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• Is this a ridiculous way to structure a DB schema, or am I completely missing something?

  - by Jim

  I have done a fair bit of work with relational databases, and think I understand the basic concepts of good schema design pretty well. I recently was tasked with taking over a project where the DB was designed by a highly-paid consultant. Please let me know if my gut intinct - "WTF??!?" - is warranted, or is this guy such a genius that he's operating out of my realm? DB in question is an in-house app used to enter requests from employees. Just looking at a small section of it, you have information on the users, and information on the request being made. I would design this like so: User table: UserID (primary Key, indexed, no dupes) FirstName LastName Department Request table RequestID (primary Key, indexed, no dupes) <...> various data fields containing request details UserID -- foreign key associated with User table Simple, right? Consultant designed it like this (with sample data): UsersTable UserID FirstName LastName 234 John Doe 516 Jane Doe 123 Foo Bar DepartmentsTable DepartmentID Name 1 Sales 2 HR 3 IT UserDepartmentTable UserDepartmentID UserID Department 1 234 2 2 516 2 3 123 1 RequestTable RequestID UserID <...> 1 516 blah 2 516 blah 3 234 blah The entire database is constructed like this, with every piece of data encapsulated in its own table, with numeric IDs linking everything together. Apparently the consultant had read about OLAP and wanted the 'speed of integer lookups' He also has a large number of stored procedures to cross reference all of these tables. Is this valid design for a small to mid-sized SQL DB? Thanks for comments/answers...

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• Example: Cross Cutting Concerns of an Application

  A little while ago I was given an opportunity to design and implement a new system that sent data via an HTTP Post method and then processed the results that were returned so that they could be inserted in to a database. My system had eight core concerns that it needed to fulfill. Eight Core Concerns Database Access Data Entities Worker Result Processing Process Flow Manager Email/Notification Error Handling Logging Of these eight, five were actually cross cutting concerns. 5 Cross Cutting Concerns Database Access Data Entities Email/Notification Error Handling Logging These five cross cutting concerns were determined after I created an aspect oriented model to help identity the system components that could be factored out into separate components.  These separated components would then be included in the system so that they could be used by various other components.  These five components allow all of the other components to access the database, store data, send notifications, handle errors, and log all system events.  Thus, these components are used to share unique aspects to the system via their implementation. The use of Aspect oriented architecture greatly helped me define what components I needed to create and what each of those components could do.  It also showed how all of the other aspects depended on each other so that each component did not have to re-implement code that was already created in the existing system.

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• functional requirements - use wording based on verbs?

  - by yas

  Question: Should the functional requirements in a requirements doc use wording based on verbs? Context: School assignment, working in a team, working through the SDLC. The requirements doc has been done and we are now into design. Problem: The requirements doc has an enumerated list of what I'd call features of the app - the functional requirements. In that list are things that I'd think of as "how's" rather than "what's" and now, trying to work on design, I feel like a part of design has been prematurely dictated. I've not done this before! To me, I should be dealing strictly with things that describe "what." Example of current: Pretend that the job is to make an omelet. Listing: crack the egg, break into bowl, scramble, etc.; crosses over the line into the territory of how. Along that track, so does wording like: create, generate, list, calculate, determine, validate, etc. - verbs, basically. Right now, I have a list of requirements that are partially rooted in verbs. My idea of a requirements doc for an omelet would be more like: has two eggs, x ounces of ham, x ounces of bacon, x ounces of montery-jack cheese, x ounces of cilantro, etc. - nothing but what (nouns). I might have, and could have, spoken up before finalizing the requirements doc if I'd had any experience.

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• Do you write unit tests for all the time in TDD?

  - by mcaaltuntas

  I have been designing and developing code with TDD style for a long time. What disturbs me about TDD is writing tests for code that does not contain any business logic or interesting behaviour. I know TDD is a design activity more than testing but sometimes I feel it's useless to write tests in these scenarios. For example I have a simple scenario like "When user clicks check button, it should check file's validity". For this scenario I usually start writing tests for presenter/controller class like the one below. @Test public void when_user_clicks_check_it_should_check_selected_file_validity(){ MediaService service =mock(MediaService); View view =mock(View); when(view.getSelectedFile).thenReturns("c:\\Dir\\file.avi"); MediaController controller =new MediaController(service,view); controller.check(); verify(service).check("c:\\Dir\\file.avi"); } As you can see there is no design decision or interesting code to verify behaviour. I am testing values from view passed to MediaService. I usually write but don't like these kind of tests. What do yo do about these situations ? Do you write tests for all the time ? UPDATE : I have changed the test name and code after complaints. Some users said that you should write tests for the trivial cases like this so in the future someone might add interesting behaviour. But what about “Code for today, design for tomorrow.” ? If someone, including myself, adds more interesting code in the future the test can be created for it then. Why should I do it now for the trivial cases ?

