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  • DOT implementation

    - by Denis Ermolin
    I have some DOT(damage over time) implementation problems. My game runs on 30 FPS speed. Current implementation is: let's say hero cast spell which make 1 damage per second. So on every frame i do (pseudo code): damage_done = getRandomDamage() * delta_time; I accumulate damage and when it becomes more then 0 then subtract rounded damage from current health and so on. With 30 FPS and 1 DPS it will be 1/33 = 0.05... We know that floats a not precise enough to sum 30 circulating decimals and have exact 1 in the end. But HP is discrete value and that's why 1 DPS will not have 1 damage after 1 second because value will be 0.9999..... It's not so big deal when you have 100000 DPS - +/- 1 damage will not be noticeable. But if i have 1, 5 DPS? How modern RPG's implemented DOT's?

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  • Problem upgrading from 13.04 to 13.10

    - by Charles
    Part way through upgrading from 13.04 to 13.10 the process ground to a halt with an error message. Now on retrying by going to 'Check for updates' I get the following: Failed to load the package list This is a serious problem. Try again later. If this problem appears again, please report an error to the developers. E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_saucy_universe_i18n_Translation-en%%5fGB, E:The package lists or status file could not be parsed or opened. Problem reported but my question is, "what can I do now?; Do I have to do a fresh install?; if so will settings etc. in my Home folder (on its own partition) be saved?" 13.04 still seems to be working perfectly, while upgrading I had a terrible internet connection varying between 'dead slow' and 'dead stop', not sure if that caused the problem.

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  • Is there any web application to manage people doing Link Building? [closed]

    - by Alexandru Trandafir Catalin
    I am doing SEO for a website and collaborating with 4-5 people that are working on Link Building for my keywords. I was wondering if there is any application similar to a project management tool but oriented to SEO, Link building, Content writing. This application would allow you to set tasks and your collaborators will update with the links they add in a spreadsheet format so you can later check how many liks have been added for each of your keywords, on wich websites, and how efective is the collaborator.

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  • Inheritance vs composition in this example

    - by Gerenuk
    I'm wondering about the differences between inheritance and composition examined with concrete code relevant arguments. In particular my example was Inheritance: class Do: def do(self): self.doA() self.doB() def doA(self): pass def doB(self): pass class MyDo(Do): def doA(self): print("A") def doB(self): print("B") x=MyDo() vs Composition: class Do: def __init__(self, a, b): self.a=a self.b=b def do(self): self.a.do() self.b.do() x=Do(DoA(), DoB()) (Note for composition I'm missing code so it's not actually shorter) Can you name particular advantages of one or the other? I'm think of: composition is useful if you plan to reuse DoA() in another context inheritance seems easier; no additional references/variables/initialization method doA can access internal variable (be it a good or bad thing :) ) inheritance groups logic A and B together; even though you could equally introduce a grouped delegate object inheritance provides a preset class for the users; with composition you'd have to encapsule the initialization in a factory so that the user does have to assemble the logic and the skeleton ... Basically I'd like to examine the implications of inheritance vs composition. I heard often composition is prefered, but I'd like to understand that by example. Of course I can always start with one and refactor later to the other.

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  • Relationship DAO, Servlet, JSP and POJO

    - by John Hendrik
    I want to implement a JSP, POJO, DAO and Servlet in my J2EE program. However, I don't fully understand how the relationship between these elements should be. Is the following (MVC) setup the right way to do it? Main class creates servlet(controller) Servlet has a DAO defined in its class DAO has a POJO defined in its class Servlet communicates with the view (JSP page) Please give your feedback.

