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• Refactor This (Ugly Code)!

  - by Alois Kraus

  Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor:         private void HandleMessageCompletion(                                      Message message,                                      TransactionScope tx,                                      OpenedQueue messageQueue,                                      Exception exception,                                      Action<CurrentMessageInformation, Exception> messageCompleted,                                      Action<CurrentMessageInformation> beforeTransactionCommit)         {             var txDisposed = false;             if (exception == null)             {                 try                 {                     if (tx != null)                     {                         if (beforeTransactionCommit != null)                             beforeTransactionCommit(currentMessageInformation);                         tx.Complete();                         tx.Dispose();                         txDisposed = true;                     }                     try                     {                         if (messageCompleted != null)                             messageCompleted(currentMessageInformation, exception);                     }                     catch (Exception e)                     {                         Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);                     }                     return;                 }                 catch (Exception e)                 {                     Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e);                     exception = e;                 }             }             try             {                 if (txDisposed == false && tx != null)                 {                     Trace.TraceWarning("Disposing transaction in error mode");                     tx.Dispose();                 }             }             catch (Exception e)             {                 Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e);             }             if (message == null)                 return;                 try             {                 if (messageCompleted != null)                     messageCompleted(currentMessageInformation, exception);             }             catch (Exception e)             {                 Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);             }               try             {                 var copy = MessageProcessingFailure;                 if (copy != null)                     copy(currentMessageInformation, exception);             }             catch (Exception moduleException)             {                 Trace.TraceError("Module failed to process message failure: " + exception.Message+                                              moduleException);             }               if (messageQueue.IsTransactional == false)// put the item back in the queue             {                 messageQueue.Send(message);             }         }     You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary.  Lets see what the author of this code did intend:          private void HandleMessageCompletion(             TransactionHandler transactionHandler,             MessageCompletionHandler handler,             CurrentMessageInformation messageInfo,             ErrorCollector errors             )         {               // commit current pending transaction             transactionHandler.CallHandlerAndCommit(messageInfo, errors);               // We have an error for a null message do not send completion event             if (messageInfo.CurrentMessage == null)                 return;               // Send completion event in any case regardless of errors             handler.OnMessageCompleted(messageInfo, errors);               // put message back if queue is not transactional             transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors);         }   I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state.          class ErrorCollector          {              List<Exception> _Errors = new List<Exception>();                public void Add(Exception ex, string description)              {                  ex.Data["Description"] = description;                  _Errors.Add(ex);              }                public Exception Last              {                  get                  {                      return _Errors.LastOrDefault();                  }              }                public bool HasError              {                  get                  {                      return _Errors.Count > 0;                  }              }          }   Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures.          class TransactionHandler          {              TransactionScope _Tx;              Action<CurrentMessageInformation> _BeforeCommit;              OpenedQueue _MessageQueue;                public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue)              {                  _Tx = tx;                  _BeforeCommit = beforeCommit;                  _MessageQueue = messageQueue;              }                public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  if (_Tx != null && !errors.HasError)                  {                      try                      {                          if (_BeforeCommit != null)                          {                              _BeforeCommit(currentMessageInfo);                          }                            _Tx.Complete();                          _Tx.Dispose();                      }                      catch (Exception ex)                      {                          errors.Add(ex, "Failed to complete transaction, moving to error mode");                          Trace.TraceWarning("Disposing transaction in error mode");                          try                          {                              _Tx.Dispose();                          }                          catch (Exception ex2)                          {                              errors.Add(ex2, "Failed to dispose of transaction in error mode.");                          }                      }                  }              }                public void ResendMessageOnError(Message message, ErrorCollector errors)              {                  if (errors.HasError && !_MessageQueue.IsTransactional)                  {                      _MessageQueue.Send(message);                  }              }          } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred.            class MessageCompletionHandler          {              Action<CurrentMessageInformation, Exception> _MessageCompletedHandler;              Action<CurrentMessageInformation, Exception> _MessageProcessingFailure;                public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler,                                              Action<CurrentMessageInformation, Exception> messageProcessingFailure)              {                  _MessageCompletedHandler = messageCompletedHandler;                  _MessageProcessingFailure = messageProcessingFailure;              }                  public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageCompletedHandler != null)                      {                          _MessageCompletedHandler(currentMessageInfo, errors.Last);                      }                  }                  catch (Exception ex)                  {                      errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing");                  }                    if (errors.HasError)                  {                      SignalFailedMessage(currentMessageInfo, errors);                  }              }                void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageProcessingFailure != null)                          _MessageProcessingFailure(currentMessageInfo, errors.Last);                  }                  catch (Exception moduleException)                  {                      errors.Add(moduleException, "Module failed to process message failure");                  }              }            }   If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together:   Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo         Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler        TransactionScope tx        OpenedQueue messageQueue        Action<CurrentMessageInformation> beforeTransactionCommit Exception exception,             ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler          Action<CurrentMessageInformation, Exception> messageCompleted          Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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• Thoughts on my new template language?

  - by Ralph

  Let's start with an example: using "html5" using "extratags" html { head { title "Ordering Notice" jsinclude "jquery.js" } body { h1 "Ordering Notice" p "Dear @name," p "Thanks for placing your order with @company. It's scheduled to ship on {@ship_date|dateformat}." p "Here are the items you've ordered:" table { tr { th "name" th "price" } for(@item in @item_list) { tr { td @item.name td @item.price } } } if(@ordered_warranty) p "Your warranty information will be included in the packaging." p(class="footer") { "Sincerely," br @company } } } The "using" keyword indicates which tags to use. "html5" might include all the html5 standard tags, but your tags names wouldn't have to be based on their HTML counter-parts at all if you didn't want to. The "extratags" library for example might add an extra tag, called "jsinclude" which gets replaced with something like <script type="text/javascript" src="@content"></script> Tags can be optionally be followed by an opening brace. They will automatically be closed as the closing brace. If no brace is used, they will be closed after taking on element. Variables are prefixed with the @ symbol. They may be used inside double-quoted strings. I think I'll use single-quotes to indicate "no variable substitution" like PHP does. Filter functions can be applied to variables like @variable|filter. Arguments can be passed to the filter @variable|filter:@arg1,arg2="y" Attributes can be passed to tags by including them in (), like p(class="classname"). Some questions: Which symbol should I use to prefix variables? @ (like Razor), $ (like PHP), or something else? Should the @ symbol be necessary in "for" and "if" statements? It's kind of implied that those are variables. Tags and controls (like if,for) presently have the exact same syntax. Should I do something to differentiate the two? If so, what? Do you like the attribute syntax? (round brackets) I'll add more questions in a few minutes, once I get some feedback.

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• Misunderstanding Scope in JavaScript?

  - by Jeff

  I've seen a few other developers talk about binding scope in JavaScript but it has always seemed to me like this is an inaccurate phrase. The Function.prototype.call and Function.prototype.apply don't pass scope around between two methods; they change the caller of the function - two very different things. For example: function outer() { var item = { foo: 'foo' }; var bar = 'bar'; inner.apply(item, null); } function inner() { console.log(this.foo); //foo console.log(bar); //ReferenceError: bar is not defined } If the scope of outer was really passed into inner, I would expect that inner would be able to access bar, but it can't. bar was in scope in outer and it is out of scope in inner. Hence, the scope wasn't passed. Even the Mozilla docs don't mention anything about passing scope: Calls a function with a given this value and arguments provided as an array. Am I misunderstanding scope or specifically scope as it applies to JavaScript? Or is it these other developers that are misunderstanding it?

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• Building applications with WCF - Intro

