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• How to get started with embedded systems in the aircraft or submarine industries?

  - by Jason

  Hi, Not 100% sure how to frame this question but here goes... I currently work as a Rails developer but want to work on more substancial / "meaty" projects and have always been very interested in embedded systems, especially systems that run on aircraft and especially submarines.....I know strange combination. I have been doing some searching & found lockheed martin produces a lot of underwater systems for various navys around the world e.g. http://www.naval-technology.com/projects/nssn/ However, there is very little information about what software is used within these systems, what OS's they use or anything else "technical", presume there is a lot of C / C++ involved but that is just a guess... so its hard to know where to even begin learning what is required to potential work in these areas. Just wondering if anyone has any experiance working with or more information about embeddeed systems in either the airline (onboard flight systems) or especially submarine systems? Thanks!

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• OOP App Architecture: Which layer does a lazy loader sit in?

  - by JW

  I am planning the implemention an Inheritance Mapper pattern for an application component http://martinfowler.com/eaaCatalog/inheritanceMappers.html One feature it needs to have is for a domain object to reference a large list of aggreageted items (10,000 other domain objects) So I need some kind of lazy loading collection to be passed out of the aggregate root domain object to other domain objects. To keep my (php) model scripts organised i am storing them in two folders: MyComponent\ controllers\ models\ domain\ <- domain objects, DDD repository, DDD factory daccess\ <- PoEAA data mappers, SQL queries etc views\ But now I am racking my brains wondering where my lazy loading collection sits. Any suggestions / justifications for putting it in one place over another another? DDD = Domain Driven Design Patterns, Eric Evans - book PoEAA = Patterns of Application Architecture Patterns, Martin Fowler - book

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• iPhone, special characters in JSON Response

  - by eddit

  Writing an iphone app, and I'm getting my data from a REST API that returns JSON. My problem is, some of the data has special characters embedded and Im getting errors. Example: MartÌn Petite-RiviËre-Saint-FranÁois Here is my current code: NSString *jsonString = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding]; NSMutableArray *tempResults = [[[jsonString JSONValue] objectForKey:@"getRegionResortsLastUpdatedResponse"] objectForKey:@"return"]; Whenever the data has special characters in it "jsonString" return "(null)", otherwise everything works fine. Is this something I can handle on my end, or does the API need to be modified to output the character codes?

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• Select calls seems to not time out.

  - by martsbradley

  HI Folks, I have a threaded C++ program where up to three threads are calling select on a three separate socket descriptors waiting for data to become available. Each thread handles one socket and adds it to the readfds with a timeout of 300 seconds. After select returns if there is data available I'm calling recv to read it. Is there anything that I need to be aware of with winsock and threads because for some reason after a number of hours the select calls all seem to be not timing out. Can a multi threaded program select from a number of threads without issue? I know that I should have one thread listening to all three sockets however that would be a large change for this app and I'm only looking to apply a bug fix. cheers, Martin.

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• design patterns for hierarchical structures

  - by JLBarros

  Anyone knows some design patterns for hierarchical structures? For example, to manage inventory categories, accounting chart of accounts, divisions of human resources, etc.. Thank you very much in advance EDIT: Thanks for your interest. I am looking for a better way of dealing with hierarchical items to which they should apply operations depending on the level of hierarchy. I have been studying the patterns by Martin Fowler, for example Accounting, but I wonder if there are other more generic. The problem is that operations apply to the items must be possible to change even at run time and may depend on other external variables. I thought of a kind of strategy pattern but would like to combine it with the fact that it is a hierarchical scheme. I would appreciate any reference to hierarchical patterns and you'll take care of them in depth.

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• Doesn't Spring really support Interface injection at all?

  - by mrCoder

  Hi I know that Spring doesn't supports Interface injection and I've read that many a times. But today as I came across an article about IOC by Martin Fowler (link), it seems using ApplicationContextAware in Spring is some what similar to the Interface injection. when ever Spring' context reference is required in our Spring bean, we'll implement ApplicationContextAware and will implement the setApplicationContext(ApplicationContext context) method, and we'll include the bean in the config file. Is not this the same as Interface injection, where where telling the Spring to inject (or), say, pass the reference of the context into this bean? Or I m missing something here? Thanks for any information! ManiKanta

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• Function for getting localized path?

  - by MartinStettner

  Windows 7 (and probably Windows Vista) display localized folder names using the LocalizedResourceName entry in the desktop.ini file. For my Documents folder, this looks like [.ShellClassInfo] LocalizedResourceName=@%SystemRoot%\system32\shell32.dll,-21770 IconResource=%SystemRoot%\system32\imageres.dll,-112 IconFile=%SystemRoot%\system32\shell32.dll IconIndex=-235 (see this question) This way the explorer displays the path "C:\Users\Username\Documents" as "C:\Benutzer\Username\Dokumente" on a german Windows. I wonder, if there's any build-in shell function to automatically get this localized name or, even better, transform a whole path into its localized form (best would be anything in .NET)? This is even more interesting as the LocalizedResourceName entry is only documented for Windows CE (see here). Thanks Martin

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• is the + in += on a Map a prefix operator of =?

  - by Steve

  In the book "Programming in Scala" from Martin Odersky there is a simple example in the first chapter: var capital = Map("US" -> "Washington", "France" -> "Paris") capital += ("Japan" -> "Tokyo") The second line can also be written as capital = capital + ("Japan" -> "Tokyo") I am curious about the += notation. In the class Map, I didn't found a += method. I was able to the same behaviour in an own example like class Foo() { def +(value:String) = { println(value) this } } object Main { def main(args: Array[String]) = { var foo = new Foo() foo = foo + "bar" foo += "bar" } } I am questioning myself, why the += notation is possible. It doesn't work if the method in the class Foo is called test for example. This lead me to the prefix notation. Is the + a prefix notation for the assignment sign (=)? Can somebody explain this behaviour?

