives

    - by jsavit
    I'm very pleased to announce that after a tiny :-) wait of about 5 years, my patent application for a workload manager was finally approved. Background Many operating systems have a resource manager which lets you control machine resources. For example, Solaris provides controls for CPU with several options: shares for proportional CPU allocation. If you have twice as many shares as me, and we are competing for CPU, you'll get about twice as many CPU cycles), dedicated CPU allocation in which a number of CPUs are exclusively dedicated to an application's use. You can say that a zone or project "owns" 8 CPUs on a 32 CPU machine, for example. And, capped CPU in which you specify the upper bound, or cap, of how much CPU an application gets. For example, you can throttle an application to 0.125 of a CPU. (This isn't meant to be an exhaustive list of Solaris RM controls.) Workload management Useful as that is (and tragic that some other operating systems have little resource management and isolation, and frighten people into running only 1 app per OS instance - and wastefully size every server for the peak workload it might experience) that's not really workload management. With resource management one controls the resources, and hope that's enough to meet application service objectives. In fact, we hold resource distribution constant, see if that was good enough, and adjust resource distribution if that didn't meet service level objectives. Here's an example of what happens today: Let's try 30% dedicated CPU. Not enough? Let's try 80% Oh, that's too much, and we're achieving much better response time than the objective, but other workloads are starving. Let's back that off and try again. It's not the process I object to - it's that we to often do this manually. Worse, we sometimes identify and adjust the wrong resource and fiddle with that to no useful result. Back in my days as a customer managing large systems, one of my users would call me up to beg for a "CPU boost": Me: "it won't make any difference - there's plenty of spare CPU to be had, and your application is completely I/O bound." User: "Please do it anyway." Me: "oh, all right, but it won't do you any good." (I did, because he was a friend, but it didn't help.) Prior art There are some operating environments that take a stab about workload management (rather than resource management) but I find them lacking. I know of one that uses synthetic "service units" composed of the sum of CPU, I/O and memory allocations multiplied by weighting factors. A workload is set to make a target rate of service units consumed per second. But this seems to be missing a key point: what is the relationship between artificial 'service units' and actually meeting a throughput or response time objective? What if I get plenty of one of the components (so am getting enough service units), but not enough of the resource whose needed to remove the bottleneck? Actual workload management That's not really the answer either. What is needed is to specify a workload's service levels in terms of externally visible metrics that are meaningful to a business, such as response times or transactions per second, and have the workload manager figure out which resources are not being adequately provided, and then adjust it as needed. If an application is not meeting its service level objectives and the reason is that it's not getting enough CPU cycles, adjust its CPU resource accordingly. If the reason is that the application isn't getting enough RAM to keep its working set in memory, then adjust its RAM assignment appropriately so it stops swapping. Simple idea, but that's a task we keep dumping on system administrators. In other words - don't hold the number of CPU shares constant and watch the achievement of service level vary. Instead, hold the service level constant, and dynamically adjust the number of CPU shares (or amount of other resources like RAM or I/O bandwidth) in order to meet the objective. Instrumenting non-instrumented applications There's one little problem here: how do I measure application performance in a way relating to a service level. I don't want to do it based on internal resources like number of CPU seconds it received per minute - We need to make resource decisions based on externally visible and meaningful measures of performance, not synthetic items or internal resource counters. If I have a way of marking the beginning and end of a transaction, I can then measure whether or not the application is meeting an objective based on it. If I can observe the delay factors for an application, I can see which resource shortages are slowing an application enough to keep it from meeting its objectives. I can then adjust resource allocations to relieve those shortages. Fortunately, Solaris provides facilities for both marking application progress and determining what factors cause application latency. The Solaris DTrace facility let's me introspect on application behavior: in particular I can see events like "receive a web hit" and "respond to that web hit" so I can get transaction rate and response time. DTrace (and tools like prstat) let me see where latency is being added to an application, so I know which resource to adjust. Summary After a delay of a mere few years, I am the proud creator of a patent (advice to anyone interested in going through the process: don't hold your breath!). The fundamental idea is fairly simple: instead of holding resource constant and suffering variable levels of success meeting service level objectives, properly characterise the service level objective in meaningful terms, instrument the application to see if it's meeting the objective, and then have a workload manager change resource allocations to remove delays preventing service level attainment. I've done it by hand for a long time - I think that's what a computer should do for me.

