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• DDD: Enum like entities

  - by Chris

  Hi all, I have the following DB model: **Person table** ID | Name | StateId ------------------------------ 1 Joe 1 2 Peter 1 3 John 2 **State table** ID | Desc ------------------------------ 1 Working 2 Vacation and domain model would be (simplified): public class Person { public int Id { get; } public string Name { get; set; } public State State { get; set; } } public class State { private int id; public string Name { get; set; } } The state might be used in the domain logic e.g.: if(person.State == State.Working) // some logic So from my understanding, the State acts like a value object which is used for domain logic checks. But it also needs to be present in the DB model to represent a clean ERM. So state might be extended to: public class State { private int id; public string Name { get; set; } public static State New {get {return new State([hardCodedIdHere?], [hardCodeNameHere?]);}} } But using this approach the name of the state would be hardcoded into the domain. Do you know what I mean? Is there a standard approach for such a thing? From my point of view what I am trying to do is using an object (which is persisted from the ERM design perspective) as a sort of value object within my domain. What do you think? Question update: Probably my question wasn't clear enough. What I need to know is, how I would use an entity (like the State example) that is stored in a database within my domain logic. To avoid things like: if(person.State.Id == State.Working.Id) // some logic or if(person.State.Id == WORKING_ID) // some logic

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• Can I add a feature to Visual Studio to "Create Copy of Project For [XXXX]"?

  - by Kevin

  If you are doing XNA Programming, you have an option in the context menu for your project similar to "Create Copy of Project For Windows" or "Create Copy of Project for XBox360". I would like to add the same functionality to extend VS.NET to duplicate a current project but target a different platform for an effort I'm working on. Is this possible? If so how?

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• What are the most difficult aspects of project management in Software Engineering?

  - by Jamie Chapman

  I have been asked to provide a brief summary of the what the most difficult aspects of being a project manager of a software engineering project. However, I have no experience of this as I'm still at University and have no "hands on" experience of project management. I was hoping that someone on SO would be able to provide some insight based on their experience. What are the most difficult aspects of project management in Software Engineering?

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• MVC2 Data Annotation Buddy Classes Doesn't seem to work when Classes and EOM Model is in separate Project

  - by Danish Ali

  Dear All Iam new to MVC2 and having a little problem with implementing validation via buddy classes. Iam using Repository pattern with dependency injection. My Entity Object Model is in Data Layer Project and Buddy Classes are in Business Layer project and MVC 2 Project as a separate Presentation Layer Project. Can any one help me out with implementing Buddy Classes in this Architecture. Thanks and Regards Dani

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• Resource not found using library project in Android

  - by hgpc

  I'm converting an existing project into a library project. I configured the original project as a library project and added an application project which references the original project as a library. The library project has an activity (MainActivity) and its layout (main.xml). The application project declares this activity as the main activity in the manifest like this: <activity android:name="com.example.MainActivity" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> When I run the application project I get the following error... android.content.res.Resources$NotFoundException: Resource ID #0x7f030002 ...on the following line of the onCreate method of the main activity: setContentView(R.layout.main); 0x7f030002 is the ID of R.layout.main in the library project. The application project has no main resource. If I run the original project I don't get this error. Both projects neither have compilation errors nor warnings and are built with Android 2.2 with min SDK version 3. What might be the problem?

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• Question About Example In Robert C Martin's _Clean Code_

