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• When does logic belong in the Business Object/Entity, and when does it belong in a Service?

  - by Casey

  In trying to understand Domain Driven Design I keep returning to a question that I can't seem to definitively answer. How do you determine what logic belongs to a Domain entity, and what logic belongs to a Domain Service? Example: We have an Order class for an online store. This class is an entity and an aggregate root (it contains OrderItems). Public Class Order:IOrder { Private List<IOrderItem> OrderItems Public Order(List<IOrderItem>) { OrderItems = List<IOrderItem> } Public Decimal CalculateTotalItemWeight() //This logic seems to belong in the entity. { Decimal TotalWeight = 0 foreach(IOrderItem OrderItem in OrderItems) { TotalWeight += OrderItem.Weight } return TotalWeight } } I think most people would agree that CalculateTotalItemWeight belongs on the entity. However, at some point we have to ship this order to the customer. To accomplish this we need to do two things: 1) Determine the postage rate necessary to ship this order. 2) Print a shipping label after determining the postage rate. Both of these actions will require dependencies that are outside the Order entity, such as an external webservice to retrieve postage rates. How should we accomplish these two things? I see a few options: 1) Code the logic directly in the domain entity, like CalculateTotalItemWeight. We then call: Order.GetPostageRate Order.PrintLabel 2) Put the logic in a service that accepts IOrder. We then call: PostageService.GetPostageRate(Order) PrintService.PrintLabel(Order) 3) Create a class for each action that operates on an Order, and pass an instance of that class to the Order through Constructor Injection (this is a variation of option 1 but allows reuse of the RateRetriever and LabelPrinter classes): Public Class Order:IOrder { Private List<IOrderItem> OrderItems Private RateRetriever _Retriever Private LabelPrinter _Printer Public Order(List<IOrderItem>, RateRetriever Retriever, LabelPrinter Printer) { OrderItems = List<IOrderItem> _Retriever = Retriever _Printer = Printer } Public Decimal GetPostageRate { _Retriever.GetPostageRate(this) } Public void PrintLabel { _Printer.PrintLabel(this) } } Which one of these methods do you choose for this logic, if any? What is the reasoning behind your choice? Most importantly, is there a set of guidelines that led you to your choice?

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• What's the best way to handle modules that use each other?

  - by Axeman

  What's the best way to handle modules that use each other? Let's say I have a module which has functions for hashes: # Really::Useful::Functions::On::Hash.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::List qw<transform_list>; our @EXPORT_OK = qw<transform_hash transform_hash_as_list ...>; #... sub transform_hash { ... } #... sub transform_hash_as_list { return transform_list( %{ shift() } ); } #... 1 And another module has been segmented out for lists: # Really::Useful::Functions::On::List.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::Hash qw<transform_hash>; our @EXPORT_OK = qw<transform_list some_func ...>; #... sub transform_list { ... } #... sub some_func { my %params = transform_hash @_; #... } #... 1 Suppose that enough of these utility functions are handy enough that I'll want to use them in BEGIN statements and import functions to process parameter lists or configuration data. I have been putting sub definitions into BEGIN blocks to make sure they are ready to use whenever somebody includes the module. But I have gotten into hairy race conditions where a definition is not completed in a BEGIN block. I put evolving code idioms into modules so that I can reuse any idiom I find myself coding over and over again. For instance: sub list_if { my $condition = shift; return unless $condition; my $more_args = scalar @_; my $arg_list = @_ > 1 ? \@_ : @_ ? shift : $condition; if (( reftype( $arg_list ) || '' ) eq 'ARRAY' ) { return wantarray ? @$arg_list : $arg_list; } elsif ( $more_args ) { return $arg_list; } return; } captures two idioms that I'm kind of tired of typing: @{ func_I_hope_returns_a_listref() || [] } and ( $condition ? LIST : ()) The more I define functions in BEGIN blocks, the more likely I'll use these idiom bricks to express the logic the more likely that bricks are needed in BEGIN blocks. Do people have standard ways of dealing with this sort of language-idiom-brick model? I've been doing mostly Pure-Perl; will XS alleviate some of this?

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• NSFetchedResultsController on secondary UITableView - how to query data?

  - by Jason

  I am creating a core-data based Navigation iPhone app with multiple screens. Let's say it is a flash-card application. The data model is very simple, with only two entities: Language, and CardSet. There is a one-to-many relationship between the Language entity and the CardSet entities, so each Language may contain multiple CardSets. In other words, Language has a one-to-many relationship Language.cardSets which points to the list of CardSets, and CardSet has a relationship CardSet.language which points to the Language. There are two screens: (1) An initial TableView screen, which displays the list of languages; and (2) a secondary TableView screen, which displays the list of CardSets in the Language. In the initial screen, which lists the languages, I am using NSFetchedResultsController to keep the list of languages up-to-date. The screen passes the Language selected to the secondary screen. On the secondary screen, I am trying to figure out whether I should again use an NSFetchedResultsController to maintain the list of CardSets, or if I should work through Language.cardSets to simply pull the list out of the object model. The latter makes the most sense programatically because I already have the Language - but then it would not automatically be updated on changes. I have looked at the NSFetchedResultsController documentation, and it seems like I can easily create predicates based on attributes - but not relationships. I.e., I can create the following NSFetchedResultsController: NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name LIKE[c] 'Chuck Norris'"]; How can I access my data through the direct relationship - Language.cardSets - and also have the table auto-update using NSFetchedResultsController? Is this possible?

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• C#: Thread.CurrentThread.CurrentUICulture not working consistently

  - by xTRUMANx

  I've been working on a pet project on the weekends to learn more about C# and have encountered an odd problem when working with localization. To be more specific, the problem I have is with System.Threading.Thread.CurrentThread.CurrentUICulture. I've set up my app so that the user can quickly change the language of the app by clicking a menu item. The menu item in turn, saves the two-letter code for the language (e.g. "en", "fr", etc.) in a user setting called 'Language' and then restarts the application. Properties.Settings.Default.Language = "en"; Properties.Settings.Default.Save(); Application.Restart(); When the application is started up, the first line of code in the Form's constructor (even before InitializeComponent()) fetches the Language string from the settings and sets the CurrentUICulture like so: public Form1() { Thread.CurrentThread.CurrentUICulture = new CultureInfo(Properties.Settings.Default.Language); InitializeComponent(); } The thing is, this doesn't work consistently. Sometimes, all works well and the application loads the correct language based on the string saved in the settings file. Other times, it doesn't, and the language remains the same after the application is restarted. At first I thought that I didn't save the language before restarting the application but that is definitely not the case. When the correct language fails to load, if I were to close the application and run it again, the correct language would come up correctly. So this implies that the Language string has been saved but the CurrentUICulture assignment in my form constructor is having no effect sometimes. Any help? Is there something I'm missing of how threading works in C#? This could be machine-specific, so if it makes any difference I'm using Pentium Dual-Core CPU.

