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• Multitenant Design for SQL Azure: White Paper Available

  - by Herve Roggero

  Cloud computing is about scaling out all your application tiers, from web application to the database layer. In fact, the whole promise of Azure is to pay for just what you need. You need more IIS servers? No problemo... just spin another web server. You expect to double your storage needs for Azure Tables? No problemo; you are covered there too... just pay for your storage needs. But what about the database tier, SQL Azure? How do you add new databases easily, and transparently, so that your application simply uses more of SQL Azure if its needs to? Without changing a single line of code? And what if you need to scale back down? Welcome to the world of database scalability. There are many terms that describe database scalability, including data federation, multitenant designs, and even NoSQL depending on the technical solution you are implementing.  Because SQL Azure is a transactional database system, NoSQL is not really an option. However data federation and multitenant designs offer some very interesting scalability options that are worth considering. Data federation, a feature of SQL Azure that will be offered in the future, offers very interesting capabilities available natively on the SQL Azure platform. More to come in a few weeks... Multitenant designs on the other hand are design practices and technologies designed to help you reach flexible scalability options not available otherwise. The first incarnation of such a method was made available on CodePlex as an open source project (http://enzosqlshard.codeplex.com).  This project was an attempt to provide a sharding library for educational purposes.  All that sounds really cool... and really esoteric... almost a form of database "voodoo"... However after being on multiple Azure projects I am starting to see a real need. Customers want to be able to free themselves from the database tier, so that if they have 10 new customers tomorrow, all they need to do is add 2 more SQL Azure instances. It's that simple. How you achieve this, and suggested application design guidelines, are available in a white paper I just published.  The white paper offers two primary sections. The first section describes the business and technical problem at hand, and how to classify it according to specific design patterns. For example, I discuss compressed shards through schema separation. The second section offers a method for addressing the needs of a multitenant design using a new library, the big bother of the codeplex project mentioned previously (that I created earlier this year), complete with management interface and such. A Beta of this platform will be made available within weeks; as soon as the documentation will be ready.   I would like to ask you to drop me a quick email at [email protected] if you are going to download the white paper. It's not required, but it would help me get in touch with you for feedback.  You can download this white paper here:   http://www.bluesyntax.net/files/EnzoFramework.pdf . Thank you, and I am looking for feedback, thoughts and implementation opportunities.

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• Factory pattern vs ease-of-use?

  - by Curtis White

  Background, I am extending the ASP.NET Membership with custom classes and extra tables. The ASP.NET MembershipUser has a protected constructor and a public method to read the data from the database. I have extended the database structure with custom tables and associated classes. Instead of using a static method to create a new member, as in the original API: I allow the code to instantiate a simple object and fill the data because there are several entities. Original Pattern #1 Protected constructor > static CreateUser(string mydata, string, mydata, ...) > User.Data = mydata; > User.Update() My Preferred Pattern #2 Public constructor > newUser = new MembershipUser(); > newUser.data = ... > newUser.ComplextObject.Data = ... > newUser.Insert() > newUser.Load(string key) I find pattern #2 to be easier and more natural to use. But method #1 is more atomic and ensured to contain proper data. I'd like to hear any opinions on pros/cons. The problem in my mind is that I prefer a simple CRUD/object but I am, also, trying to utilize the underlying API. These methods do not match completely. For example, the API has methods, like UnlockUser() and a readonly property for the IsLockedOut

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• What's the proper approach for writing multi-path "story" flows?

  - by Basiclife

  Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

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• LINQ to SQL - Lightweight O/RM?

  - by CoffeeAddict

  I've heard from some that LINQ to SQL is good for lightweight apps. But then I see LINQ to SQL being used for Stackoverflow, and a bunch of other .coms I know (from interviewing with them). Ok, so is this true? for an e-commerce site that's bringing in millions and you're typically only doing basic CRUDs most the time with the exception of an occasional stored proc for something more complex, is LINQ to SQL complete enough and performance-wise good enough or able to be tweaked enough to run happily on an e-commerce site? I've heard that you just need to tweak performance on the DB side when using LINQ to SQL for a better approach. So there are really 2 questions here: 1) Meaning/scope/definition of a "Lightweight" O/RM solution: What the heck does "lightweight" mean when people say LINQ to SQL is a "lightweight O/RM" and is that true??? If this is so lightweight then why do I see a bunch of huge .coms using it? Is it good enough to run major .coms (obviously it looks like it is) and what determines what the context of "lightweight" is...it's such a generic statement. 2) Performance: I'm working on my own .com and researching different O/RMs. I'm not really looking at the Entity Framework (yet), just want to figure out the LINQ to SQL basics here and determine if it will be efficient enough for me. The problem I think is you can't tweak or control the SQL it generates...