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  • DDD and validation of aggregate root

    - by Mik378
    Suppose an aggregate root : MailConfiguration (wrapping an AddressPart object). The AddressPart object is a simple immutable value object with some fields like senderAdress, recipentAddress (to make example simple). As being an invariant object, AddressPart should logically wrap its own Validator (by the way of external a kind of AddressValidator for respecting Single Responsibility Principle) I read some articles that claimed an aggregateRoot must validate its 'children'. However, if we follow this principle, one could create an AddressPart with an uncohesive/invalid state. What are your opinion? Should I move the collaborator AddressValidator(used in constructor so in order to validate immediately the cohesion of an AddressPart) from AddressPart and assign it to aggregateRoot (MailConfiguration) ?

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  • What is the best way to diagrammatically represent a system threading architecture?

    - by thegreendroid
    I am yet to find the perfect way to diagrammatically represent the overall threading architecture for a system (using UML or otherwise). I am after a diagramming technique that would show all the threads in a given system and how they interact with each other. There are a few similar questions - Drawing Thread Interaction, UML Diagrams of Multithreaded Applications and Intuitive UML Approach to Depict Threads but they don't fully answer my question. What are some of the techniques that you've found useful to depict the overall threading architecture for a system?

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  • How to have operations with character/items in binary with concrete operations?

    - by Piperoman
    I have the next problem. A item can have a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can have some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have tried to set binary flags to states, and use AND to combine different states, checking before if it is possible or not to do it, or change to another status. Does there exist a concrete approach to solve this problem efficiently without having an interminable switch that checks every state with every new state? It is relatively easy to check 2 different states, but if there exists a third state it is not trivial to do.

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  • Is it bad practice to make an iterator that is aware of its own end

    - by aaronman
    For some background of why I am asking this question here is an example. In python the method chain chains an arbitrary number of ranges together and makes them into one without making copies. Here is a link in case you don't understand it. I decided I would implement chain in c++ using variadic templates. As far as I can tell the only way to make an iterator for chain that will successfully go to the next container is for each iterator to to know about the end of the container (I thought of a sort of hack in where when != is called against the end it will know to go to the next container, but the first way seemed easier and safer and more versatile). My question is if there is anything inherently wrong with an iterator knowing about its own end, my code is in c++ but this can be language agnostic since many languages have iterators. #ifndef CHAIN_HPP #define CHAIN_HPP #include "iterator_range.hpp" namespace iter { template <typename ... Containers> struct chain_iter; template <typename Container> struct chain_iter<Container> { private: using Iterator = decltype(((Container*)nullptr)->begin()); Iterator begin; const Iterator end;//never really used but kept it for consistency public: chain_iter(Container & container, bool is_end=false) : begin(container.begin()),end(container.end()) { if(is_end) begin = container.end(); } chain_iter & operator++() { ++begin; return *this; } auto operator*()->decltype(*begin) { return *begin; } bool operator!=(const chain_iter & rhs) const{ return this->begin != rhs.begin; } }; template <typename Container, typename ... Containers> struct chain_iter<Container,Containers...> { private: using Iterator = decltype(((Container*)nullptr)->begin()); Iterator begin; const Iterator end; bool end_reached = false; chain_iter<Containers...> next_iter; public: chain_iter(Container & container, Containers& ... rest, bool is_end=false) : begin(container.begin()), end(container.end()), next_iter(rest...,is_end) { if(is_end) begin = container.end(); } chain_iter & operator++() { if (begin == end) { ++next_iter; } else { ++begin; } return *this; } auto operator*()->decltype(*begin) { if (begin == end) { return *next_iter; } else { return *begin; } } bool operator !=(const chain_iter & rhs) const { if (begin == end) { return this->next_iter != rhs.next_iter; } else return this->begin != rhs.begin; } }; template <typename ... Containers> iterator_range<chain_iter<Containers...>> chain(Containers& ... containers) { auto begin = chain_iter<Containers...>(containers...); auto end = chain_iter<Containers...>(containers...,true); return iterator_range<chain_iter<Containers...>>(begin,end); } } #endif //CHAIN_HPP

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  • Is my Document Type Definition Still Up to Date?