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• SOA: Simplifying Cloud, Mobile, and On-premise Integration–Webcast October 24th 2013

  - by JuergenKress

  Proliferation of mobile devices, data explosion, and cloud enablement has caused a dramatic shift in IT. Organizations need to rethink their application infrastructures to accommodate increased processing speeds, heightened security and availability concerns for their applications, all while meeting lowered total cost of ownership. Traditional infrastructures may not be sufficient to accommodate the diversity and complexity of integrations in this new era. Many of today’s IT organizations rely on a Service Oriented Architecture (SOA) backbone to keep their businesses running. SOA adoption and acceptance across industries have led to platform maturity at the application layer level. However, we are at the start of an era where there is a new modus operandi for organizations to thrive and deliver continuously on competitive differentiation. This change is a result of market globalization, explosion in the number of mobile devices, unparalleled growth in voluminous data and innovation that crosses organizational boundaries. Social, mobile, cloud are terms that are revolutionizing the way organizations operate. Oracle SOA Suite is a hot-pluggable software suite to build, deploy and manage Service-Oriented Architectures (SOA).Oracle SOA transforms complex application integration into agile and reusable service-based connectivity by mediating, routing, and managing interactions between services and applications in the enterprise and in the cloud. Oracle SOA Suite's hot-pluggable architecture helps businesses lower upfront costs by allowing maximum re-use of existing IT investments and assets. Join us on this webcast to find out how you can optimize the use of Oracle SOA Suite, simplifying integration, and what does the next generation of SOA has to offer to you. Agenda: What's new in Oracle SOA Simplifying integration Application Integration and SOA Cloud integration with SOA Mobile Integration leveraging Oracle SOA Suite Oracle Delivers on Next Generation SOA Customer Examples Summary and Q&A Webcast Thursday October 24th, 2013 10am CET (8am UTC / 11am EEST)Details at the Registration Page SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: cloud integration,mobile integration,training,webcast middeware,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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• A Better Way to Plan, Execute and Manage Enterprise Architecture

  - by JuergenKress

  IT Strategies from Oracle is an authorized library of guidelines and reference architectures that will help you better plan, execute, and manage your enterprise architecture and IT initiatives. The IT Strategies from Oracle library offers two types of best practice documents: practitioner guides containing pragmatic advice and approaches, and reference architectures containing the proven technology patterns to jumpstart your initiative. The IT Strategies from Oracle library can help you establish a reliable set of principles and standards to guide your use of Oracle technology. We will expand this library over time across all of Oracle's technologies. Today, you can access: Overview documents providing an introduction to all the resources available in the library and best practices maturity models Oracle Reference Architectures covering the application infrastructure foundation, management and monitoring, security, software engineering, service-oriented integration, service orientation, user interaction, engineered systems, and a master glossary. Enterprise Technology Strategies for Service-Oriented Architecture offering practitioner guides on creating a SOA roadmap, frameworks for governance, determining ROI, identifying services, software engineering, and white papers. Enterprise Technology Strategies for Event-Driven Architecture offering practitioner guides on creating an EDA roadmap and reference architectures on an EDA foundation and EDA infrastructure. Enterprise Technology Strategies for Business Process Management including practitioner guides on creating a BPM roadmap, business process engineering, governance, and reference architectures on a BPM foundation and BPM infrastructure. Enterprise Technology Strategies for Cloud Computing including reference architectures on a Cloud foundation and Cloud infrastructure. Enterprise Technology Strategies for Business Analytics includes a practitioner guide for creating a BA roadmap, and reference architectures for a BA foundation and BA infrastructure. Get the Oracle Enterprise Architecture content here. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: Architecture,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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• Feedback on meeting of the MSCC - 20.07.2013

  Impression of our meetup on 20.07.2013 Low quantity but high quality! Meetup summary: Quick introduction to ?MSCC? and interesting topics in general, especially for freshman from/at university. It also seems that the open concept of OUYA (Android-based gaming console) got some attention and hopefully new fans. More info is available online: http://www.ouya.tv/ Design contest The design contest is still going on... There's currently only one submission. Come on, you web & graphic designers in Mauritius - SHOW YOUR WORKAny draft will be published over here: MSCC Design Contest - https://www.facebook.com/media/set/?set=a.200036533488751.1073741829.181737551985316&type=3 Goodies give-away And the first 2 one-month subscriptions for Pluralsight have been well received by attendees, too. Unfortunately, we didn't have any free WiFi at Talking Drums - so, we might have to consider another location for the next meetup. Change of schedule As we spoke about the advantages of gathering during the weekend, we worked out a schedule that could be applied to future meetups of the MSCC. I'm going to address this tomorrow during our regular meetings on Wednesday to see about the response of other members, too.

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• GlassFish T-shirt at JavaOne 2012

  - by arungupta

  There were 12 entries to the GlassFish T-shirt design contest. Each design was unique and very well thought out. But only one had to be picked and here is the winner! Many thanks to all the participants! A t-shirt will be reserved for each one of you whenever we meet :-) T-shirt designed by the community, for the community, and will be given to the community. Want to know more details about the design and concept ? Hear from the winner - Markus Eisele in his blog GlassFish City Revisited. So where do you get this t-shirt ? These t-shirts will be handed to the community members attending GlassFish Community Event (9/30, 11am - 1pm) and BoF (10/2, 6:30 pm). Other than the t-shirts, here are nine reasons to attend the community event. You need a JavaOne pass to attend this event so make sure to register for the conference. You don't necessarily need a full conference pass as any of the available options will do. Learn more about Java EE and GlassFish's presence at JavaOne 2012 at glassfish.org/javaone2012. Looking forward to see you at JavaOne!

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• Loading any MVC page fails with the error "An item with the same key has already been added."