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• Why is rails called a dsl?

  - by b_ayan

  Recently, when I tried to explain why Rails is a DSL to an intern at my organisation, I was not able to articulate my reasonings to the effect I would like to. Maybe I do not understand the space well enough to teach the nuances. Redirecting him to Martin Fowler' article or the google ranked one InfoQ or other material has not helped much either. Can some explain why Rails is a DSL with an example / parallel situation which is not voodoo stuff for someone who is fairly new to the world of code? Understanding the ideology might also help in elaborating the intricacies of the rails ecosystem?

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• TomCat starts, but does not load properly

  - by user37136

  Hey guys, I've been working on this for a day now and still don't know what's wrong. I am essentially building a second environment for our web and app server. I got apache to load up just fine, but tomcat is proving to be difficult. It appears to start and load just fine, but when it comes to loading our application, its just got stuck for 2-5 minutes and then shut down. Here is the log on the original machine where it works fine: 2010-02-12 11:52:40,506 INFO Web application servlet context is initializing... 2010-02-12 11:52:40,540 DEBUG Servlet context attribute added: select_jobType=[{1,Undefined}, {100,Completion}, {200,Plugging}, {300,R+M}, {400,Workover}, {500,Swab - tubing}, {600,Swab - fluid}] 2010-02-12 11:52:40,540 DEBUG Servlet context attribute added: select_jobTaskType=[{1,Undefined}, {100,Rod part}, {200,Tubing leak}, {300,Pump change}, {400,Stripping job}, {500,Long stroke}, {600,A/L optimization}] 2010-02-12 11:52:40,541 DEBUG Servlet context attribute added: select_wellType=[{1,Undefined}, {100,Rod pump}, {200,ESP}, {300,Injector}, {400,PC pump}, {500,Co-Rod}, {600,Flowing}, {700,Storage}] 2010-02-12 11:52:40,541 DEBUG Servlet context attribute added: select_assetType=[{1,Rig}, {100,Disabled rig}] 2010-02-12 11:52:40,542 DEBUG Servlet context attribute added: select_state=[{AL,Alabama}, {AK,Alaska}, {AZ,Arizona}, {AR,Arkansas}, {CA,California}, {CO,Colorado}, {CT,Connecticut}, {DE,Delaware}, {FL,Florida}, {GA,Georgia}, {HI,Hawaii}, {ID,Idaho}, {IL,Illinois}, {IN,Indiana}, {IA,Iowa}, {KS,Kansas}, {KY,Kentucky}, {LA,Louisiana}, {ME,Maine}, {MD,Maryland}, {MA,Massachusetts}, {MI,Michigan}, {MN,Minnesota}, {MS,Mississippi}, {MO,Missouri}, {MT,Montana}, {NE,Nebraska}, {NV,Nevada}, {NH,New Hampshire}, {NJ,New Jersey}, {NM,New Mexico}, {NY,New York}, {NC,North Carolina}, {ND,North Dakota}, {OH,Ohio}, {OK,Oklahoma}, {OR,Oregon}, {PA,Pennsylvania}, {RI,Rhode Island}, {SC,South Carolina}, {SD,South Dakota}, {TN,Tennessee}, {TX,Texas}, {UT,Utah}, {VT,Vermont}, {VA,Virginia}, {WA,Washington}, {WV,West Virginia}, {WI,Wisconsin}, {WY,Wyoming}, {ACO,Atlantic Coast Offshore}, {FOAK,Federal Offshore Alaska}, {NGOM,Northern Gulf of Mexico}, {PCO,Pacific Coastal Offshore}] 2010-02-12 11:52:40,542 INFO KeyviewContextMonitor.contextInitialized: Loaded drop-down lists:com/key/portal/web/common/lists.properties 2010-02-12 11:52:40,937 DEBUG Servlet context attribute added: org.apache.struts.action.SERVLET_MAPPING=*.do 2010-02-12 11:52:40,937 DEBUG Servlet context attribute added: org.apache.struts.action.ACTION_SERVLET=org.apache.struts.action.ActionServlet@155d578 2010-02-12 11:52:41,939 DEBUG Servlet context attribute added: org.apache.struts.action.MODULE=org.apache.struts.config.impl.ModuleConfigImpl@e08e9d 2010-02-12 11:52:41,962 DEBUG Servlet context attribute added: org.apache.struts.action.FORM_BEANS=org.apache.struts.action.ActionFormBeans@b31c3c 2010-02-12 11:52:41,967 DEBUG Servlet context attribute added: org.apache.struts.action.FORWARDS=org.apache.struts.action.ActionForwards@102c646 2010-02-12 11:52:41,973 DEBUG Servlet context attribute added: org.apache.struts.action.MAPPINGS=org.apache.struts.action.ActionMappings@127276a 2010-02-12 11:52:41,974 DEBUG Servlet context attribute added: org.apache.struts.action.MESSAGE=org.apache.struts.util.PropertyMessageResources@18cae13 2010-02-12 11:52:41,984 DEBUG Servlet context attribute added: org.apache.struts.action.PLUG_INS=[Lorg.apache.struts.action.PlugIn;@f875ae 2010-02-12 11:52:46,816 INFO Sucessfully loaded application properties com/key/core/properties/application On my second environment, it didn't execute the last line. I start tomcat with the exact same command line !/bin/ksh export JAVA_HOME=/app/java export CATALINA_HOME=/app/tomcat export CATALINA_BASE=/app/keyview/appserver CATALINA_OPTS=" -Xms128m -Xmx800m -Dapplication.props=com/key/core/properties/application -Dlog4j.configuration=com/key/core/log/log4j.xml -Djava.awt.headless=true -Dlog4j.debug" export CATALINA_OPTS ${CATALINA_HOME}/bin/startup.sh I bolded the line that I think are in error. Thanks