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• Installed SQL Server 2008 and now TFS is broken.

  - by johnnycakes

  Hi, My W2K3 server was running TFS 2008 SP1, SQL Server 2005 Development edition. I installed SQL Server 2008 Standard. I installed it while leaving SQL Server 2005 alone. Upgrading was not possible due to the differences in editions of the SQL Servers. Now TFS is broken. On a client computer, if I go Team - Connect to Team Foundation Server, I get this error: Team Foundation services are not available from server myserver. Technical information (for administrator): TF30059: Fatal error while initializing web service. So I head on over to my event viewer on the server. Under Application, I see one warning and two errors. First, the warning: Source: SQLSERVERAGENT Event ID: 208 Description: SQL Server Scheduled Job 'TfsWorkItemTracking Process Identities Job' (0x21F395C1F444CA499A63EBF05D717749) - Status: Failed - Invoked on: 2010-04-26 13:30:00 - Message: The job failed. The Job was invoked by Schedule 9 (ProcessIdentitiesSchedule). The last step to run was step 1 (Process Identities). Then the first error: Source: TFS Services Event ID: 3017 Description: TF53010: The following error has occurred in a Team Foundation component or extension: Date (UTC): 4/26/2010 5:36:29 PM Machine: myserver Application Domain: /LM/W3SVC/799623628/Root/Services-2-129167769888923968 Assembly: Microsoft.TeamFoundation.Server, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a; v2.0.50727 Process Details: Process Name: w3wp Process Id: 4008 Thread Id: 224 Account name: DOMAIN\TFSService Detailed Message: TF53013: A crash report is being prepared for Microsoft. The following information is included in that report: System Values OS Version Information=Microsoft Windows NT 5.2.3790 Service Pack 2 CLR Version Information=2.0.50727.3053 Machine Name=myserver Processor Count=1 Working Set=34897920 System Directory=C:\WINDOWS\system32 Process Values ExitCode=0 Interactive=False Has Shutdown Started=False Process Environment Variables Path = C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Microsoft SQL Server\80\Tools\Binn\;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\Program Files\Microsoft SQL Server\90\DTS\Binn\;C:\Program Files\Microsoft SQL Server\90\Tools\Binn\VSShell\Common7\IDE\;C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\PrivateAssemblies\;C:\Program Files\Microsoft SQL Server\100\Tools\Binn\;C:\Program Files\Microsoft SQL Server\100\DTS\Binn\;C:\Program Files\Microsoft SQL Server\100\Tools\Binn\VSShell\Common7\IDE\;C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\;C:\WINDOWS\system32\WindowsPowerShell\v1.0 PATHEXT = .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.PSC1 PROCESSOR_ARCHITECTURE = x86 SystemDrive = C: windir = C:\WINDOWS TMP = C:\WINDOWS\TEMP USERPROFILE = C:\Documents and Settings\Default User ProgramFiles = C:\Program Files FP_NO_HOST_CHECK = NO COMPUTERNAME = myserver APP_POOL_ID = Microsoft Team Foundation Server Application Pool NUMBER_OF_PROCESSORS = 1 PROCESSOR_IDENTIFIER = x86 Family 16 Model 5 Stepping 2, AuthenticAMD ClusterLog = C:\WINDOWS\Cluster\cluster.log SystemRoot = C:\WINDOWS ComSpec = C:\WINDOWS\system32\cmd.exe CommonProgramFiles = C:\Program Files\Common Files PROCESSOR_LEVEL = 16 PROCESSOR_REVISION = 0502 lib = C:\Program Files\SQLXML 4.0\bin\ ALLUSERSPROFILE = C:\Documents and Settings\All Users TEMP = C:\WINDOWS\TEMP OS = Windows_NT Request Details Url=http://myserver.domain.local:8080/Services/v1.0/Registration.asmx [method = POST] User Agent=Team Foundation (devenv.exe, 10.0.30128.1) Headers=Content-Length=390&Content-Type=text%2fxml%3b+charset%3dutf-8&Accept-Encoding=gzip%2cgzip%2cgzip&Accept-Language=en-US&Authorization=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%2f6h5U30CEXgoAEAAAAAAAAAAAAAAAAAAAAAAACQAyAEgAVABUAFAALwB0AGkAdABhAG4ALgBoAHkAcABlAHIAaQBvAG4ALgBsAG8AYwBhAGwAAAAAAAAAAAA%3d&Expect=100-continue&Host=myserver.domain.local%3a8080&User-Agent=Team+Foundation+(devenv.exe%2c+10.0.30128.1)&X-TFS-Version=1.0.0.0&X-TFS-Session=b7e7fdec-e7ee-48fc-92e8-537d1cd87ea4&SOAPAction=%22http%3a%2f%2fschemas.microsoft.com%2fTeamFoundation%2f2005%2f06%2fServices%2fRegistration%2f03%2fGetRegistrationEntries%22 Path=/Services/v1.0/Registration.asmx Local Request=False User Host Address=10.0.5.78 User=DOMAIN\Johnny [auth = NTLM] Application Provided Information Team Foundation Application Information Event Log Source = TFS Services Configured Team Foundation Server = http://myserver:8080 License Type = WorkgroupLicense Server Culture = en-US Activity Logging Name = Integration Component Name = CS Initialized = No Requests Processed = 0 Exception: TypeInitializationException Message: The type initializer for 'Microsoft.TeamFoundation.Server.IntegrationResourceComponent' threw an exception. Stack Trace: at Microsoft.TeamFoundation.Server.IntegrationResourceComponent.RegisterExceptions() at Microsoft.TeamFoundation.Server.Global.Initialize() at Microsoft.TeamFoundation.Server.TeamFoundationApplication.Init() Inner Exception Details Exception: ReflectionTypeLoadException Message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. Stack Trace: at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at Microsoft.TeamFoundation.Server.SqlResourceComponent.RegisterExceptions(Assembly assembly) at Microsoft.TeamFoundation.Server.IntegrationResourceComponent.RegisterExceptions() at Microsoft.TeamFoundation.Server.IntegrationResourceComponent..cctor() Application Domain Information Assembly Name=mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll Assembly File Version: File: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll InternalName: mscorlib.dll OriginalFilename: mscorlib.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: Microsoft Common Language Runtime Class Library Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\System.Web\2.0.0.0__b03f5f7f11d50a3a\System.Web.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\System.Web\2.0.0.0__b03f5f7f11d50a3a\System.Web.dll InternalName: System.Web.dll OriginalFilename: System.Web.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: System.Web.dll Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System\2.0.0.0__b77a5c561934e089\System.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\System\2.0.0.0__b77a5c561934e089\System.dll InternalName: System.dll OriginalFilename: System.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: .NET Framework Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Xml\2.0.0.0__b77a5c561934e089\System.Xml.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\System.Xml\2.0.0.0__b77a5c561934e089\System.Xml.dll InternalName: System.Xml.dll OriginalFilename: System.Xml.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: .NET Framework Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Configuration\2.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\System.Configuration\2.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll InternalName: System.Configuration.dll OriginalFilename: System.Configuration.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: System.Configuration.dll Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=Microsoft.JScript, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=8.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\Microsoft.JScript\8.0.0.0__b03f5f7f11d50a3a\Microsoft.JScript.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\Microsoft.JScript\8.0.0.0__b03f5f7f11d50a3a\Microsoft.JScript.dll InternalName: Microsoft.JScript.dll OriginalFilename: Microsoft.JScript.dll FileVersion: 8.0.50727.3053 FileDescription: Microsoft.JScript.dll Product: Microsoft (R) Visual Studio (R) 2005 ProductVersion: 8.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=App_global.asax.4nq_g1xi, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null Assembly CLR Version=v2.0.50727 Assembly Version=0.0.0.0 Assembly Location=C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\services\87e24ff8\921625fe\App_global.asax.4nq_g1xi.dll Assembly File Version: File: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\services\87e24ff8\921625fe\App_global.asax.4nq_g1xi.dll InternalName: App_global.asax.4nq_g1xi.dll OriginalFilename: App_global.asax.4nq_g1xi.dll FileVersion: 0.0.0.0 FileDescription: Product: ProductVersion: 0.0.0.0 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=Microsoft.TeamFoundation.Server, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\services\87e24ff8\921625fe\assembly\dl3\9051eeb6\603ea9a2_d822c801\Microsoft.TeamFoundation.Server.DLL Assembly File Version: File: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\services\87e24ff8\921625fe\assembly\dl3\9051eeb6\603ea9a2_d822c801\Microsoft.TeamFoundation.Server.DLL InternalName: Microsoft.TeamFoundation.Server.dll OriginalFilename: Microsoft.TeamFoundation.Server.dll FileVersion: 9.0.21022.8 FileDescription: Microsoft.TeamFoundation.Server.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.21022.8 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=Microsoft.TeamFoundation.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.dll InternalName: Microsoft.TeamFoundation.Common.dll OriginalFilename: Microsoft.TeamFoundation.Common.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.Common.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=Microsoft.TeamFoundation, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.dll InternalName: Microsoft.TeamFoundation.dll OriginalFilename: Microsoft.TeamFoundation.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=System.Security, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Security\2.0.0.0__b03f5f7f11d50a3a\System.Security.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\System.Security\2.0.0.0__b03f5f7f11d50a3a\System.Security.dll InternalName: System.Security.dll OriginalFilename: System.Security.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: System.Security.dll Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\System.Data\2.0.0.0__b77a5c561934e089\System.Data.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\System.Data\2.0.0.0__b77a5c561934e089\System.Data.dll InternalName: system.data.dll OriginalFilename: system.data.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: .NET Framework Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=Microsoft.TeamFoundation.Common.Library, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common.Library\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.Library.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common.Library\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.Library.dll InternalName: Microsoft.TeamFoundation.Common.Library.dll OriginalFilename: Microsoft.TeamFoundation.Common.Library.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.Common.Library.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=System.Web.Mobile, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Web.Mobile\2.0.0.0__b03f5f7f11d50a3a\System.Web.Mobile.dll As And finally, the second error: Source: Team Foundation Error Reporting Event ID: 5000 Description: EventType teamfoundationue, P1 1.0.0.0, P2 tfs, P3 9.0.30729.1, P4 9.0.0.0, P5 general, P6 typeinitializationexcept, P7 4758b22a940fe6d9, P8 d15c14bb, P9 NIL, P10 NIL. Any ideas? Thanks.