    - by Sam
    Hi folks, currently all my php generated rich html webpages start with this line, which I have been adding to my tempaltes YEARS ago... <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Am I still up to date and 2011-proof? or Should I be changing this into something fasterloaden/more agile/more flexible? I have heard of XHTML 1.1. When I remove this line all still works fine. Is it very much needed still? What are my alternatives? Thanks very much for your suggestions.

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  • Developing a live video-streaming website

    - by cawecoy
    I'm a computer science student and know a little about some technology to start developing my website, like PHP, RubyOnRails and Python, and MySQL and PostgreSQL for Database. I need to know what are the best (secure, stable, low-price, etc) to get started, based on my business information: My website will be a live video-streaming one, similar to livestream.com We need to provide a secure service for our customers. They need to have a page to create and configure their own Live-Streaming-Videos, get statistics, etc. We work with Wowza Media Server ruuning on an Apache Server In addition, I would like to know some good practices for this kind of website development, as I am new to this. Thanks in advance!

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  • Pattern for a class that does only one thing

    - by Heinzi
    Let's say I have a procedure that does stuff: void doStuff(initalParams) { ... } Now I discover that "doing stuff" is quite a compex operation. The procedure becomes large, I split it up into multiple smaller procedures and soon I realize that having some kind of state would be useful while doing stuff, so that I need to pass less parameters between the small procedures. So, I factor it out into its own class: class StuffDoer { private someInternalState; public Start(initalParams) { ... } // some private helper procedures here ... } And then I call it like this: new StuffDoer().Start(initialParams); or like this: new StuffDoer(initialParams).Start(); And this is what feels wrong. When using the .NET or Java API, I always never call new SomeApiClass().Start(...);, which makes me suspect that I'm doing it wrong. Sure, I could make StuffDoer's constructor private and add a static helper method: public static DoStuff(initalParams) { new StuffDoer().Start(initialParams); } But then I'd have a class whose external interface consists of only one static method, which also feels weird. Hence my question: Is there a well-established pattern for this type of classes that have only one entry point and have no "externally recognizable" state, i.e., instance state is only required during execution of that one entry point?

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  • Can you point me to a nontrivial strategy pattern implementation?

    - by Eugen Martynov
    We are faced implementing a registration workflow with many branches. There are three main flows which in some conditions lead to one another. Each flow has at least four different steps; some steps interact with the server, and every step adds more information to the state. Also the requirement is to have it persistent between sessions, so if the user closes the app (this is a mobile app), it will restore the process from the last completed step with the state from the previous session. I think this could benefit from the use of the strategy pattern, but I've never had to implement it for such a complex case. Does anyone know of any examples in open source or articles from which I could find inspiration? Preferably the examples would be from a live/working/stable application. I'm interested in Java implementation mostly; we are developing for Java mobile phones: android, blackberry and J2ME. We have an SDK which is quite well separated from platform specific implementations, but examples in C++, C#, Objective-C or Python would be acceptable.

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  • DotNetNuke 6 beta released

    - by Chris Hammond
    DotNetNuke 6 is coming, DotNetNuke 6 is coming! That’s right, we’re getting close, close enough that we had our first “beta” for DNN6 today. While we’ve had a couple of CTP (community technology preview) releases, the beta today has quite a bit of things wrapped up and addressed. There are a number of new things coming in DotNetNuke 6, and rather than try to explain them all I’ll point you to Joe Brinkman’s blog post from this morning . The biggest thing is that most of the Admin and Module settings...(read more)

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  • How can I keep directories in sync

