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• best way to send messages to all subscribers with multiple subscriptions and multiple providers

  - by coding_idiot

  I'm writing an application in which - Many users can subsribe to posts made by another users. So for a single publisher there can be many subscribers. When a message is posted by an user X, all users who have subscribed to messages of User X will be sent an email. How to achieve this ? I'm thinking of using publish-subscribe pattern. And then I came through JMS. Which is the best JMS implementation to use according to your experience ? Or else what else solution do you propose to the given problem ? Shall I go for a straight-forward solution ?: User x posts a message, I find all users (from database) who subscribe to user x and then for every user, I call the sendEmail() method. [EDIT] My intention here is not to send-emails. I'm really sorry if it wasn't clear. I also have to send kind of system-notifications apart from Email to all subscribers. Right now, I've implemented the email-sending as a threadPool

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• Is there a name for the Builder Pattern where the Builder is implemented via interfaces so certain parameters are required?

  - by Zipper

  So we implemented the builder pattern for most of our domain to help in understandability of what actually being passed to a constructor, and for the normal advantages that a builder gives. The one twist was that we exposed the builder through interfaces so we could chain required functions and unrequired functions to make sure that the correct parameters were passed. I was curious if there was an existing pattern like this. Example below: public class Foo { private int someThing; private int someThing2; private DateTime someThing3; private Foo(Builder builder) { this.someThing = builder.someThing; this.someThing2 = builder.someThing2; this.someThing3 = builder.someThing3; } public static RequiredSomething getBuilder() { return new Builder(); } public interface RequiredSomething { public RequiredDateTime withSomething (int value); } public interface RequiredDateTime { public OptionalParamters withDateTime (DateTime value); } public interface OptionalParamters { public OptionalParamters withSeomthing2 (int value); public Foo Build ();} public static class Builder implements RequiredSomething, RequiredDateTime, OptionalParamters { private int someThing; private int someThing2; private DateTime someThing3; public RequiredDateTime withSomething (int value) {someThing = value; return this;} public OptionalParamters withDateTime (int value) {someThing = value; return this;} public OptionalParamters withSeomthing2 (int value) {someThing = value; return this;} public Foo build(){return new Foo(this);} } } Example of how it's called: Foo foo = Foo.getBuilder().withSomething(1).withDateTime(DateTime.now()).build(); Foo foo2 = Foo.getBuilder().withSomething(1).withDateTime(DateTime.now()).withSomething2(3).build();

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• MVVM- Expose Model object in ViewModel

  - by Angel

  I have a wpf MVVM application , I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel , and instead of creating seperate VM properties , I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy classes. Here is my Model class : public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel , public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM, I know this will cause a strong dependency. So , 1- Whats the best way to expose Model object in ViewModel ? 2- Whats the best way to use DataService in VM ?

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• Layout Columns - Equal Height

  - by Kyle

  I remember first starting out using tables for layouts and learned that I should not be doing that. I am working on a new site and can not seem to do equal height columns without using tables. Here is an example of the attempt with div tags. <div class="row"> <div class="column">column1</div> <div class="column">column2</div> <div class="column">column3</div> <div style="clear:both"></div> </div> Now what I tried with that was doing making columns float left and setting their widths to 33% which works fine, I use the clear:both div so that the row would be the size of the biggest column, but the columns will be different sizes based on how much content they have. I have found many fixes which mostly involve css hacks and just making it look like its right but that's not what I want. I thought of just doing it in javascript but then it would look different for those who choose to disable their javascript. The only true way of doing it that I can think of is using tables since the cells all have equal heights in the same row. But I know its bad to use tables. After searching forever I than came across this: http://intangiblestyle.com/lab/equal-height-columns-with-css/ What it seems to do is exactly the same as tables since its just setting its display exactly like tables. Would using that be just as bad as using tables? I honestly can't find anything else that I could do. edit @Su' I have looked into "faux columns" and do not think that is what I want. I think I would be able to implement better designs for my site using the display:table method. I posted this question because I just wasn't sure if I should since I have always heard its bad using tables in website layouts.

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• The balance between client and server functionality

  - by Eugen Martynov

  I want to bring the discussion that started in our teams and get your opinion about it. Assume we have an user account which could have different credentials for authentication and associated email to recover. An user has possibility to do signup with an email or use his social profile to complete signup process. As an Rest API from the backend to client looks like: Create account Authorise Update user data Link social account Register email Verify email In addition our BE is distributed and divided between several services/servers/clusters. So different calls are related to different end points. In case of the social sign up some of steps should be skipped or simplified. For example, with Facebook signup we could already skip email registration and verification step (we ask email permission form user), linking the social account and pre-fill user displayed name. So we proposed to have another end point which will hide/combine different calls on BE and return whole process result to the clients. The pros for this approach: No more duplication of functionality between clients Speed up the networking and user experience The cons for this approach: Additional work for backend Probably most complex scenarios in future updates I would like to get your opinion or experience with this situation. Especially if you already experienced point #2 from against reasons.