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• Tykie

  - by Brian

  Here’s the obituary my mother wrote for Tykie, I still miss the little guy quite a bit. Anyone who’s interested in further information on hearing dogs should check out the IHDI website. I cannot begin to express how helpful a hearing dog can be for the hearing impaired. If you feel so inclined, please make a donation. In Memoriam, Tykie 1993-2010 The American Legion Post 401, South Wichita, KS, supported one of its members and commander by sponsoring a service dog for him. Unlike most service dogs this one was for the hearing impaired. Both Ocie and Betty Sims had hearing loss – Ocie more than Betty. The Post and Auxilliary had garage sales, auctions and other fund-raising endeavors to get donations for the dog. Betty made Teddy bears with growlers that were auctioned for donations to bring a hearing dog from International Hearing Dog, Henderson, Colorado. Tykie, a small wiry, salt and pepper terrier, arrived September 1, 1994 to begin his work that included attending Post 401 meetings and celebrations as well as raising more money to be donated to IHD to help others have hearing dogs. Tykie was a young dog less than a year old when he came to Wichita. He was always anxious to please and seldom barked, though he did put out a kind of cry when he was giving his urgent announcement that someone was at the door or the telephone was ringing. He also enjoyed chasing squirrels in the backyard garden that Ocie prized. In 1995, Betty almost died of a lung infection. Tykie was at the hospital with Ocie when he could visit. Several weeks after she was able to come home after a miraculous recovery, Tykie and Ocie went to a car show in downtown Wichita. Ocie’s retina tore loose in the only eye he could see out of and he almost blind was in great pain. How Ocie and Tykie got home is still a mystery, but the family legend goes that Tykie added seeing eye dog to his repertoire and helped drive him home. Health problems continued for Ocie and when he was placed in a nursing home, Tykie was moved to be Betty’s hearing dog. No problem for Tykie, he still saw his friends at the post and continued to help with visitors at the door. The night of May 3, 1999, Betty and Tykie were in the bedroom watching TV when Tykie began hitting her with both front paws as he would if something were urgent. She said later she thought he wanted to go out. As she and the dog walked down the hall towards the back of the house, Tykie hit her again with his front paws with such urgency that she fell into a small coat closet. That small 2-by-2 closet became their refuge as that very second the roof of her house went off as the f4 tornado raced through the city. Betty acquired one small wound on her hand from a piece of flying glass as she pulled Tykie into the closet with her. Tykie was a hero that day and a lot of days after. He kept Betty going as she rebuilt her home and after her husband died April 15, 2000. Tykie had to be cared for so she had to take him outside and bring him inside. He attended weddings of grandchildren and funerals of Post friends. When Betty died February 17, 2002 Tykie’s life changed again. IHD gave approval for his transfer and retirement to Betty and Ocie’s grandson, Brian Laird, who has a similar hearing loss to his grandfather. A few days after the funeral Tykie flew to his new home in Rutherford, NJ where he was able to take long walks for a couple of years before moving back to the Kansas City area. He was still full of adventure. He was written up in a book about service dogs and his story of the tornado and his picture appeared. He spent weekends at Brian’s mother’s farm to get muddy and be afraid of cats and chickens. He also took on an odyssey as he slipped from his fenced yard in Lenexa one day and walked more than seven miles in Overland Park traffic before being found by a good Samaritan who called IHD to find out where he belonged. Tykie was deaf for about the last two years of his long life and became blind as well, but he continued to strive to please. Tykie was 16 years and 4 months when he was cremated. His ashes were scattered on the graves of Betty and Ocie Sims at Greenwood Cemetery west of Wichita on the afternoon of March 21, 2010, with about a dozen family and Post 401 members. It is still the rule. Service dogs are the only dogs allowed inside the Post home. Submitted by Linda Laird, daughter of Betty and Ocie and mother of Brian Laird.

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• Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 1