  - by skjagini

  I am going to write series of articles using Windows Communication Framework (WCF) to develop client and server applications and this is the first part of that series. What is WCF As Juwal puts in his Programming WCF book, WCF provides an SDK for developing and deploying services on Windows, provides runtime environment to expose CLR types as services and consume services as CLR types. Building services with WCF is incredibly easy and it’s implementation provides a set of industry standards and off the shelf plumbing including service hosting, instance management, reliability, transaction management, security etc such that it greatly increases productivity Scenario: Lets consider a typical bank customer trying to create an account, deposit amount and transfer funds between accounts, i.e. checking and savings. To make it interesting, we are going to divide the functionality into multiple services and each of them working with database directly. We will run test cases with and without transactional support across services. In this post we will build contracts, services, data access layer, unit tests to verify end to end communication etc, nothing big stuff here and we dig into other features of the WCF in subsequent posts with incremental changes. In any distributed architecture we have two pieces i.e. services and clients. Services as the name implies provide functionality to execute various pieces of business logic on the server, and clients providing interaction to the end user. Services can be built with Web Services or with WCF. Service built on WCF have the advantage of binding independent, i.e. can run against TCP and HTTP protocol without any significant changes to the code. Solution Services Profile: For creating a new bank customer, getting details about existing customer ProfileContract ProfileService Checking Account: To get checking account balance, deposit or withdraw amount CheckingAccountContract CheckingAccountService Savings Account: To get savings account balance, deposit or withdraw amount SavingsAccountContract SavingsAccountService ServiceHost: To host services, i.e. running the services at particular address, binding and contract where client can connect to Client: Helps end user to use services like creating account and amount transfer between the accounts BankDAL: Data access layer to work with database     BankDAL It’s no brainer not to use an ORM as many matured products are available currently in market including Linq2Sql, Entity Framework (EF), LLblGenPro etc. For this exercise I am going to use Entity Framework 4.0, CTP 5 with code first approach. There are two approaches when working with data, data driven and code driven. In data driven we start by designing tables and their constrains in database and generate entities in code while in code driven (code first) approach entities are defined in code and the metadata generated from the entities is used by the EF to create tables and table constrains. In previous versions the entity classes had  to derive from EF specific base classes. In EF 4 it  is not required to derive from any EF classes, the entities are not only persistence ignorant but also enable full test driven development using mock frameworks.  Application consists of 3 entities, Customer entity which contains Customer details; CheckingAccount and SavingsAccount to hold the respective account balance. We could have introduced an Account base class for CheckingAccount and SavingsAccount which is certainly possible with EF mappings but to keep it simple we are just going to follow 1 –1 mapping between entity and table mappings. Lets start out by defining a class called Customer which will be mapped to Customer table, observe that the class is simply a plain old clr object (POCO) and has no reference to EF at all. using System;   namespace BankDAL.Model { public class Customer { public int Id { get; set; } public string FullName { get; set; } public string Address { get; set; } public DateTime DateOfBirth { get; set; } } }   In order to inform EF about the Customer entity we have to define a database context with properties of type DbSet<> for every POCO which needs to be mapped to a table in database. EF uses convention over configuration to generate the metadata resulting in much less configuration. using System.Data.Entity;   namespace BankDAL.Model { public class BankDbContext: DbContext { public DbSet<Customer> Customers { get; set; } } }   Entity constrains can be defined through attributes on Customer class or using fluent syntax (no need to muscle with xml files), CustomerConfiguration class. By defining constrains in a separate class we can maintain clean POCOs without corrupting entity classes with database specific information.   using System; using System.Data.Entity.ModelConfiguration;   namespace BankDAL.Model { public class CustomerConfiguration: EntityTypeConfiguration<Customer> { public CustomerConfiguration() { Initialize(); }   private void Initialize() { //Setting the Primary Key this.HasKey(e => e.Id);   //Setting required fields this.HasRequired(e => e.FullName); this.HasRequired(e => e.Address); //Todo: Can't create required constraint as DateOfBirth is not reference type, research it //this.HasRequired(e => e.DateOfBirth); } } }   Any queries executed against Customers property in BankDbContext are executed against Cusomers table. By convention EF looks for connection string with key of BankDbContext when working with the context.   We are going to define a helper class to work with Customer entity with methods for querying, adding new entity etc and these are known as repository classes, i.e., CustomerRepository   using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CustomerRepository { private readonly IDbSet<Customer> _customers;   public CustomerRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _customers = bankDbContext.Customers; }   public IQueryable<Customer> Query() { return _customers; }   public void Add(Customer customer) { _customers.Add(customer); } } }   From the above code it is observable that the Query methods returns customers as IQueryable i.e. customers are retrieved only when actually used i.e. iterated. Returning as IQueryable also allows to execute filtering and joining statements from business logic using lamba expressions without cluttering the data access layer with tens of methods.   Our CheckingAccountRepository and SavingsAccountRepository look very similar to each other using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CheckingAccountRepository { private readonly IDbSet<CheckingAccount> _checkingAccounts;   public CheckingAccountRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _checkingAccounts = bankDbContext.CheckingAccounts; }   public IQueryable<CheckingAccount> Query() { return _checkingAccounts; }   public void Add(CheckingAccount account) { _checkingAccounts.Add(account); }   public IQueryable<CheckingAccount> GetAccount(int customerId) { return (from act in _checkingAccounts where act.CustomerId == customerId select act); }   } } The repository classes look very similar to each other for Query and Add methods, with the help of C# generics and implementing repository pattern (Martin Fowler) we can reduce the repeated code. Jarod from ElegantCode has posted an article on how to use repository pattern with EF which we will implement in the subsequent articles along with WCF Unity life time managers by Drew Contracts It is very easy to follow contract first approach with WCF, define the interface and append ServiceContract, OperationContract attributes. IProfile contract exposes functionality for creating customer and getting customer details.   using System; using System.ServiceModel; using BankDAL.Model;   namespace ProfileContract { [ServiceContract] public interface IProfile { [OperationContract] Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth);   [OperationContract] Customer GetCustomer(int id);   } }   ICheckingAccount contract exposes functionality for working with checking account, i.e., getting balance, deposit and withdraw of amount. ISavingsAccount contract looks the same as checking account.   using System.ServiceModel;   namespace CheckingAccountContract { [ServiceContract] public interface ICheckingAccount { [OperationContract] decimal? GetCheckingAccountBalance(int customerId);   [OperationContract] void DepositAmount(int customerId,decimal amount);   [OperationContract] void WithdrawAmount(int customerId, decimal amount);   } }   Services   Having covered the data access layer and contracts so far and here comes the core of the business logic, i.e. services.   .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } ProfileService implements the IProfile contract for creating customer and getting customer detail using CustomerRepository. using System; using System.Linq; using System.ServiceModel; using BankDAL; using BankDAL.Model; using BankDAL.Repositories; using ProfileContract;   namespace ProfileService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Profile: IProfile { public Customer CreateAccount( string customerName, string address, DateTime dateOfBirth) { Customer cust = new Customer { FullName = customerName, Address = address, DateOfBirth = dateOfBirth };   using (var bankDbContext = new BankDbContext()) { new CustomerRepository(bankDbContext).Add(cust); bankDbContext.SaveChanges(); } return cust; }   public Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth) { return CreateAccount(customerName, address, dateOfBirth); } public Customer GetCustomer(int id) { return new CustomerRepository(new BankDbContext()).Query() .Where(i => i.Id == id).FirstOrDefault(); }   } } From the above code you shall observe that we are calling bankDBContext’s SaveChanges method and there is no save method specific to customer entity because EF manages all the changes centralized at the context level and all the pending changes so far are submitted in a batch and it is represented as Unit of Work. Similarly Checking service implements ICheckingAccount contract using CheckingAccountRepository, notice that we are throwing overdraft exception if the balance falls by zero. WCF has it’s own way of raising exceptions using fault contracts which will be explained in the subsequent articles. SavingsAccountService is similar to CheckingAccountService. using System; using System.Linq; using System.ServiceModel; using BankDAL.Model; using BankDAL.Repositories; using CheckingAccountContract;   namespace CheckingAccountService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Checking:ICheckingAccount { public decimal? GetCheckingAccountBalance(int customerId) { using (var bankDbContext = new BankDbContext()) { CheckingAccount account = (new CheckingAccountRepository(bankDbContext) .GetAccount(customerId)).FirstOrDefault();   if (account != null) return account.Balance;   return null; } }   public void DepositAmount(int customerId, decimal amount) { using(var bankDbContext = new BankDbContext()) { var checkingAccountRepository = new CheckingAccountRepository(bankDbContext); CheckingAccount account = (checkingAccountRepository.GetAccount(customerId)) .FirstOrDefault();   if (account == null) { account = new CheckingAccount() { CustomerId = customerId }; checkingAccountRepository.Add(account); }   account.Balance = account.Balance + amount; if (account.Balance < 0) throw new ApplicationException("Overdraft not accepted");   bankDbContext.SaveChanges(); } } public void WithdrawAmount(int customerId, decimal amount) { DepositAmount(customerId, -1*amount); } } }   BankServiceHost The host acts as a glue binding contracts with it’s services, exposing the endpoints. The services can be exposed either through the code or configuration file, configuration file is preferred as it allows run time changes to service behavior even after deployment. We have 3 services and for each of the service you need to define name (the class that implements the service with fully qualified namespace) and endpoint known as ABC, i.e. address, binding and contract. We are using netTcpBinding and have defined the base address with for each of the contracts .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } <system.serviceModel> <services> <service name="ProfileService.Profile"> <endpoint binding="netTcpBinding" contract="ProfileContract.IProfile"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Profile"/> </baseAddresses> </host> </service> <service name="CheckingAccountService.Checking"> <endpoint binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Checking"/> </baseAddresses> </host> </service> <service name="SavingsAccountService.Savings"> <endpoint binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Savings"/> </baseAddresses> </host> </service> </services> </system.serviceModel> Have to open the services by creating service host which will handle the incoming requests from clients.   using System;   namespace ServiceHost { class Program { static void Main(string[] args) { CreateHosts(); Console.ReadLine(); }   private static void CreateHosts() { CreateHost(typeof(ProfileService.Profile),"Profile Service"); CreateHost(typeof(SavingsAccountService.Savings), "Savings Account Service"); CreateHost(typeof(CheckingAccountService.Checking), "Checking Account Service"); }   private static void CreateHost(Type type, string hostDescription) { System.ServiceModel.ServiceHost host = new System.ServiceModel.ServiceHost(type); host.Open();   if (host.ChannelDispatchers != null && host.ChannelDispatchers.Count != 0 && host.ChannelDispatchers[0].Listener != null) Console.WriteLine("Started: " + host.ChannelDispatchers[0].Listener.Uri); else Console.WriteLine("Failed to start:" + hostDescription); } } } BankClient    The client has no knowledge about service business logic other than the functionality it exposes through the contract, end points and a proxy to work against. The endpoint data and server proxy can be generated by right clicking on the project reference and choosing ‘Add Service Reference’ and entering the service end point address. Or if you have access to source, you can manually reference contract dlls and update clients configuration file to point to the service end point if the server and client happens to be being built using .Net framework. One of the pros with the manual approach is you don’t have to work against messy code generated files.   <system.serviceModel> <client> <endpoint name="tcpProfile" address="net.tcp://localhost:1000/Profile" binding="netTcpBinding" contract="ProfileContract.IProfile"/> <endpoint name="tcpCheckingAccount" address="net.tcp://localhost:1000/Checking" binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <endpoint name="tcpSavingsAccount" address="net.tcp://localhost:1000/Savings" binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/>   </client> </system.serviceModel> The client uses a façade to connect to the services   using System.ServiceModel; using CheckingAccountContract; using ProfileContract; using SavingsAccountContract;   namespace Client { public class ProxyFacade { public static IProfile ProfileProxy() { return (new ChannelFactory<IProfile>("tcpProfile")).CreateChannel(); }   public static ICheckingAccount CheckingAccountProxy() { return (new ChannelFactory<ICheckingAccount>("tcpCheckingAccount")) .CreateChannel(); }   public static ISavingsAccount SavingsAccountProxy() { return (new ChannelFactory<ISavingsAccount>("tcpSavingsAccount")) .CreateChannel(); }   } }   With that in place, lets get our unit tests going   using System; using System.Diagnostics; using BankDAL.Model; using NUnit.Framework; using ProfileContract;   namespace Client { [TestFixture] public class Tests { private void TransferFundsFromSavingsToCheckingAccount(int customerId, decimal amount) { ProxyFacade.CheckingAccountProxy().DepositAmount(customerId, amount); ProxyFacade.SavingsAccountProxy().WithdrawAmount(customerId, amount); }   private void TransferFundsFromCheckingToSavingsAccount(int customerId, decimal amount) { ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, amount); ProxyFacade.CheckingAccountProxy().WithdrawAmount(customerId, amount); }     [Test] public void CreateAndGetProfileTest() { IProfile profile = ProxyFacade.ProfileProxy(); const string customerName = "Tom"; int customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)).Id; Customer customer = profile.GetCustomer(customerId); Assert.AreEqual(customerName,customer.FullName); }   [Test] public void DepositWithDrawAndTransferAmountTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Smith" + DateTime.Now.ToString("HH:mm:ss"); var customer = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)); // Deposit to Savings ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 100); ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 25); Assert.AreEqual(125, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); // Withdraw ProxyFacade.SavingsAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(95, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id));   // Deposit to Checking ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 60); ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 40); Assert.AreEqual(100, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); // Withdraw ProxyFacade.CheckingAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(70, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Savings to Checking TransferFundsFromSavingsToCheckingAccount(customer.Id,10); Assert.AreEqual(85, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Checking to Savings TransferFundsFromCheckingToSavingsAccount(customer.Id, 50); Assert.AreEqual(135, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(30, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); }   [Test] public void FundTransfersWithOverDraftTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Angelina" + DateTime.Now.ToString("HH:mm:ss");   var customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1972, 1, 1)).Id;   ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, 100); TransferFundsFromSavingsToCheckingAccount(customerId,80); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId));   try { TransferFundsFromSavingsToCheckingAccount(customerId,30); } catch (Exception e) { Debug.WriteLine(e.Message); }   Assert.AreEqual(110, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId)); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); } } }   We are creating a new instance of the channel for every operation, we will look into instance management and how creating a new instance of channel affects it in subsequent articles. The first two test cases deals with creation of Customer, deposit and withdraw of month between accounts. The last case, FundTransferWithOverDraftTest() is interesting. Customer starts with depositing $100 in SavingsAccount followed by transfer of $80 in to checking account resulting in $20 in savings account.  Customer then initiates $30 transfer from Savings to Checking resulting in overdraft exception on Savings with $30 being deposited to Checking. As we are not running both the requests in transactions the customer ends up with more amount than what he started with $100. In subsequent posts we will look into transactions handling.  Make sure the ServiceHost project is set as start up project and start the solution. Run the test cases either from NUnit client or TestDriven.Net/Resharper which ever is your favorite tool. Make sure you have updated the data base connection string in the ServiceHost config file to point to your local database