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• Contructor parameters for dependent classes with Unity Framework

  - by Onisemus

  I just started using the Unity Application Block to try to decouple my classes and make it easier for unit testing. I ran into a problem though that I'm not sure how to get around. Looked through the documentation and did some Googling but I'm coming up dry. Here's the situation: I have a facade-type class which is a chat bot. It is a singleton class which handles all sort of secondary classes and provides a central place to launch and configure the bot. I also have a class called AccessManager which, well, manages access to bot commands and resources. Boiled down to the essence, I have the classes set up like so. public class Bot { public string Owner { get; private set; } public string WorkingDirectory { get; private set; } private IAccessManager AccessManager; private Bot() { // do some setup // LoadConfig sets the Owner & WorkingDirectory variables LoadConfig(); // init the access mmanager AccessManager = new MyAccessManager(this); } public static Bot Instance() { // singleton code } ... } And the AccessManager class: public class MyAccessManager : IAccessManager { private Bot botReference; public MyAccesManager(Bot botReference) { this.botReference = botReference; SetOwnerAccess(botReference.Owner); } private void LoadConfig() { string configPath = Path.Combine( botReference.WorkingDirectory, "access.config"); // do stuff to read from config file } ... } I would like to change this design to use the Unity Application Block. I'd like to use Unity to generate the Bot singleton and to load the AccessManager interface in some sort of bootstrapping method that runs before anything else does. public static void BootStrapSystem() { IUnityContainer container = new UnityContainer(); // create new bot instance Bot newBot = Bot.Instance(); // register bot instance container.RegisterInstance<Bot>(newBot); // register access manager container.RegisterType<IAccessManager,MyAccessManager>(newBot); } And when I want to get a reference to the Access Manager inside the Bot constructor I can just do: IAcessManager accessManager = container.Resolve<IAccessManager>(); And elsewhere in the system to get a reference to the Bot singleton: // do this Bot botInstance = container.Resolve<Bot>(); // instead of this Bot botInstance = Bot.Instance(); The problem is the method BootStrapSystem() is going to blow up. When I create a bot instance it's going to try to resolve IAccessManager but won't be able to because I haven't registered the types yet (that's the next line). But I can't move the registration in front of the Bot creation because as part of the registration I need to pass the Bot as a parameter! Circular dependencies!! Gah!!! This indicates to me I have a flaw in the way I have this structured. But how do I fix it? Help!!