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  • rotate player based off of joystick

    - by pengume
    Hey everyone I have this game that i am making in android and I have a touch screen joystick that moves the player around based on the joysticks position. I cant figure out how to also get the player to rotate at the same angle of the joystick. so when the joystick is to the left the players bitmap is rotated to the left as well. Maybe someone here has some sample code I could look at here is the joysticks class that I am using. `public class GameControls implements OnTouchListener { public float initx = DroidzActivity.screenWidth - 45; //255; // 320 og 425 public float inity = DroidzActivity.screenHeight - 45;//425; // 480 og 267 public Point _touchingPoint = new Point( DroidzActivity.screenWidth - 45, DroidzActivity.screenHeight - 45); public Point _pointerPosition = new Point(DroidzActivity.screenWidth - 100, DroidzActivity.screenHeight - 100); // ogx 220 ogy 150 private Boolean _dragging = false; private boolean attackMode = false; @Override public boolean onTouch(View v, MotionEvent event) { update(event); return true; } private MotionEvent lastEvent; public boolean ControlDragged; private static double angle; public void update(MotionEvent event) { if (event == null && lastEvent == null) { return; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } // drag drop if (event.getAction() == MotionEvent.ACTION_DOWN) { if ((int) event.getX() > 0 && (int) event.getX() < 50 && (int) event.getY() > DroidzActivity.screenHeight - 160 && (int) event.getY() < DroidzActivity.screenHeight - 0) { setAttackMode(true); } else { _dragging = true; } } else if (event.getAction() == MotionEvent.ACTION_UP) { if(isAttackMode()){ setAttackMode(false); } _dragging = false; } if (_dragging) { ControlDragged = true; // get the pos _touchingPoint.x = (int) event.getX(); _touchingPoint.y = (int) event.getY(); // Log.d("GameControls", "x = " + _touchingPoint.x + " y = " //+ _touchingPoint.y); // bound to a box if (_touchingPoint.x < DroidzActivity.screenWidth - 75) { // og 400 _touchingPoint.x = DroidzActivity.screenWidth - 75; } if (_touchingPoint.x > DroidzActivity.screenWidth - 15) {// og 450 _touchingPoint.x = DroidzActivity.screenWidth - 15; } if (_touchingPoint.y < DroidzActivity.screenHeight - 75) {// og 240 _touchingPoint.y = DroidzActivity.screenHeight - 75; } if (_touchingPoint.y > DroidzActivity.screenHeight - 15) {// og 290 _touchingPoint.y = DroidzActivity.screenHeight - 15; } // get the angle setAngle(Math.atan2(_touchingPoint.y - inity, _touchingPoint.x - initx) / (Math.PI / 180)); // Move the ninja in proportion to how far // the joystick is dragged from its center _pointerPosition.y += Math.sin(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // og 180 70 _pointerPosition.x += Math.cos(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // make the pointer go thru if (_pointerPosition.x > DroidzActivity.screenWidth) { _pointerPosition.x = 0; } if (_pointerPosition.x < 0) { _pointerPosition.x = DroidzActivity.screenWidth; } if (_pointerPosition.y > DroidzActivity.screenHeight) { _pointerPosition.y = 0; } if (_pointerPosition.y < 0) { _pointerPosition.y = DroidzActivity.screenHeight; } } else if (!_dragging) { ControlDragged = false; // Snap back to center when the joystick is released _touchingPoint.x = (int) initx; _touchingPoint.y = (int) inity; // shaft.alpha = 0; } } public void setAttackMode(boolean attackMode) { this.attackMode = attackMode; } public boolean isAttackMode() { return attackMode; } public void setAngle(double angle) { this.angle = angle; } public static double getAngle() { return angle; } }` I should also note that the player has animations based on when he is moving or attacking. EDIT: I got the angle and am rotating the sprite around in the correct angle however it rotates on the wrong spot. My sprite is one giant bitmap that gets cut into four pieces and only one shown at a time to animate walking. here is the code I am using to rotate him right now. ` public void draw(Canvas canvas,int pointerX, int pointerY) { Matrix m; if (setRotation){ // canvas.save(); m = new Matrix(); m.reset(); // spriteWidth and spriteHeight are for just the current frame showed //m.setTranslate(spriteWidth / 2, spriteHeight / 2); //get and set rotation for ninja based off of joystick m.preRotate((float) GameControls.getRotation()); //create the rotated bitmap flipedSprite = Bitmap.createBitmap(bitmap , 0, 0,bitmap.getWidth(),bitmap.getHeight() , m, true); //set new bitmap to rotated ninja setBitmap(flipedSprite); setRotation = false; // canvas.restore(); Log.d("Ninja View", "angle of rotation= " +(float) GameControls.getRotation()); } ` And then the draw method // create the destination rectangle for the ninjas current animation frame // pointerX and pointerY are from the joystick moving the ninja around destRect = new Rect(pointerX, pointerY, pointerX + spriteWidth, pointerY + spriteHeight); canvas.drawBitmap(bitmap, getSourceRect(), destRect, null);