  - by MajorRefactoring

  I am having an intermittent issue that is appearing on one server only, and is causing all MVC pages to fail to load with the error "An item with the same key has already been added." Restarting the application pool fixes the issue, but until then, loading any mvc page throws the following exception: Event code: 3005 Event message: An unhandled exception has occurred. Event time: 10/11/2012 08:09:24 Event time (UTC): 10/11/2012 08:09:24 Event ID: d76264aedc4241d4bce9247692510466 Event sequence: 6407 Event occurrence: 30 Event detail code: 0 Application information: Application domain: /LM/W3SVC/21/ROOT-2-129969647741292058 Trust level: Full Application Virtual Path: / Application Path: d:\websites\SiteAndAppPoolName\ Machine name: UKSERVER Process information: Process ID: 6156 Process name: w3wp.exe Account name: IIS APPPOOL\SiteAndAppPoolName Exception information: Exception type: ArgumentException Exception message: An item with the same key has already been added. Server stack trace: at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) at System.Web.WebPages.Scope.WebConfigScopeDictionary.<>c__DisplayClass4.<.ctor>b__0() at System.Lazy`1.CreateValue() Exception rethrown at [0]: at System.Lazy`1.get_Value() at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue) at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes) at System.Web.Mvc.Html.FormExtensions.BeginForm(HtmlHelper htmlHelper, String actionName, String controllerName) at ASP._Page_Views_Dashboard_Functions_BookingQuickLookup_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions\BookingQuickLookup.cshtml:line 3 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) at ASP._Page_Views_Dashboard_Functions_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions.cshtml:line 5 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName, Object model) at ASP._Page_Views_Dashboard_Index_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Index.cshtml:line 9 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d() at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Request information: Request URL: http://SiteAndAppPoolName.spawtz.com/Dashboard Request path: /Dashboard User host address: 86.164.135.41 User: Is authenticated: False Authentication Type: Thread account name: IIS APPPOOL\SiteAndAppPoolName Thread information: Thread ID: 17 Thread account name: IIS APPPOOL\SiteAndAppPoolName Is impersonating: False Stack trace: at System.Lazy`1.get_Value() at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue) at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes) at System.Web.Mvc.Html.FormExtensions.BeginForm(HtmlHelper htmlHelper, String actionName, String controllerName) at ASP._Page_Views_Dashboard_Functions_BookingQuickLookup_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions\BookingQuickLookup.cshtml:line 3 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) at ASP._Page_Views_Dashboard_Functions_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Functions.cshtml:line 5 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName, Object model) at ASP._Page_Views_Dashboard_Index_cshtml.Execute() in d:\Websites\SiteAndAppPoolName\Views\Dashboard\Index.cshtml:line 9 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d() at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Custom event details: As mentioned, it's every MVC action that throws this error until the app pool is restarted, and the error seems to be occurring in System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) Has anyone seen this issue before? It's only happening on this server, on any of the app pools on the server (not confined to this one) and an app pool restart sorts it. Any help much appreciated. Cheers, Matthew

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• xsd validation againts xsd generated class level validation

  - by Miral

  In my project I have very big XSD file which i use to validate some XML request and response to a 3rd party. For the above scenario I can have 2 approaches 1) Create XML and then validate against give XSD 2) Create classes from XSD with the help of XSD gen tool, add xtra bit of attirbutes and use them for validation. Validation in the second way will work somewhat in this manner, a) convert xml request/response into object with XML Serialization b) validate the object with custom attributes set on each property, i.e. Pass the object to a method which will validate the object by iterating through properties and its custom attributes set on the each property, and this will return a boolean value if the object validates and that determines whether the xml request is valid or not? Now the concern which approach is good in terms of performance and anything else???

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• SelectionChanged event binding in Silverlight+MVVM-Light

  - by Budda

  The handler of the "SelectionChanged" event of the ComboBox control has the following signature: void SelectionChangedMethod(object sender, SelectionChangedEventArgs e) How to bind to that property under Silverlight 4 and MVVM-Light to the corresponding method of the ViewModel object? As far as I know, I need to do something like this: public void Changed(Object obj, SelectionChangedEventArgs e) { // .... implement logic here } RelayCommand<Object, SelectionChangedEventArgs> _command; public ICommand ObjectSelectionChanged { get { if (_command == null) { _command = new RelayCommand<Object, SelectionChangedEventArgs>(Changed); } return _command; } } The problem is that RelayCommand class in the MVVM-Light framework doesn't support 2 generic parameters... Is there any solution or workaround for this case? How bind control event to the method with 2 parameters?

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• Usabe of Python 3 super()

  - by deamon

  I wonder when to use what flavour of Python 3 super(). Help on class super in module builtins: class super(object) | super() -> same as super(__class__, <first argument>) | super(type) -> unbound super object | super(type, obj) -> bound super object; requires isinstance(obj, type) | super(type, type2) -> bound super object; requires issubclass(type2, type) Until now I've used super() only without arguments and it worked as expected (by a Java developer). Questions: What does "bound" mean in this context? What is the difference between bound and unbound super object? When to use super(type, obj) and when super(type, type2)? Would it be better to name the super class like in Mother.__init__(...)?

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• Linq to SQL, Repository, IList and Persist All

  - by Dr. Zim

  This discusses a repository which returns IList that also uses Linq to SQL as a DAL. Once you do a .ToList(), IQueryable object is gone once you exit the Repository. This means that I need to send the objects back in to the Repo methods .Create(Model model), .Update(Model model), and .Delete(int ID). Assuming that is correct, how do you do the PersistAll()? For example, if you did the following, how would you code that in the repository? Changed a single string property in the object Called .Update(object); Changed a different string property in the object Called .Update(object); Called .PersistAll(), which would update the database with both changed strings. How would you associate the objects in the Repository parameters with the objects in the Linq to Sql data context, especially over multiple calls? I am sure this is a standard thing. Links to examples on the web would be great!

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• Usage of Python 3 super()

  - by deamon

  I wonder when to use what flavour of Python 3 super(). Help on class super in module builtins: class super(object) | super() -> same as super(__class__, <first argument>) | super(type) -> unbound super object | super(type, obj) -> bound super object; requires isinstance(obj, type) | super(type, type2) -> bound super object; requires issubclass(type2, type) Until now I've used super() only without arguments and it worked as expected (by a Java developer). Questions: What does "bound" mean in this context? What is the difference between bound and unbound super object? When to use super(type, obj) and when super(type, type2)? Would it be better to name the super class like in Mother.__init__(...)?