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• Domain Validation in a CQRS architecture

  - by Jupaol

  Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

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• Advice on Factory Method

  - by heath

  Using php 5.2, I'm trying to use a factory to return a service to the controller. My request uri would be of the format www.mydomain.com/service/method/param1/param2/etc. My controller would then call a service factory using the token sent in the uri. From what I've seen, there are two main routes I could go with my factory. Single method: class ServiceFactory { public static function getInstance($token) { switch($token) { case 'location': return new StaticPageTemplateService('location'); break; case 'product': return new DynamicPageTemplateService('product'); break; case 'user' return new UserService(); break; default: return new StaticPageTemplateService($token); } } } or multiple methods: class ServiceFactory { public static function getLocationService() { return new StaticPageTemplateService('location'); } public static function getProductService() { return new DynamicPageTemplateService('product'); } public static function getUserService() { return new UserService(); } public static function getDefaultService($token) { return new StaticPageTemplateService($token); } } So, given this, I will have a handful of generic services in which I will pass that token (for example, StaticPageTemplateService and DynamicPageTemplateService) that will probably implement another factory method just like this to grab templates, domain objects, etc. And some that will be specific services (for example, UserService) which will be 1:1 to that token and not reused. So, this seems to be an ok approach (please give suggestions if it is not) for a small amount of services. But what about when, over time and my site grows, I end up with 100s of possibilities. This no longer seems like a good approach. Am I just way off to begin with or is there another design pattern that would be a better fit? Thanks. UPDATE: @JSprang - the token is actually sent in the uri like mydomain.com/location would want a service specific to loction and mydomain.com/news would want a service specific to news. Now, for a lot of these, the service will be generic. For instance, a lot of pages will call a StaticTemplatePageService in which the token is passed in to the service. That service in turn will grab the "location" template or "links" template and just spit it back out. Some will need DynamicTemplatePageService in which the token gets passed in, like "news" and that service will grab a NewsDomainObject, determine how to present it and spit that back out. Others, like "user" will be specific to a UserService in which it will have methods like Login, Logout, etc. So basically, the token will be used to determine which service is needed AND if it is generic service, that token will be passed to that service. Maybe token isn't the correct terminology but I hope you get the purpose. I wanted to use the factory so I can easily swap out which Service I need in case my needs change. I just worry that after the site grows larger (both pages and functionality) that the factory will become rather bloated. But I'm starting to feel like I just can't get away from storing the mappings in an array (like Stephen's solution). That just doesn't feel OOP to me and I was hoping to find something more elegant.

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• Configurable Values in Enum

  - by Omer Akhter

  I often use this design in my code to maintain configurable values. Consider this code: public enum Options { REGEX_STRING("Some Regex"), REGEX_PATTERN(Pattern.compile(REGEX_STRING.getString()), false), THREAD_COUNT(2), OPTIONS_PATH("options.config", false), DEBUG(true), ALWAYS_SAVE_OPTIONS(true), THREAD_WAIT_MILLIS(1000); Object value; boolean saveValue = true; private Options(Object value) { this.value = value; } private Options(Object value, boolean saveValue) { this.value = value; this.saveValue = saveValue; } public void setValue(Object value) { this.value = value; } public Object getValue() { return value; } public String getString() { return value.toString(); } public boolean getBoolean() { Boolean booleanValue = (value instanceof Boolean) ? (Boolean) value : null; if (value == null) { try { booleanValue = Boolean.valueOf(value.toString()); } catch (Throwable t) { } } // We want a NullPointerException here return booleanValue.booleanValue(); } public int getInteger() { Integer integerValue = (value instanceof Number) ? ((Number) value).intValue() : null; if (integerValue == null) { try { integerValue = Integer.valueOf(value.toString()); } catch (Throwable t) { } } return integerValue.intValue(); } public float getFloat() { Float floatValue = (value instanceof Number) ? ((Number) value).floatValue() : null; if (floatValue == null) { try { floatValue = Float.valueOf(value.toString()); } catch (Throwable t) { } } return floatValue.floatValue(); } public static void saveToFile(String path) throws IOException { FileWriter fw = new FileWriter(path); Properties properties = new Properties(); for (Options option : Options.values()) { if (option.saveValue) { properties.setProperty(option.name(), option.getString()); } } if (DEBUG.getBoolean()) { properties.list(System.out); } properties.store(fw, null); } public static void loadFromFile(String path) throws IOException { FileReader fr = new FileReader(path); Properties properties = new Properties(); properties.load(fr); if (DEBUG.getBoolean()) { properties.list(System.out); } Object value = null; for (Options option : Options.values()) { if (option.saveValue) { Class<?> clazz = option.value.getClass(); try { if (String.class.equals(clazz)) { value = properties.getProperty(option.name()); } else { value = clazz.getConstructor(String.class).newInstance(properties.getProperty(option.name())); } } catch (NoSuchMethodException ex) { Debug.log(ex); } catch (InstantiationException ex) { Debug.log(ex); } catch (IllegalAccessException ex) { Debug.log(ex); } catch (IllegalArgumentException ex) { Debug.log(ex); } catch (InvocationTargetException ex) { Debug.log(ex); } if (value != null) { option.setValue(value); } } } } } This way, I can save and retrieve values from files easily. The problem is that I don't want to repeat this code everywhere. Like as we know, enums can't be extended; so wherever I use this, I have to put all these methods there. I want only to declare the values and that if they should be persisted. No method definitions each time; any ideas?