  - by shiju

  In this post, I will demonstrate web application development using ASP. NET MVC 3, Razor and EF code First. This post will also cover Dependency Injection using Unity 2.0 and generic Repository and Unit of Work for EF Code First. The following frameworks will be used for this step by step tutorial. ASP.NET MVC 3 EF Code First CTP 5 Unity 2.0 Define Domain Model Let’s create domain model for our simple web application Category class public class Category {     public int CategoryId { get; set; }     [Required(ErrorMessage = "Name Required")]     [StringLength(25, ErrorMessage = "Must be less than 25 characters")]     public string Name { get; set;}     public string Description { get; set; }     public virtual ICollection<Expense> Expenses { get; set; } }   Expense class public class Expense {             public int ExpenseId { get; set; }            public string  Transaction { get; set; }     public DateTime Date { get; set; }     public double Amount { get; set; }     public int CategoryId { get; set; }     public virtual Category Category { get; set; } } We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First.    public class MyFinanceContext : DbContext {     public MyFinanceContext() : base("MyFinance") { }     public DbSet<Category> Categories { get; set; }     public DbSet<Expense> Expenses { get; set; }         }   The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’.  If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class     {         void Add(T entity);         void Delete(T entity);         T GetById(long Id);         IEnumerable<T> All();     }   RepositoryBasse – Generic Repository class public abstract class RepositoryBase<T> where T : class { private MyFinanceContext database; private readonly IDbSet<T> dbset; protected RepositoryBase(IDatabaseFactory databaseFactory) {     DatabaseFactory = databaseFactory;     dbset = Database.Set<T>(); }   protected IDatabaseFactory DatabaseFactory {     get; private set; }   protected MyFinanceContext Database {     get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) {     dbset.Add(entity);            }        public virtual void Delete(T entity) {     dbset.Remove(entity); }   public virtual T GetById(long id) {     return dbset.Find(id); }   public virtual IEnumerable<T> All() {     return dbset.ToList(); } }   DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory {     private MyFinanceContext database;     public MyFinanceContext Get()     {         return database ?? (database = new MyFinanceContext());     }     protected override void DisposeCore()     {         if (database != null)             database.Dispose();     } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work   public interface IUnitOfWork {     void Commit(); }   UniOfWork class public class UnitOfWork : IUnitOfWork {     private readonly IDatabaseFactory databaseFactory;     private MyFinanceContext dataContext;       public UnitOfWork(IDatabaseFactory databaseFactory)     {         this.databaseFactory = databaseFactory;     }       protected MyFinanceContext DataContext     {         get { return dataContext ?? (dataContext = databaseFactory.Get()); }     }       public void Commit()     {         DataContext.Commit();     } }   The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class.   Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>.   public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository     {     public CategoryRepository(IDatabaseFactory databaseFactory)         : base(databaseFactory)         {         }                } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext.   public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable {     public override object GetValue()     {         return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName];     }     public override void RemoveValue()     {         HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName);     }     public override void SetValue(object newValue)     {         HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue;     }     public void Dispose()     {         RemoveValue();     } }   Let’s create controller factory for Unity in the ASP.NET MVC 3 application. public class UnityControllerFactory : DefaultControllerFactory { IUnityContainer container; public UnityControllerFactory(IUnityContainer container) {     this.container = container; } protected override IController GetControllerInstance(RequestContext reqContext, Type controllerType) {     IController controller;     if (controllerType == null)         throw new HttpException(                 404, String.Format(                     "The controller for path '{0}' could not be found" +     "or it does not implement IController.",                 reqContext.HttpContext.Request.Path));       if (!typeof(IController).IsAssignableFrom(controllerType))         throw new ArgumentException(                 string.Format(                     "Type requested is not a controller: {0}",                     controllerType.Name),                     "controllerType");     try     {         controller= container.Resolve(controllerType) as IController;     }     catch (Exception ex)     {         throw new InvalidOperationException(String.Format(                                 "Error resolving controller {0}",                                 controllerType.Name), ex);     }     return controller; }   }   Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies.   private void ConfigureUnity() {     //Create UnityContainer               IUnityContainer container = new UnityContainer()                 .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>())     .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>())     .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>());                 //Set container for Controller Factory                ControllerBuilder.Current.SetControllerFactory(             new UnityControllerFactory(container)); }   In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity.   protected void Application_Start() {     AreaRegistration.RegisterAllAreas();     RegisterGlobalFilters(GlobalFilters.Filters);     RegisterRoutes(RouteTable.Routes);     ConfigureUnity(); }   Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller   public class CategoryController : Controller {     private readonly ICategoryRepository categoryRepository;     private readonly IUnitOfWork unitOfWork;           public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork)     {         this.categoryRepository = categoryRepository;         this.unitOfWork = unitOfWork;     }       public ActionResult Index()     {         var categories = categoryRepository.All();         return View(categories);     }     [HttpGet]     public ActionResult Edit(int id)     {         var category = categoryRepository.GetById(id);         return View(category);     }       [HttpPost]     public ActionResult Edit(int id, FormCollection collection)     {         var category = categoryRepository.GetById(id);         if (TryUpdateModel(category))         {             unitOfWork.Commit();             return RedirectToAction("Index");         }         else return View(category);                 }       [HttpGet]     public ActionResult Create()     {         var category = new Category();         return View(category);     }           [HttpPost]     public ActionResult Create(Category category)     {         if (!ModelState.IsValid)         {             return View("Create", category);         }                     categoryRepository.Add(category);         unitOfWork.Commit();         return RedirectToAction("Index");     }       [HttpPost]     public ActionResult Delete(int  id)     {         var category = categoryRepository.GetById(id);         categoryRepository.Delete(category);         unitOfWork.Commit();         var categories = categoryRepository.All();         return PartialView("CategoryList", categories);       }        }   Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application.  Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category>      <table>         <tr>         <th>Actions</th>         <th>Name</th>          <th>Description</th>         </tr>     @foreach (var item in Model) {             <tr>             <td>                 @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId })                 @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" })                           </td>             <td>                 @item.Name             </td>             <td>                 @item.Description             </td>         </tr>          }       </table>     <p>         @Html.ActionLink("Create New", "Create")     </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList  Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{     ViewBag.Title = "Index"; }    <h2>Category List</h2>    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>    <div id="divCategoryList">               @Html.Partial("CategoryList", Model) </div>   We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Let’s create view page for insert Category information   @model MyFinance.Domain.Category   @{     ViewBag.Title = "Save"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) {     @Html.ValidationSummary(true)     <fieldset>         <legend>Category</legend>                @Html.EditorFor(model => model)               <p>             <input type="submit" value="Create" />         </p>     </fieldset> }   <div>     @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory  and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder.      @{     Layout = "~/Views/Shared/_Layout.cshtml"; }   Source Code You can download the source code from http://efmvc.codeplex.com/ . The source will be refactored on over time.   Summary In this post, we have created a simple web application using ASP.NET MVC 3 and EF Code First. We have discussed on technologies and practices such as ASP.NET MVC 3, Razor, EF Code First, Unity 2, generic Repository and Unit of Work. In my later posts, I will modify the application and will be discussed on more things. Stay tuned to my blog  for more posts on step by step application building.

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• To 'seal' or to 'wrap': that is the question ...