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• How to determine if class meets single responsibility principle ?

  - by user1483278

  Single Responsibility Principle is based on high cohesion principle. The difference between the two is that highly cohesive classes feature a set of responsibilities that are strongly related, while classes adhering to SRP have just one responsibility. But how do we determine whether particular class features a set of responsibilities and is thus just highly cohesive, or whether it has only one responsibility and is thus adhering to SRP? Namely, isn't it more or less subjective, since some may find class very granular ( and as such will consider a class as adhering to SRP ), while others may find it not granular enough?

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• Should a web designer know server-side coding?

  - by Rasoul Zabihi

  We're implementing an CMS based on ASP.NET MVC. Now, any designer should be able to provide themes for this CMS. But to write a theme, they need to be able to modify the generated HTML, thus the concept of View. In other words, they should be capable to either modify current views, or create new views from scratch, to fit their requirements. However, now we're not sure that we're taking the right path. Should a web designer (HTML, CSS, JavaScript + Photoshop) really know about server-side platforms like Razor or PHP, or classic ASP, or anything else?

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• Can the Abstract Factory pattern be considered as a case of polymorphism?

  - by rogcg

  I was looking for a pattern/solution that allows me call a method as a runtime exception in a group of different methods without using Reflection. I've recently become aware of the Abstract Factory Pattern. To me, it looks so much like polymorphism, and I thought it could be a case of polymorphism but without the super class WidgetFactory, as you can see in the example of the link above. Am I correct in this assumption?

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• Anemic Domain Model, Business Logic and DataMapper (PHP)

  - by sunwukung

  I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly layer using a SQL abstraction layer). Following the DataMapper pattern, I've endeavoured to keep all persistence operations in the Mapper - including the location of related entities. My Entities have access to their Mapper, although I try not to call Mapper logic from the Entity interface (although this would be simple enough). The result is: // get a mapper and produce an entity $ProductMapper = $di->get('product_mapper'); $Product = $ProductMapper->find('[email protected]','email'); //.. mutaute some values.. save $ProductMapper->save($Product) // uses __get to trigger relation acquisition $Manufacturer = $Product->manufacturer; I've read some articles regarding the concept of an Anemic Domain model, i.e. a Model that does not contain any "business logic". When demonstrating the sort of business logic ideally suited to a Domain Model, however, acquiring related data items is a common example. Therefore I wanted to ask this question: Is persistence logic appropriate in Domain Model objects?

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• Collision Systems Implementation

  - by hrr4

  Just curious what might be a good way to implement a decent collision system. As a class inherited by a base Entity class? Currently I'm stuck and could just use a couple better ideas than my own. Any help is appreciated! Edit: Sorry, it's 2D Collisioning but honestly, I'm not looking for specific collision methods. I'm looking more about the lines of implementation. Just curious of some of the common methods of how to implement collision systems such as: Should the entire collision system be it's own class? What, if anything, should be inheritable? These are some of my questions. Sorry for the confusion.

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• What books/references are recommended on the subject of planning and developing efficient web sites [closed]

  - by Shakil

  Once I visited a site containing videos; a well-known web developer creating a site from scratch via planning(paper, software), management, designing then development. I bookmarked the site but unable to find it now. My question is : How to do web-development effectively? What books or videos are recommended ???(I tried google but unable to find useful books or videos). I want to learn how people does it. Can you share resources(books, videos, links) about this... Thanks in advance.. Note: I created a job site for my university project. It gave me huge pain. Thats why I want to learn efficient way. I know html, css, javascript, jquery, php[learning(mvc and framework not yet completed)], phpmyadmin.

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• Creating an online community - use templates or self-develop?

  - by ican ican

  PHPMotion, Joomla or develop my own? I'm thinking of developing a common interest online community. It will be have UGC, stats, etc.. functionality, and perhaps an online store. Though cost is an issue at this time, I want to be professional and effective. Should I use existing free platform templates, like PHP, Joomla, or should I develop my own? What are the advantages/disadvantages of either option? As a rough estimate, how much will it cost me to develop and manage my own? And how long will it take. In general what should I be careful about on this journey?