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• What does a WinForm application need to be designed for usability, and be robust, clean, and profess

  - by msorens

  One of the principal problems impeding productivity in software implementation is the classic conundrum of “reinventing the wheel”. Of late I am a .NET developer and even the wonderful wizardry of .NET and Visual Studio covers only a portion of this challenging issue. Below I present my initial thoughts both on what is available and what should be available from .NET on a WinForm, focusing on good usability. That is, aspects of an application exposed to the user and making the user experience easier and/or better. (I do include a couple items not visible to the user because I feel strongly about them, such as diagnostics.) I invite you to contribute to these lists. LIST A: Components provided by .NET These are substantially complete components provided by .NET, i.e. those requiring at most trivial coding to use. “About” dialog -- add it with a couple clicks then customize. Persist settings across invocations -- .NET has the support; just use a few lines of code to glue them together. Migrate settings with a new version -- a powerful one, available with one line of code. Tooltips (and infotips) -- .NET includes just plain text tooltips; third-party libraries provide richer ones. Diagnostic support -- TraceSources, TraceListeners, and more are built-in. Internationalization -- support for tailoring your app to languages other than your own. LIST B: Components not provided by .NET These are not supplied at all by .NET or supplied only as rudimentary elements requiring substantial work to be realized. Splash screen -- a small window present during program startup with your logo, loading messages, etc. Tip of the day -- a mini-tutorial presented one bit at a time each time the user starts your app. Check for available updates -- facility to query a server to see if the user is running the latest version of your app, then provide a simple way to upgrade if a new version is found. Maximize to multiple monitors -- the canonical window allows you to maximize to a single monitor only; in my apps I allow maximizing across multiple monitors with a click. Taskbar notifier -- flash the taskbar when your backgrounded app has new info for the user. Options dialogs -- multi-page dialogs letting the user customize the app settings to his/her own preferences. Progress indicator -- for long running operations give the user feedback on how far there is left to go. Memory gauge -- an indicator (either absolute or percentage) of how much memory is used by your app. LIST C: Stylistic and/or tiny bits of functionality This list includes bits of functionality that are too tiny to merit being called a component, along with stylistic concerns (that admittedly do overlap with the Windows User Experience Interaction Guidelines). Design a form for resizing -- unless you are restricting your form to be a fixed size, use anchors and docking so that it does what is reasonable when enlarged or shrunk by the user. Set tab order on a form -- repeated tab presses by the user should advance from field to field in a logical order rather than the default order in which you added fields. Adjust controls to be aware of operating modes -- When starting a background operation with, for example, a “Go” button, disable that “Go” button until the operation completes. Provide access keys for all menu items (per UXGuide). Provide shortcut keys for commonly used menu items (per UXGuide). Set up some (global or important or common) shortcut keys without associating to menu items. Allow some menu items to be invoked with or without modifier keys (shift, control, alt) where the modifier key is useful to vary the operation slightly. Hook up Escape and Enter on child forms to do what is reasonable. Decorate any library classes with documentation-comments and attributes -- this allows Visual Studio to leverage them for Intellisense and property descriptions. Spell check your code! What else would you include?

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• Keeping video viewing statistics breakdown by video time in a database

  - by Septagram

  I need to keep a number of statistics about the videos being watched, and one of them is what parts of the video are being watched most. The design I came up with is to split the video into 256 intervals and keep the floating-point number of views for each of them. I receive the data as a number of intervals the user watched continuously. The problem is how to store them. There are two solutions I see. Row per every video segment Let's have a database table like this: CREATE TABLE `video_heatmap` ( `id` int(11) NOT NULL AUTO_INCREMENT, `video_id` int(11) NOT NULL, `position` tinyint(3) unsigned NOT NULL, `views` float NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `idx_lookup` (`video_id`,`position`) ) ENGINE=MyISAM Then, whenever we have to process a number of views, make sure there are the respective database rows and add appropriate values to the views column. I found out it's a lot faster if the existence of rows is taken care of first (SELECT COUNT(*) of rows for a given video and INSERT IGNORE if they are lacking), and then a number of update queries is used like this: UPDATE video_heatmap SET views = views + ? WHERE video_id = ? AND position >= ? AND position < ? This seems, however, a little bloated. The other solution I came up with is Row per video, update in transactions A table will look (sort of) like this: CREATE TABLE video ( id INT NOT NULL AUTO_INCREMENT, heatmap BINARY (4 * 256) NOT NULL, ... ) ENGINE=InnoDB Then, upon every time a view needs to be stored, it will be done in a transaction with consistent snapshot, in a sequence like this: If the video doesn't exist in the database, it is created. A row is retrieved, heatmap, an array of floats stored in the binary form, is converted into a form more friendly for processing (in PHP). Values in the array are increased appropriately and the array is converted back. Row is changed via UPDATE query. So far the advantages can be summed up like this: First approach Stores data as floats, not as some magical binary array. Doesn't require transaction support, so doesn't require InnoDB, and we're using MyISAM for everything at the moment, so there won't be any need to mix storage engines. (only applies in my specific situation) Doesn't require a transaction WITH CONSISTENT SNAPSHOT. I don't know what are the performance penalties of those. I already implemented it and it works. (only applies in my specific situation) Second approach Is using a lot less storage space (the first approach is storing video ID 256 times and stores position for every segment of the video, not to mention primary key). Should scale better, because of InnoDB's per-row locking as opposed to MyISAM's table locking. Might generally work faster because there are a lot less requests being made. Easier to implement in code (although the other one is already implemented). So, what should I do? If it wasn't for the rest of our system using MyISAM consistently, I'd go with the second approach, but currently I'm leaning to the first one. But maybe there are some reasons to favour one approach or another?

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• referencing part of the composite primary key