  - by Jonah

  This is a question about the concept of a function doing only one thing. It won't make sense without some relevant passages for context, so I'll quote them here. They appear on pgs 37-38: To say this differently, we want to be able to read the program as though it were a set of TO paragraphs, each of which is describing the current level of abstraction and referencing subsequent TO paragraphs at the next level down. To include the setups and teardowns, we include setups, then we include the test page content, and then we include the teardowns. To include the setups, we include the suite setup if this is a suite, then we include the regular setup. It turns out to be very dif?cult for programmers to learn to follow this rule and write functions that stay at a single level of abstraction. But learning this trick is also very important. It is the key to keeping functions short and making sure they do “one thing.” Making the code read like a top-down set of TO paragraphs is an effective technique for keeping the abstraction level consistent. He then gives the following example of poor code: public Money calculatePay(Employee e) throws InvalidEmployeeType { switch (e.type) { case COMMISSIONED: return calculateCommissionedPay(e); case HOURLY: return calculateHourlyPay(e); case SALARIED: return calculateSalariedPay(e); default: throw new InvalidEmployeeType(e.type); } } and explains the problems with it as follows: There are several problems with this function. First, it’s large, and when new employee types are added, it will grow. Second, it very clearly does more than one thing. Third, it violates the Single Responsibility Principle7 (SRP) because there is more than one reason for it to change. Fourth, it violates the Open Closed Principle8 (OCP) because it must change whenever new types are added. Now my questions. To begin, it's clear to me how it violates the OCP, and it's clear to me that this alone makes it poor design. However, I am trying to understand each principle, and it's not clear to me how SRP applies. Specifically, the only reason I can imagine for this method to change is the addition of new employee types. There is only one "axis of change." If details of the calculation needed to change, this would only affect the submethods like "calculateHourlyPay()" Also, while in one sense it is obviously doing 3 things, those three things are all at the same level of abstraction, and can all be put into a TO paragraph no different from the example one: TO calculate pay for an employee, we calculate commissioned pay if the employee is commissioned, hourly pay if he is hourly, etc. So aside from its violation of the OCP, this code seems to conform to Martin's other requirements of clean code, even though he's arguing it does not. Can someone please explain what I am missing? Thanks.

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• Seperation of game- and rendering logic

  - by Qua

  What is the best way to seperate rendering code from the actually game engine/logic code? And is it even a good idea to seperate those? Let's assume we have a game object called Knight. The Knight has to be rendered on the screen for the user to see. We're now left with two choices. Either we give the Knight a Render/Draw method that we can call, or we create a renderer class that takes care of rendering all knights. In the scenario where the two is seperated the Knight should the knight still contain all the information needed to render him, or should this be seperated as well? In the last project we created we decided to let all the information required to render an object be stored inside the object itself, but we had a seperate component to actually read those informations and render the objects. The object would contain information such as size, rotation, scale, and which animation was currently playing and based on this the renderer object would compose the screen. Frameworks such as XNA seem to think joining the object and rendering is a good idea, but we're afraid to get tied up to a specific rendering framework, whereas building a seperate rendering component gives us more freedom to change framework at any given time.

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• Which project management software for technophobes who've never worked with something like that?

  - by Ernst

  Hi, Our director has asked me to get something to manage projects. Note that so far we haven't used anything of the sort. I did not get very clear instructions yet, probably because she doesn't know exactly what we need either. My guess is, we'll only find out while using something. I've looked at some, openworkbench, ganttproject, and microsoft project. The latter has the advantage of easy importing of users from exchange, are there others that do that (even if not directly, easily)? I don't think it's a critical requirement though. We're using some other custom software where I have to add users manually anyway and we're small enough that it's maybe once a month that I have to add or remove a user. In any case, I'm not in favour of buying anything, since I'm skeptic about us actually succeeding in putting it to good use, and even if we do, we will only during usage discover what we need. We're also not a tech shop, most people vary from not very technically adept to technophobic. This means we need something very userfriendly. I prefer to stay away from online solutions, since we deal with sensitive information and I prefer to keep that in house, but I guess it would be acceptable for the trial period. An intranet site is an option though, but preferably something that is easy to set up with IIS. Xplanner plus and redmine I found too hard to set up for this experiment. Some other options I haven't yet tried to install, but which look to complex for our technophobes: Endeavour Software Project Management, Project-Open, Trac. Any suggestions? Thanks, Ernst

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• Patterns for dynamic CMS components (event driven?)

  - by CitrusTree

  Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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• Re-add missing project without having to re-add it to all projects referencing it

  - by coffeeaddict

  Lets say you open a .NET solution (mine being VS 2010) after you just moved your entire folder to some new location locally. Now one of the projects that was being referenced in that solution is not there and so when you launch VS, it naturally tells you that the project is missing and therefore as always you see the project greyed out in Solution Explorer. Ok, well I can't go re-add that project (specify a different path for where that project lives) unless I remove the missing project reference and then try to re-add it back to the solution. But how can I reassociate a project without losing all references in other projects that were referencing that missing project? Is this possible? Otherwise every time I re-add that missing project, I end up having to go through about 8 projects of mine that are referencing it and re-reference it for each one of those projects which is tedious. I guess it makes sense since each project was referencing that missing project at that old path so it would break it there as well but is there an easier way to re-associate a project and references to that missing project without having to take 10 minutes every time to re-associate it all over the place if simply the path has changed?