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• What happened to Alan Cooper's Unified File Model?

  - by PAUL Mansour

  For a long time Alan Cooper (in the 3 versions of his book "About Face") has been promoting a "unified file model" to, among other things, dispense with what he calls the most idiotic message box ever invented - the one the pops up when hit the close button on an app or form saying "Do you want to discard your changes?" I like the idea and his arguments, but also have the knee-jerk reaction against it that most seasoned programmers and users have. While Cooper's book seems quite popular and respected, there is remarkably little discussion of this particular issue on the Web that I can find. Petter Hesselberg, the author of "Programming Industrial Strength Windows" mentions it but that seems about it. I have an opportunity to implement this in the (desktop) project I am working on, but face resistance by customers and co-workers, who are of course familiar with the MS Word and Excel way of doing things. I'm in a position to override their objections, but am not sure if I should. My questions are: Are there any good discussions of this that I have failed to find? Is anyone doing this in their apps? Is it a good idea that it is unfortunately not practical to implement until, say, Microsoft does it?

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• Adding SSE support in Java EE 8

  - by delabassee

  SSE (Server-Sent Event) is a standard mechanism used to push, over HTTP, server notifications to clients.  SSE is often compared to WebSocket as they are both supported in HTML 5 and they both provide the server a way to push information to their clients but they are different too! See here for some of the pros and cons of using one or the other. For REST application, SSE can be quite complementary as it offers an effective solution for a one-way publish-subscribe model, i.e. a REST client can 'subscribe' and get SSE based notifications from a REST endpoint. As a matter of fact, Jersey (JAX-RS Reference Implementation) already support SSE since quite some time (see the Jersey documentation for more details). There might also be some cases where one might want to use SSE directly from the Servlet API. Sending SSE notifications using the Servlet API is relatively straight forward. To give you an idea, check here for 2 SSE examples based on the Servlet 3.1 API.  We are thinking about adding SSE support in Java EE 8 but the question is where as there are several options, in the platform, where SSE could potentially be supported: the Servlet API the WebSocket API JAX-RS or even having a dedicated SSE API, and thus a dedicated JSR too! Santiago Pericas-Geertsen (JAX-RS Co-Spec Lead) conducted an initial investigation around that question. You can find the arguments for the different options and Santiago's findings here. So at this stage JAX-RS seems to be a good choice to support SSE in Java EE. This will obviously be discussed in the respective JCP Expert Groups but what is your opinion on this question?

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• Part 2&ndash;Load Testing In The Cloud