  - by Zavael

  I have problems with setting the reference on database table. I have following structure: CREATE TABLE club( id INTEGER NOT NULL, name_short VARCHAR(30), name_full VARCHAR(70) NOT NULL ); CREATE UNIQUE INDEX club_uix ON club(id); ALTER TABLE club ADD CONSTRAINT club_pk PRIMARY KEY (id); CREATE TABLE team( id INTEGER NOT NULL, club_id INTEGER NOT NULL, team_name VARCHAR(30) ); CREATE UNIQUE INDEX team_uix ON team(id, club_id); ALTER TABLE team ADD CONSTRAINT team_pk PRIMARY KEY (id, club_id); ALTER TABLE team ADD FOREIGN KEY (club_id) REFERENCES club(id); CREATE TABLE person( id INTEGER NOT NULL, first_name VARCHAR(20), last_name VARCHAR(20) NOT NULL ); CREATE UNIQUE INDEX person_uix ON person(id); ALTER TABLE person ADD PRIMARY KEY (id); CREATE TABLE contract( person_id INTEGER NOT NULL, club_id INTEGER NOT NULL, wage INTEGER ); CREATE UNIQUE INDEX contract_uix on contract(person_id); ALTER TABLE contract ADD CONSTRAINT contract_pk PRIMARY KEY (person_id); ALTER TABLE contract ADD FOREIGN KEY (club_id) REFERENCES club(id); ALTER TABLE contract ADD FOREIGN KEY (person_id) REFERENCES person(id); CREATE TABLE player( person_id INTEGER NOT NULL, team_id INTEGER, height SMALLINT, weight SMALLINT ); CREATE UNIQUE INDEX player_uix on player(person_id); ALTER TABLE player ADD CONSTRAINT player_pk PRIMARY KEY (person_id); ALTER TABLE player ADD FOREIGN KEY (person_id) REFERENCES person(id); -- ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id); --this is not working It gives me this error: Error code -5529, SQL state 42529: a UNIQUE constraint does not exist on referenced columns: TEAM in statement [ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id)] As you can see, team table has composite primary key (club_id + id), the person references club through contract. Person has some common attributes for player and other staff types. One club can have multiple teams. Employed person has to have a contract with a club. Player (is the specification of person) - if emplyed - can be assigned to one of the club's teams. Is there better way to design my structure? I thought about excluding the club_id from team's primary key, but I would like to know if this is the only way. Thanks. UPDATE 1 I would like to have the id as team identification only within the club, so multiple teams can have equal id as long as they belong to different clubs. Is it possible? UPDATE 2 updated the naming convention as adviced by philip Some business rules to better understand the structure: One club can have 1..n teams (Main squad, Reserve squad, Youth squad or Team A, Team B... only team can play match, not club) One team belongs to one club only A player is type of person (other types (staff) are scouts, coaches etc so they do not need to belong to specific team, just to the club, if employed) Person can have 0..1 contract with 1 club (that means he is employed or unemployed) Player (if employed) belongs to one team of the club Now thinking about it - moving team_id from player to contract would solve my problem, and it could hold the condition "Player (if employed) belongs to one team of the club", but it would be redundant for other staff types. What do you think?

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• Please clarify how create/update happens against child entities of an aggregate root

  - by christian

  After much reading and thinking as I begin to get my head wrapped around DDD, I am a bit confused about the best practices for dealing with complex hierarchies under an aggregate root. I think this is a FAQ but after reading countless examples and discussions, no one is quite talking about the issue I'm seeing. If I am aligned with the DDD thinking, entities below the aggregate root should be immutable. This is the crux of my trouble, so if that isn't correct, that is why I'm lost. Here is a fabricated example...hope it holds enough water to discuss. Consider an automobile insurance policy (I'm not in insurance, but this matches the language I hear when on the phone w/ my insurance company). Policy is clearly an entity. Within the policy, let's say we have Auto. Auto, for the sake of this example, only exists within a policy (maybe you could transfer an Auto to another policy, so this is potential for an aggregate as well, which changes Policy...but assume it simpler than that for now). Since an Auto cannot exist without a Policy, I think it should be an Entity but not a root. So Policy in this case is an aggregate root. Now, to create a Policy, let's assume it has to have at least one auto. This is where I get frustrated. Assume Auto is fairly complex, including many fields and maybe a child for where it is garaged (a Location). If I understand correctly, a "create Policy" constructor/factory would have to take as input an Auto or be restricted via a builder to not be created without this Auto. And the Auto's creation, since it is an entity, can't be done beforehand (because it is immutable? maybe this is just an incorrect interpretation). So you don't get to say new Auto and then setX, setY, add(Z). If Auto is more than somewhat trivial, you end up having to build a huge hierarchy of builders and such to try to manage creating an Auto within the context of the Policy. One more twist to this is later, after the Policy is created and one wishes to add another Auto...or update an existing Auto. Clearly, the Policy controls this...fine...but Policy.addAuto() won't quite fly because one can't just pass in a new Auto (right!?). Examples say things like Policy.addAuto(VIN, make, model, etc.) but are all so simple that that looks reasonable. But if this factory method approach falls apart with too many parameters (the entire Auto interface, conceivably) I need a solution. From that point in my thinking, I'm realizing that having a transient reference to an entity is OK. So, maybe it is fine to have a entity created outside of its parent within the aggregate in a transient environment, so maybe it is OK to say something like: auto = AutoFactory.createAuto(); auto.setX auto.setY or if sticking to immutability, AutoBuilder.new().setX().setY().build() and then have it get sorted out when you say Policy.addAuto(auto) This insurance example gets more interesting if you add Events, such as an Accident with its PolicyReports or RepairEstimates...some value objects but most entities that are all really meaningless outside the policy...at least for my simple example. The lifecycle of Policy with its growing hierarchy over time seems the fundamental picture I must draw before really starting to dig in...and it is more the factory concept or how the child entities get built/attached to an aggregate root that I haven't seen a solid example of. I think I'm close. Hope this is clear and not just a repeat FAQ that has answers all over the place.

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• Do I must expose the aggregate children as public properties to implement the Persistence ignorance?

  - by xuehua

  Hi all, I'm very glad that i found this website recently, I've learned a lot from here. I'm from China, and my English is not so good. But i will try to express myself what i want to say. Recently, I've started learning about Domain Driven Design, and I'm very interested about it. And I plan to develop a Forum website using DDD. After reading lots of threads from here, I understood that persistence ignorance is a good practice. Currently, I have two questions about what I'm thinking for a long time. Should the domain object interact with repository to get/save data? If the domain object doesn't use repository, then how does the Infrastructure layer (like unit of work) know which domain object is new/modified/removed? For the second question. There's an example code: Suppose i have a user class: public class User { public Guid Id { get; set; } public string UserName { get; set; } public string NickName { get; set; } /// <summary> /// A Roles collection which represents the current user's owned roles. /// But here i don't want to use the public property to expose it. /// Instead, i use the below methods to implement. /// </summary> //public IList<Role> Roles { get; set; } private List<Role> roles = new List<Role>(); public IList<Role> GetRoles() { return roles; } public void AddRole(Role role) { roles.Add(role); } public void RemoveRole(Role role) { roles.Remove(role); } } Based on the above User class, suppose i get an user from the IUserRepository, and add an Role for it. IUserRepository userRepository; User user = userRepository.Get(Guid.NewGuid()); user.AddRole(new Role() { Name = "Administrator" }); In this case, i don't know how does the repository or unit of work can know that user has a new role? I think, a real persistence ignorance ORM framework should support POCO, and any changes occurs on the POCO itself, the persistence framework should know automatically. Even if change the object status through the method(AddRole, RemoveRole) like the above example. I know a lot of ORM can automatically persistent the changes if i use the Roles property, but sometimes i don't like this way because of the performance reason. Could anyone give me some ideas for this? Thanks. This is my first question on this site. I hope my English can be understood. Any answers will be very appreciated.