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• Separating code logic from the actual data structures. Best practices?

  - by Patrick

  I have an application that loads lots of data into memory (this is because it needs to perform some mathematical simulation on big data sets). This data comes from several database tables, that all refer to each other. The consistency rules on the data are rather complex, and looking up all the relevant data requires quite some hashes and other additional data structures on the data. Problem is that this data may also be changed interactively by the user in a dialog. When the user presses the OK button, I want to perform all the checks to see that he didn't introduce inconsistencies in the data. In practice all the data needs to be checked at once, so I cannot update my data set incrementally and perform the checks one by one. However, all the checking code work on the actual data set loaded in memory, and use the hashing and other data structures. This means I have to do the following: Take the user's changes from the dialog Apply them to the big data set Perform the checks on the big data set Undo all the changes if the checks fail I don't like this solution since other threads are also continuously using the data set, and I don't want to halt them while performing the checks. Also, the undo means that the old situation needs to be put aside, which is also not possible. An alternative is to separate the checking code from the data set (and let it work on explicitly given data, e.g. coming from the dialog) but this means that the checking code cannot use hashing and other additional data structures, because they only work on the big data set, making the checks much slower. What is a good practice to check user's changes on complex data before applying them to the 'application's' data set?

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• Strategy pattern and "action" classes explosion

  - by devoured elysium

  Is it bad policy to have lots of "work" classes(such as Strategy classes), that only do one thing? Let's assume I want to make a Monster class. Instead of just defining everything I want about the monster in one class, I will try to identify what are its main features, so I can define them in interfaces. That will allow to: Seal the class if I want. Later, other users can just create a new class and still have polymorphism by means of the interfaces I've defined. I don't have to worry how people (or myself) might want to change/add features to the base class in the future. All classes inherit from Object and they implement inheritance through interfaces, not from mother classes. Reuse the strategies I'm using with this monster for other members of my game world. Con: This model is rigid. Sometimes we would like to define something that is not easily achieved by just trying to put together this "building blocks". public class AlienMonster : IWalk, IRun, ISwim, IGrowl { IWalkStrategy _walkStrategy; IRunStrategy _runStrategy; ISwimStrategy _swimStrategy; IGrowlStrategy _growlStrategy; public Monster() { _walkStrategy = new FourFootWalkStrategy(); ...etc } public void Walk() { _walkStrategy.Walk(); } ...etc } My idea would be next to make a series of different Strategies that could be used by different monsters. On the other side, some of them could also be used for totally different purposes (i.e., I could have a tank that also "swims"). The only problem I see with this approach is that it could lead to a explosion of pure "method" classes, i.e., Strategy classes that have as only purpose make this or that other action. In the other hand, this kind of "modularity" would allow for high reuse of stratagies, sometimes even in totally different contexts. What is your opinion on this matter? Is this a valid reasoning? Is this over-engineering? Also, assuming we'd make the proper adjustments to the example I gave above, would it be better to define IWalk as: interface IWalk { void Walk(); } or interface IWalk { IWalkStrategy WalkStrategy { get; set; } //or something that ressembles this } being that doing this I wouldn't need to define the methods on Monster itself, I'd just have public getters for IWalkStrategy (this seems to go against the idea that you should encapsulate everything as much as you can!) Why? Thanks

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• how to design a database for a specific website.

  - by Steven Spielberg

  i want to design a Database for a website. how i can design it better. are you know any particular thing, tips , technique to design it in better way. in a table of information user can allow to website to show it or hide it. how can i do this like info1 = show info2 = show info3 = show i have a much more field that user can be showed and hide. how i can handle this situation or condition in Database

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• How to start recognizing design patterns as you are programming?

  - by Jon Erickson

  I have general academic knowledge of the various design patterns that are discussed in GoF and Head First Design Patterns, but I have a difficult time applying them to the code that I am writing. A goal for me this year is to be able to recognize design patterns that are emerging from the code that I write. Obviously this comes with experience (I have about 2 years in the field), but my question is how can I jumpstart my ability to recognize design patterns as I am coding, maybe a suggestion as to what patterns are easiest to start applying in client-server applications (in my case mainly c# webforms with ms sql db's, but this could definitely be language agnostic).

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• When are you truly forced to use UUID as part of the design?

  - by Pyrolistical

  I don't really see the point of UUID. I know the probability of a collision is effectively nil, but effectively nil is not even close to impossible. Can somebody give an example where you have no choice but to use UUID? From all the uses I've seen, I can see an alternative design without UUID. Sure the design might be slightly more complicated, but at least it doesn't have a non-zero probability of failure. UUID smells like global variables to me. There are many ways global variables make for simpler design, but its just lazy design.