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• Java File URI error ?

  - by Frank

  I need to get a file object online, and I know the file is located at : http://nmjava.com/Dir_App_IDs/Dir_GlassPaneDemo/GlassPaneDemo_2010_04_06_15_00_SNGRGLJAMX If I paste it into my browser's url, I'll be able to download this file, now I'm trying to get it with Java, my code looks like this : String File_Url="http://nmjava.com/Dir_App_IDs/Dir_GlassPaneDemo/GlassPaneDemo_2010_04_06_15_00_SNGRGLJAMX"; Object myObject=Get_Online_File(new URI(File_Url)); Object Get_Online_File(URI File_Uri) throws IOException { return readObject(new ObjectInputStream(new FileInputStream(new File(File_Uri)))); } public static synchronized Object readObject(ObjectInput in) throws IOException { Object o; ...... return o; } But I got the following error message : java.lang.IllegalArgumentException: URI scheme is not "file" at java.io.File.<init>(File.java:366) Why ? How to fix it ? Frank

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• What's the Best Practice for Firing Manual OnClick Events?

  - by Tyler Murry

  Hey guys, I've got an XNA project that will be drawing several objects on the screen. I would like the user to be able to interact with those items. So I'm trying to build a method that checks to see which object the mouse is over, out of those which is the top most, and then fire an OnClick event for that object. Checking for the things above is not the problem, but where to actually put that logic is most of the issue. My initial feeling is that the checking should be handled by a master object - since it doesn't make sense for an object, who ideally knows only about itself, to determine information about the other objects. However, calling OnClick events remotely from the master object seems to be counter-intuitive as well. What's the best practice in this situation? Thanks, Tyler

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• Does business logic belong in the service layer?

  - by antony.trupe

  I've got a set of classes, namely, a data transfer object, a service implementation object, and a data access object. I currently have business logic in the service implementation object; it uses the dao to get data to populate the dto that is shipped back to the client/gui code. The issue is that I can't create a lightweight junit test of the service implementtion object(it's a servlet); I think the business logic should be elsewhere, but the only thing I can think of is putting business logic in the dao or in yet another layer that goes between the dao and the service implementation. Are there other options, or am I thinking about this the wrong way? It's a GWT/App Engine project.

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• How do i translate movement on the Canvas3D to movement in the virtual 3D world

  - by Coder

  My goal is to move a shape in the virtual world in such a way so that it ends up where the mouse pointer is on the canvas. What i have: -mouse position (x,y) on a Canvas3D object -Point3d object of where a pick ray starting from the Canvas3D viewport intersects with the first scene object. (point in 3D space of where i want to start the drag) What i want: -Some way to translate the Point3d's coordinates so that the initial point of intersection (the Point3d object) is always overlapping the the mouse position on the canvas (same as when i used the pick ray to determine what the user clicked on from the Canvas3D object). Thanks!

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• Does the DataAnnotations.DisplayAttribute.Order property not work with ASP.NET MVC 2?

  - by Zack Peterson

  I set values for the Order property of the Display attribute in my model metadata. [MetadataType(typeof(OccasionMetadata))] public partial class Occasion { private class OccasionMetadata { [ScaffoldColumn(false)] public object Id { get; set; } [Required] [DisplayName("Title")] [Display(Order = 0)] public object Designation { get; set; } [Required] [DataType(DataType.MultilineText)] [Display(Order = 3)] public object Summary { get; set; } [Required] [DataType(DataType.DateTime)] [Display(Order = 1)] public object Start { get; set; } [Required] [DataType(DataType.DateTime)] [Display(Order = 2)] public object Finish { get; set; } } } I present my models in strongly-typed views using the DisplayForModel and EditorForModel methods. <%= Html.DisplayForModel() %> and <%= Html.EditorForModel() %> But, ASP.NET MVC 2 displays the fields out of order! What might I have wrong?