    - by Guillaume Boudreau
    I have a directory, dirA, that users can work in: they can create, modify, rename and delete files & sub-directores in dirA. I want to keep another directory, dirB, in sync with dirA. What I'd like, is a discussion on finding a working algorithm that would achieve the above, with the limitations listed below. Requirements: 1. Something asynchronous - I don't want to stop file operations in dirA while I work in dirB. 2. I can't assume that I can just blindly rsync dirA to dirB on regular interval - dirA could contain millions of files & directories, and terrabytes of data. Completely walking the dirA tree could take hours. Those two requirements makes this really difficult. Having it asynchronous means that when I start working on a specific file from dirA, it might have moved a lot since it appeared. And the second limitation means that I really need to watch dirA, and work on atomic file operations that I notice. Current (broken) implementation: 1. Log all file & directory operations in dirA. 2. Using a separate process, read that log, and 'repeat' all the logged operations in dirB. Why is it broken: echo 1 > dirA/file1 # Allow the 'log reader' process to create dirB/file1: log = "write dirA/file1"; action = cp dirA/file1 dirB/file1; result = OK echo 1 > dirA/file2 mv dirA/file1 dirA/file3 mv dirA/file2 dirA/file1 rm dirA/file3 # End result: file1 contains '1' # 'log reader' process starts working on the 4 above file operations: log = "write file2"; action = cp dirA/file2 dirB/file2; result = failed: there is no dirA/file2 log = "rename file1 file3"; action = mv dirB/file1 dirB/file3; result = OK log = "rename file2 file1"; action = mv dirB/file2 dirB/file1; result = failed: there is no dirB/file2 log = "delete file3"; action = rm dirB/file3; result = OK # End result in dirB: no more files! Another broken example: echo 1 > dirA/dir1/file1 mv dirA/dir1 dirA/dir2 # 'log reader' process starts working on the 2 above file operations: log = "write file1"; action = cp dirA/dir1/file1 dirB/dir1/file1; result = failed: there is no dirA/dir1/file1 log = "rename dir1 dir2"; action = mv dirB/dir1 dirB/dir2; result = failed: there is no dirA/dir1 # End result if dirB: nothing!

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  • How do I make the jump from developing for Android to Windows Phone 7?

    - by Rob S.
    I'm planning on making the jump over from developing apps for Android to developing apps for Windows Phone 7 as well. For starters, I figured I would port over my simplest app. The code itself isn't much of a problem as the transition from Java to C# isn't that bad. If anything, this transition is actually easier than I expected. What is troublesome is switching SDKs. I've already compiled some basic Windows Phone 7 apps and ran through some tutorials but I'm still feeling a bit lost. For example, I'm not sure what the equivalent of a ScrollView on Android would be on Windows Phone 7. So does anyone have any advice or any resources they can offer me to help me make this transition? Additionally, any comments on the Windows Phone 7 app market (especially in comparison to the Android market) would also be greatly appreciated. Thank you very much in advance for your time.

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  • How to safely copy an object?

    - by Prog
    This question is going to be a little long. Please bear with me. Something that happened in a project of mine made me think about how to safely copy objects. I'll present the situation I had and then ask a question. There was a class SomeClass: class SomeClass{ Thing[] things; public SomeClass(Thing[] things){ this.things = things; } // irrelevant stuff omitted public SomeClass copy(){ return new SomeClass(things); } } There was another class Processor that takes SomeClass objects, copies them (via someClassInstance.copy()), manipulates the copy's state, and returns the copy. Here it is: class Processor{ public SomeClass processObject(SomeClass object){ SomeClass copy = object.copy(); manipulateTheCopy(copy); return copy; } // irrelevant stuff omitted } I ran this, and it had bugs. I looked into these bugs, and it turned out that the manipulations Processor does on copy actually affect not only the copy, but also the original SomeClass object that was passed into processObject. I found out that it was because the original and the copy shared state - because the original passed it's field things into the copy when creating it. This made me realize that copying objects is harder than simply instantiating them with the same fields as the original. For the two objects to be completely disconnected, without any shared state, each of the fields passed to the copy also has to be copied. And if that object contains other objects - they have to be copied too. And so on. So basically, in order to be able to actually copy an object, each class in the system must have a copy() method, that also invokes copy() on all of it's fields, and so on. So for example, for copy() in SomeClass to work, it needs to look like this: public SomeClass copy(){ Thing[] copyThings = new Thing[things.length]; for(int i=0; i<things.length; i++) copyThings[i] = things[i].copy(); return new SomeClass(copyThings); } And if Thing has object fields of it's own, than it's own copy() method must be appropriate: class Thing{ Apple apple; Pencil pencil; int number; public Thing(Apple apple, Pencil pencil, int number){ this.apple = apple; this.pencil = pencil; this.number = number; } public Thing copy(){ // 'number' is a primitve. return new Thing(apple.getCopy(), pencil.getCopy(), number); } } And so on. Of course, instead of all classes having a copy() method, the copying mechanism can happen in all of the getters and the constructors of classes (unless places where it isn't suitable, for example when the field points to an external object, not to an object that 'is part' of this object). Still, that means that in order to be able to safely copy an object - most classes would have to have copying mechanisms in their getters. My question is divided into two parts: How frequently do you need to get a copy of an object? Is this a regular issue? Is the technique described common and/or reasonable? Or is there a better way to make safe copies of objects? Or is there an easier way to safely copy objects, without them sharing any state?