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  • Using XA Transactions in Coherence-based Applications

    - by jpurdy
    While the costs of XA transactions are well known (e.g. increased data contention, higher latency, significant disk I/O for logging, availability challenges, etc.), in many cases they are the most attractive option for coordinating logical transactions across multiple resources. There are a few common approaches when integrating Coherence into applications via the use of an application server's transaction manager: Use of Coherence as a read-only cache, applying transactions to the underlying database (or any system of record) instead of the cache. Use of TransactionMap interface via the included resource adapter. Use of the new ACID transaction framework, introduced in Coherence 3.6.   Each of these may have significant drawbacks for certain workloads. Using Coherence as a read-only cache is the simplest option. In this approach, the application is responsible for managing both the database and the cache (either within the business logic or via application server hooks). This approach also tends to provide limited benefit for many workloads, particularly those workloads that either have queries (given the complexity of maintaining a fully cached data set in Coherence) or are not read-heavy (where the cost of managing the cache may outweigh the benefits of reading from it). All updates are made synchronously to the database, leaving it as both a source of latency as well as a potential bottleneck. This approach also prevents addressing "hot data" problems (when certain objects are updated by many concurrent transactions) since most database servers offer no facilities for explicitly controlling concurrent updates. Finally, this option tends to be a better fit for key-based access (rather than filter-based access such as queries) since this makes it easier to aggressively invalidate cache entries without worrying about when they will be reloaded. The advantage of this approach is that it allows strong data consistency as long as optimistic concurrency control is used to ensure that database updates are applied correctly regardless of whether the cache contains stale (or even dirty) data. Another benefit of this approach is that it avoids the limitations of Coherence's write-through caching implementation. TransactionMap is generally used when Coherence acts as system of record. TransactionMap is not generally compatible with write-through caching, so it will usually be either used to manage a standalone cache or when the cache is backed by a database via write-behind caching. TransactionMap has some restrictions that may limit its utility, the most significant being: The lock-based concurrency model is relatively inefficient and may introduce significant latency and contention. As an example, in a typical configuration, a transaction that updates 20 cache entries will require roughly 40ms just for lock management (assuming all locks are granted immediately, and excluding validation and writing which will require a similar amount of time). This may be partially mitigated by denormalizing (e.g. combining a parent object and its set of child objects into a single cache entry), at the cost of increasing false contention (e.g. transactions will conflict even when updating different child objects). If the client (application server JVM) fails during the commit phase, locks will be released immediately, and the transaction may be partially committed. In practice, this is usually not as bad as it may sound since the commit phase is usually very short (all locks having been previously acquired). Note that this vulnerability does not exist when a single NamedCache is used and all updates are confined to a single partition (generally implying the use of partition affinity). The unconventional TransactionMap API is cumbersome but manageable. Only a few methods are transactional, primarily get(), put() and remove(). The ACID transactions framework (accessed via the Connection class) provides atomicity guarantees by implementing the NamedCache interface, maintaining its own cache data and transaction logs inside a set of private partitioned caches. This feature may be used as either a local transactional resource or as logging XA resource. However, a lack of database integration precludes the use of this functionality for most applications. A side effect of this is that this feature has not seen significant adoption, meaning that any use of this is subject to the usual headaches associated with being an early adopter (greater chance of bugs and greater risk of hitting an unoptimized code path). As a result, for the moment, we generally recommend against using this feature. In summary, it is possible to use Coherence in XA-oriented applications, and several customers are doing this successfully, but it is not a core usage model for the product, so care should be taken before committing to this path. For most applications, the most robust solution is normally to use Coherence as a read-only cache of the underlying data resources, even if this prevents taking advantage of certain product features.