  - by Simon Thorpe

  If you follow this blog you will already have a good idea of what Oracle Information Rights Management (IRM) does. By encrypting documents Oracle IRM secures and tracks all copies of those documents, everywhere they are shared, stored and used, inside and outside your firewall. Unlike earlier encryption products authorized end users can transparently use IRM-encrypted documents within standard desktop applications such as Microsoft Office, Adobe Reader, Internet Explorer, etc. without first having to manually decrypt the documents. Oracle refers to this encryption process as 'sealing', and it is thanks to the freely available Oracle IRM Desktop that end users can transparently open 'sealed' documents within desktop applications without needing to know they are encrypted and without being able to save them out in unencrypted form. So Oracle IRM provides an amazing, unprecedented capability to secure and track every copy of your most sensitive information - even enabling end user access to be revoked long after the documents have been copied to home computers or burnt to CD/DVDs. But what doesn't it do? The main limitation of Oracle IRM (and IRM products in general) is format and platform support. Oracle IRM supports by far the broadest range of desktop applications and the deepest range of application versions, compared to other IRM vendors. This is important because you don't want to exclude sensitive business processes from being 'sealed' just because either the file format is not supported or users cannot upgrade to the latest version of Microsoft Office or Adobe Reader. But even the Oracle IRM Desktop can only open 'sealed' documents on Windows and does not for example currently support CAD (although this is coming in a future release). IRM products from other vendors are much more restrictive. To address this limitation Oracle has just made available the Oracle IRM Wrapper all-format, any-platform encryption/decryption utility. It uses the same core Oracle IRM web services and classification-based rights model to manually encrypt and decrypt files of any format on any Java-capable operating system. The encryption envelope is the same, and it uses the same role- and classification-based rights as 'sealing', but before you can use 'wrapped' files you must manually decrypt them. Essentially it is old-school manual encryption/decryption using the modern classification-based rights model of Oracle IRM. So if you want to share sensitive CAD documents, ZIP archives, media files, etc. with a partner, and you already have Oracle IRM, it's time to get 'wrapping'! Please note that the Oracle IRM Wrapper is made available as a free sample application (with full source code) and is not formally supported by Oracle. However it is informally supported by its author, Martin Lambert, who also created the widely-used Oracle IRM Hot Folder automated sealing application.

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• Java Space on Parleys

  - by Yolande Poirier

  Now available! A great selection of JavaOne 2010 and JVM Language Summit 2010 sessions as well as Oracle Technology Network TechCasts on the new Java Space on Parleys website. Oracle partnered with Stephan Janssen, founder of Parleys to make this happen. Parleys website offers a user friendly experience to view online content. You can download some of the talks to your desktop or watch them on the go on mobile devices. The current selection is a well of expertise from top Java luminaries and Oracle experts. JavaOne 2010 sessions: ·        Best practices for signing code by Sean Mullan   ·        Building software using rich client platforms by Rickard Thulin ·        Developing beyond the component libraries by Ryan Cuprak ·        Java API for keyhole markup language by Florian Bachmann ·        Avoiding common user experience anti-patterns by Burk Hufnagel ·        Accelerating Java workloads via GPUs by Gary Frost JVM Languages Summit 2010 sessions: ·      Mixed language project compilation in Eclipse by Andy Clement  ·      Gathering the threads by John Rose  ·      LINQ: language features for concurrency by Neal Gafter  ·      Improvements in OpenJDK useful for JVM languages by Eric Caspole  ·      Symmetric Multilanguage - VM Architecture by Oleg Pliss  Special interviews with Oracle experts on product innovations: ·      Ludovic Champenois, Java EE architect on Glassfish 3.1 and Java EE. ·      John Jullion-Ceccarelli and Martin Ryzl on NetBeans IDE 6.9 You can chose to listen to a section of talks using the agenda view and search for related content while watching a presentation.  Enjoy the Java content and vote on it! 

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• Is your test method self-validating ?

  - by mehfuzh

  Writing state of art unit tests that can validate your every part of the framework is challenging and interesting at the same time, its like becoming a samurai. One of the key concept in this is to keep our test synced all the time as underlying code changes and thus breaking them to the furthest unit as possible.  This also means, we should avoid  multiple conditions embedded in a single test. Let’s consider the following example of transfer funds. [Fact] public void ShouldAssertTranserFunds() {     var currencyService = Mock.Create<ICurrencyService>();     //// current rate     Mock.Arrange(() => currencyService.GetConversionRate("AUS", "CAD")).Returns(0.88f);       Account to = new Account { Currency = "AUS", Balance = 120 };     Account from = new Account { Currency = "CAD" };       AccountService accService = new AccountService(currencyService);       Assert.Throws<InvalidOperationException>(() => accService.TranferFunds(to, from, 200f));       accService.TranferFunds(to, from, 100f);       Assert.Equal(from.Balance, 88);     Assert.Equal(20, to.Balance); } At first look,  it seems ok but as you look more closely , it is actually doing two tasks in one test. At line# 10 it is trying to validate the exception for invalid fund transfer and finally it is asserting if the currency conversion is successfully made. Here, the name of the test itself is pretty vague. The first rule for writing unit test should always reflect to inner working of the target code, where just by looking at their names it is self explanatory. Having a obscure name for a test method not only increase the chances of cluttering the test code, but it also gives the opportunity to add multiple paths into it and eventually makes things messy as possible. I would rater have two test methods that explicitly describes its intent and are more self-validating. ShouldThrowExceptionForInvalidTransferOperation ShouldAssertTransferForExpectedConversionRate Having, this type of breakdown also helps us pin-point reported bugs easily rather wasting any time on debugging for something more general and can minimize confusion among team members. Finally, we should always make our test F.I.R.S.T ( Fast.Independent.Repeatable.Self-validating.Timely) [ Bob martin – Clean Code]. Only this will be enough to ensure, our test is as simple and clean as possible.   Hope that helps

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• PeopleSoft HCM @ OHUG 11: Enter the Matrix