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  • Information Spilling Across Object Boundaries

    - by Winston Ewert
    Many times my business objects tend to have situations where information needs to cross object boundaries too often. When doing OO, we want information to be in one object and as much as possible all code dealing with that information should be in that object. However, business rules do not follow this principle giving me trouble. As an example suppose that we have an Order which has a number of OrderItems which refers to an InventoryItem which has a price. I invoke Order.GetTotal() which sums the result of OrderItem.GetPrice() which multiples a quantity by InventoryItem.GetPrice(). So far so good. But then we find out that some items are sold with a two for one deal. We can handle this by having OrderItem.GetPrice() do something like InventoryItem.GetPrice( quantity ) and letting InventoryItem deal with this. However, then we find out that the two-for-one deal only lasts for a particular time period. This time period needs to be based on the date of the order. Now we change OrderItem.GetPrice() to be InventoryItem.GetPrice( quatity, order.GetDate() ) But then we need to support different prices depending on how long the customer has been in the system: InventoryItem.GetPrice( quantity, order.GetDate(), order.GetCustomer() ) But then it turns out that the two-for-one deals apply not just to buying multiple of the same inventory item but multiple for any item in a InventoryCategory. At this point we throw up our hands and just give the InventoryItem the order item and allow it to travel over the object reference graph via accessors to get the information its needs: InventoryItem.GetPrice( this ) TL;DR I want to have coupling in objects, but business rules often force me to access information from all over the place in order to make particular decisions. Are there good techniques for dealing with this? Do others find the same problem?

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  • Which numeral systems are useful in computer science?

    - by authchir
    I am wondering which numeral system different programmers are using, or would use if their language has support for them. As an example, in C++ we can use: Octal by prefixing with 0 (e.g. 0377) Decimal by default (e.g. 255) Hexadecimal by prefixing with 0x (e.g. 0xff) When working with bitmask, I am using hexadecimal but would sometimes want to be able to express binary numbers directly. I know some programming language support it with 0b syntax (e.g. 0b11111111). Is there any other numeric system useful in some computer science domain (e.g. cryptography, codecs, 3D graphics, etc)?

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  • Distinguishing between UI command & domain commands