  - by Tarun Arora

  Welcome to Part 2, In Part 1 we discussed the advantages of creating a Test Rig in the cloud, the Azure edge and the Test Rig Topology we want to get to. In Part 2, Let’s start by understanding the components of Azure we’ll be making use of followed by manually putting them together to create the test rig, so… let’s get down dirty start setting up the Test Rig.  What Components of Azure will I be using for building the Test Rig in the Cloud? To run the Test Agents we’ll make use of Windows Azure Compute and to enable communication between Test Controller and Test Agents we’ll make use of Windows Azure Connect.  Azure Connect The Test Controller is on premise and the Test Agents are in the cloud (How will they talk?). To enable communication between the two, we’ll make use of Windows Azure Connect. With Windows Azure Connect, you can use a simple user interface to configure IPsec protected connections between computers or virtual machines (VMs) in your organization’s network, and roles running in Windows Azure. With this you can now join Windows Azure role instances to your domain, so that you can use your existing methods for domain authentication, name resolution, or other domain-wide maintenance actions. For more details refer to an overview of Windows Azure connect. A very useful video explaining everything you wanted to know about Windows Azure connect.  Azure Compute Windows Azure compute provides developers a platform to host and manage applications in Microsoft’s data centres across the globe. A Windows Azure application is built from one or more components called ‘roles.’ Roles come in three different types: Web role, Worker role, and Virtual Machine (VM) role, we’ll be using the Worker role to set up the Test Agents. A very nice blog post discussing the difference between the 3 role types. Developers are free to use the .NET framework or other software that runs on Windows with the Worker role or Web role. Developers can also create applications using languages such as PHP and Java. More on Windows Azure Compute. Each Windows Azure compute instance represents a virtual server... Virtual Machine Size CPU Cores Memory Cost Per Hour Extra Small Shared 768 MB $0.04 Small 1 1.75 GB $0.12 Medium 2 3.50 GB $0.24 Large 4 7.00 GB $0.48 Extra Large 8 14.00 GB $0.96   You might want to review the Windows Azure Pricing FAQ. Let’s Get Started building the Test Rig… Configuration Machine Role Comments VM – 1 Domain Controller for Playpit.com On Premise VM – 2 TFS, Test Controller On Premise VM – 3 Test Agent Cloud   In this blog post I would assume that you have the domain, Team Foundation Server and Test Controller Installed and set up already. If not, please refer to the TFS 2010 Installation Guide and this walkthrough on MSDN to set up your Test Controller. You can also download a preconfigured TFS 2010 VM from Brian Keller's blog, Brian also has some great hands on Labs on TFS 2010 that you may want to explore. I. Lets start building VM – 3: The Test Agent Download the Windows Azure SDK and Tools Open Visual Studio and create a new Windows Azure Project using the Cloud Template                   Choose the Worker Role for reasons explained in the earlier post         The WorkerRole.cs implements the Run() and OnStart() methods, no code changes required. You should be able to compile the project and run it in the compute emulator (The compute emulator should have been installed as part of the Windows Azure Toolkit) on your local machine.                   We will only be making changes to WindowsAzureProject, open ServiceDefinition.csdef. Ensure that the vmsize is small (remember the cost chart above). Import the “Connect” module. I am importing the Connect module because I need to join the Worker role VM to the Playpit domain. <?xml version="1.0" encoding="utf-8"?> <ServiceDefinition name="WindowsAzureProject2" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition"> <WorkerRole name="WorkerRole1" vmsize="Small"> <Imports> <Import moduleName="Diagnostics" /> <Import moduleName="Connect"/> </Imports> </WorkerRole> </ServiceDefinition> Go to the ServiceConfiguration.Cloud.cscfg and note that settings with key ‘Microsoft.WindowsAzure.Plugins.Connect.%%%%’ have been added to the configuration file. This is because you decided to import the connect module. See the config below. <?xml version="1.0" encoding="utf-8"?> <ServiceConfiguration serviceName="WindowsAzureProject2" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration" osFamily="1" osVersion="*"> <Role name="WorkerRole1"> <Instances count="1" /> <ConfigurationSettings> <Setting name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.ActivationToken" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Refresh" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.WaitForConnectivity" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Upgrade" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.EnableDomainJoin" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainFQDN" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainControllerFQDN" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainAccountName" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainPassword" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainOU" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Administrators" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainSiteName" value="" /> </ConfigurationSettings> </Role> </ServiceConfiguration>             Let’s go step by step and understand all the highlighted parameters and where you can find the values for them.       osFamily – By default this is set to 1 (Windows Server 2008 SP2). Change this to 2 if you want the Windows Server 2008 R2 operating system. The Advantage of using osFamily = “2” is that you get Powershell 2.0 rather than Powershell 1.0. In Powershell 2.0 you could simply use “powershell -ExecutionPolicy Unrestricted ./myscript.ps1” and it will work while in Powershell 1.0 you will have to change the registry key by including the following in your command file “reg add HKLM\Software\Microsoft\PowerShell\1\ShellIds\Microsoft.PowerShell /v ExecutionPolicy /d Unrestricted /f” before you can execute any power shell. The other reason you might want to move to os2 is if you wanted IIS 7.5.       Activation Token – To enable communication between the on premise machine and the Windows Azure Worker role VM both need to have the same token. Log on to Windows Azure Management Portal, click on Connect, click on Get Activation Token, this should give you the activation token, copy the activation token to the clipboard and paste it in the configuration file. Note – Later in the blog I’ll be showing you how to install connect on the on premise machine.                       EnableDomainJoin – Set the value to true, ofcourse we want to join the on windows azure worker role VM to the domain.       DomainFQDN, DomainControllerFQDN, DomainAccountName, DomainPassword, DomainOU, Administrators – This information is specific to your domain. I have extracted this information from the ‘service manager’ and ‘Active Directory Users and Computers’. Also, i created a new Domain-OU namely ‘CloudInstances’ so all my cloud instances joined to my domain show up here, this is optional. You can encrypt the DomainPassword – refer to the instructions here. Or hold fire, I’ll be covering that when i come to certificates and encryption in the coming section.       Now once you have filled all this information up, the configuration file should look something like below, <?xml version="1.0" encoding="utf-8"?> <ServiceConfiguration serviceName="WindowsAzureProject2" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration" osFamily="2" osVersion="*"> <Role name="WorkerRole1"> <Instances count="1" /> <ConfigurationSettings> <Setting name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.ActivationToken" value="45f55fea-f194-4fbc-b36e-25604faac784" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Refresh" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.WaitForConnectivity" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Upgrade" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.EnableDomainJoin" value="true" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainFQDN" value="play.pit.com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainControllerFQDN" value="WIN-KUDQMQFGQOL.play.pit.com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainAccountName" value="playpit\Administrator" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainPassword" value="************************" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainOU" value="OU=CloudInstances, DC=Play, DC=Pit, DC=com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Administrators" value="Playpit\Administrator" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainSiteName" value="" /> </ConfigurationSettings> </Role> </ServiceConfiguration> Next we will be enabling the Remote Desktop module in to the ServiceDefinition.csdef, we could make changes manually or allow a beautiful wizard to help us make changes. I prefer the second option. So right click on the Windows Azure project and choose Publish       Now once you get the publish wizard, if you haven’t already you would be asked to import your Windows Azure subscription, this is simply the Msdn subscription activation key xml. Once you have done click Next to go to the Settings page and check ‘Enable Remote Desktop for all roles’.       As soon as you do that you get another pop up asking you the details for the user that you would be logging in with (make sure you enter a reasonable expiry date, you do not want the user account to expire today). Notice the more information tag at the bottom, click that to get access to the certificate section. See screen shot below.       From the drop down select the option to create a new certificate        In the pop up window enter the friendly name for your certificate. In my case I entered ‘WAC – Test Rig’ and click ok. This will create a new certificate for you. Click on the view button to see the certificate details. Do you see the Thumbprint, this is the value that will go in the config file (very important). Now click on the Copy to File button to copy the certificate, we will need to import the certificate to the windows Azure Management portal later. So, make sure you save it a safe location.                                Click Finish and enter details of the user you would like to create with permissions for remote desktop access, once you have entered the details on the ‘Remote desktop configuration’ screen click on Ok. From the Publish Windows Azure Wizard screen press Cancel. Cancel because we don’t want to publish the role just yet and Yes because we want to save all the changes in the config file.       Now if you go to the ServiceDefinition.csdef file you will see that the RemoteAccess and RemoteForwarder roles have been imported for you. <?xml version="1.0" encoding="utf-8"?> <ServiceDefinition name="WindowsAzureProject2" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition"> <WorkerRole name="WorkerRole1" vmsize="Small"> <Imports> <Import moduleName="Diagnostics" /> <Import moduleName="Connect" /> <Import moduleName="RemoteAccess" /> <Import moduleName="RemoteForwarder" /> </Imports> </WorkerRole> </ServiceDefinition> Now go to the ServiceConfiguration.Cloud.cscfg file and you see a whole bunch for setting “Microsoft.WindowsAzure.Plugins.RemoteAccess.%%%” values added for you. <?xml version="1.0" encoding="utf-8"?> <ServiceConfiguration serviceName="WindowsAzureProject2" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration" osFamily="2" osVersion="*"> <Role name="WorkerRole1"> <Instances count="1" /> <ConfigurationSettings> <Setting name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.ActivationToken" value="45f55fea-f194-4fbc-b36e-25604faac784" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Refresh" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.WaitForConnectivity" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Upgrade" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.EnableDomainJoin" value="true" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainFQDN" value="play.pit.com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainControllerFQDN" value="WIN-KUDQMQFGQOL.play.pit.com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainAccountName" value="playpit\Administrator" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainPassword" value="************************" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainOU" value="OU=CloudInstances, DC=Play, DC=Pit, DC=com" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.Administrators" value="Playpit\Administrator" /> <Setting name="Microsoft.WindowsAzure.Plugins.Connect.DomainSiteName" value="" /> <Setting name="Microsoft.WindowsAzure.Plugins.RemoteAccess.Enabled" value="true" /> <Setting name="Microsoft.WindowsAzure.Plugins.RemoteAccess.AccountUsername" value="Administrator" /> <Setting name="Microsoft.WindowsAzure.Plugins.RemoteAccess.AccountEncryptedPassword" value="MIIBnQYJKoZIhvcNAQcDoIIBjjCCAYoCAQAxggFOMIIBSgIBADAyMB4xHDAaBgNVBAMME1dpbmRvd 3MgQXp1cmUgVG9vbHMCEGa+B46voeO5T305N7TSG9QwDQYJKoZIhvcNAQEBBQAEggEABg4ol5Xol66Ip6QKLbAPWdmD4ae ADZ7aKj6fg4D+ATr0DXBllZHG5Umwf+84Sj2nsPeCyrg3ZDQuxrfhSbdnJwuChKV6ukXdGjX0hlowJu/4dfH4jTJC7sBWS AKaEFU7CxvqYEAL1Hf9VPL5fW6HZVmq1z+qmm4ecGKSTOJ20Fptb463wcXgR8CWGa+1w9xqJ7UmmfGeGeCHQ4QGW0IDSBU6ccg vzF2ug8/FY60K1vrWaCYOhKkxD3YBs8U9X/kOB0yQm2Git0d5tFlIPCBT2AC57bgsAYncXfHvPesI0qs7VZyghk8LVa9g5IqaM Cp6cQ7rmY/dLsKBMkDcdBHuCTAzBgkqhkiG9w0BBwEwFAYIKoZIhvcNAwcECDRVifSXbA43gBApNrp40L1VTVZ1iGag+3O1" /> <Setting name="Microsoft.WindowsAzure.Plugins.RemoteAccess.AccountExpiration" value="2012-11-27T23:59:59.0000000+00:00" /> <Setting name="Microsoft.WindowsAzure.Plugins.RemoteForwarder.Enabled" value="true" /> </ConfigurationSettings> <Certificates> <Certificate name="Microsoft.WindowsAzure.Plugins.RemoteAccess.PasswordEncryption" thumbprint="AA23016CF0BDFC344400B5B82706B608B92E4217" thumbprintAlgorithm="sha1" /> </Certificates> </Role> </ServiceConfiguration>          Okay let’s look at them one at a time,       Enabled - Yes, we would like to enable Remote Access.       AccountUserName – This is the user name you entered while you were on the publish windows azure role screen, as detailed above.       AccountEncrytedPassword – Try and decode that, the certificate is used to encrypt the password you specified for the user account. Remember earlier i said, either use the instructions or wait and i’ll be showing you encryption, now the user account i am using for rdp has the same password as my domain password, so i can simply copy the value of the AccountEncryptedPassword to the DomainPassword as well.       AccountExpiration – This is the expiration as you specified in the wizard earlier, make sure your account does not expire today.       Remote Forwarder – Check out the documentation, below is how I understand it, -- One role in an application that implements a remote desktop connection must import the RemoteForwarder module. The two modules work together to enable the remote desktop connections to role instances. -- If you have multiple roles defined in the service model, it does not matter which role you add the RemoteForwarder module to, but you must add it to only one of the role definitions.       Certificate – Remember the certificate thumbprint from the wizard, the on premise machine and windows azure role machine that need to speak to each other must have the same thumbprint. More on that when we install Windows Azure connect Endpoints on the on premise machine. As i said earlier, in this blog post, I’ll be showing you the manual process so i won’t be scripting any star up tasks to install the test agent or register the test agent with the TFS Server. I’ll be showing you all this cool stuff in the next blog post, that’s because it’s important to understand the manual side of it, it becomes easier for you to troubleshoot in case something fails. Having said that, the changes we have made are sufficient to spin up the Windows Azure Worker Role aka Test Agent VM, have it connected with the play.pit.com domain and have remote access enabled on it. Before we deploy the Test Agent VM we need to set up Windows Azure Connect on the TFS Server. II. Windows Azure Connect: Setting up Connect on VM – 2 i.e. TFS & Test Controller Glad you made it so far, now to enable communication between the on premise TFS/Test Controller and Azure-ed Test Agent we need to enable communication. We have set up the Azure connect module in the Test Agent configuration, now the connect end points need to be enabled on the on premise machines, let’s have a look at how we can do this. Log on to VM – 2 running the TFS Server and Test Controller Log on to the Windows Azure Management Portal and click on Virtual Network Click on Virtual Network, if you already have a subscription you should see the below screen shot, if not, you would be asked to complete the subscription first        Click on Install Local Endpoints from the top left on the panel and you get a url appended with a token id in it, remember the token i showed you earlier, in theory the token you get here should match the token you added to the Test Agent config file.        Copy the url to the clip board and paste it in IE explorer (important, the installation at present only works out of IE and you need to have cookies enabled in order to complete the installation). As stated in the pop up, you can NOT download and run the software later, you need to run it as is, since it contains a token. Once the installation completes you should see the Windows Azure connect icon in the system tray.                         Right click the Azure Connect icon, choose Diagnostics and refer to this link for diagnostic detail terminology. NOTE – Unfortunately I could not see the Windows Azure connect icon in the system tray, a bit of binging with Google revealed that the azure connect icon is only shown when the ‘Windows Azure Connect Endpoint’ Service is started. So go to services.msc and make sure that the service is started, if not start it, unfortunately again, the service did not start for me on a manual start and i realised that one of the dependant services was disabled, you can look at the service dependencies and start them and then start windows azure connect. Bottom line, you need to start Windows Azure connect service before you can proceed. Please refer here on MSDN for more on Troubleshooting Windows Azure connect. (Follow the next step as well)   Now go back to the Windows Azure Management Portal and from Groups and Roles create a new group, lets call it ‘Test Rig’. Make sure you add the VM – 2 (the TFS Server VM where you just installed the endpoint).       Now if you go back to the Azure Connect icon in the system tray and click ‘Refresh Policy’ you will notice that the disconnected status of the icon should change to ready for connection. III. Importing Certificate in to Windows Azure Management Portal But before that you need to import the certificate you created in Step I in to the Windows Azure Management Portal. Log on to the Windows Azure Management Portal and click on ‘Hosted Services, Storage Accounts & CDN’ and then ‘Management Certificates’ followed by Add Certificates as shown in the screen shot below        Browse to the location where you saved the certificate earlier, remember… Refer to Step I in case you forgot.        Now you should be able to see the imported certificate here, make sure the thumbprint of the certificate matches the one you inserted in the config files        IV. Publish Windows Azure Worker Role aka Test Agent Having completed I, II and III, you are ready to publish the Test Agent VM – 3 to the cloud. Go to Visual Studio and right click the Windows Azure project and select Publish. Verify the infomration in the wizard, from the advanced settings tab, you can also enabled capture of intellitrace or profiling information.         Click Next and Click Publish! From the view menu bar select the Windows Azure Activity Log window.       Now you should be able to see the deployment progress in real time.             In the Windows Azure Management Portal, you should also be able to see the progress of creation of a new Worker Role.       Once the deployment is complete you should be able to RDP (go to run prompt type mstsc and in the pop up the machine name) in to the Test Agent Worker Role VM from the Playpit network using the domain admin user account. In case you are unable to log in to the Test Agent using the domain admin user account it means the process of joining the Test Agent to the domain has failed! But the good news is, because you imported the connect module, you can connect to the Test Agent machine using Windows Azure Management Portal and troubleshoot the reason for failure, you will be able to log in with the user name and password you specified in the config file for the keys ‘RemoteAccess.AccountUsername, RemoteAccess.EncryptedPassword (just that enter the password unencrypted)’, fix it or manually join the machine to the domain. Once you have managed to Join the Test Agent VM to the Domain move to the next step.      So, log in to the Test Agent Worker Role VM with the Playpit Domain Administrator and verify that you can log in, the machine is connected to the domain and the connect service is successfully running. If yes, give your self a pat on the back, you are 80% mission accomplished!         Go to the Windows Azure Management Portal and click on Virtual Network, click on Groups and Roles and click on Test Rig, click Edit Group, the edit the Test Rig group you created earlier. In the Connect to section, click on Add to select the worker role you have just deployed. Also, check the ‘Allow connections between endpoints in the group’ with this you will enable to communication between test controller and test agents and test agents/test agents. Click Save.      Now, you are ready to deploy the Test Agent software on the Worker Role Test Agent VM and configure it to work with the Test Controller. V. Configuring VM – 3: Installing Test Agent and Associating Test Agent to Controller Log in to the Worker Role Test Agent VM that you have just successfully deployed, make sure you log in with the domain administrator account. Download the All Agents software from MSDN, ‘en_visual_studio_agents_2010_x86_x64_dvd_509679.iso’, extract the iso and navigate to where you have extracted the iso. In my case, i have extracted the iso to “C:\Resources\Temp\VsAgentSetup”. Open the Test Agent folder and double click on setup.exe. Once you have installed the Test Agent you should reach the configuration window. If you face any issues installing TFS Test Agent on the VM, refer to the walkthrough on MSDN.       Once you have successfully installed the Test Agent software you will need to configure the test agent. Right click the test agent configuration tool and run as a different user. i.e. an Administrator. This is really to run the configuration wizard with elevated privileges (you might have UAC block something's otherwise).        In the run options, you can select ‘service’ you do not need to run the agent as interactive un less you are running coded UI tests. I have specified the domain administrator to connect to the TFS Test Controller. In real life, i would never do that, i would create a separate test user service account for this purpose. But for the blog post, we are using the most powerful user so that any policies or restrictions don’t block you.        Click the Apply Settings button and you should be all green! If not, the summary usually gives helpful error messages that you can resolve and proceed. As per my experience, you may run in to either a permission or a firewall blocking communication issue.        And now the moment of truth! Go to VM –2 open up Visual Studio and from the Test Menu select Manage Test Controller       Mission Accomplished! You should be able to see the Test Agent that you have just configured here,         VI. Creating and Running Load Tests on your brand new Azure-ed Test Rig I have various blog posts on Performance Testing with Visual Studio Ultimate, you can follow the links and videos below, Blog Posts: - Part 1 – Performance Testing using Visual Studio 2010 Ultimate - Part 2 – Performance Testing using Visual Studio 2010 Ultimate - Part 3 – Performance Testing using Visual Studio 2010 Ultimate Videos: - Test Tools Configuration & Settings in Visual Studio - Why & How to Record Web Performance Tests in Visual Studio Ultimate - Goal Driven Load Testing using Visual Studio Ultimate Now that you have created your load tests, there is one last change you need to make before you can run the tests on your Azure Test Rig, create a new Test settings file, and change the Test Execution method to ‘Remote Execution’ and select the test controller you have configured the Worker Role Test Agent against in our case VM – 2 So, go on, fire off a test run and see the results of the test being executed on the Azur-ed Test Rig. Review and What’s next? A quick recap of the benefits of running the Test Rig in the cloud and what i will be covering in the next blog post AND I would love to hear your feedback! Advantages Utilizing the power of Azure compute to run a heavy virtual user load. Benefiting from the Azure flexibility, destroy Test Agents when not in use, takes < 25 minutes to spin up a new Test Agent. Most important test Network Latency, (network latency and speed of connection are two different things – usually network latency is very hard to test), by placing the Test Agents in Microsoft Data centres around the globe, one can actually test the lag in transferring the bytes not because of a slow connection but because the page has been requested from the other side of the globe. Next Steps The process of spinning up the Test Agents in windows Azure is not 100% automated. I am working on the Worker process and power shell scripts to make the role deployment, unattended install of test agent software and registration of the test agent to the test controller automated. In the next blog post I will show you how to make the complete process unattended and automated. Remember to subscribe to http://feeds.feedburner.com/TarunArora. Hope you enjoyed this post, I would love to hear your feedback! If you have any recommendations on things that I should consider or any questions or feedback, feel free to leave a comment. See you in Part III.   Share this post : CodeProject