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• Employee Info Starter Kit: Project Mission

  - by Mohammad Ashraful Alam

  Employee Info Starter Kit is an open source ASP.NET project template that is intended to address different types of real world challenges faced by web application developers when performing common CRUD operations. Using a single database table ‘Employee’, it illustrates how to utilize Microsoft ASP.NET 4.0, Entity Framework 4.0 and Visual Studio 2010 effectively in that context. Employee Info Starter Kit is highly influenced by the concept ‘Pareto Principle’ or 80-20 rule. where it is targeted to enable a web developer to gain 80% productivity with 20% of effort with respect to learning curve and production. User Stories The user end functionalities of this starter kit are pretty simple and straight forward that are focused in to perform CRUD operation on employee records as described below. Creating a new employee record Read existing employee record Update an existing employee record Delete existing employee records Key Technology Areas ASP.NET 4.0 Entity Framework 4.0 T-4 Template Visual Studio 2010 Architectural Objective There is no universal architecture which can be considered as the best for all sorts of applications around the world. Based on requirements, constraints, environment, application architecture can differ from one to another. Trade-off factors are one of the important considerations while deciding a particular architectural solution. Employee Info Starter Kit is highly influenced by the concept ‘Pareto Principle’ or 80-20 rule, where it is targeted to enable a web developer to gain 80% productivity with 20% of effort with respect to learning curve and production. “Productivity” as the architectural objective typically also includes other trade-off factors as well as, such as testability, flexibility, performance etc. Fortunately Microsoft .NET Framework 4.0 and Visual Studio 2010 includes lots of great features that have been implemented cleverly in this project to reduce these trade-off factors in the minimum level. Why Employee Info Starter Kit is Not a Framework? Application frameworks are really great for productivity, some of which are really unavoidable in this modern age. However relying too many frameworks may overkill a project, as frameworks are typically designed to serve wide range of different usage and are less customizable or editable. On the other hand having implementation patterns can be useful for developers, as it enables them to adjust application on demand. Employee Info Starter Kit provides hundreds of “connected” snippets and implementation patterns to demonstrate problem solutions in actual production environment. It also includes Visual Studio T-4 templates that generate thousands lines of data access and business logic layer repetitive codes in literally few seconds on the fly, which are fully mock testable due to language support for partial methods and latest support for mock testing in Entity Framework. Why Employee Info Starter Kit is Different than Other Open-source Web Applications? Software development is one of the rapid growing industries around the globe, where the technology is being updated very frequently to adapt greater challenges over time. There are literally thousands of community web sites, blogs and forums that are dedicated to provide support to adapt new technologies. While some are really great to enable learning new technologies quickly, in most cases they are either too “simple and brief” to be used in real world scenarios or too “complex and detailed” which are typically focused to achieve a product goal (such as CMS, e-Commerce etc) from "end user" perspective and have a long duration learning curve with respect to the corresponding technology. Employee Info Starter Kit, as a web project, is basically "developer" oriented which actually considers a hybrid approach as “simple and detailed”, where a simple domain has been considered to intentionally illustrate most of the architectural and implementation challenges faced by web application developers so that anyone can dive into deep into the corresponding new technology or concept quickly. Roadmap Since its first release by 2008 in MSDN Code Gallery, Employee Info Starter Kit gained a huge popularity in ASP.NET community and had 1, 50,000+ downloads afterwards. Being encouraged with this great response, we have a strong commitment for the community to provide support for it with respect to latest technologies continuously. Currently hosted in Codeplex, this community driven project is planned to have a wide range of individual editions, each of which will be focused on a selected application architecture, framework or platform, such as ASP.NET Webform, ASP.NET Dynamic Data, ASP.NET MVC, jQuery Ajax (RIA), Silverlight (RIA), Azure Service Platform (Cloud), Visual Studio Automated Test etc. See here for full list of current and future editions.

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• Is this kind of Design by Contract useless?