  - by Jay Zuckert

  The PeopleSoft HCM team is back from a very busy and exciting OHUG conference in Orlando. The packed, standing-room only PeopleSoft HCM Roadmap keynote was the highlight of the conference for many attendees and the reviews are in : PeopleSoft rocked the house ! Great demonstration of products in the keynote. Best keynote in a long time, and fun. Engaging and entertaining, great demonstration of capabilities. Message received loud and clear, PeopleSoft applications are here to stay.  PeopleSoft has a real vision moving forward. Real-time polls using mobile texting were cutting edge.                          Tracy Martin (as Trinity) and other members of the PeopleSoft HCM team presented a ‘must-see’ Matrix-themed session while dressed as movie characters. The keynote highlighted planned HCM capabilities for Matrix administration and future organization visualization enhancements. The team also previewed the planned Manager Dashboard and Talent Summary.                           Following the keynote, some of the cast posed for photo opportunities at the OHUG booth in the exhibition hall. As you can imagine, they received some interesting looks walking by the other vendor booths. The PeopleSoft HCM team also presented numerous other OHUG sessions covering PeopleSoft Talent Management, Compensation, HR HelpDesk, Payroll, Global HCM Practices, Time & Labor, Absence Management, and Benefits. All of those presentations are available from the OHUG site at www.ohug.org. When not in one of the well-attended PeopleSoft HCM sessions, conference attendees filled the Oracle booth in the exhibition hall to see live product demonstrations. True to their PeopleSoft roots, some of the PeopleSoft HCM team played as hard as they worked in Orlando and enjoyed the OHUG Appreciation event along with customers at the Hard Rock. We are already busy planning for Oracle OpenWorld 2011 and prepping sessions our PeopleSoft HCM customers are sure to like. We hope to see you there in San Francisco from Oct. 2-6. To learn more about OpenWorld or to register, click here.

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• Performance problems loading XML with SSIS, an alternative way!

  - by AtulThakor

  I recently needed to load several thousand XML files into a SQL database, I created an SSIS package which was created as followed: Using a foreach container to loop through a directory and load each file path into a variable, the “Import XML” dataflow would then load each XML file into a SQL table.       Running this, it took approximately 1 second to load each file which seemed a massive amount of time to parse the XML and load the data, speaking to my colleague Martin Croft, he suggested the use of T-SQL Bulk Insert and OpenRowset, so we adjusted the package as followed:     The same foreach container was used but instead the following SQL command was executed (this is an expression):     "INSERT INTO MyTable(FileDate) SELECT   CAST(bulkcolumn AS XML)     FROM OPENROWSET(         BULK         '" + @[User::CurrentFile]  + "',         SINGLE_BLOB ) AS x"     Using this method we managed to load approximately 20 records per second, much faster…for data loading! For what we wanted to achieve this was perfect but I’ll leave you with the following points when making your own decision on which solution you decide to choose!      Openrowset Method Much faster to get the data into SQL You’ll need to parse or create a view over the XML data to allow the data to be more usable(another post on this!) Not able to apply validation/transformation against the data when loading it The SQL Server service account will need permission to the file No schema validation when loading files SSIS Slower (in our case) Schema validation Allows you to apply transformations/joins to the data Permissions should be less of a problem Data can be loaded into the final form through the package When using a schema validation errors can fail the package (I’ll do another post on this)

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• Java Spotlight Episode 78: Jasper Potts on the JavaFX Scene Builder

  - by Roger Brinkley

  Tweet An interview with Jasper Potts about the new JavaFX Scene Builder. Joining us this week on the Java All Star Developer Panel are Dalibor Topic, Java Free and Open Source Software Ambassador and Arun Gupta, Java EE Guy. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News JavaFX Scene Builder Developer Preview available for testing. Java EE Unlock the Java EE 6 Platform using NetBeans 7.1 Tuning GlassFish for Production JSF 2.2 Update from Ed Burns John Rose at Microsoft's Lang.NEXT summit Recording of John's Java 8 presentation Jeroen Frijters' presentation on IKVM.NET Martin Odersky's keynote JVM Language Summit 2012 July 30 – August 1; Oracle Santa Clara (same as last year) CFP coming in a few days JVM Language Summit 2011 Presentations & Recordings Proposed development schedule for JDK 8 Say hello to Mathias Axelsson Events April 11, Cleveland JUG, Cleveland, OH April 12, GreenJUG, Greenville, SC April 17-18, JavaOne Russia, Moscow Russia April 18–20, Devoxx France, Paris, France April 17-20, GIDS, Bangalore April 21, Java Summit, Chennai April 26, Mix-IT, Lyon, France, May 3-4, JavaOne India, Hyderabad, India May 5, Bangalore, Pune, ?? - JUG outreach May 7, OTN Developer Day, Mumbai May 8, OTN Developer Day, Delhi Feature InterviewJasper Potts is the Developer Experience Architect for the Java Client Group at Oracle. Responsible for technical design for everything thats sis on the core platform including Controls, Tools, Samples and Blueprints. Formally a lead engineer on the JavaFX & Swing teams working on the new JavaFX UI Controls and Graphics frameworks. Also responsible for designing, developing and presenting demos during the keynotes at JavaOne and Devoxx. A JavaOne Rockstar presenter having presented many sessions on JavaFX and Swing at many conferences. Prior to Sun he founded Xerto a desktop applications company developing Imagery a Java professional photo management application. In this interview Jasper talks about the recently release JavaFX Scene Builder. Mail Bag What’s Cool Contribute to GlassFish in Five Different Ways Stephen Chin and James Weaver join Oracle Adam Bien - Building Java FX 2 Libraries From Source With Maven 3 Paul Sandoz - Java Boomerang Building Jigsaw on Mac OS X using VirtualBox Mandy Chung: Jigsaw for Mac OS X

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• SQL Saturday #162 Cambridge

  - by Most Valuable Yak (Rob Volk)