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• .NET Security Part 2

  - by Simon Cooper

  So, how do you create partial-trust appdomains? Where do you come across them? There are two main situations in which your assembly runs as partially-trusted using the Microsoft .NET stack: Creating a CLR assembly in SQL Server with anything other than the UNSAFE permission set. The permissions available in each permission set are given here. Loading an assembly in ASP.NET in any trust level other than Full. Information on ASP.NET trust levels can be found here. You can configure the specific permissions available to assemblies using ASP.NET policy files. Alternatively, you can create your own partially-trusted appdomain in code and directly control the permissions and the full-trust API available to the assemblies you load into the appdomain. This is the scenario I’ll be concentrating on in this post. Creating a partially-trusted appdomain There is a single overload of AppDomain.CreateDomain that allows you to specify the permissions granted to assemblies in that appdomain – this one. This is the only call that allows you to specify a PermissionSet for the domain. All the other calls simply use the permissions of the calling code. If the permissions are restricted, then the resulting appdomain is referred to as a sandboxed domain. There are three things you need to create a sandboxed domain: The specific permissions granted to all assemblies in the domain. The application base (aka working directory) of the domain. The list of assemblies that have full-trust if they are loaded into the sandboxed domain. The third item is what allows us to have a fully-trusted API that is callable by partially-trusted code. I’ll be looking at the details of this in a later post. Granting permissions to the appdomain Firstly, the permissions granted to the appdomain. This is encapsulated in a PermissionSet object, initialized either with no permissions or full-trust permissions. For sandboxed appdomains, the PermissionSet is initialized with no permissions, then you add permissions you want assemblies loaded into that appdomain to have by default: PermissionSet restrictedPerms = new PermissionSet(PermissionState.None); // all assemblies need Execution permission to run at all restrictedPerms.AddPermission( new SecurityPermission(SecurityPermissionFlag.Execution)); // grant general read access to C:\config.xml restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.Read, @"C:\config.xml")); // grant permission to perform DNS lookups restrictedPerms.AddPermission( new DnsPermission(PermissionState.Unrestricted)); It’s important to point out that the permissions granted to an appdomain, and so to all assemblies loaded into that appdomain, are usable without needing to go through any SafeCritical code (see my last post if you’re unsure what SafeCritical code is). That is, partially-trusted code loaded into an appdomain with the above permissions (and so running under the Transparent security level) is able to create and manipulate a FileStream object to read from C:\config.xml directly. It is only for operations requiring permissions that are not granted to the appdomain that partially-trusted code is required to call a SafeCritical method that then asserts the missing permissions and performs the operation safely on behalf of the partially-trusted code. The application base of the domain This is simply set as a property on an AppDomainSetup object, and is used as the default directory assemblies are loaded from: AppDomainSetup appDomainSetup = new AppDomainSetup { ApplicationBase = @"C:\temp\sandbox", }; If you’ve read the documentation around sandboxed appdomains, you’ll notice that it mentions a security hole if this parameter is set correctly. I’ll be looking at this, and other pitfalls, that will break the sandbox when using sandboxed appdomains, in a later post. Full-trust assemblies in the appdomain Finally, we need the strong names of the assemblies that, when loaded into the appdomain, will be run as full-trust, irregardless of the permissions specified on the appdomain. These assemblies will contain methods and classes decorated with SafeCritical and Critical attributes. I’ll be covering the details of creating full-trust APIs for partial-trust appdomains in a later post. This is how you get the strongnames of an assembly to be executed as full-trust in the sandbox: // get the Assembly object for the assembly Assembly assemblyWithApi = ... // get the StrongName from the assembly's collection of evidence StrongName apiStrongName = assemblyWithApi.Evidence.GetHostEvidence<StrongName>(); Creating the sandboxed appdomain So, putting these three together, you create the appdomain like so: AppDomain sandbox = AppDomain.CreateDomain( "Sandbox", null, appDomainSetup, restrictedPerms, apiStrongName); You can then load and execute assemblies in this appdomain like any other. For example, to load an assembly into the appdomain and get an instance of the Sandboxed.Entrypoint class, implementing IEntrypoint, you do this: IEntrypoint o = (IEntrypoint)sandbox.CreateInstanceFromAndUnwrap( "C:\temp\sandbox\SandboxedAssembly.dll", "Sandboxed.Entrypoint"); // call method the Execute method on this object within the sandbox o.Execute(); The second parameter to CreateDomain is for security evidence used in the appdomain. This was a feature of the .NET 2 security model, and has been (mostly) obsoleted in the .NET 4 model. Unless the evidence is needed elsewhere (eg. isolated storage), you can pass in null for this parameter. Conclusion That’s the basics of sandboxed appdomains. The most important object is the PermissionSet that defines the permissions available to assemblies running in the appdomain; it is this object that defines the appdomain as full or partial-trust. The appdomain also needs a default directory used for assembly lookups as the ApplicationBase parameter, and you can specify an optional list of the strongnames of assemblies that will be given full-trust permissions if they are loaded into the sandboxed appdomain. Next time, I’ll be looking closer at full-trust assemblies running in a sandboxed appdomain, and what you need to do to make an API available to partial-trust code.

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• Flex AdvancedDataGrid with Grouping, how do I get objects to appear under first GroupingField if the

  - by shadenite

  I am using an AdvancedDataGrid with two GroupingFields. The dataProvider has a list of objects with these two field values, but occasionally the second field value can be null. When it loads, the AdvancedDataGrid UI has a root folder (first GroupingField) and some additional subfolders (second GroupingField). This is all good. However, the objects with a null value for the second GroupingField, just get placed in a subfolder with no label. I want the objects with a null second GroupingField value to appear as leaf nodes beneath the root folder (first GroupingField) minus the blank subfolder. A good way to picture this would be a file explorer. Is there a good way to do this? Make the folder icon disappear maybe after expanding this node through actionscript? ParentFolder SubFolder Leaf Object Leaf Object SubFolder Leaf Object Leaf Object Leaf Object

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• JPA behaviour...