  - by Charlie Pigarelli

  I've just started informatics university and I'm attending a programming course about C(++). The programming professor prefers to teach very few things (in 3 month we have just reached the functions topic) and connect every topic with a type of programming design that somehow is similar to the Design by Contract design. Basically what he ask us to do is to write every exercise with comments Pre-conditions, Post-conditions and Invariants that should prove the correctness of each program we write. But this doesn't make any sense to me. I mean, ok: maybe writing down your thoughts prevent you from doing some mistakes, but if this is all an abstract thing, then if your program intuition is wrong you'll write your program wrong and then you'll also write pre and post conditions wrong probably auto convincing your self about its correctness. Most of the time, both me and other students have written programs that seemed ok and that had correct pre and post condition too. But at the moment of testing it was just completely wrong. I had some experience before this course of programming and I had written a lot of line of code before and I found myself comfortably with just writing a program and unit test it. It take less time to accomplish and is less "abstract" than just thinking about what every single piece of your program should do in every case (which is kinda like mentally testing it). Finally, all this pre and post conditions takes me like 80% of the total time of the exercise. It's harder to think about putting down this pre and post correct than to write the program itself. Since we are like the only course of the only university probably in the entire world that makes this things, could someone please tell me how should I manage this thing? Am I right thinking that this doesn't worth anything? Should I change university? (there are like double of the people attending that course and it seems that usually very few people passes the exam the first year). Should I convince myself it's method is right?

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• The Endeca UI Design Pattern Library Returns

  - by Joe Lamantia

  I'm happy to announce that the Endeca UI Design Pattern Library - now titled the Endeca Discovery Pattern Library - is once again providing guidance and good practices on the design of discovery experiences.  Launched publicly in 2010 following several years of internal development and usage, the Endeca Pattern Library is a unique and valued source of industry-leading perspective on discovery - something I've come to appreciate directly through  fielding the consistent stream of inquiries about the library's status, and requests for its rapid return to public availability. Restoring the library as a public resource is only the first step!  For the next stage of the library's evolution, we plan to increase the scope of the guidance it offers beyond user interface design to the broader topic of discovery.  This could include patterns for architecture at the systems, user experience, and business levels; information and process models; analytical method and activity patterns for conducting discovery; and organizational and resource patterns for provisioning discovery capability in different settings.  We'd like guidance from the community on the kinds of patterns that are most valuable - so make sure to let us know. And we're also considering ways to increase the number of patterns the library offers, possibly by expanding the set of contributors and the authoring mechanisms. If you'd like to contribute, please get in touch. Here's the new address of the library: http://www.oracle.com/goto/EndecaDiscoveryPatterns And I should say 'Many thanks' to the UXDirect team and all the others within the Oracle family who helped - literally - keep the library alive, and restore it as a public resource.

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• Software design of a browser-based strategic MMO game

  - by Mehran

  I wonder if there are any known tested software designs for Travian-like browser-based strategic MMO games? I mean how would they implement the server of such games or what is stored in database and what is stored in RAM? Is the state of the world stored in one piece or is it distributed among a number of storage? Does anyone know a resource to study the problems and solutions of creating such games? [UPDATE] Suggested in comments, I'm going to give an example how would I design such a project. Even though I'm not sure if I'm proposing the right one. Having stored the world state in a MongoDB, I would implement an event collection in which all the changes to the world will register. Changes that are meant to happen in the future will come with an action date set to the future and those that are to be carried out immediately will be set to now. Having this datastore as the central point of the system, players will issue their actions as events inserted in datastore. At the other end of the system, I'll have a constant-running software taking out events out of the datastore which are due to be carried out and not done yet. Executing an event means apply some update on the world's state and thus the datastore. As scalable as this design sounds, I'm not sure if it will be worth implementing. For one, it is pointless to cache the datastore as most of updates happen once without any follow ups. For instance if you have the growth of resources in your game, you'll be updating the whole world state periodically in which case, having incorporated a cache, you are keeping the whole world in RAM (which most likely is impossible). So can someone come up with a better design?

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• Good design for a simple site that contains a blog

  - by bporter

  What is a good design for a simple web site with mostly static pages and a blog? I am helping a friend build this for their small business. We are looking for a simple approach that can be implemented fairly quickly. (I am a programmer and can help with coding, hosting, etc.) One option is to use a site like virb, which lets you choose from one of their themes and build a site pretty easily. You can also include a blog. They host the site for a pretty low monthly rate. I recommended this option, but my friend wants a design that is unique and custom. So, I took one of the themes and started modifying the HTML and CSS. This might still be a good option, but... ...If we are going to greatly modify it, why not just create the static pages from scratch and use something like Wordpress for the blog. Is this a good option? It looks fairly easy to integrate Wordpress with a site so that the design and behavior are really cohesive. Is this a good idea? Do you recommend any other approaches?