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• JavaScript objects and Crockford's The Good Parts

  - by Jonathan

  I've been thinking quite a bit about how to do OOP in JS, especially when it comes to encapsulation and inheritance, recently. According to Crockford, classical is harmful because of new(), and both prototypal and classical are limited because their use of constructor.prototype means you can't use closures for encapsulation. Recently, I've considered the following couple of points about encapsulation: Encapsulation kills performance. It makes you add functions to EACH member object rather than to the prototype, because each object's methods have different closures (each object has different private members). Encapsulation forces the ugly "var that = this" workaround, to get private helper functions to have access to the instance they're attached to. Either that or make sure you call them with privateFunction.apply(this) everytime. Are there workarounds for either of two issues I mentioned? if not, do you still consider encapsulation to be worth it? Sidenote: The functional pattern Crockford describes doesn't even let you add public methods that only touch public members, since it completely forgoes the use of new() and constructor.prototype. Wouldn't a hybrid approach where you use classical inheritance and new(), but also call Super.apply(this, arguments) to initialize private members and privileged methods, be superior?

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• Can mediatomb VLC profile transcode audio as MP3 rather than mpga ?

  - by djangofan

  In the /etc/mediatomb/config.xml, can mediatomb VLC profile transcode audo as MP3 rather than mpga ? My Sony GoogleTV wont render streamed .avi files files with a mpga audio in them. The original files are Divx encoded with 128kbs MP3 audio but mediatomb is transcoding them. How can I change this? Any ideas? Can I turn off the audio and video transcoding somehow? I need some ideas to try. <profile name="vlcprof" enabled="yes" type="external"> <mimetype>video/mpeg</mimetype> <agent command="vlc" arguments="-I dummy %in --sout #transcode{venc=ffmpeg,vcodec=mp2v,vb=4096,fps=25,aenc=ffmpeg,acodec=mpga,ab=192,samplerate=44100,channels=2}:standard{access=file,mux=ps,dst=%out} vlc:quit"/> <buffer size="10485760" chunk-size="131072" fill-size="2621440"/> <accept-url>yes</accept-url> <first-resource>yes</first-resource> </profile> I know that that MP3 encoding support is external to FFmpeg and must be configured appropriately, but I have no idea how to handle that. I would guess I can work around that by somehow telling ffmpeg to not transcode the audio stream? Also, should I create a separate vlcprof entry for video/avi ? Can you create more than one profile for VLC in the config.xml for mediatomb?

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• Ajax application: using SOAP vs REST ?