  - by Marcel

  Hi I have some trouble understanding a JPA behaviour. Mabye someone could give me a hint. Situation: Product entity: @Entity public class Product implements Serializable { ... @OneToMany(mappedBy="product", fetch=FetchType.EAGER) private List<ProductResource> productResources = new ArrayList<ProductResource>(); .... public List<ProductResource> getProductResources() { return productResources; } public boolean equals(Object obj) { if (obj == this) return true; if (obj == null) return false; if (!(obj instanceof Product)) return false; Product p = (Product) obj; return p.productId == productId; } } Resource entity: @Entity public class Resource implements Serializable { ... @OneToMany(mappedBy="resource", fetch=FetchType.EAGER) private List<ProductResource> productResources = new ArrayList<ProductResource>(); ... public void setProductResource(List<ProductResource> productResource) { this.productResources = productResource; } public List<ProductResource> getProductResources() { return productResources; } public boolean equals(Object obj) { if (obj == this) return true; if (obj == null) return false; if (!(obj instanceof Resource)) return false; Resource r = (Resource) obj; return (long)resourceId==(long)r.resourceId; } } ProductResource Entity: This is a JoinTable (association class) with additional properties (amount). It maps Product and Resources. @Entity public class ProductResource implements Serializable { ... @JoinColumn(nullable=false, updatable=false) @ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.PERSIST) private Product product; @JoinColumn(nullable=false, updatable=false) @ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.PERSIST) private Resource resource; private int amount; public void setProduct(Product product) { this.product = product; if(!product.getProductResources().contains((this))){ product.getProductResources().add(this); } } public Product getProduct() { return product; } public void setResource(Resource resource) { this.resource = resource; if(!resource.getProductResources().contains((this))){ resource.getProductResources().add(this); } } public Resource getResource() { return resource; } ... public boolean equals(Object obj) { if (obj == this) return true; if (obj == null) return false; if (!(obj instanceof ProductResource)) return false; ProductResource pr = (ProductResource) obj; return (long)pr.productResourceId == (long)productResourceId; } } This is the Session Bean (running on glassfish). @Stateless(mappedName="PersistenceManager") public class PersistenceManagerBean implements PersistenceManager { @PersistenceContext(unitName = "local_mysql") private EntityManager em; public Object create(Object entity) { em.persist(entity); return entity; } public void delete(Object entity) { em.remove(em.merge(entity)); } public Object retrieve(Class entityClass, Long id) { Object entity = em.find(entityClass, id); return entity; } public void update(Object entity) { em.merge(entity); } } I call the session Bean from a java client: public class Start { public static void main(String[] args) throws NamingException { PersistenceManager pm = (PersistenceManager) new InitialContext().lookup("java:global/BackITServer/PersistenceManagerBean"); ProductResource pr = new ProductResource(); Product p = new Product(); Resource r = new Resource(); pr.setProduct(p); pr.setResource(r); ProductResource pr_stored = (ProductResource) pm.create(pr); pm.delete(pr_stored); Product p_ret = (Product) pm.retrieve(Product.class, pr_stored.getProduct().getProductId()); // prints out true ???????????????????????????????????? System.out.println(p_ret.getProductResources().contains(pr_stored)); } } So here comes my problem. Why is the ProductResource entity still in the List productResources(see code above). The productResource tuple in the db is gone after the deletion and I do newly retrieve the Product entity. If I understood right every method call of the client happens in a new persistence context, but here i obviously get back the non-refreshed product object!? Any help is appreciated Thanks Marcel

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• ResponseStatusLine protocol violation

  - by Tom Hines

  I parse/scrape a few web page every now and then and recently ran across an error that stated: "The server committed a protocol violation. Section=ResponseStatusLine".   After a few web searches, I found a couple of suggestions – one of which said the problem could be fixed by changing the HttpWebRequest ProtocolVersion to 1.0 with the command: 1: HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(strURI); 2: req.ProtocolVersion = HttpVersion.Version10;   …but that did not work in my particular case.   What DID work was the next suggestion I found that suggested the use of the setting: “useUnsafeHeaderParsing” either in the app.config file or programmatically. If added to the app.config, it would be: 1: <!