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• Plug-in based software design

  - by gekod

  I'm a software developer who is willing to improve his software design skills. I think software should not only work but have a solid and elegant design too to be reusable and extensive to later purposes. Now I'm in search of some help figuring out good practices for specific problems. Actually, I'm trying to find out how to design a piece of software that would be extensible via plug-ins. The questions I have are the following: Should plug-ins be able to access each others functionality? This would bring dependencies I guess. What should the main application offer to the plug-ins if I want to let's say develop a multimedia software which would play videos and music but which could later on get functionality added over plug-ins that would let's say be able to read video status (time, bps, ...) and display it. Would this mean that the player itself would have to be part of the main program and offer services to plug-ins to get such information or would there be a way to develop the player as a plug-in also but offer in some way the possibility to other plug-ins to interact with it? As you see, my questions are mainly for learning purposes as I strive to improve my software development skills. I hope to find help here and apologize if something is wrong with my question.

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• Balancing dependency injection with public API design

  - by kolektiv

  I've been contemplating how to balance testable design using dependency injection with providing simple fixed public API. My dilemma is: people would want to do something like var server = new Server(){ ... } and not have to worry about creating the many dependencies and graph of dependencies that a Server(,,,,,,) may have. While developing, I don't worry too much, as I use an IoC/DI framework to handle all that (I'm not using the lifecycle management aspects of any container, which would complicate things further). Now, the dependencies are unlikely to be re-implemented. Componentisation in this case is almost purely for testability (and decent design!) rather than creating seams for extension, etc. People will 99.999% of the time wish to use a default configuration. So. I could hardcode the dependencies. Don't want to do that, we lose our testing! I could provide a default constructor with hard-coded dependencies and one which takes dependencies. That's... messy, and likely to be confusing, but viable. I could make the dependency receiving constructor internal and make my unit tests a friend assembly (assuming C#), which tidies the public API but leaves a nasty hidden trap lurking for maintenance. Having two constructors which are implicitly connected rather than explicitly would be bad design in general in my book. At the moment that's about the least evil I can think of. Opinions? Wisdom?

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• A fix for the design time error in MVVM Light V4.1

  - by Laurent Bugnion

  For those of you who installed V4.1 of MVVM Light and created a project for Windows Phone 8, you will have noticed an error showing up in the design surface (either in Visual Studio designer, or in Expression Blend). The error says: “Could not load type ‘System.ComponentModel.INotifyPropertyChanging’ from assembly ‘mscorlib.extensions’” with additional information about version numbers. The error is caused by an incompatibility between versions of System.Windows.Interactivity. Because this assembly is strongly named, any version incompatibility is causing the kind of error shown here (for an interesting discussion on the strong naming issue, see this thread on Codeplex). I managed to resolve the issue for Windows Phone 8 and will publish a cleaned up installer next week. In the mean time, in order to allow you to continue development, please follow the steps: Download the new DLLs zip package (MVVMLight_V4_1_25_WP8). Right click on the Zip file and select Properties from the context menu. Press the “Unblock” button (if available) and then OK. Right click again on the zip package and select “Extract all…”. Select a known location for the new DLLs. Open the MVVM Light project with the design time error in Visual Studio 2012. Open the References folder in the Solution Explorer. Select the following DLLs: GalaSoft.MvvmLight.dll, GalaSoft.MvvmLight.Extras.dll, Microsoft.Practices.ServiceLocation.dll and System.Windows.Interactivity.dll. Press “delete” and confirm to remove the DLLs from your project. Right click on References and select Add Reference from the context menu. Browse to the folder with the new DLLs. Select the four new DLLs and press OK. Rebuild your application, and open it again in Blend or in the Visual Studio designer. The error should be gone now. In the next few days, as time allows, I will publish a new MSI containing a fixed version of the DLLs as well as a few other improvements. This quick fix should however allow you to continue working on your Windows Phone 8 projects in design mode too.   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• Website Design; SEO Dilemma

  - by lemonpole

  Okay so I designed a website for a restaurant and the design is aimed mostly to entice the viewer by using images of the restaurant's platters and foods. Not to say that text is totally non-existent but the design makes it hard to have enough keywords. Most keywords are found in the ALT attribute of image tags and a couple of headers. The reason as to why I am in this dilemma? I'm still new to web development and at the time I made the design, I didn't really know much about SEO. So I come here in search of help because I have an idea... Would it be good practice to have hidden SPAN blocks that would help me fill with keywords? For example a hidden SPAN would have text in bold to help with SEO. Of course, I will play it safe and not exploit this technique if it works. I have searched that this may be considered spamming by search engines and some companies are taking measures to prevent this. Thanks in advance!