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  • Entity Attribute Value Database vs. strict Relational Model Ecommerce question

    - by Dr. Zim
    It is safe to say that the EAV/CR database model is bad. That said, Question: What database model, technique, or pattern should be used to deal with "classes" of attributes describing e-commerce products which can be changed at run time? In a good E-commerce database, you will store classes of options (like TV resolution then have a resolution for each TV, but the next product may not be a TV and not have "TV resolution"). How do you store them, search efficiently, and allow your users to setup product types with variable fields describing their products? If the search engine finds that customers typically search for TVs based on console depth, you could add console depth to your fields, then add a single depth for each tv product type at run time. There is a nice common feature among good e-commerce apps where they show a set of products, then have "drill down" side menus where you can see "TV Resolution" as a header, and the top five most common TV Resolutions for the found set. You click one and it only shows TVs of that resolution, allowing you to further drill down by selecting other categories on the side menu. These options would be the dynamic product attributes added at run time. Further discussion: So long story short, are there any links out on the Internet or model descriptions that could "academically" fix the following setup? I thank Noel Kennedy for suggesting a category table, but the need may be greater than that. I describe it a different way below, trying to highlight the significance. I may need a viewpoint correction to solve the problem, or I may need to go deeper in to the EAV/CR. Love the positive response to the EAV/CR model. My fellow developers all say what Jeffrey Kemp touched on below: "new entities must be modeled and designed by a professional" (taken out of context, read his response below). The problem is: entities add and remove attributes weekly (search keywords dictate future attributes) new entities arrive weekly (products are assembled from parts) old entities go away weekly (archived, less popular, seasonal) The customer wants to add attributes to the products for two reasons: department / keyword search / comparison chart between like products consumer product configuration before checkout The attributes must have significance, not just a keyword search. If they want to compare all cakes that have a "whipped cream frosting", they can click cakes, click birthday theme, click whipped cream frosting, then check all cakes that are interesting knowing they all have whipped cream frosting. This is not specific to cakes, just an example.

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  • Where do you start your design - code, UI or workflow?

    - by Mmarquee
    Hi I was discussing this at work, and was wondering where people start their designs? We tend to start with designing code to solve the problem presented to us, but that is probably all of us are (or were) programmers. I was wondering where other people and organisations start their design. Do they start with solving the problem as a coding problem, sit down and design what UI to use, or map out the data or workflow? Thanks

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  • Where do you start your design - code, UI, workflow or whatever?

    - by Mmarquee
    Hi I was discussing this at work, and was wondering where people start their designs? We tend to start with designing code to solve the problem presented to us, but that is probably all of us are (or were) programmers. I was wondering where other people and organisations start their design. Do they start with solving the problem as a coding problem, sit down and design what UI to use, or map out the data or workflow? Thanks

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  • Is it better to use a relational database or document-based database for an app like Wufoo?

    - by mboyle
    I'm working on an application that's similar to Wufoo in that it allows our users to create their own databases and collect/present records with auto generated forms and views. Since every user is creating a different schema (one user might have a database of their baseball card collection, another might have a database of their recipes) our current approach is using MySQL to create separate databases for every user with its own tables. So in other words, the databases our MySQL server contains look like: main-web-app-db (our web app containing tables for users account info, billing, etc) user_1_db (baseball_cards_table) user_2_db (recipes_table) .... And so on. If a user wants to set up a new database to keep track of their DVD collection, we'd do a "create database ..." with "create table ...". If they enter some data in and then decide they want to change a column we'd do an "alter table ....". Now, the further along I get with building this out the more it seems like MySQL is poorly suited to handling this. 1) My first concern is that switching databases every request, first to our main app's database for authentication etc, and then to the user's personal database, is going to be inefficient. 2) The second concern I have is that there's going to be a limit to the number of databases a single MySQL server can host. Pretending for a moment this application had 500,000 user databases, is MySQL designed to operate this way? What if it were a million, or more? 3) Lastly, is this method going to be a nightmare to support and scale? I've never heard of MySQL being used in this way so I do worry about how this affects things like replication and other methods of scaling. To me, it seems like MySQL wasn't built to be used in this way but what do I know. I've been looking at document-based databases like MongoDB, CouchDB, and Redis as alternatives because it seems like a schema-less approach to this particular problem makes a lot of sense. Can anyone offer some advice on this?

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  • How can i implement the NULL Object Design Pattern in a generic form?

    - by Colour Blend
    Is there a way to implement the null object design pattern in a generic form so that i don't need to implement it for every buisness object. For me, there are two high level classes you'll need for every business class. One for a single record and another for a list. So i think there should be a way to implement the NULL Object design pattern at a high level and not have to implement it for every class. Is there a way and how please?