  Despite the efforts of American Airlines, this past weekend I attended the first SQL Saturday in the UK!  Hosted by the SQLCambs Chapter of PASS and organized by Mark (b|t) & Lorraine Broadbent, ably assisted by John Martin (b|t), Mark Pryce-Maher (b|t) and other folks whose names I've unfortunately forgotten, it was held at the Crowne Plaza Hotel, which is completely surrounded by Cambridge University. On Friday, they presented 3 pre-conference sessions given by the brilliant American Cloud & DBA Guru, Buck Woody (b|t), the brilliant Danish SQL Server Internals Guru, Mark Rasmussen (b|t), and the brilliant Scottish Business Intelligence Guru and recent Outstanding Pass Volunteer, Jen Stirrup (b|t).  While I would have loved to attend any of their pre-cons (having seen them present several times already), finances and American Airlines ultimately made that impossible.  But not to worry, I caught up with them during the regular sessions and at the speaker dinner.  And I got back the money they all owed me.  (Actually I owed Mark some money) The schedule was jam-packed even with only 4 tracks, there were 8 regular slots, a lunch session for sponsor presentations, and a 15 minute keynote given by Buck Woody, who besides giving an excellent history of SQL Server at Microsoft (and before), also explained the source of the "unknown contact" image that appears in Outlook.  Hint: it's not Buck himself. Amazingly, and against all better judgment, I even got to present at SQL Saturday 162!  I did a 5 minute Lightning Talk on Regular Expressions in SSMS.  I then did a regular 50 minute session on Constraints.  You can download the content for the regular session at that link, and for the regular expression presentation here. I had a great time and had a great audience for both of my sessions.  You would never have guessed this was the first event for the organizers, everything went very smoothly, especially for the number of attendees and the relative smallness of the space.  The event sponsors also deserve a lot of credit for making themselves fit in a small area and for staying through the entire event until the giveaways at the very end. Overall this was one of the best SQL Saturdays I've ever attended and I have to congratulate Mark B, Lorraine, John, Mark P-M, and all the volunteers and speakers for making this an astoundingly hard act to follow!  Well done!

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• Oracle Developer Day, Poland, 2012

  - by Geertjan

  Oracle Developer Day took place in Poland today. Oracle's Gregor Rayman did the keynote, where NetBeans was positioned, yet again, as Oracle's IDE for the Java Platform, via the JavaFX Roadmap: Well, it's not so clear from my pic above, but NetBeans is closely tied to the JavaFX Roadmap, as well as the JDK Roadmap too. Then the tracks started, one of which was the Java Track (the other two tracks were on ADF/WebLogic and SOA/BPM/BAM), where among other things I demonstrated the Java EE 6 Platform via tools in NetBeans IDE at some length. The room could hardly have been fuller, chairs had to be brought in and people were standing along the walls. The above pic shows the session being set up, with the room full of developers ready to hear about Java EE 6. I also did a session on pluggable Java desktop development (i.e., NetBeans Platform) and on "What's New in NetBeans IDE 7.1?", while Martin Grebac had a session on Java EE Web Services. Some of the many questions asked during the day that I thought were interesting: Is there localization support for the @Pattern annotation? I.e., what if I want to display the error message in Polish, what do I do? Is there filtering/sorting support for the DataTable component in JSF? Why is there no visual editor for ejb-jar.xml, in the same way that there is for web.xml? "Would be handy if there were to be a JSR for IDE Keyboard Shortcuts." (Two different people asked this question, separately, without knowing about each other. The second didn't know about the Eclipse and IntelliJ keyboard shortcut support in NetBeans IDE and was happy when I told them about it.) Wouldn't it be cool if, on start up, or during installation, there'd be a question: "Are you migrating from Eclipse/IntelliJ?" Then, if "yes", reset the keyboard shortcuts to match the IDE they're coming from.Is there a way in NetBeans to find subclasses of a class? "Would be cool if HTML or JSF files could be visualized in the same way as JavaFX and Swing classes." I.e., Visual Debugger for web developers. I had a great day and am looking at the Oracle Developer Day that will be held in Cluj, Romania, on Friday.

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• A Bad Day at Work

  - by TehGrumpyCoder

  There's lots of ways of having a bad day at work... I suppose for many people, just being *at* work makes it a bad day, but I happen to be one of those people that found a way to do something I like for a living. I've always said "if you're not having fun, what's the point?" ... on the latest Zune podcast, they were interviewing someone from the WP7 team and he said they're mantra is "It's not done until it's fun" ... I like that too. But, even when you're doing what you like for a living, it can get tedious. There were times that I didn't look forward to going out and playing guitar on a Friday or Saturday night, and some nights I was looking at my watch just waiting for it to be over. Well, that was today... like Steve Martin in "The Jerk" ... the first hour was like a regular hour, but then the rest of the morning was like a day, and the afternoon has been like a week. I've got a list of stuff I need to get into my head, and it's tough when the highest technology you have during 9 hours of your day is .NET 2.0 and you can only run what IT installed. I get wrapped around the power take-off reading something and dearly want to write some code to try, but with the state of technology here, it's like trying to teach jazz chords to someone that showed up for their lesson with that stupid plastic guitar from Guitar Hero. I tried to watch a training video... downloaded it zipped so maybe it wouldn't be noticed like it might if I streamed it. Then nothing on this machine would play the video... dang! Well, if someone doesn't take me out on the drive tonight or back in tomorrow, maybe it'll be a better day... or maybe I'll d/l a bunch of training videos in a different format, or bring in a decent viewer, or download them to my Zune maybe... that would work. I suppose at age 61 there are worse things than feeling stifled... for instance, so far I've lived 2 years longer than my father... but at the same time, he's the one that pointed out that in my first letter home from Boot Camp "He's complaining, he's fine"... guess he had my number :) I think he'd appreciate "Teh Grumpy Coder"

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• Code review recommendations and Code Smells