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• How to Avoid Your Next 12-Month Science Project

  - by constant

  While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack. After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades? On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea. Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company. Engineering Systems is Hard Work! The backbone of Exalogic is its InfiniBand network: 4 times better bandwidth than even 10 Gigabit Ethernet, and only about a tenth of its latency. What a potential for increased scalability and throughput across the middleware and database layers! But InfiniBand is a beast that needs to be tamed: It is true that Exalogic uses a standard, open-source Open Fabrics Enterprise Distribution (OFED) InfiniBand driver stack. Unfortunately, this software has been developed by the HPC community with fastest speed in mind (which is good) but, despite the name, not many other enterprise-class requirements are included (which is less good). Here are some of the improvements that Oracle's InfiniBand development team had to add to the OFED stack to make it enterprise-ready, simply because typical HPC users didn't have the need to implement them: More than 100 bug fixes in the pieces that were not related to the Message Passing Interface Protocol (MPI), which is the protocol that HPC users use most of the time, but which is less useful in the enterprise. Performance optimizations and tuning across the whole IB stack: From Switches, Host Channel Adapters (HCAs) and drivers to low-level protocols, middleware and applications. Yes, even the standard HPC IB stack could be improved in terms of performance. Ethernet over IB (EoIB): Exalogic uses InfiniBand internally to reach high performance, but it needs to play nicely with datacenters around it. That's why Oracle added Ethernet over InfiniBand technology to it that allows for creating many virtual 10GBE adapters inside Exalogic's nodes that are aggregated and connected to Exalogic's IB gateway switches. While this is an open standard, it's up to the vendor to implement it. In this case, Oracle integrated the EoIB stack with Oracle's own IB to 10GBE gateway switches, and made it fully virtualized from the beginning. This means that Exalogic customers can completely rewire their server infrastructure inside the rack without having to physically pull or plug a single cable - a must-have for every cloud deployment. Anybody who wants to match this level of integration would need to add an InfiniBand switch development team to their project. Or just buy Oracle's gateway switches, which are conveniently shipped with a whole server infrastructure attached! IPv6 support for InfiniBand's Sockets Direct Protocol (SDP), Reliable Datagram Sockets (RDS), TCP/IP over IB (IPoIB) and EoIB protocols. Because no IPv6 = not very enterprise-class. HA capability for SDP. High Availability is not a big requirement for HPC, but for enterprise-class application servers it is. Every node in Exalogic's InfiniBand network is connected twice for redundancy. If any cable or port or HCA fails, there's always a replacement link ready to take over. This requires extra magic at the protocol level to work. So in addition to Weblogic's failover capabilities, Oracle implemented IB automatic path migration at the SDP level to avoid unnecessary failover operations at the middleware level. Security, for example spoof-protection. Another feature that is less important for traditional users of InfiniBand, but very important for enterprise customers. InfiniBand Partitioning and Quality-of-Service (QoS): One of the first questions we get from customers about Exalogic is: “How can we implement multi-tenancy?” The answer is to partition your IB network, which effectively creates many networks that work independently and that are protected at the lowest networking layer possible. In addition to that, QoS allows administrators to prioritize traffic flow in multi-tenancy environments so they can keep their service levels where it matters most. Resilient IB Fabric Management: InfiniBand is a self-managing network, so a lot of the magic lies in coming up with the right topology and in teaching the subnet manager how to properly discover and manage the network. Oracle's Infiniband switches come with pre-integrated, highly available fabric management with seamless integration into Oracle Enterprise Manager Ops Center. In short: Oracle elevated the OFED InfiniBand stack into an enterprise-class networking infrastructure. Many years and multiple teams of manpower went into the above improvements - this is something you can only get from Oracle, because no other InfiniBand vendor can give you these features across the whole stack! Exabus: Because it's not About the Size of Your Network, it's How You Use it! So let's assume that you somehow were able to get your hands on an enterprise-class IB driver stack. Or maybe you don't care and are just happy with the standard OFED one? Anyway, the next step is to actually leverage that InfiniBand performance. Here are the choices: Use traditional TCP/IP on top of the InfiniBand stack, Develop your own integration between your middleware and the lower-level (but faster) InfiniBand protocols. While more bandwidth is always a good thing, it's actually the low latency that enables superior