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• Testing for Adjacent Cells In a Multi-level Grid

  - by Steve

  I'm designing an algorithm to test whether cells on a grid are adjacent or not. The catch is that the cells are not on a flat grid. They are on a multi-level grid such as the one drawn below. Level 1 (Top Level) | - - - - - | | A | B | C | | - - - - - | | D | E | F | | - - - - - | | G | H | I | | - - - - - | Level 2 | -Block A- | -Block B- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | | -Block D- | -Block E- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | . . . . . . This diagram is simplified from my actual need but the concept is the same. There is a top level block with many cells within it (level 1). Each block is further subdivided into many more cells (level 2). Those cells are further subdivided into level 3, 4 and 5 for my project but let's just stick to two levels for this question. I'm receiving inputs for my function in the form of "A8, A9, B7, D3". That's a list of cell Ids where each cell Id has the format (level 1 id)(level 2 id). Let's start by comparing just 2 cells, A8 and A9. That's easy because they are in the same block. private static RelativePosition getRelativePositionInTheSameBlock(String v1, String v2) { RelativePosition relativePosition; if( v1-v2 == -1 ) { relativePosition = RelativePosition.LEFT_OF; } else if (v1-v2 == 1) { relativePosition = RelativePosition.RIGHT_OF; } else if (v1-v2 == -BLOCK_WIDTH) { relativePosition = RelativePosition.TOP_OF; } else if (v1-v2 == BLOCK_WIDTH) { relativePosition = RelativePosition.BOTTOM_OF; } else { relativePosition = RelativePosition.NOT_ADJACENT; } return relativePosition; } An A9 - B7 comparison could be done by checking if A is a multiple of BLOCK_WIDTH and whether B is (A-BLOCK_WIDTH+1). Either that or just check naively if the A/B pair is 3-1, 6-4 or 9-7 for better readability. For B7 - D3, they are not adjacent but D3 is adjacent to A9 so I can do a similar adjacency test as above. So getting away from the little details and focusing on the big picture. Is this really the best way to do it? Keeping in mind the following points: I actually have 5 levels not 2, so I could potentially get a list like "A8A1A, A8A1B, B1A2A, B1A2B". Adding a new cell to compare still requires me to compare all the other cells before it (seems like the best I could do for this step is O(n)) The cells aren't all 3x3 blocks, they're just that way for my example. They could be MxN blocks with different M and N for different levels. In my current implementation above, I have separate functions to check adjacency if the cells are in the same blocks, if they are in separate horizontally adjacent blocks or if they are in separate vertically adjacent blocks. That means I have to know the position of the two blocks at the current level before I call one of those functions for the layer below. Judging by the complexity of having to deal with mulitple functions for different edge cases at different levels and having 5 levels of nested if statements. I'm wondering if another design is more suitable. Perhaps a more recursive solution, use of other data structures, or perhaps map the entire multi-level grid to a single-level grid (my quick calculations gives me about 700,000+ atomic cell ids). Even if I go that route, mapping from multi-level to single level is a non-trivial task in itself.

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• &lsquo;Responsive Web Design with Macaw&rsquo;&ndash; free book updated

  - by ihaynes

  Originally posted on: http://geekswithblogs.net/ihaynes/archive/2014/08/12/lsquoresponsive-web-design-with-macawrsquondash-free-book-updated.aspxThe free book on Macaw by Schonne Eldridge that I mentioned before has been updated. If you’re already subscribed you’ll get alerts for updates. If not the book is well worth getting to start you off with Macaw. If you haven’t tried Macaw yet, heck, you’re missing something big. The book is available from http://schonne.com/macaw Macaw itself is at http://macaw.co

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• How to pass XML to DB using XMLTYPE

  - by James Taylor

  Probably not a common use case but I have seen it pop up from time to time. The question how do I pass XML from a queue or web service and insert it into a DB table using XMLTYPE.In this example I create a basic table with the field PAYLOAD of type XMLTYPE. I then take the full XML payload of the web service and insert it into that database for auditing purposes.I use SOA Suite 11.1.1.2 using composite and mediator to link the web service with the DB adapter.1. Insert Database Objects Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} --Create XML_EXAMPLE_TBL Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} CREATE TABLE XML_EXAMPLE_TBL (PAYLOAD XMLTYPE); Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} --Create procedure LOAD_TEST_XML Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} CREATE or REPLACE PROCEDURE load_test_xml (xmlFile in CLOB) IS   BEGIN     INSERT INTO xml_example_tbl (payload) VALUES (XMLTYPE(xmlFile));   --Handle the exceptions EXCEPTION   WHEN OTHERS THEN     raise_application_error(-20101, 'Exception occurred in loadPurchaseOrder procedure :'||SQLERRM || ' **** ' || xmlFile ); END load_test_xml; / 2. Creating New SOA Project TestXMLTYPE in JDeveloperIn JDeveloper either create a new Application or open an existing Application you want to put this work.Under File -> New -> SOA Tier -> SOA Project   Provide a name for the Project, e.g. TestXMLType Choose Empty Composite When selected Empty Composite click Finish.3. Create Database Connection to Stored ProcedureA Blank composite will be displayed. From the Component Palette drag a Database Adapter to the  External References panel. and configure the Database Adapter Wizard to connect to the DB procedure created above.Provide a service name InsertXML Select a Database connection where you installed the table and procedure above. If it doesn't exist create a new one. Select Call a Stored Procedure or Function then click NextChoose the schema you installed your Procedure in step 1 and query for the LOAD_TEST_XML procedure.Click Next for the remaining screens until you get to the end, then click Finish to complete the database adapter wizard.4. Create the Web Service InterfaceDownload this sample schema that will be used as the input for the web service. It does not matter what schema you use this solution will work with any. Feel free to use your own if required. singleString.xsd Drag from the component palette the Web Service to the Exposed Services panel on the component.Provide a name InvokeXMLLoad for the service, and click the cog icon.Click the magnify glass for the URL to browse to the location where you downloaded the xml schema above.  Import the schema file by selecting the import schema iconBrowse to the location to where you downloaded the singleString.xsd above.Click OK for the Import Schema File, then select the singleString node of the imported schema.Accept all the defaults until you get back to the Web Service wizard screen. The click OK. This step has created a WSDL based on the schema we downloaded earlier.Your composite should now look something like this now.5. Create the Mediator Routing Rules Drag a Mediator component into the middle of the Composite called ComponentsGive the name of Route, and accept the defaultsLink the services up to the Mediator by connecting the reference points so your Composite looks like this.6. Perform Translations between Web Service and the Database Adapter.From the Composite double click the Route Mediator to show the Map Plan. Select the transformation icon to create the XSLT translation file.Choose Create New Mapper File and accept the defaults.From the Component Palette drag the get-content-as-string component into the middle of the translation file.Your translation file should look something like thisNow we need to map the root element of the source 'singleString' to the XMLTYPE of the database adapter, applying the function get-content-as-string.To do this drag the element singleString to the left side of the function get-content-as-string and drag the right side of the get-content-as-string to the XMLFILE element of the database adapter so the mapping looks like this. You have now completed the SOA Component you can now save your work, deploy and test.When you deploy I have assumed that you have the correct database configurations in the WebLogic Console based on the connection you setup connecting to the Stored Procedure. 7. Testing the ApplicationOpen Enterprise Manager and navigate to the TestXMLTYPE Composite and click the Test button. Load some dummy variables in the Input Arguments and click the 'Test Web Service' buttonOnce completed you can run a SQL statement to check the install. In this instance I have just used JDeveloper and opened a SQL WorksheetSQL Statement Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} select * from xml_example_tbl; Result, you should see the full payload in the result.