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• How to Structure a Trinary state in DB and Application

  - by ABMagil

  How should I structure, in the DB especially, but also in the application, a trinary state? For instance, I have user feedback records which need to be reviewed before they are presented to the general public. This means a feedback reviewer must see the unreviewed feedback, then approve or reject them. I can think of a couple ways to represent this: Two boolean flags: Seen/Unseen and Approved/Rejected. This is the simplest and probably the smallest database solution (presumably boolean fields are simple bits). The downside is that there are really only three states I care about (unseen/approved/rejected) and this creates four states, including one I don't care about (a record which is seen but not approved or rejected is essentially unseen). String column in the DB with constants/enum in application. Using Rating::APPROVED_STATE within the application and letting it equal whatever it wants in the DB. This is a larger column in the db and I'm concerned about doing string comparisons whenever I need these records. Perhaps mitigatable with an index? Single boolean column, but allow nulls. A true is approved, a false is rejected. A null is unseen. Not sure the pros/cons of this solution. What are the rules I should use to guide my choice? I'm already thinking in terms of DB size and the cost of finding records based on state, as well as the readability of code the ends up using this structure.

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• What kind of graphics would you like better? [ pictures ] [closed]

  - by Roger Travis

  I am looking forward to make an android game, something angrybirds style. I've already made my own engine and now have to decide what kind of graphics should I make. It could be either realistic, like that or a doodle-style like this Right now the first one looks more appealing to me... on the other hand, doodle-graphics are very easy to draw and their transparency doesn't seem to slow down the engine much. What do you think?

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• Implementing traffic conditions in TORCS

  - by user1837811

  I am working on a project about "Effects of Traffic conditions and Track Complexity on Car Driving Behavior". Is it possible to implement traffic in TORCS, or should I use another car simulator? By the word "traffic" I mean there are cars running on both tracks in both directions and I can detect the distances, direction and speed of these cars. Depending on this information I can decide whether I should slow down, speed up and calculate the correct timing to overtake.

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• Why do programming languages allow shadowing/hiding of variables and functions?

  - by Simon

  Many of the most popular programming languges (such as C++, Java, Python etc.) have the concept of hiding / shadowing of variables or functions. When I've encountered hiding or shadowing they have been the cause of hard to find bugs and I've never seen a case where I found it necessary to use these features of the languages. To me it would seem better to disallow hiding and shadowing. Does anybody know of a good use of these concepts?

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• Using Dynamic LINQ to get a filter for my Web API

  - by Espo

  We are considering using the Dynamic.CS linq-sample included in the "Samples" directory of visual studio 2008 for our WebAPI project to allow clients to query our data. The interface would be something like this (In addition to the normal GET-methods): public HttpResponseMessage List(string filter = null); The plan is to use the dynamic library to parse the "filter"-variable and then execute the query agains the DB. Any thoughts if this is a good idea? Is it a security problem?

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• How one could use a live editor

  - by Sathvik

  I was thinking about a live editing environment where code / a source file is synchronized so that, changes made by one user would be carried across to all others editing the file. Something like Google Wave, but for code. Could this kind of an environment be better for the code, as changes are shared instantly? (with revision-control, of course) Has anyone tried (or has had a need for) using a shared environment for code?

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• What is MVC, really?

  - by NickC

  As a serious programmer, how do you answer the question What is MVC? In my mind, MVC is sort of a nebulous topic — and because of that, if your audience is a learner, then you're free to describe it in general terms that are unlikely to be controversial. However, if you are speaking to a knowledgeable audience, especially an interviewer, I have a hard time thinking of a direction to take that doesn't risk a reaction of "well that's not right!...". We all have different real-world experience, and I haven't truly met the same MVC implementation pattern twice. Specifically, there seem to be disagreements regarding strictness, component definition, separation of parts (what piece fits where), etc. So, how should I explain MVC in a way that is correct, concise, and uncontroversial?

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• Designing a system with different business rules for different customers

  - by user1595846

  My company is rewriting our proprietary business application. The current architecture is poorly done and inflexible. It is coded more procedural oriented as opposed to object oriented. It has become difficult to maintain. Our system is a web application written in .Net Webforms. I am considering ASP.Net MVC for the rewrite. We intend to rewrite it with a good, solid architecture with the goal of maintainability and reusable classes for some of our other systems and services. We would also like the system to be customizable for different customers in the event that we market the system. I am considering redesigning the system based on the layered architecture (Presentation, Business, Data Access layers) described in the Microsoft Patterns and Practices Application Architecture Guide. http://msdn.microsoft.com/en-us/library/ff650706.aspx Hopefully this isn't too open ended, but how would you recommend allowing for different business logic/rules for different customers? I'm aware of Windows Workflow Foundation, but from what I've read about it, it seems many business rules could be too complicated to handle there. Also, Can anyone point me to where I can download an example of a .net solution that is based on the Application Architecture Guide? I have already downloaded the Layered Architecture Solution Guidance and the Expense Sample on codeplex. I was looking for something a bit larger and more robust that I could step through the code and see how it works. If you feel there are better architectures to base our redesign on please feel free to share. I appreciate your help!