performance for your applications when running on any networking infrastructure: The lower the latency, the faster the response travels through the network and the more transactions you can close per second. The reason why InfiniBand is such a low latency technology is that it gets rid of most if not all of your traditional networking protocol stack: Data is literally beamed from one region of RAM in one server into another region of RAM in another server with no kernel/drivers/UDP/TCP or other networking stack overhead involved! Which makes option 1 a no-go: Adding TCP/IP on top of InfiniBand is like adding training wheels to your racing bike. It may be ok in the beginning and for development, but it's not quite the performance IB was meant to deliver. Which only leaves option 2: Integrating your middleware with fast, low-level InfiniBand protocols. And this is what Exalogic's "Exabus" technology is all about. Here are a few Exabus features that help applications leverage the performance of InfiniBand in Exalogic: RDMA and SDP integration at the JDBC driver level (SDP), for Oracle Weblogic (SDP), Oracle Coherence (RDMA), Oracle Tuxedo (RDMA) and the new Oracle Traffic Director (RDMA) on Exalogic. Using these protocols, middleware can communicate a lot faster with each other and the Oracle database than by using standard networking protocols, Seamless Integration of Ethernet over InfiniBand from Exalogic's Gateway switches into the OS, Oracle Weblogic optimizations for handling massive amounts of parallel transactions. Because if you have an 8-lane Autobahn, you also need to improve your ramps so you can feed it with many cars in parallel. Integration of Weblogic with Oracle Exadata for faster performance, optimized session management and failover. As you see, “Exabus” is Oracle's word for describing all the InfiniBand enhancements Oracle put into Exalogic: OFED stack enhancements, protocols for faster IB access, and InfiniBand support and optimizations at the virtualization and middleware level. All working together to deliver the full potential of InfiniBand performance. Who else has 100% control over their middleware so they can develop their own low-level protocol integration with InfiniBand? Even if you take an open source approach, you're looking at years of development work to create, test and support a whole new networking technology in your middleware! The Extras: Less Hassle, More Productivity, Faster Time to Market And then there are the other advantages of Engineered Systems that are true for Exalogic the same as they are for every other Engineered System: One simple purchasing process: No headaches due to endless RFPs and no “Will X work with Y?” uncertainties. Everything has been engineered together: All kinds of bugs and problems have been already fixed at the design level that would have only manifested themselves after you have built the system from scratch. Everything is built, tested and integrated at the factory level . Less integration pain for you, faster time to market. Every Exalogic machine world-wide is identical to Oracle's own machines in the lab: Instant replication of any problems you may encounter, faster time to resolution. Simplified patching, management and operations. One throat to choke: Imagine finger-pointing hell for systems that have been put together using several different vendors. Oracle's Engineered Systems have a single phone number that customers can call to get their problems solved. For more business-centric values, read The Business Value of Engineered Systems. Conclusion: Buy Exalogic, or get ready for a 6-12 Month Science Project And here's the reason why it's not easy to "build your own Exalogic": There's a lot of work required to make such a system fly. In fact, anybody who is starting to "just put together a bunch of servers and an InfiniBand network" is really looking at a 6-12 month science project. And the outcome is likely to not be very enterprise-class. And it won't have Exalogic's performance either. Because building an Engineered System is literally rocket science: It takes a lot of time, effort, resources and many iterations of design/test/analyze/fix to build such a system. That's why InfiniBand has been reserved for HPC scientists for such a long time. And only Oracle can bring the power of InfiniBand in an enterprise-class, ready-to use, pre-integrated version to customers, without the develop/integrate/support pain. For more details, check the new Exalogic overview white paper which was updated only recently. P.S.: Thanks to my colleagues Ola, Paul, Don and Andy for helping me put together this article! var flattr_uid = '26528'; var flattr_tle = 'How to Avoid Your Next 12-Month Science Project'; var flattr_dsc = 'While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack.After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades?On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea.Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company.'; var flattr_tag = 'Engineered Systems,Engineered Systems,Infiniband,Integration,latency,Oracle,performance'; var flattr_cat = 'text'; var flattr_url = 'http://constantin.glez.de/blog/2012/04/how-avoid-your-next-12-month-science-project'; var flattr_lng = 'en_GB'

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• Can a loosely typed language be considered true object oriented?