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  • Passing ViewModel for backbone.js from MVC3 Server-Side

    - by Roman
    In ASP.NET MVC there is Model, View and Controller. MODEL represents entities which are stored in database and essentially is all the data used in a application (for example, generated by EntityFramework, "DB First" approach). Not all data from model you want to show in the view (for example, hashs of passwords). So you create VIEW MODEL, each for every strongly-typed-razor-view you have in application. Like this: using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace MyProject.ViewModels.SomeController.SomeAction { public class ViewModel { public ViewModel() { Entities1 = new List<ViewEntity1>(); Entities2 = new List<ViewEntity2>(); } public List<ViewEntity1> Entities1 { get; set; } public List<ViewEntity2> Entities2 { get; set; } } public class ViewEntity1 { //some properties from original DB-entity you want to show } public class ViewEntity2 { } } When you create complex client-side interfaces (I do), you use some pattern for javascript on client, MVC or MVVM (I know only these). So, with MVC on client you have another model (Backbone.Model for example), which is third model in application. It is a bit much. Why don`t we use the same ViewModel model on a client (in backbone.js or another framework)? Is there a way to transfer CS-coded model to JS-coded? Like in MVVM pattern, with knockout.js, when you can do like this: in SomeAction.cshtml: <div style="display: none;" id="view_model">@Json.Encode(Model)</div> after that in Javascript-code var ViewModel = ko.mapping.fromJSON($("#view_model").get(0).innerHTML); now you can extend your ViewModel with some actions, event handlers, etc: ko.utils.extend(ViewModel, { some_function: function () { //some code } }); So, we are not building the same view model on the client again, we are transferring existing view model from server. At least, data. But knockout.js is not suitable for me, you can`t build complex UI with it, it is just data-binding. I need something more structural, like backbone.js. The only way to build ViewModel for backbone.js I can see now is re-writing same ViewModel in JS from server with hands. Is there any ways to transfer it from server? To reuse the same viewmodel on server view and client view?

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  • Ops Center 12c - Provisioning Solaris Using a Card-Based NIC