  - by Michael Freidgeim

  Some time ago Twitter told that I am similar to Boris Lipschitz . Indeed he is also .Net programmer from Russia living in Australia. I‘ve read his list of Code Review points and found them quite comprehensive. A few points  were not clear for me, and it forced me for a further reading.In particular the statement “Exception should not be used to return a status or an error code.” wasn’t fully clear for me, because sometimes we store an exception as an object with all error details and I believe it’s a valid approach. However I agree that throwing exceptions should be avoided, if you expect to return error as a part of a normal flow. Related link: http://codeutopia.net/blog/2010/03/11/should-a-failed-function-return-a-value-or-throw-an-exception/ Another point slightly puzzled me“If Thread.Sleep() is used, can it be replaced with something else, ei Timer, AutoResetEvent, etc” . I believe, that there are very rare cases, when anyone using Thread.Sleep in any production code. Usually it is used in mocks and prototypes.I had to look further to clarify “Dependency injection is used instead of Service Location pattern”.Even most of articles has some preferences to Dependency injection, there are also advantages to use Service Location. E.g see http://geekswithblogs.net/KyleBurns/archive/2012/04/27/dependency-injection-vs.-service-locator.aspx. http://www.cookcomputing.com/blog/archives/000587.html  refers to Concluding Thoughts of Martin Fowler The choice between Service Locator and Dependency Injection is less important than the principle of separating service configuration from the use of services within an applicationThe post had a link to excellent article Code Smells of Jeff Atwood, but the statement, that “code should not pass a review if it violates any of the  code smells” sound too strict for my environment. In particular, I disagree with “Dead Code” recommendation “Ruthlessly delete code that isn't being used. That's why we have source control systems!”. If there is a chance that not used code will be required in a future, it is convenient to keep it as commented or #if/#endif blocks with appropriate explanation, why it could be required in the future. TFS is a good source control system, but context search in source code of current solution is much easier than finding something in the previous versions of the code.I also found a link to a good book “Clean Code.A.Handbook.of.Agile.Software”

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• Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

  - by Motti Strom

  Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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• Diving into Scala with Cay Horstmann

  - by Janice J. Heiss

  A new interview with Java Champion Cay Horstmann, now up on otn/java, titled  "Diving into Scala: A Conversation with Java Champion Cay Horstmann," explores Horstmann's ideas about Scala as reflected in his much lauded new book,  Scala for the Impatient.  None other than Martin Odersky, the inventor of Scala, called it "a joy to read" and the "best introduction to Scala". Odersky was so enthused by the book that he asked Horstmann if the first section could be made available as a free download on the Typesafe Website, something Horstmann graciously assented to. Horstmann acknowledges that some aspects of Scala are very complex, but he encourages developers to simply stay away from those parts of the language. He points to several ways Java developers can benefit from Scala: "For example," he says, " you can write classes with less boilerplate, file and XML handling is more concise, and you can replace tedious loops over collections with more elegant constructs. Typically, programmers at this level report that they write about half the number of lines of code in Scala that they would in Java, and that's nothing to sneeze at. Another entry point can be if you want to use a Scala-based framework such as Akka or Play; you can use these with Java, but the Scala API is more enjoyable. " Horstmann observes that developers can do fine with Scala without grasping the theory behind it. He argues that most of us learn best through examples and not through trying to comprehend abstract theories. He also believes that Scala is the most attractive choice for developers who want to move beyond Java and C++.  When asked about other choices, he comments: "Clojure is pretty nice, but I found its Lisp syntax a bit off-putting, and it seems very focused on software transactional memory, which isn't all that useful to me. And it's not statically typed. I wanted to like Groovy, but it really bothers me that the semantics seems under-defined and in flux. And it's not statically typed. Yes, there is Groovy++, but that's in even sketchier shape. There are a couple of contenders such as Kotlin and Ceylon, but so far they aren't real. So, if you want to do work with a statically typed language on the JVM that exists today, Scala is simply the pragmatic choice. It's a good thing that it's such a nice choice." Learn more about Scala by going to the interview here.

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• ArchBeat Link-o-Rama for July 2, 2013

  - by Bob Rhubart

  One Week To Go: OTN Architect Day: Cloud Computing - July 9, 2013, Redwood Shores, CA. The first OTN Architect Day event of 2013 happens in just one week, on Tuesday July 9 at the Oracle Conference Center in Redwood Shores, CA. Registration is free and you get three sessions by three experts on cloud computing in the real world — plus a panel Q&A for answers to all of your questions. Register now! Oracle Database 12c: Flashback Moving Forward | Lucas Jellema Oracle ACE Director Lucas Jellema's latest of several recent blog posts dealing with various aspects of the recently released Oracle Database 12c. Detroit, Embracing New Auto Technologies, Seeks App Builders This story from the New York Times paints a rosy picture indeed for app developers as the internet of things continues to evolve. Advanced View Criteria Implementation in ADF BC | Andrejus Baranovskis Oracle ACE Director Andrejus Baranovskis' post focuses on advanced declarative View Criteria features. JDeveloper: Showing a Popup when Selecting an af:selectOneRadio | Timo Hahn Oracle ACE Timo Hahn illustrates a use case in which a popup is displayed each time the user clicks on one of the radio buttons of a button group. Can Technology Innovation Save The New York Times? One of the standout keynotes from the recent QCon New York event, this presentation by New York Times Sr. VP/CIO Marc Frons and CTO/VP Rajiv Pant paints a detailed portrait of the complete transformation of an organization -- not just the IT. Enterprise architects will find this particularly interesting. Video: Meet Growing IT Demand for Databases with Private DBaaS Do you understand the difference between traditional database deployment and database as a service? If not, you'll want to check out this video, which includes an overview of Oracle Enterprise Manager's capabilities for rapid deployment of DBaaS. S Webcast: Zero-Downtime Migration to Oracle Exadata Using Oracle GoldenGate: A Customer Case Study Presenters Alok Pareek (VP, Product Management/Development, Oracle Data Integration) and John F. Martin (CEO of Emerging Markets and CTO IQNavigator) discuss how IQNavigator is using Oracle GoldenGate with Oracle Exadata. Free eBook: Building a Database Cloud for Dummies This free quick-reference guide, organized into six short chapters and supplemented with helpful illustrations, provides a clear overview of the cloud and step-by-step instructions on deploying database as a service. (Registration required.) Thought for the Day "My motto is: Live every day to the fullest – in moderation." — Lindsay Lohan (Born July 2, 1986) Source: brainyquote.com

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