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• Triggering Data Changes in N-Tier

  - by Ryan Kinal

  I've been studying n-tier architectures as of late, particularly in VB.NET with Entity Framework and/or LINQ to SQL. I understand the basic concepts, but have been wondering about best practices in regard to triggering CRUD-type operations from user input/action. So, the arcitecture looks something like the following: [presentation layer] - [business layer] - [data layer] - (database) Getting information from the database into the presentation layer is simple and abstracted. It's just a matter of instantiating a new object from the business layer, which in turn uses the data layer to get at the correct information. However, saving (updating and inserting), and deleting seem to require particular APIs on the relevant business objects. I have to assume this is standard practice, unless a business object will save itself on various operations (which seems inefficient), or on disposal (which seems like it just wouldn't work, or may be unwieldy and unreliable). Should my "savable" business objects all implement a particular "ISavable" or "IDatabaseObject" interface? Is this a recognized (anti-)pattern? Are there other, better patterns I should be using that I'm just unaware of? The TLDR question, I suppose, is How does the presentation layer trigger database changes?

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• How to handle sorting of complex objects?

  - by AedonEtLIRA

  How would one sort a list of objects that have more than one sortable element? Suppose you have a simple object Car and car is a defined as such: class Car { public String make; public String model; public int year; public String color; // ... No methods, just a structure / container } I designed a simple framework that would allow for multiple SortOptions to be provided to a Sorter that would then sort the list. interface ISorter<T> { List<T> sort(List<T> items); void addSortOption(ISortOption<T> option); ISortOption<T>[] getSortOptions(); void setSortOption(ISortOption<T> option); } interface ISortOption<T> { String getLabel(); int compare(T t1, T t2); } Example use class SimpleStringSorter extends MergeSorter<String> { { addSorter(new AlphaSorter()); } private static final class AlphaSorter implements ISortOption<String> { // ... implementation of alpha compare and get label } } The issue with this solution is that it is not easily expandable. If car was to ever receive a new field, say, currentOwner. I would need to add the field, then track down the sorter class file, implement a new sort option class then recompile the application for redistribution. Is there an easier more expandable/practical way to sort data like this?

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• Are null references really a bad thing?

  - by Tim Goodman

  I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of the language can be a source of errors if used improperly. And what's the alternative? I suppose instead of saying this: Customer c = Customer.GetByLastName("Goodman"); // returns null if not found if (c != null) { Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } You could say this: if (Customer.ExistsWithLastName("Goodman")) { Customer c = Customer.GetByLastName("Goodman") // throws error if not found Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } But how is that better? Either way, if you forget to check that the customer exists, you get an exception. I suppose that a CustomerNotFoundException is a bit easier to debug than a NullReferenceException by virtue of being more descriptive. Is that all there is to it?

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• is there a checklist that a small website should

  - by Mecon

  I am not a web developer - this would be my first foray. I can do HTML/CSS/Javascript, but never created a website for a company. If anybody is creating a site for small company (expecting some 10-15 static pages), what kinda things would it need to have? I am thinking of the following: Make the eventual owner buy in his/her name: Domain name, Web Hosting package and Email package. Q - DO Web Developers generally ask their clients to buy this stuff and then ask them to share their passwords? OR - Do Web Developers ship the source files to clients so that they can upload it? Create Cross Browser compatible HTML+CSS+javascript pages Add SEO stuff like Meta tags and xml file for crawler Buy professional images from stock website Q - IS there is a best-practice for this step? Add Copyright stuff. Q - ANY idea about how to do this? Add Faceboook widgets, so people can 'like' my website. Register website somewhere so that its searchable from multiple search-engine/yellopages. Q - DOES such a thing exist? Please check my checklist :) and let me know what you think could be missing? Thanks!

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• Splitting Logic, Data, Layout and "Hacks"

  - by fjdumont

  Sure, we all heard of programming patterns such as MVVM, MVC and such. But that isn't really what I'm looking into as Layout, Data and Logic is already pretty much split up (XML-Layout markup, Database, insert your language of choice here). The platform I am developing for is hard to maintain over the updated versions and older OSes. The project significantly grew up over the last few months and dealing with different platform versions really is a pain. For example simply disabling an user interface control for all existing versions took me around 40 lines of code in the logic layer, wrangling around with invocation, delegation, singletons that provide UI handling and so on. Is there a clean way to keep track of those "hacks" by maybe excluding it into separate classes or even packages? Should I overwrite existing framework code in order to handle my requirements correctly? If so, does that concept have a name?

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