  - by user61852

  Can a loosely typed programming language like PHP be really considered object oriented? I mean, the methods don't have returning types and method parameters has no declared type either. Doesn't class design require methods to have a return type? Don't methods signatures have specifically-typed parameters? How can OOP techniques help you code in PHP if you always have to check the types of parameters received because the language doesn't enforce types? Please, if I'm wrong, explain it to me. When you design things using UML, then code classes in PHP with no return-typed methods and no-type parameters... Is the code really compliant with the UML design? You spend time designing the architecture of your software, then the compiler doesn't force the programmer to follow your design while coding, letting he/she assign any object variable to any other variable with no "type-mismatch" warning.

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• Designing persistence schema for BigTable on AppEngine

  - by Vitalij Zadneprovskij

  I have tried to design the datastore schema for a very small application. That schema would have been very simple, if not trivial, using a relational database with foreign keys, many-to-many relations, joins, etc. But the problem was that my application was targeted for Google App Engine and I had to design for a database that was not relational. At the end I gave up. Is there a book or an article that describes design principles for applications that are meant for such databases? The books that I have found are about programming for App Engine and they don't spend many words about database design principles.

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• 15 Stylish Navigation Menus For Inspiration

  - by Jyoti

  A site’s navigation menu is one of the most prominent things that users see when they first visit. There are many ways to design a navigation menu  and since almost all websites have some form of navigation designers have to push their creative limits to build one that’s remarkable and outstanding. In this article, you’ll find a showcase of beautiful, creative, and stylish navigation menus for your inspiration. Tennessee Vacation: Alpine Meadows: White House: The Hole In Our Gospel: Navigant Consulting: The Lippincott: Torrance Web Design: Viget Extend: David Hellmann: Candes: Brad Colbow: Cheesetique : Satsu Design: Blue Moon: Africa Oasis Project

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• TechEd 2010 Day Three: The Database Designer (Isn't)

  - by BuckWoody

  Yesterday at TechEd 2010 here in New Orleans I worked the front-booth, answering general SQL Server questions for the masses. I was actually a little surprised to find most of the questions I got were from folks that wanted to know more about Stream Insight and Master Data Services. In past conferences I've been asked a lot of "free consulting" questions, about problems folks have had from older products. I don't mind that a bit - in fact, I'm always happy to help in any way I can. But this time people are really interested in the new features in the product, and I like that they are thinking ahead, not just having to solve problems in production. My presentation was on "Database Design in an Hour". We had the usual fun, and SideShow Bob made an appearance - I kid you not. The guy in the back of the room looked just like Sideshow Bob, so I quickly held a "bes thair" contest, and he won. Duing the presentation, I explain the tools you can use to design databases. I also explain that the "Database Designer" tool in SQL Server Management Studio (SSMS) isn't truly a desinger - it uses non-standard notation, doesn't have a meta-data dictionary, and worst of all, it works at the physical level. In other words, whatever you do in SSMS will automatically change the field/table/relationship structures in the database. We fixed this in SSMS 2008 and higher by adding an option to block that, but the tool is not a good design function nonetheless. To be fair, no one I know of at Microsoft recommends that it is - but I was shocked to hear so many developers in the room defending it as a good tool. I think the main issue for someone who doesn't have to work with Relational Systems a great deal is that it can be difficult to figure out Foreign Keys. The syntax makes them look "backwards", so it's just easier to grab a field and place it on the table you want to point to. There are options. You can download a couple of free tools (CA has a community edition of ER-WIN, Quest has one, and Embarcadero also has one) and if you design more than one or two databases a year, it may be worth buying a true design tool. For years I used Visio, but we changed it so that it doesn't forward-engineer (create the DDL) any more, so it isn't a true design tool either. So investigate those free and not-so-free tools. You'll find they help you in your job - but stay away from the Database Designer in SSMS. Or I'll send Sideshow Bob over there to straighten you out. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Car Modelling for race game

  - by Mert Toka

  I am taking Computer Graphics course this semester and we have a video game competition. I am making racing game with simulated dynamics. Our professor told us that we don't have to do much of a modelling but since we haven't started the gaming part and since I have free time I want to model the car. My question is firstly which software do you recommend to design game components? I know Maya right now. Secondly, if I design the car or any other part, what should its polygon count in order to run game smoothly? I can design pretty much everything but I assume that it is hard to design low-poly models.

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