    - by SonOfPirate
    I am building a WPF client application using the MVVM pattern that provides an interface on top of an existing set of business logic residing in a library which is shared with other applications. The business library followed a domain-driven architecture using CQRS to separate the read and write models (no event sourcing). The combination of technologies and patterns has brought up an interesting conundrum: The MVVM pattern uses the command pattern for handling user-interaction with the view models. .NET provides an ICommand interface which is implemented by most MVVM frameworks, like MVVM Light's RelayCommand and Prism's DelegateCommand. For example, the view model would expose a number of command objects as properties that are bound to the UI and respond when the user performs actions like clicking buttons. Many implementations of the CQRS use the command pattern to isolate and encapsulate individual behaviors. In my business library, we have implemented the write model as command / command-handler pairs. As such, when we want to do some work, such as create a new order, we 'issue' a command (CreateOrderCommand) which is routed to the command-handler responsible for executing the command. This is great, clearly explained in many sources and I am good with it. However, take this scenario: I have a ToolbarViewModel which exposes a CreateNewOrderCommand property. This ICommand object is bound to a button in the UI. When clicked, the UI command creates and issues a new CreateOrderCommand object to the domain which is handled by the CreateOrderCommandHandler. This is difficult to explain to other developers and I am finding myself getting tongue-tied because everything is a command. I'm sure I'm not the first developer to have patterns overlap like this where the naming/terminology also overlap. How have you approached distinguishing your commands used in the UI from those used in the domain? (Edit: I should mention that the business library is UI-agnostic, i.e. no UI technology-specific code exists, or will exists, in this library.)

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  • What is the best way to generate income from mobile games?

    - by Thomas
    As the title states, what is the best way to get income from mobile games? (taking into consideration that creating the games only costs a lot of time and the games are relatively simple) As I see it, there are multiple ways of getting money from mobile games, Selling them for a fixed price (seems like a high threshold for potential buyers) In-game purchases (I can imagine this only works for several types of games, I don't see this working well for monopoly unless you like really fancy hotels ;) Ingame advertisements / sponsorships Which way will most likely bring the most profit?

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  • How can I store all my level data in a single file instead of spread out over many files?

    - by Jon
    I am currently generating my level data, and saving to disk to ensure that any modifications done to the level are saved. I am storing "chunks" of 2048x2048 pixels into a file. Whenever the player moves over a section that doesn't have a file associated with the position, a new file is created. This works great, and is very fast. My issue, is that as you are playing the file count gets larger and larger. I'm wondering what are techniques that can be used to alleviate the file count, without taking a performance hit. I am interested in how you would store/seek/update this data in a single file instead of multiple files efficiently.

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  • Do ORMs enable the creation of rich domain models?

    - by Augusto
    After using Hibernate on most of my projects for about 8 years, I've landed on a company that discourages its use and wants applications to only interact with the DB through stored procedures. After doing this for a couple of weeks, I haven't been able to create a rich domain model of the application I'm starting to build, and the application just looks like a (horrible) transactional script. Some of the issues I've found are: Cannot navigate object graph as the stored procedures just load the minimum amount of data, which means that sometimes we have similar objects with different fields. One example is: we have a stored procedure to retrieve all the data from a customer, and another to retrieve account information plus a few fields from the customer. Lots of the logic ends up in helper classes, so the code becomes more structured (with entities used as old C structs). More boring scaffolding code, as there's no framework that extracts result sets from a stored procedure and puts it in an entity. My questions are: has anyone been in a similar situation and didn't agree with the store procedure approch? what did you do? Is there an actual benefit of using stored procedures? appart from the silly point of "no one can issue a drop table". Is there a way to create a rich domain using stored procedures? I know that there's the posibility of using AOP to inject DAOs/Repositories into entities to be able to navigate the object graph. I don't like this option as it's very close to voodoo.

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  • Open source ASP.NET MVC project for a SaaS application

    - by DotnetDude
    I am working on a personal project that offers a service online. I'd like put this out to the public. I don't want to reinvent the wheel and use an existing template/open source project and add my service specific functionality. The features I am looking for are: Support for different roles (I need to have an admin role, customer and preferred customer roles) An admin section where admins can manage user accounts, login as with users credentials for providing support Customer pages that are role specific (Ex: Some functionality can be used by preferred customers but not non preferred ones) Preferably a pricing/plans page with payment gateway integration These are some of the basic pages available in most of service sites online. Is there a MVC 3 (preferably 4) written in C# that I can use as a shell to build upon? Thanks

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