    - by scottdickson
    It's been a long time since last I added something here, but having some conversations this last week, I got inspired to update things. I've been spending a lot of time with Ops Center for managing and installing systems these days.  So, I suspect a number of my upcoming posts will be in that area. Today, I want to look at how to provision Solaris using Ops Center when your network is not connected to one of the built-in NICs.  We'll talk about how this can work for both Solaris 10 and Solaris 11, since they are pretty similar.  In both cases, WANboot is a key piece of the story. Here's what I want to do:  I have a Sun Fire T2000 server with a Quad-GbE nxge card installed.  The only network is connected to port 2 on that card rather than the built-in network interfaces.  I want to install Solaris on it across the network, either Solaris 10 or Solaris 11.  I have met with a lot of customers lately who have a similar architecture.  Usually, they have T4-4 servers with the network connected via 10GbE connections. Add to this mix the fact that I use Ops Center to manage the systems in my lab, so I really would like to add this to Ops Center.  If possible, I would like this to be completely hands free.  I can't quite do that yet. Close, but not quite. WANBoot or Old-Style NetBoot? When a system is installed from the network, it needs some help getting the process rolling.  It has to figure out what its network configuration (IP address, gateway, etc.) ought to be.  It needs to figure out what server is going to help it boot and install, and it needs the instructions for the installation.  There are two different ways to bootstrap an installation of Solaris on SPARC across the network.   The old way uses a broadcast of RARP or more recently DHCP to obtain the IP configuration and the rest of the information needed.  The second is to explicitly configure this information in the OBP and use WANBoot for installation WANBoot has a number of benefits over broadcast-based installation: it is not restricted to a single subnet; it does not require special DHCP configuration or DHCP helpers; it uses standard HTTP and HTTPS protocols which traverse firewalls much more easily than NFS-based package installation.  But, WANBoot is not available on really old hardware and WANBoot requires the use o Flash Archives in Solaris 10.  Still, for many people, this is a great approach. As it turns out, WANBoot is necessary if you plan to install using a NIC on a card rather than a built-in NIC. Identifying Which Network Interface to Use One of the trickiest aspects to this process, and the one that actually requires manual intervention to set up, is identifying how the OBP and Solaris refer to the NIC that we want to use to boot.  The OBP already has device aliases configured for the built-in NICs called net, net0, net1, net2, net3.  The device alias net typically points to net0 so that when you issue the command  "boot net -v install", it uses net0 for the boot.  Our task is to figure out the network instance for the NIC we want to use.  We will need to get to the OBP console of the system we want to install in order to figure out what the network should be called.  I will presume you know how to get to the ok prompt.  Once there, we have to see what networks the OBP sees and identify which one is associated with our NIC using the OBP command show-nets. SunOS Release 5.11 Version 11.0 64-bit Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. {4} ok banner Sun Fire T200, No Keyboard Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548. Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c. {4} ok show-nets a) /pci@7c0/pci@0/pci@2/network@0,1 b) /pci@7c0/pci@0/pci@2/network@0 c) /pci@780/pci@0/pci@8/network@0,3 d) /pci@780/pci@0/pci@8/network@0,2 e) /pci@780/pci@0/pci@8/network@0,1 f) /pci@780/pci@0/pci@8/network@0 g) /pci@780/pci@0/pci@1/network@0,1 h) /pci@780/pci@0/pci@1/network@0 q) NO SELECTION Enter Selection, q to quit: d /pci@780/pci@0/pci@8/network@0,2 has been selected. Type ^Y ( Control-Y ) to insert it in the command line. e.g. ok nvalias mydev ^Y for creating devalias mydev for /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias ... net3 /pci@7c0/pci@0/pci@2/network@0,1 net2 /pci@7c0/pci@0/pci@2/network@0 net1 /pci@780/pci@0/pci@1/network@0,1 net0 /pci@780/pci@0/pci@1/network@0 net /pci@780/pci@0/pci@1/network@0 ... name aliases By looking at the devalias and the show-nets output, we can see that our Quad-GbE card must be the device nodes starting with  /pci@780/pci@0/pci@8/network@0.  The cable for our network is plugged into the 3rd slot, so the device address for our network must be /pci@780/pci@0/pci@8/network@0,2. With that, we can create a device alias for our network interface.  Naming the device alias may take a little bit of trial and error, especially in Solaris 11 where the device alias seems to matter more with the new virtualized network stack. So far in my testing, since this is the "next" network interface to be used, I have found success in naming it net4, even though it's a NIC in the middle of a card that might, by rights, be called net6 (assuming the 0th interface on the card is the next interface identified by Solaris and this is the 3rd interface on the card).  So, we will call it net4.  We need to assign a device alias to it: {4} ok nvalias net4 /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias net4 /pci@780/pci@0/pci@8/network@0,2 ... We also may need to have the MAC for this particular interface, so let's get it, too.  To do this, we go to the device and interrogate its properties. {4} ok cd /pci@780/pci@0/pci@8/network@0,2 {4} ok .properties assigned-addresses 82060210 00000000 03000000 00000000 01000000 82060218 00000000 00320000 00000000 00008000 82060220 00000000 00328000 00000000 00008000 82060230 00000000 00600000 00000000 00100000 local-mac-address 00 21 28 20 42 92 phy-type mif ... From this, we can see that the MAC for this interface is  00:21:28:20:42:92.  We will need this later. This is all we need to do at the OBP.  