  - by coder

  I'm building an ajax heavy application (client-side strictly html/css/js) which will be getting all the data and using server business logic via webservices. I know REST seems to be the hot topic but I can't find any good arguments. The main argument seems to be its "light-weight". My impression so far is that wsdl/soap based services are more expressive and allow for more a more complex transfer of data. It appears that soap would be more useful in the application I'm building where the only code consuming the services will be the js downloaded in the client browser. REST on the other hand seems to have a smaller entry barrier and so can be more useful for services like twitter in allowing other developers to consume these services easily. Also, REST seems to Te better suited for simple data transfers. So in summary SOAP is useful for complex data transfer and REST is useful in simple data transfer. I'm currently under the impression that using SOAP would be best due to the complexity of the messages but perhaps there's other factors. What are your thoughts on the pros/cons of soap/rest for a heavy ajax web app? EDIT: While the wsdl is in xml, the data I'm transferring back and forth is actually in JSON. It just appears more natural to use wsdl/soap here due to the nature of the app. The verbs GET and POST may not be enough. I may want to say something like: processQueue, or executeTimer. This is why my conclusion has been wsdl/soap would be good for bridging a complex layer between two applications (client and server) whereas REST would be better (due to its simplicity) for allowing many developer-users to consume resources programmatically. So you could say the choice falls along two lines Will the app be verb-oriented (completing tasks: use soap) or noun-oriented (consuming resources: use REST) Will the api be consumed by few developers or many developers (REST is strong for many developers)? Since such an ajax heavy app would potentially use many verbs and would only be used by the client developer it appears soap/wsdl would be the best fit.

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• Questioning pythonic type checking

  - by Pace

  I've seen countless times the following approach suggested for "taking in a collection of objects and doing X if X is a Y and ignoring the object otherwise" def quackAllDucks(ducks): for duck in ducks: try: duck.quack("QUACK") except AttributeError: #Not a duck, can't quack, don't worry about it pass The alternative implementation below always gets flak for the performance hit caused by type checking def quackAllDucks(ducks): for duck in ducks: if hasattr(duck,"quack"): duck.quack("QUACK") However, it seems to me that in 99% of scenarios you would want to use the second solution because of the following: If the user gets the parameters wrong then they will not be treated like a duck and there will be no indication. A lot of time will be wasted debugging why there is no quacking going on until the user finally realizes his silly mistake. The second solution would throw a stack trace as soon the user tried to quack. If the user has any bugs in their quack() method which cause an AttributeError then those bugs will be silently swallowed. Once again time will be wasted digging for the bug when the second solution would simply give a stack trace showing the immediate issue. In fact, it seems to me that the only time you would ever want to use the first method is when: The block of code in question is in an extremely performance critical section of your application. Following the principal of "avoid premature optimization" you would only realize this of course, after you had implemented the safer approach and found it to be a bottleneck. There are many types of quacking objects out there and you are only interested in quacking objects that quack with a very specific set of arguments (this seems to be a very rare case to me). Given this, why is it that so many people prefer the first approach over the second approach? What is it that I am missing? Also, I realize there are other solutions (such as using abcs) but these are the two solutions I seem to see most often for the basic case.

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• C#/.NET Little Wonders: Tuples and Tuple Factory Methods

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can really help improve your code by making it easier to write and maintain.  This week, we look at the System.Tuple class and the handy factory methods for creating a Tuple by inferring the types. What is a Tuple? The System.Tuple is a class that tends to inspire a reaction in one of two ways: love or hate.  Simply put, a Tuple is a data structure that holds a specific number of items of a specific type in a specific order.  That is, a Tuple<int, string, int> is a tuple that contains exactly three items: an int, followed by a string, followed by an int.  The sequence is important not only to distinguish between two members of the tuple with the same type, but also for comparisons between tuples.  Some people tend to love tuples because they give you a quick way to combine multiple values into one result.  This can be handy for returning more than one value from a method (without using out or ref parameters), or for creating a compound key to a Dictionary, or any other purpose you can think of.  They can be especially handy when passing a series of items into a call that only takes one object parameter, such as passing an argument to a thread's startup routine.  In these cases, you do not need to define a class, simply create a tuple containing the types you wish to return, and you are ready to go? On the other hand, there are some people who see tuples as a crutch in object-oriented design.  They may view the tuple as a very watered down class with very little inherent semantic meaning.  As an example, what if you saw this in a piece of code: 1: var x = new Tuple<int, int>(2, 5); What are the contents of this tuple?  If the tuple isn't named appropriately, and if the contents of each member are not self evident from the type this can be a confusing question.  The people who tend to be against tuples would rather you explicitly code a class to contain the values, such as: 1: public sealed class RetrySettings 2: { 3: public int TimeoutSeconds { get; set; } 4: public int MaxRetries { get; set; } 5: } Here, the meaning of each int in the class is much more clear, but it's a bit more work to create the class and can clutter a solution with extra classes. So, what's the correct way to go?  That's a tough call.  You will have people who will argue quite well for one or the other.  For me, I consider the Tuple to be a tool to make it easy to collect values together easily.  There are times when I just need to combine items for a key or a result, in which case the tuple is short lived and so the meaning isn't easily lost and I feel this is a good compromise.  If the scope of the collection of items, though, is more application-wide I tend to favor creating a full class. Finally, it should be noted that tuples are immutable.  That means they are assigned a value at construction, and that value cannot be changed.  Now, of course if the tuple contains an item of a reference type, this means that the reference is immutable and not the item referred to. Tuples from 1 to N Tuples come in all sizes, you can have as few as one element in your tuple, or as many as you like.  However, since C# generics can't have an infinite generic type parameter list, any items after 7 have to be collapsed into another tuple, as we'll show shortly. So when you declare your tuple from sizes 1 (a 1-tuple or singleton) to 7 (a 7-tuple or septuple), simply include the appropriate number of type arguments: 1: // a singleton tuple of integer 2: Tuple<int> x; 3:  4: // or more 5: Tuple<int, double> y; 6:  7: // up to seven 8: Tuple<int, double, char, double, int, string, uint> z; Anything eight and above, and we have to nest tuples inside of tuples.  The last element of the 8-tuple is the generic type parameter Rest, this is special in that the Tuple checks to make sure at runtime that the type is a Tuple.  This means that a simple 8-tuple must nest a singleton tuple (one of the good uses for a singleton tuple, by the way) for the Rest property. 1: // an 8-tuple 2: Tuple<int, int, int, int, int, double, char, Tuple<string>> t8; 3:  4: // an 9-tuple 5: Tuple<int, int, int, int, double, int, char, Tuple<string, DateTime>> t9; 6:  7: // a 16-tuple 8: Tuple<int, int, int, int, int, int, int, Tuple<int, int, int, int, int, int, int, Tuple<int,int>>> t14; Notice that on the 14-tuple we had to have a nested tuple in the nested tuple.  Since the tuple can only support up to seven items, and then a rest element, that means that if the nested tuple needs more than seven items you must nest in it as well.  Constructing tuples Constructing tuples is just as straightforward as declaring them.  That said, you have two distinct ways to do it.  The first is to construct the tuple explicitly yourself: 1: var t3 = new Tuple<int, string, double>(1, "Hello", 3.1415927); This creates a triple that has an int, string, and double and assigns the values 1, "Hello", and 3.1415927 respectively.  Make sure the order of the arguments supplied matches the order of the types!  Also notice that we can't half-assign a tuple or create a default tuple.  Tuples are immutable (you can't change the values once constructed), so thus you must provide all values at construction time. Another way to easily create tuples is to do it implicitly using the System.Tuple static class's Create() factory methods.  These methods (much like C++'s std::make_pair method) will infer the types from the method call so you don't have to type them in.  This can dramatically reduce the amount of typing required especially for complex tuples! 1: // this 4-tuple is typed Tuple<int, double, string, char> 2: var t4 = Tuple.Create(42, 3.1415927, "Love", 'X'); Notice how much easier it is to use the factory methods and infer the types?  This can cut down on typing quite a bit when constructing tuples.  The Create() factory method can construct from a 1-tuple (singleton) to an 8-tuple (octuple), which of course will be a octuple where the last item is a singleton as we described before in nested tuples. Accessing tuple members Accessing a tuple's members is simplicity itself… mostly.  The properties for accessing up to the first seven items are Item1, Item2, …, Item7.  If you have an octuple or beyond, the final property is Rest which will give you the nested tuple which you can then access in a similar matter.  Once again, keep in mind that these are read-only properties and cannot be changed. 1: // for septuples and below, use the Item properties 2: var t1 = Tuple.Create(42, 3.14); 3:  4: Console.WriteLine("First item is {0} and second is {1}", 5: t1.Item1, t1.Item2); 6:  7: // for octuples and above, use Rest to retrieve nested tuple 8: var t9 = new Tuple<int, int, int, int, int, int, int, 9: Tuple<int, int>>(1,2,3,4,5,6,7,Tuple.Create(8,9)); 10:  11: Console.WriteLine("The 8th item is {0}", t9.Rest.Item1); Tuples are IStructuralComparable and IStructuralEquatable Most of you know about IComparable and IEquatable, what you may not know is that there are two sister interfaces to these that were added in .NET 4.0 to help support tuples.  These IStructuralComparable and IStructuralEquatable make it easy to compare two tuples for equality and ordering.  This is invaluable for sorting, and makes it easy to use tuples as a compound-key to a dictionary (one of my favorite uses)! Why is this so important?  Remember when we said that some folks think tuples are too generic and you should define a custom class?  This is all well and good, but if you want to design a custom class that can automatically order itself based on its members and build a hash code for itself based on its members, it is no longer a trivial task!  Thankfully the tuple does this all for you through the explicit implementations of these interfaces. For equality, two tuples are equal if all elements are equal between the two tuples, that is if t1.Item1 == t2.Item1 and t1.Item2 == t2.Item2, and so on.  For ordering, it's a little more complex in that it compares the two tuples one at a time starting at Item1, and sees which one has a smaller Item1.  If one has a smaller Item1, it is the smaller tuple.  However if both Item1 are the same, it compares Item2 and so on. For example: 1: var t1 = Tuple.Create(1, 3.14, "Hi"); 2: var t2 = Tuple.Create(1, 3.14, "Hi"); 3: var t3 = Tuple.Create(2, 2.72, "Bye"); 4:  5: // true, t1 == t2 because all items are == 6: Console.WriteLine("t1 == t2 : " + t1.Equals(t2)); 7:  8: // false, t1 != t2 because at least one item different 9: Console.WriteLine("t2 == t2 : " + t2.Equals(t3)); The actual implementation of IComparable, IEquatable, IStructuralComparable, and IStructuralEquatable is explicit, so if you want to invoke the methods defined there you'll have to manually cast to the appropriate interface: 1: // true because t1.Item1 < t3.Item1, if had been same would check Item2 and so on 2: Console.WriteLine("t1 < t3 : " + (((IComparable)t1).CompareTo(t3) < 0)); So, as I mentioned, the fact that tuples are automatically equatable and comparable (provided the types you use define equality and comparability as needed) means that we can use tuples for compound keys in hashing and ordering containers like Dictionary and SortedList: 1: var tupleDict = new Dictionary<Tuple<int, double, string>, string>(); 2:  3: tupleDict.Add(t1, "First tuple"); 4: tupleDict.Add(t2, "Second tuple"); 5: tupleDict.Add(t3, "Third tuple"); Because IEquatable defines GetHashCode(), and Tuple's IStructuralEquatable implementation creates this hash code by combining the hash codes of the members, this makes using the tuple as a complex key quite easy!  For example, let's say you are creating account charts for a financial application, and you want to cache those charts in a Dictionary based on the account number and the number of days of chart data (for example, a 1 day chart, 1 week chart, etc): 1: // the account number (string) and number of days (int) are key to get cached chart 2: var chartCache = new Dictionary<Tuple<string, int>, IChart>(); Summary The System.Tuple, like any tool, is best used where it will achieve a greater benefit.  I wouldn't advise overusing them, on objects with a large scope or it can become difficult to maintain.  However, when used properly in a well defined scope they can make your code cleaner and easier to maintain by removing the need for extraneous POCOs and custom property hashing and ordering. They are especially useful in defining compound keys to IDictionary implementations and for returning multiple values from methods, or passing multiple values to a single object parameter. Tweet Technorati Tags: C#,.NET,Tuple,Little Wonders