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• web site development best practices, design or code by first?

  - by pygabriel

  I'm using an MVC framework to develop a web site, I've to care about the design in the sense of look and feel (views) and the code (models, controllers). I don't know what is the best way to proceed: code and design iteratively by small chunks? design first ? you've got the point

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• DB Interface Design Optimization: Is it better to optimise for Fewer requests of smaller data size?

  - by Overflow

  The prevailing wisdom in webservices/web requests in general is to design your api such that you use as few requests as possible, and that each request returns therefore as much data as is needed In database design, the accepted wisdom is to design your queries to minimise size over the network, as opposed to minimizing the number of queries. They are both remote calls, so what gives?

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• Which well known systems were built using design by contract?

  - by Kaka Woef

  To convince my team mates of the usefulness of design-by-contract, I am looking for well known examples of realistic systems that were built using design by contract. Pointers to realistic, critical evaluations are appreciated. In other words: what is the best example of a system successfully built using design-by-contract?

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• authentication problem with SQL when AD user deleted and recreated problem

  - by iyad jadaa

  I have deleted the user from AD and recreated it again with the same display name. Everything works except the SQL since it has a different SID. How can I fix it? I'm afraid to delete the SQL user since it will delete all its entries. Iyad Jadaa

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• Is "White-Board-Coding" inappropriate during interviews?

  - by Eoin Campbell

  This is a somewhat subjective quesiton but I'd love to hear feedback/opinions from either interviewers/interviewees on the topic. We split our technical part into 4 parts. Write Code, Read & Analyse Code, Design Session & Code on the white board. For the last part what we ask interviewees to do is write a small code snippet (4-5 lines) on the whiteboard and explain as they go through it. Let me be clear the purpose is not to catch people out. We're not looking for perfect syntax. Hell it can even be pseudo-code. but the point is to give them a very simple problem and see if their brain can communicate the solution to us. By simple problems I mean "Reverse a string", "FizzBuzz" etc... EDIT Just with regards the comment about Pseudo-Code. We always ask for an explicit language first. We;re a .NET C# house. we've only said "pseudo-code" where someone has been blanking/really struggling with the code. My question is "Is it innappropriate / unreasonable to expect a programmer to write a code snippet on a whiteboard during an interview ?"

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• My first time in the gambling industry

  - by sfrj

  I am a Java enterprise developer with almost 3 years of professional experience. Soon i am going to have a face to face interview with a company in the gambling industry. I already did successfully a phone screening and now for the personal interview i suppose they will ask me about some kind of white board problem or system design task. I think i am in the right place to ask about this, and would appreciate a lot if someone would give me some tips or share something related to his own experience. The things i am more interested in regarding my interview are: What are the most common challenges for programmers, in this industry? Any idea or suggestion on a white board problem they may ask me? Could you point me to some links where i can find information on the topic or sample problems in this industry?. I personally find this question very interesting not just for me. Also i think, the given answers can help also others in a similar situation. Just what i want to say whit this last comment is: Please avoid, answers like: www.google.com and so on...

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• Calculating 3d rotation around random axis

  - by mitim

  This is actually a solved problem, but I want to understand why my original method didn't work (hoping someone with more knowledge can explain). (Keep in mind, I've not very experienced in 3d programming, having only played with the very basic for a little bit...nor do I have a lot of mathematical experience in this area). I wanted to animate a point rotating around another point at a random axis, say a 45 degrees along the y axis (think of an electron around a nucleus). I know how to rotate using the transform matrix along the X, Y and Z axis, but not an arbitrary (45 degree) axis. Eventually after some research I found a suggestion: Rotate the point by -45 degrees around the Z so that it is aligned. Then rotate by some increment along the Y axis, then rotate it back +45 degrees for every frame tick. While this certainly worked, I felt that it seemed to be more work then needed (too many method calls, math, etc) and would probably be pretty slow at runtime with many points to deal with. I thought maybe it was possible to combine all the rotation matrixes involve into 1 rotation matrix and use that as a single operation. Something like: [ cos(-45) -sin(-45) 0] [ sin(-45) cos(-45) 0] rotate by -45 along Z [ 0 0 1] multiply by [ cos(2) 0 -sin(2)] [ 0 1 0 ] rotate by 2 degrees (my increment) along Y [ sin(2) 0 cos(2)] then multiply that result by (in that order) [ cos(45) -sin(45) 0] [ sin(45) cos(45) 0] rotate by 45 along Z [ 0 0 1] I get 1 mess of a matrix of numbers (since I was working with unknowns and 2 angles), but I felt like it should work. It did not and I found a solution on wiki using a different matirx, but that is something else. I'm not sure if maybe I made an error in multiplying, but my question is: this is actually a viable way to solve the problem, to take all the separate transformations, combine them via multiplying, then use that or not?