Now, we can configure Ops Center to use this interface. Network Boot in Solaris 10 Solaris 10 turns out to be a little simpler than Solaris 11 for this sort of a network boot.  Since WANBoot in Solaris 10 fetches a specified In order to install the system using Ops Center, it is necessary to create a OS Provisioning profile and its corresponding plan.  I am going to presume that you already know how to do this within Ops Center 12c and I will just cover the differences between a regular profile and a profile that can use an alternate interface. Create a OS Provisioning profile for Solaris 10 as usual.  However, when you specify the network resources for the primary network, click on the name of the NIC, probably GB_0, and rename it to GB_N/netN, where N is the instance number you used previously in creating the device alias.  This is where the trial and error may come into play.  You may need to try a few instance numbers before you, the OBP, and Solaris all agree on the instance number.  Mark this as the boot network. For Solaris 10, you ought to be able to then apply the OS Provisioning profile to the server and it should install using that interface.  And if you put your cards in the same slots and plug the networks into the same NICs, this profile is reusable across multiple servers. Why This Works If you watch the console as Solaris boots during the OSP process, Ops Center is going to look for the device alias netN.  Since WANBoot requires a device alias called just net, Ops Center uses the value of your netN device alias and assigns that device to the net alias.  That means that boot net will automatically use this device.  Very cool!  Here's a trace from the console as Ops Center provisions a server: Sun Sun Fire T200, No KeyboardCopyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548.Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c.auto-boot? =            false{0} ok  {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2 See what happened?  Ops Center looked for the network device alias called net4 that we specified in the profile, took the value from it, and made it the net device alias for the boot.  Pretty cool! WANBoot and Solaris 11 Solaris 11 requires an additional step since the Automated Installer in Solaris 11 uses the MAC address of the network to figure out which manifest to use for system installation.  In order to make sure this is available, we have to take an extra step to associate the MAC of the NIC on the card with the host.  So, in addition to creating the device alias like we did above, we also have to declare to Ops Center that the host has this new MAC. Declaring the NIC Start out by discovering the hardware as usual.  Once you have discovered it, take a look under the Connectivity tab to see what networks it has discovered.  In the case of this system, it shows the 4 built-in networks, but not the networks on the additional cards.  These are not directly visible to the system controller.  In order to add the additional network interface to the hardware asset, it is necessary to Declare it.  We will declare that we have a server with this additional NIC, but we will also  specify the existing GB_0 network so that Ops Center can associate the right resources together.  The GB_0 acts as sort of a key to tie our new declaration to the old system already discovered.  Go to the Assets tab, select All Assets, and then in the Actions tab, select Add Asset.  Rather than going through a discovery this time, we will manually declare a new asset. When we declare it, we will give the hostname, IP address, system model that match those that have already been discovered.  Then, we will declare both GB_0 with its existing MAC and the new GB_4 with its MAC.  Remember that we collected the MAC for GB_4 when we created its device alias. After you declare the asset, you will see the new NIC in the connectivity tab for the asset.  You will notice that only the NICs you listed when you declared it are seen now.  If you want Ops Center to see all of the existing NICs as well as the additional one, declare them as well.  Add the other GB_1, GB_2, GB_3 links and their MACs just as you did GB_0 and GB_4.  Installing the OS  Once you have declared the asset, you can create an OS Provisioning profile for Solaris 11 in the same way that you did for Solaris 10.  The only difference from any other provisioning profile you might have created already is the network to use for installation.  Again, use GB_N/netN where N is the interface number you used for your device alias and in your declaration.  And away you go.  When the system boots from the network, the automated installer (AI) is able to see which system manifest to use, based on the new MAC that was associated, and the system gets installed. {0} ok {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2...SunOS Release 5.11 Version 11.0 64-bitCopyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved.Remounting root read/writeProbing for device nodes ...Preparing network image for useDownloading solaris.zlib--2012-02-17 15:10:17--  http://10.140.204.22:5555/var/js/AI/sparc//solaris.zlibConnecting to 10.140.204.22:5555... connected.HTTP request sent, awaiting response... 200 OKLength: 126752256 (121M) [text/plain]Saving to: `/tmp/solaris.zlib'100%[======================================>] 126,752,256 28.6M/s   in 4.4s    2012-02-17 15:10:21 (27.3 MB/s) - `/tmp/solaris.zlib' saved [126752256/126752256] Conclusion So, why go to all of this trouble?  More and more, I find that customers are wiring their data center to only use higher speed networks - 10GbE only to the hosts.  Some customers are moving aggressively toward consolidated networks combining storage and network on CNA NICs.  All of this means that network-based provisioning cannot rely exclusively on the built-in network interfaces.  So, it's important to be able to provision a system using other than the built-in networks.  Turns out, that this is pretty straight-forward for both Solaris 10 and Solaris 11 and fits into the Ops Center deployment process quite nicely. Hopefully, you will be able to use this as you build out your own private cloud solutions with Ops Center.