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• Are C++ templates just a kind of glorified macros?

  - by Gulshan

  From different comparisons among C++ templates and C#/Java generics like this one- http://stackoverflow.com/questions/31693/what-are-the-differences-between-generics-in-c-and-java-and-templates-in-c/31929#31929 I have a got a perception that, C++ templates are implemented by some kind of preprocessing, not compiling. In other words, they are just a kind of C macros. Is this right? Then I felt that, if C++ templates are implemented by preprocessing, dynamic linking(.dll) cannot be used. A quick google search also supports this. And lastly, how can we use macros in C to deliver C++ templates like functionalities? Another thing came in my mind about templates similar to some kind of preprocessor that, there can be integers passed as arguments to some templates. And it even supports kind of recursion. But the recursion is not in the assembly/machine code. So, am I wrong calling templates glorified macros? Unlike normal macros, it has some superior abilities. But isn't it a kind of preprocessing?

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• Why is there never any controversy regarding the switch statement? [closed]

  - by Nick Rosencrantz

  We all know that the gotostatement should only be used on very rare occasions if at all. It has been discouraged to use the goto statement countless places countless times. But why it there never anything like that about the switch statement? I can understand the position that the switch statement should always be avoided since anything with switch can always be expressed by if...else... which is also more readable and the syntax of the switch statement if difficult to remember. Do you agree? What are the arguments in favor of keeping the 'switch` statement? It can also be difficult to use if what you're testing changes from say an integer to an object, then C++ or Java won't be able to perform the switch and neither C can perform switch on something like a struct or a union. And the technique of fall-through is so very rarely used that I wonder why it was never presented any regret of having switch at all? The only place I know where it is best practice is GUI code and even that switch is probably better coded in a more object-oriented way.

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• SkyDrive and Consumer Cloud Services

  - by Tim Murphy

  Paul Thurrrott recently posted an article on the future of SkyDrive and I was asked what I thought about its future by @UserCommunity.  So let’s take a look. The breakdown from Microsoft that Paul described I believe is an accurate representation of users and usages. While I can’t say that I leverage SkyDrive to the extent that it was meant to be I do enjoy having OneNote hosted their and being able to consult and edit it from the desktop, web and Windows Phone. Taking that one step further is the Midwest Geeks group which started as the community of Microsoft related user groups in our region uses SkyDrive groups and shares calendars and documents.  This collaboration aspect isn’t new in itself, but having it connected with the rest of your cloud assets makes life easier. Another recent usage of this type of cloud service is storing your personal music files in order to get that same universal access.  This is a scenario that has some arguments for and against.  On the one hand own once and listen anywhere is great, but the on the other hand the bandwidth cost becomes a giant downside.  This is especially the case since most carriers are now doing away with unlimited data packages. Ultimately I see this type of resource growing an evolving at a phenomenal rate over the next few years as we continue to become more mobile.  Having multiple players such as SkyDrive and iCloud will only help to give us more options.  Only time will tell where we end up next. del.icio.us Tags: SkyDrive,Cloud Services,Paul Thurrott,UserCommunity

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• Start Debugging in Visual Studio

  - by Daniel Moth

  Every developer is familiar with hitting F5 and debugging their application, which starts their app with the Visual Studio debugger attached from the start (instead of attaching later). This is one way to achieve step 1 of the Live Debugging process. Hitting F5, F11, Ctrl+F10 and the other ways to start the process under the debugger is covered in this MSDN "How To". The way you configure the debugging experience, before you hit F5, is by selecting the "Project" and then the "Properties" menu (Alt+F7 on my keyboard bindings). Dependent on your project type there are different options, but if you browse to the Debug (or Debugging) node in the properties page you'll have a way to select local or remote machine debugging, what debug engines to use, command line arguments to use during debugging etc. Currently the .NET and C++ project systems are different, but one would hope that one day they would be unified to use the same mechanism and UI (I don't work on that product team so I have no knowledge of whether that is a goal or if it will ever happen). Personally I like the C++ one better, here is what it looks like (and it is described on this MSDN page): If you were following along in the "Attach to Process" blog post, the equivalent to the "Select Code Type" dialog is the "Debugger Type" dropdown: that is how you change the debug engine. Some of the debugger properties options appear on the standard toolbar in VS. With Visual Studio 11, the Debug Type option has been added to the toolbar If you don't see that in your installation, customize the toolbar to show it - VS 11 tends to be conservative in what you see by default, especially for the non-C++ Visual Studio profiles. Comments about this post by Daniel Moth welcome at the original blog.

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• links for 2011-03-07

  - by Bob Rhubart

  DON CIO News: DON CIO Discusses Future IT Initiatives Audio links and a little background information on a recent town hall meetings hosted by Department of the Navy Chief Information Officer Terry Halvorsen. (tags: usgov usnavy cio enterprisearchitecture) Strassmann's Blog: Why So Many Data Centers? "The idea of datacenter consolidation involves much more that applying simple technical solutions." - Paul Strassmann (tags: enterprisearchitecture datacenter consolidation) Satyajith Nair: Coherence - The next big thing for the cloud!! "Disk-based computing is fraught with performance and management issues and doing away with Disks though not practical now, maybe true in the future. This also calls for a re-think of our current application architecture which is so focussed on disk-based persistence." - Satyajith Nair (tags: oracle infosys coherence grid cloud) TechCast: GlassFish Server and WebLogic - Interoperability and Integration - Oracle media - developer Fusion VP Development Anil Gaur and Product Manager Adam Leftik explain Oracle&#39;s strategy for creating increasing integration between GlassFish Server and Oracle WebLogic Server with an overview of new features and functionality for developers in GlassFish 3.1. (tags: ping.fm) Oracle Fusion and Oracle Fusion Applications : Overview | OracleApps Epicenter So WHAT IS ORACLE FUSION? People often get confuse with this term .To start with, it will be a good idea to know the difference between Fusion (tags: ping.fm) Marc Kelderman: OSB: Automatic update of Service Acounts Solution architect Marc Kelderman shares a work-around for using different Service Accounts for multiple environments. (tags: oracle otn sca bpel soa bpm servicebus) Perfect Integration 1 - Architectural Approach "First post in a series of 5-10, I will release all my views and opinions on the Art of Integration. I challenge you to disagree, and bash me with arguments and reasoning." -- Martijn Linssen (tags: enterprisearchitecture integration) Edwin Biemond: Set the Initial Focus on a component in a Page or a Fragment Edwin says: "This is not so hard to do, but sometimes it can be tricky to find the id of a component when you use regions ( Bounded Task Flows )." (tags: oracle otn oracleace java soa) Oracle Linux and Oracle Virtualization at Collaborate 2011 Information on more than 200 Oracle-hosted sessions with the latest insights and guidance from Oracle executives, product managers, and developers. (tags: oracle virtualization linux ioug oaug)

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• Suggestions for a CMS markup language for PHP

  - by Yanick Rochon

  As a learning experience, and as project, I am attempting to write a CMS module for ZF2. One of the functionality I would like to have is the possibility of adding dynamic contents in the pages by calling PHP functions in the view scripts. However, I do not want to give the users freedom in writing PHP code directly inside the page content, but rather implement custom view helpers (or widgets) to handle logic. For example: calling partial, partialLoop, url, etc. specifying arguments and all. I liked the idea of extending Markdown but this would get complicated when trying to add custom CSS class to elements, etc. Then I had the idea of simply doing a preg_replace on some patterns. For example, the string : ### partialLoop:['partials/display.phtml',[{id:'p1',price:4.99},{id:'p2',price:12.34}]] ### would be replaced by <?php echo $this->partialLoop('partials/display.phtml', array(array('id'=>'p1','price'=>4.99),array('id'=>'p2','price'=>12.34))) ?> Obviously, there would be some caching done so the page content is not rendered everytime. Does this sound good? If not, what would be a good way of doing this? Or is there a project already being developed for doing this? (I'd like to avoid heavy third party libs and something fairly or fully compatible with ZF2 would be nice.) Thanks.