-- after the applicationSettings --> 2: <system.net> 3: <settings> 4: <httpWebRequest useUnsafeHeaderParsing ="true"/> 5: </settings> 6: </system.net>   If done programmatically, it would look like this: C++: 1: // UUHP_CPP.h 2: #pragma once 3: using namespace System; 4: using namespace System::Reflection; 5:   6: namespace UUHP_CPP 7: { 8: public ref class CUUHP_CPP 9: { 10: public: 11: static bool UseUnsafeHeaderParsing(String^% strError) 12: { 13: Assembly^ assembly = Assembly::GetAssembly(System::Net::Configuration::SettingsSection::typeid); //__typeof 14: if (nullptr==assembly) 15: { 16: strError = "Could not access Assembly"; 17: return false; 18: } 19:   20: Type^ type = assembly->GetType("System.Net.Configuration.SettingsSectionInternal"); 21: if (nullptr==type) 22: { 23: strError = "Could not access internal settings"; 24: return false; 25: } 26:   27: Object^ obj = type->InvokeMember("Section", 28: BindingFlags::Static | BindingFlags::GetProperty | BindingFlags::NonPublic, 29: nullptr, nullptr, gcnew array<Object^,1>(0)); 30:   31: if(nullptr == obj) 32: { 33: strError = "Could not invoke Section member"; 34: return false; 35: } 36:   37: FieldInfo^ fi = type->GetField("useUnsafeHeaderParsing", BindingFlags::NonPublic | BindingFlags::Instance); 38: if(nullptr == fi) 39: { 40: strError = "Could not access useUnsafeHeaderParsing field"; 41: return false; 42: } 43:   44: if (!(bool)fi->GetValue(obj)) 45: { 46: fi->SetValue(obj, true); 47: } 48:   49: return true; 50: } 51: }; 52: } C# (CSharp): 1: using System; 2: using System.Reflection; 3:   4: namespace UUHP_CS 5: { 6: public class CUUHP_CS 7: { 8: public static bool UseUnsafeHeaderParsing(ref string strError) 9: { 10: Assembly assembly = Assembly.GetAssembly(typeof(System.Net.Configuration.SettingsSection)); 11: if (null == assembly) 12: { 13: strError = "Could not access Assembly"; 14: return false; 15: } 16:   17: Type type = assembly.GetType("System.Net.Configuration.SettingsSectionInternal"); 18: if (null == type) 19: { 20: strError = "Could not access internal settings"; 21: return false; 22: } 23:   24: object obj = type.InvokeMember("Section", 25: BindingFlags.Static | BindingFlags.GetProperty | BindingFlags.NonPublic, 26: null, null, new object[] { }); 27:   28: if (null == obj) 29: { 30: strError = "Could not invoke Section member"; 31: return false; 32: } 33:   34: // If it's not already set, set it. 35: FieldInfo fi = type.GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic | BindingFlags.Instance); 36: if (null == fi) 37: { 38: strError = "Could not access useUnsafeHeaderParsing field"; 39: return false; 40: } 41:   42: if (!Convert.ToBoolean(fi.GetValue(obj))) 43: { 44: fi.SetValue(obj, true); 45: } 46:   47: return true; 48: } 49: } 50: }   F# (FSharp): 1: namespace UUHP_FS 2: open System 3: open System.Reflection 4: module CUUHP_FS = 5: let UseUnsafeHeaderParsing(strError : byref<string>) : bool = 6: // 7: let assembly : Assembly = Assembly.GetAssembly(typeof<System.Net.Configuration.SettingsSection>) 8: if (null = assembly) then 9: strError <- "Could not access Assembly" 10: false 11: else 12: 13: let myType : Type = assembly.GetType("System.Net.Configuration.SettingsSectionInternal") 14: if (null = myType) then 15: strError <- "Could not access internal settings" 16: false 17: else 18: 19: let obj : Object = myType.InvokeMember("Section", BindingFlags.Static ||| BindingFlags.GetProperty ||| BindingFlags.NonPublic, null, null, Array.zeroCreate 0) 20: if (null = obj) then 21: strError <- "Could not invoke Section member" 22: false 23: else 24: 25: // If it's not already set, set it. 26: let fi : FieldInfo = myType.GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic ||| BindingFlags.Instance) 27: if(null = fi) then 28: strError <- "Could not access useUnsafeHeaderParsing field" 29: false 30: else 31: 32: if (not(Convert.ToBoolean(fi.GetValue(obj)))) then 33: fi.SetValue(obj, true) 34: 35: // Now return true 36: true VB (Visual Basic): 1: Option Explicit On 2: Option Strict On 3: Imports System 4: Imports System.Reflection 5:   6: Public Class CUUHP_VB 7: Public Shared Function UseUnsafeHeaderParsing(ByRef strError As String) As Boolean 8:   9: Dim assembly As [Assembly] 10: assembly = [assembly].GetAssembly(GetType(System.Net.Configuration.SettingsSection)) 11:   12: If (assembly Is Nothing) Then 13: strError = "Could not access Assembly" 14: Return False 15: End If 16:   17: Dim type As Type 18: type = [assembly].GetType("System.Net.Configuration.SettingsSectionInternal") 19: If (type Is Nothing) Then 20: strError = "Could not access internal settings" 21: Return False 22: End If 23:   24: Dim obj As Object 25: obj = [type].InvokeMember("Section", _ 26: BindingFlags.Static Or BindingFlags.GetProperty Or BindingFlags.NonPublic, _ 27: Nothing, Nothing, New [Object]() {}) 28:   29: If (obj Is Nothing) Then 30: strError = "Could not invoke Section member" 31: Return False 32: End If 33:   34: ' If it's not already set, set it. 35: Dim fi As FieldInfo 36: fi = [type].GetField("useUnsafeHeaderParsing", BindingFlags.NonPublic Or BindingFlags.Instance) 37: If (fi Is Nothing) Then 38: strError = "Could not access useUnsafeHeaderParsing field" 39: Return False 40: End If 41:   42: If (Not Convert.ToBoolean(fi.GetValue(obj))) Then 43: fi.SetValue(obj, True) 44: End If 45:   46: Return True 47: End Function 48: End Class   Technorati Tags: C++,CPP,VB,Visual Basic,F#,FSharp,C#,CSharp,ResponseStatusLine,protocol violation