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• How can Google publish Dalvik as Java-language compatible since Java is a trademark?

  - by Bruno Chagas

  According to this thread Java and JVM license You can write a compiler that implements the Java Language Specification or write a JVM that implements the Java Virtual Machine specification, but when you officially want to call it "Java", you have to prove it is compatible by passing the tests of the TCK (technology compatibility kit) and pay for a license from Oracle. So, how can Google (or any other java implementation for that matter) claims that Dalvik is a Java virtual machine?

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• Dependently typed language best suited to “real world” programming?

  - by Kim

  Which dependently typed programming languages could be used for real world application development? I will mostly be writing toy applications at first, after that maybe web development or a simple DBMS. These are some points, that I think are important: documentation example programs a good/big standard library an easy to use foreign function interface a community of people using the language for real world tasks tool support

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• What's the point of adding Unicode identifier support to various language implementations?

  - by Egor Tensin

  I personally find reading code full of Unicode identifiers confusing. In my opinion, it also prevents the code from being easily maintained. Not to mention all the effort required for authors of various translators to implement such support. I also constantly notice the lack (or the presence) of Unicode identifiers support in the lists of (dis)advantages of various language implementations (like it really matters). I don't get it: why so much attention?

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• Is sexist humor more common in the Ruby community than other language communities? [closed]

  - by Andrew Grimm

  I've heard of more cases of sexist humor in the Ruby community, such as the sqoot's "women as perk" and toplessness in advertising, than in all the other programming language communities combined. Is this merely because I'm in the Ruby community, and therefore are more likely to hear about incidents in the Ruby community, or is it because there's a higher rate of sexist humor in the Ruby community compared to, say, the C community?

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• A big flat text file or a HTML site for language documentation?

  - by Bad Sector

  A project of mine is a small embeddable Tcl-like scripting language, LIL. While i'm mostly making it for my own use, i think it is interesting enough for others to use, so i want it to have a nice (but not very "wordy") documentation. So far i'm using a single flat readme.txt file. It explains the language's syntax, features, standard functions, how to use the C API, etc. Also it is easy to scan and read in almost every environment out there, from basic text-only terminals to full-fledged high-end graphical desktop environments. However, while i tried to keep things nicely formatted (as much as this is possible in plain text), i still think that being a big (and growing) wall of text, it isn't as easy on the eyes as it could be. Also i feel that sometimes i'm not writing as much as i want in order to avoid expanding the text too much. So i thought i could use another project of mine, QuHelp, which is basically a help site generator for sites like this one with a sidebar that provides a tree of topics/subtopics and offline full text search. With this i can use HTML to format the documentation and if i use QuHelp for some other project that uses LIL, i can import LIL's documentation as part of the other project's documentation. However converting the existing documentation to QuHelp/HTML isn't a small task, especially when it comes to functions (i'll need to put more detail on them than what currently exists in the readme.txt file). Also it loses the wide range of availability that it currently has (even if QuHelp's generated code degrades gracefully down to console-only web browsers, plain text is readable from everywhere, including from popular editors such as Vim and Emacs - i had someone once telling me that he likes LIL's documentation because it is readable without leaving his editor). So, my question is simply this: should i keep the documentation as it is now in the form of a single readme.txt file or should i convert it to something like the site i mentioned above? There is also the option to do both, but i'm not sure if i'll be able to always keep them in sync or if it is worth the effort. After asking around in IRC i've got mixed answers: some liked the wide availability of the single text file, others said that it is looks as bad as a man page (personally i don't mind that - i can read man pages just fine - but other people might have issues reading them). What do you think?

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• New Book! SQL Server 2012 Integration Services Design Patterns!

  - by andyleonard

  SQL Server 2012 Integration Services Design Patterns has been released! The book is done and available thanks to the hard work and dedication of a great crew: Michelle Ufford ( Blog | @sqlfool ) – co-author Jessica M. Moss ( Blog | @jessicammoss ) – co-author Tim Mitchell ( Blog | @tim_mitchell ) – co-author Matt Masson ( Blog | @mattmasson ) – co-author Donald Farmer ( Blog | @donalddotfarmer ) – foreword David Stein ( Blog | @made2mentor ) – technical editing Mark Powers – editing Jonathan Gennick...(read more)

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• Teaching "web design/development" to high-school home-school group. Good sources?

  - by anonymous coward

  I may soon begin teaching a "web design and development" class for a home-school co-op group. Any suggestions for "course" material? My first thought was to work through the Opera Web Standards Curriculum, but am interested in hearing about possible alternatives or suggestions that better cover the "very basics" of getting started with designing and developing web pages. Not necessarily looking for topics, so much as existing resources. Thanks so much for your input!

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