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• Database Schema Usage

  - by CrazyHorse

  I have a question regarding the appropriate use of SQL Server database schemas and was hoping that some database gurus might be able to offer some guidance around best practice. Just to give a bit of background, my team has recently shrunk to 2 people and we have just been merged with another 6 person team. My team had set up a SQL Server environment running off a desktop backing up to another desktop (and nightly to the network), whilst the new team has a formal SQL Server environment, running on a dedicated server, with backups and maintenance all handled by a dedicated team. So far it's good news for my team. Now to the query. My team designed all our tables to belong to a 3-letter schema name (e.g. User = USR, General = GEN, Account = ACC) which broadly speaking relate to specific applications, although there is a lot of overlap. My new team has come from an Access background and have implemented their tables within dbo with a 3-letter perfix followed by "_tbl" so the examples above would be dbo.USR_tblTableName, dbo.GEN_tblTableName and dbo.ACC_tblTableName. Further to this, neither my old team nor my new team has gone live with their SQL Servers yet (we're both coincidentally migrating away from Access environments) and the new team have said they're willing to consider adopting our approach if we can explain how this would be beneficial. We are not anticipating handling table updates at schema level, as we will be using application-level logins. Also, with regards to the unwieldiness of the 7-character prefix, I'm not overly concerned myself as we're using LINQ almost exclusively so the tables can simply be renamed in the DMBL (although I know that presents some challenges when we update the DBML). So therefore, given that both teams need to be aligned with one another, can anyone offer any convincing arguments either way?

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• Android device - C++ OpenGL 2: eglCreateWindowSurface invalid

  - by ThreaderSlash

  I am trying to debug and run OGLES on Native C++ in my Android device in order to implement a native 3D game for mobile smart phones. The point is that I got an error and see no reason for that. Here is the line from the code that the debugger complains: mSurface = eglCreateWindowSurface(mDisplay, lConfig, mApplication->window, NULL); And this is the error message: Invalid arguments ' Candidates are: void * eglCreateWindowSurface(void *, void *, unsigned long int, const int *) ' --x-- Here is the declaration: android_app* mApplication; EGLDisplay mDisplay; EGLint lFormat, lNumConfigs, lErrorResult; EGLConfig lConfig; // Defines display requirements. 16bits mode here. const EGLint lAttributes[] = { EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT, EGL_BLUE_SIZE, 5, EGL_GREEN_SIZE, 6, EGL_RED_SIZE, 5, EGL_SURFACE_TYPE, EGL_WINDOW_BIT, EGL_RENDER_BUFFER, EGL_BACK_BUFFER, EGL_NONE }; // Retrieves a display connection and initializes it. packt_Log_debug("Connecting to the display."); mDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY); if (mDisplay == EGL_NO_DISPLAY) goto ERROR; if (!eglInitialize(mDisplay, NULL, NULL)) goto ERROR; // Selects the first OpenGL configuration found. packt_Log_debug("Selecting a display config."); if(!eglChooseConfig(mDisplay, lAttributes, &lConfig, 1, &lNumConfigs) || (lNumConfigs <= 0)) goto ERROR; // Reconfigures the Android window with the EGL format. packt_Log_debug("Configuring window format."); if (!eglGetConfigAttrib(mDisplay, lConfig, EGL_NATIVE_VISUAL_ID, &lFormat)) goto ERROR; ANativeWindow_setBuffersGeometry(mApplication->window, 0, 0, lFormat); // Creates the display surface. packt_Log_debug("Initializing the display."); mSurface = eglCreateWindowSurface(mDisplay, lConfig, mApplication->window, NULL); --x-- Hope someone here can shed some light on it.

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• Programming by dictation?

  - by Andrew M

  ie. you speak out the code, and someone else across the room types it in Anyone tried this? Obviously the person taking the dictation would need to be a coder too, so you didn't have to explain everything and go into tedious detail (not 'open bracket, new line...' but more like 'create a new class called myParser that takes three arguments, first one is...'). I thought of it because sometimes I'm too easily distracted at my computer. Surrounded by buttons, instant gratification a click away, the world at my fingertips. To get stuff done, I want to get away, write my code on paper. But that would mean losing access to necessary resources, and necessitate tedious typing-up later on. The solution? Dictate. Pros: no chance to check reddit, stackexchange, gmail, etc. code while you pace the room, lie down, play billiards, whatever train your brain to think more abstractedly (have to visualize things if you can't just see the screen) skip the tedious details (closing brackets etc.) the typist gets to shadow a more experienced programmer and learn how they work the typist can provide assistance/suggestions external pressure of typist expecting instructions, urging you to stay focussed Cons might be too hard might not work any better rather inefficient use of assisting programmer need to find/pay someone to do this

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• Dummy output after upgrade from 12.04 to 12.10, even though sound card is detected

  - by user115441

  So I just recently upgraded my system from Ubuntu 12.04 to 12.10. However, when I booted into 12.10 for the first time, no sound comes out of my speakers. I checked the sound settings and the Dummy Output was the only thing showing up. I used "hwinfo --sound" to check to see if my sound card was actually installed, and it was installed. hwinfo --sound hal.1: read hal dataprocess 2687: arguments to dbus_move_error() were incorrect, assertion "(dest) == NULL || !dbus_error_is_set ((dest))" failed in file ../../dbus/dbus-errors.c line 282. This is normally a bug in some application using the D-Bus library. libhal.c 3483 : Error unsubscribing to signals, error=The name org.freedesktop.Hal was not provided by any .service files 11: PCI 1b.0: 0403 Audio device [Created at pci.318] Unique ID: u1Nb._aiKlM91Nt0 SysFS ID: /devices/pci0000:00/0000:00:1b.0 SysFS BusID: 0000:00:1b.0 Hardware Class: sound Model: "Intel 82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller" Vendor: pci 0x8086 "Intel Corporation" Device: pci 0x2668 "82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller" SubVendor: pci 0x107b "Gateway 2000" SubDevice: pci 0x4040 Revision: 0x04 Driver: "snd_hda_intel" Driver Modules: "snd_hda_intel" Memory Range: 0x50240000-0x50243fff (rw,non-prefetchable) IRQ: 44 (91 events) Module Alias: "pci:v00008086d00002668sv0000107Bsd00004040bc04sc03i00" Driver Info #0: Driver Status: snd_hda_intel is active Driver Activation Cmd: "modprobe snd_hda_intel" Config Status: cfg=new, avail=yes, need=no, active=unknown I'm not sure what to do here. The only time the sound will actually work is when I boot into my Windows partition and then reboot into Ubuntu. I mean I don't want to have to do that every time I want to use Ubuntu. I would really appreciate any help I can get on here.

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• Why do you hate Java? Is it the language or the framework? [closed]

  - by zneak

  According to you all, Java is the third most-hated language here. The two other most hated languages are PHP and VBScript. (It's quite funny how they stand together on the podium.) I'd like to make it known that the question mostly addresses people who don't like Java. I assume here a number of subjective opinions as facts because they're usually considered true among people who don't like Java, and I don't want to be convinced otherwise here. If you're a Java enthusiast, you might find this question frustrating. It's never been made clear if people hate Java itself, or if they hate it because of the framework, or if it's a mixture of the two. On a side you have the language, where you have: the "everything should be an object" philosophy, even in instances where it should obviously be something else (event handlers I'm pointing you); checked exceptions; the idea that all logic should be presented as methods and properties is a big no-no; the fact that "closures" created by anonymous types only include final variables and arguments, but will allow write access to any member of the parent class; a few more. On the other side, you have the JDK, with... its load of inconsistencies and overengineering; monolithic class hierarchies; meaningless base exceptions like IOException (though other frameworks have similar exception hierarchies); sluggish responsiveness even with Swing; a few more. My question is, do you think that, if either one (Java or the JDK) was taken alone, and the other was dropped in favor of something else, the new combination would be better? For instance, if you could use the C# syntax with the JDK (adapting get*/set* methods into properties, and interfaces with only one method into delegates), or the Java syntax with the .NET Framework (doing the inverse transformations), would things get better in your opinion?

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• Is this method pure?

  - by Thomas Levesque

  I have the following extension method: public static IEnumerable<T> Apply<T>( [NotNull] this IEnumerable<T> source, [NotNull] Action<T> action) where T : class { source.CheckArgumentNull("source"); action.CheckArgumentNull("action"); return source.ApplyIterator(action); } private static IEnumerable<T> ApplyIterator<T>(this IEnumerable<T> source, Action<T> action) where T : class { foreach (var item in source) { action(item); yield return item; } } It just applies an action to each item of the sequence before returning it. I was wondering if I should apply the Pure attribute (from Resharper annotations) to this method, and I can see arguments for and against it. Pros: strictly speaking, it is pure; just calling it on a sequence doesn't alter the sequence (it returns a new sequence) or make any observable state change calling it without using the result is clearly a mistake, since it has no effect unless the sequence is enumerated, so I'd like Resharper to warn me if I do that. Cons: even though the Apply method itself is pure, enumerating the resulting sequence will make observable state changes (which is the point of the method). For instance, items.Apply(i => i.Count++) will change the values of the items every time it's enumerated. So applying the Pure attribute is probably misleading... What do you think? Should I apply the attribute or not?

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• 2 year degree plus experience vs 4 year degree

  - by CenterOrbit

  Alright, I have searched around a bit on this site and found two somewhat similar questions: Computer Science Programming Certificate vs. Computer Science Degree? Is it possible/likely to be paid fairly without a college degree? But these do not provide an answer specifically to what I am seeking. I have my 2 year A.A.S. Degree in computer programming, along with a networking certificate from a technical college. I also have been working at a small educational game development company for 3 years now in various positions, but steadily moving up and now as a lead programmer on a few projects. Some of the higher programmers I work with claim that no matter how much experience I develop it still will not mean as much as someone with a 4 year degree. Their argument is that most employers will look over my resume because of the common '4 yr' minimum requirement. I have also heard people state (not as many though) that experience is everything and that an employer would rather have someone that has worked in the field instead of a rookie fresh out of college. I have heard both sides of this argument, but am looking for a general consensus, or more arguments from both sides from the people who have been there, or are there.

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