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  • why use mixed-based replication for mysql

    - by Alistair Prestidge
    I am in the process of configuring MySQL replication and am intending to use row-based-replication but I was also reading up about mixed-based replication. This is where statement-based is the default and then for certain circumstances (http://dev.mysql.com/doc/refman/5.1/en/binary-log-mixed.html) MySQL will switch to row-based. The list is quit vast on when it will switch to row-based. My questions are: Does any one use mixed? If yes why did you chose this over just using one or the other? Thanks in advance

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  • Backbone.js Model change events in nested collections not firing as expected

    - by Pallavi Kaushik
    I'm trying to use backbone.js in my first "real" application and I need some help debugging why certain model change events are not firing as I would expect. I have a web service at /employees/{username}/tasks which returns a JSON array of task objects, with each task object nesting a JSON array of subtask objects. For example, [{ "id":45002, "name":"Open Dining Room", "subtasks":[ {"id":1,"status":"YELLOW","name":"Clean all tables"}, {"id":2,"status":"RED","name":"Clean main floor"}, {"id":3,"status":"RED","name":"Stock condiments"}, {"id":4,"status":"YELLOW","name":"Check / replenish trays"} ] },{ "id":47003, "name":"Open Registers", "subtasks":[ {"id":1,"status":"YELLOW","name":"Turn on all terminals"}, {"id":2,"status":"YELLOW","name":"Balance out cash trays"}, {"id":3,"status":"YELLOW","name":"Check in promo codes"}, {"id":4,"status":"YELLOW","name":"Check register promo placards"} ] }] Another web service allows me to change the status of a specific subtask in a specific task, and looks like this: /tasks/45002/subtasks/1/status/red [aside - I intend to change this to a HTTP Post-based service, but the current implementation is easier for debugging] I have the following classes in my JS app: Subtask Model and Subtask Collection var Subtask = Backbone.Model.extend({}); var SubtaskCollection = Backbone.Collection.extend({ model: Subtask }); Task Model with a nested instance of a Subtask Collection var Task = Backbone.Model.extend({ initialize: function() { // each Task has a reference to a collection of Subtasks this.subtasks = new SubtaskCollection(this.get("subtasks")); // status of each Task is based on the status of its Subtasks this.update_status(); }, ... }); var TaskCollection = Backbone.Collection.extend({ model: Task }); Task View to renders the item and listen for change events to the model var TaskView = Backbone.View.extend({ tagName: "li", template: $("#TaskTemplate").template(), initialize: function() { _.bindAll(this, "on_change", "render"); this.model.bind("change", this.on_change); }, ... on_change: function(e) { alert("task model changed!"); } }); When the app launches, I instantiate a TaskCollection (using the data from the first web service listed above), bind a listener for change events to the TaskCollection, and set up a recurring setTimeout to fetch() the TaskCollection instance. ... TASKS = new TaskCollection(); TASKS.url = ".../employees/" + username + "/tasks" TASKS.fetch({ success: function() { APP.renderViews(); } }); TASKS.bind("change", function() { alert("collection changed!"); APP.renderViews(); }); // Poll every 5 seconds to keep the models up-to-date. setInterval(function() { TASKS.fetch(); }, 5000); ... Everything renders as expected the first time. But at this point, I would expect either (or both) a Collection change event or a Model change event to get fired if I change a subtask's status using my second web service, but this does not happen. Funnily, I did get change events to fire if I added one additional level of nesting, with the web service returning a single object that has the Tasks Collection embedded, for example: "employee":"pkaushik", "tasks":[{"id":45002,"subtasks":[{"id":1..... But this seems klugey... and I'm afraid I haven't architected my app right. I'll include more code if it helps, but this question is already rather verbose. Thoughts?

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  • Unit Testing (xUnit) an ASP.NET Mvc Controller with a custom input model?

    - by Danny Douglass
    I'm having a hard time finding information on what I expect to be a pretty straightforward scenario. I'm trying to unit test an Action on my ASP.NET Mvc 2 Controller that utilizes a custom input model w/ DataAnnotions. My testing framework is xUnit, as mentioned in the title. Here is my custom Input Model: public class EnterPasswordInputModel { [Required(ErrorMessage = "")] public string Username { get; set; } [Required(ErrorMessage = "Password is a required field.")] public string Password { get; set; } } And here is my Controller (took out some logic to simplify for this ex.): [HttpPost] public ActionResult EnterPassword(EnterPasswordInputModel enterPasswordInput) { if (!ModelState.IsValid) return View(); // do some logic to validate input // if valid - next View on successful validation return View("NextViewName"); // else - add and display error on current view return View(); } And here is my xUnit Fact (also simplified): [Fact] public void EnterPassword_WithValidInput_ReturnsNextView() { // Arrange var controller = CreateLoginController(userService.Object); // Act var result = controller.EnterPassword( new EnterPasswordInputModel { Username = username, Password = password }) as ViewResult; // Assert Assert.Equal("NextViewName", result.ViewName); } When I run my test I get the following error on my test fact when trying to retrieve the controller result (Act section): System.NullReferenceException: Object reference not set to an instance of an object. Thanks in advance for any help you can offer!

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  • Hierarchical object model with property inheritance and event bubbling?

    - by Winston Fassett
    I'm writing a document-based client application and I need a DOM or WPF-like, but non-visual model that: Is a tree composed of elements Can accept an unlimited number of custom properties that get/set any CLR type, including collections. Can inherit their values from their parent Can inherit their default values from an ancestor Can be derived/calculated from other properties, ancestors, or descendants Support event bubbling / tunneling There will be a core set of properties but other plugins may add their own or even create custom documents Supports full inspection by the owning document in order to persist the tree and attributes in an XML format. I realize that's a tall order but I was really hoping there would be something out there to help me get started. Unfortunately WPF DependencyObjects are too closed, proprietary, and coupled to WPF to be of any use as a document model. My needs also have a strong resemblance to the HTML DOM but I haven't been able to find any clean DOM implementations that could be decoupled from HTML or ported to .NET. My current platform is .NET/C# but if anyone knows of anything that might be useful for inspiration or embedding, regardless of the platform, I'd love to know.

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