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• Symfony app - how to add calculated fields to Propel objects?

  - by Thomas Kohl

  What is the best way of working with calculated fields of Propel objects? Say I have an object "Customer" that has a corresponding table "customers" and each column corresponds to an attribute of my object. What I would like to do is: add a calculated attribute "Number of completed orders" to my object when using it on View A but not on Views B and C. The calculated attribute is a COUNT() of "Order" objects linked to my "Customer" object via ID. What I can do now is to first select all Customer objects, then iteratively count Orders for all of them, but I'd think doing it in a single query would improve performance. But I cannot properly "hydrate" my Propel object since it does not contain the definition of the calculated field(s). How would you approach it?

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• Pluggable Rules for Entity Framework Code First

  - by Ricardo Peres

  Suppose you want a system that lets you plug custom validation rules on your Entity Framework context. The rules would control whether an entity can be saved, updated or deleted, and would be implemented in plain .NET. Yes, I know I already talked about plugable validation in Entity Framework Code First, but this is a different approach. An example API is in order, first, a ruleset, which will hold the collection of rules: 1: public interface IRuleset : IDisposable 2: { 3: void AddRule<T>(IRule<T> rule); 4: IEnumerable<IRule<T>> GetRules<T>(); 5: } Next, a rule: 1: public interface IRule<T> 2: { 3: Boolean CanSave(T entity, DbContext ctx); 4: Boolean CanUpdate(T entity, DbContext ctx); 5: Boolean CanDelete(T entity, DbContext ctx); 6: String Name 7: { 8: get; 9: } 10: } Let’s analyze what we have, starting with the ruleset: Only has methods for adding a rule, specific to an entity type, and to list all rules of this entity type; By implementing IDisposable, we allow it to be cancelled, by disposing of it when we no longer want its rules to be applied. A rule, on the other hand: Has discrete methods for checking if a given entity can be saved, updated or deleted, which receive as parameters the entity itself and a pointer to the DbContext to which the ruleset was applied; Has a name property for helping us identifying what failed. A ruleset really doesn’t need a public implementation, all we need is its interface. The private (internal) implementation might look like this: 1: sealed class Ruleset : IRuleset 2: { 3: private readonly IDictionary<Type, HashSet<Object>> rules = new Dictionary<Type, HashSet<Object>>(); 4: private ObjectContext octx = null; 5:  6: internal Ruleset(ObjectContext octx) 7: { 8: this.octx = octx; 9: } 10:  11: public void AddRule<T>(IRule<T> rule) 12: { 13: if (this.rules.ContainsKey(typeof(T)) == false) 14: { 15: this.rules[typeof(T)] = new HashSet<Object>(); 16: } 17:  18: this.rules[typeof(T)].Add(rule); 19: } 20:  21: public IEnumerable<IRule<T>> GetRules<T>() 22: { 23: if (this.rules.ContainsKey(typeof(T)) == true) 24: { 25: foreach (IRule<T> rule in this.rules[typeof(T)]) 26: { 27: yield return (rule); 28: } 29: } 30: } 31:  32: public void Dispose() 33: { 34: this.octx.SavingChanges -= RulesExtensions.OnSaving; 35: RulesExtensions.rulesets.Remove(this.octx); 36: this.octx = null; 37:  38: this.rules.Clear(); 39: } 40: } Basically, this implementation: Stores the ObjectContext of the DbContext to which it was created for, this is so that later we can remove the association; Has a collection - a set, actually, which does not allow duplication - of rules indexed by the real Type of an entity (because of proxying, an entity may be of a type that inherits from the class that we declared); Has generic methods for adding and enumerating rules of a given type; Has a Dispose method for cancelling the enforcement of the rules. A (really dumb) rule applied to Product might look like this: 1: class ProductRule : IRule<Product> 2: { 3: #region IRule<Product> Members 4:  5: public String Name 6: { 7: get 8: { 9: return ("Rule 1"); 10: } 11: } 12:  13: public Boolean CanSave(Product entity, DbContext ctx) 14: { 15: return (entity.Price > 10000); 16: } 17:  18: public Boolean CanUpdate(Product entity, DbContext ctx) 19: { 20: return (true); 21: } 22:  23: public Boolean CanDelete(Product entity, DbContext ctx) 24: { 25: return (true); 26: } 27:  28: #endregion 29: } The DbContext is there because we may need to check something else in the database before deciding whether to allow an operation or not. And here’s how to apply this mechanism to any DbContext, without requiring the usage of a subclass, by means of an extension method: 1: public static class RulesExtensions 2: { 3: private static readonly MethodInfo getRulesMethod = typeof(IRuleset).GetMethod("GetRules"); 4: internal static readonly IDictionary<ObjectContext, Tuple<IRuleset, DbContext>> rulesets = new Dictionary<ObjectContext, Tuple<IRuleset, DbContext>>(); 5:  6: private static Type GetRealType(Object entity) 7: { 8: return (entity.GetType().Assembly.IsDynamic == true ? entity.GetType().BaseType : entity.GetType()); 9: } 10:  11: internal static void OnSaving(Object sender, EventArgs e) 12: { 13: ObjectContext octx = sender as ObjectContext; 14: IRuleset ruleset = rulesets[octx].Item1; 15: DbContext ctx = rulesets[octx].Item2; 16:  17: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Added)) 18: { 19: Object entity = entry.Entity; 20: Type realType = GetRealType(entity); 21:  22: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 23: { 24: if (rule.CanSave(entity, ctx) == false) 25: { 26: throw (new Exception(String.Format("Cannot save entity {0} due to rule {1}", entity, rule.Name))); 27: } 28: } 29: } 30:  31: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Deleted)) 32: { 33: Object entity = entry.Entity; 34: Type realType = GetRealType(entity); 35:  36: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 37: { 38: if (rule.CanDelete(entity, ctx) == false) 39: { 40: throw (new Exception(String.Format("Cannot delete entity {0} due to rule {1}", entity, rule.Name))); 41: } 42: } 43: } 44:  45: foreach (ObjectStateEntry entry in octx.ObjectStateManager.GetObjectStateEntries(EntityState.Modified)) 46: { 47: Object entity = entry.Entity; 48: Type realType = GetRealType(entity); 49:  50: foreach (dynamic rule in (getRulesMethod.MakeGenericMethod(realType).Invoke(ruleset, null) as IEnumerable)) 51: { 52: if (rule.CanUpdate(entity, ctx) == false) 53: { 54: throw (new Exception(String.Format("Cannot update entity {0} due to rule {1}", entity, rule.Name))); 55: } 56: } 57: } 58: } 59:  60: public static IRuleset CreateRuleset(this DbContext context) 61: { 62: Tuple<IRuleset, DbContext> ruleset = null; 63: ObjectContext octx = (context as IObjectContextAdapter).ObjectContext; 64:  65: if (rulesets.TryGetValue(octx, out ruleset) == false) 66: { 67: ruleset = rulesets[octx] = new Tuple<IRuleset, DbContext>(new Ruleset(octx), context); 68: 69: octx.SavingChanges += OnSaving; 70: } 71:  72: return (ruleset.Item1); 73: } 74: } It relies on the SavingChanges event of the ObjectContext to intercept the saving operations before they are actually issued. Yes, it uses a bit of dynamic magic! Very handy, by the way! So, let’s put it all together: 1: using (MyContext ctx = new MyContext()) 2: { 3: IRuleset rules = ctx.CreateRuleset(); 4: rules.AddRule(new ProductRule()); 5:  6: ctx.Products.Add(new Product() { Name = "xyz", Price = 50000 }); 7:  8: ctx.SaveChanges(); //an exception is fired here 9:  10: //when we no longer need to apply the rules 11: rules.Dispose(); 12: } Feel free to use it and extend it any way you like, and do give me your feedback! As a final note, this can be easily changed to support plain old Entity Framework (not Code First, that is), if that is what you are using.

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