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• Architect: "Collaborating on Design Patterns"

  It takes an architect community to raise a collection of SOA design patterns.

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• The 10 Biggest Mistakes in Web Design -- Still!

  After a three-year hiatus, human-computer interaction expert Jakob Nielsen updates his list of the top 10 Web design mistakes you should avoid.

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• The 10 Biggest Mistakes in Web Design -- Still!

  After a three-year hiatus, human-computer interaction expert Jakob Nielsen updates his list of the top 10 Web design mistakes you should avoid.

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• design of 'game engine' for small javascript games?

  - by Matt Ball

  I'm making a group of two or three simple javascript games for fun. After someone finishes one game, they'll be presented with a harder or easier version of another game depending on whether the original game was won or lost. I have a high-level question about the design of things: So far I've created a class for one game type that manages the interaction with the UI and the state of the game itself. But for tracking how many of the subgames have been won, or for understanding whether the next game presented should be more or less difficult, are there arguments to be made for making a 'game engine' class? How does the engine communicate to the games? For instance, when a game is won, how is that information relayed to the engine? Is there a better or more common design? (If you want to see what I have so far, the games are slowly taking shape here: https://github.com/yosemitebandit/candela and can be viewed at http://yosemitebandit.com/candela)

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• Book Review: Professional ASP.NET Design Patterns by Scott Millett

  - by Sam Abraham

  In the next few lines, I will be providing a brief review of Wrox’s Professional ASP.NET Design Patterns by Scott Millett. Design patterns have been a hot topic for many years as developers looked to do more with less, re-use as much code as possible by creating common libraries, as well as make their code easier to understand, extend and collaborate on. Scott Millett’s book covered classic and emerging patterns in a practical presentation that demonstrated with thorough examples how to put each pattern to use in the context of multi-tiered ASP.NET applications. The author’s unique approach and content earned him much kudos in the foreword by Scott Hanselman as well as online reviews. The book has 14 chapters of which 5 are dedicated to a comprehensive case study. Patterns covered therein include S.O.L.I.D, Gang of Four (GoF) as well as Martin Fowler’s Patterns of Enterprise Applications. Many thanks to the Wiley/Wrox User Group Program for their support of our West Palm Beach Developers’ Group. Best regards, --Sam You can access my reviews of books I recently read: Professional WCF 4.0 Inside Windows Communication Foundation Inside Microsoft SQL Server 2008 series

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• Google I/O 2010 - Android UI design patterns

  Google I/O 2010 - Android UI design patterns Google I/O 2010 - Android UI design patterns Android 201 Chris Nesladek, German Bauer, Richard Fulcher, Christian Robertson, Jim Palmer In this session, the Android User Experience team will show the types of patterns you can use to build a great Android application. We'll cover things like how to use Interactive Titlebars, Quick Contacts, and Bottom bars as well some new patterns which will get an I/O-only preview. The team will be also available for a no holds barred Q&A session. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 6 0 ratings Time: 58:42 More in Science & Technology

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• Time Bomb Design - A Longer Fuse

  In a sequel to his first article on Time Bomb Design, David Poole examines the issues we find between development environments and production ones.

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• La première beta de Ubuntu 10.04 LTS est sortie : nouveau design, nouveau kernel, nouveaux logiciels

  La beta 1 de Ubuntu 10.04 LTS est sortie Nouveau design, nouveau kernel, nouveaux logiciels Fini le marron dans Ubuntu. Le choc est rude, certes. Mais la première beta de la mouture 10.04 de l'OS consolera les nostalgique de l'ancien design de la distribution Linux (certainement) la plus connue au monde. Bien qu'il ne s'agisse que de la première beta, Lucid Lynx propose en effet déjà plusieurs nouveautés majeures. Sous le capot, on trouve par exemple le kernel 2.6.32 de Linux, Gnome 2.30 et une prise en charge améliorée des cartes graphiques NVIDIA. Coté logiciel, Ubuntu 10.04 propose notamment OpenOffice.org 3.2.0 (la suite bureautique de Su...

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• Photoshop Elements 9 VS Paintshop Photo Pro X3 For Web Design

  - by Brian

  I need a good image creation program for web design. I have downloaded both Elements 9 and Paintshop X3. So far I have found them both to be great programs. X3 seems like it has a lot of features, Elements seems like it's quite easy and stable to use. I think I'm going to go with Elements, but I wanted to get other opinions. Which program do you guys like better overall? What things do you think they lack for image creation/editing pertaining to web design, or what features do they have that are great for it? Thanks!

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