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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • Forcing an External Activation with Service Broker

    - by Davide Mauri
    In these last days I’ve been working quite a lot with Service Broker, a technology I’m really happy to work with, since it can give a lot of satisfaction. The scale-out solution one can easily build is simply astonishing. I’m helping a company to build a very scalable and – yet almost inexpensive – invoicing system that has to be able to scale out using commodity hardware. To offload the work from the main server to satellite “compute nodes” (yes, I’ve borrowed this term from PDW) we’re using Service Broker and the External Activator application available in the SQL Server Feature Pack. For those who are not used to work with SSB, the External Activation is a feature that allows you to intercept the arrival of a message in a queue right from your application code. http://msdn.microsoft.com/en-us/library/ms171617.aspx (Look for “Event-Based Activation”) In order to make life even more easier, Microsoft released the External Activation application that saves you even from writing even this code. http://blogs.msdn.com/b/sql_service_broker/archive/tags/external+activator/ The External Activator application can be configured to execute your own application so that each time a message – an invoice in my case – arrives in the target queue, the invoking application is executed and the invoice is calculated. The very nice feature of External Activator is that it can automatically execute as many configured application in order to process as many messages as your system can handle.  This also a lot of create a scale-out solution, leaving to the developer only a fraction of the problems that usually came with asynchronous programming. Developers are also shielded from Service Broker since everything can be encapsulated in Stored Procedures, so that – for them – developing such scale-out asynchronous solution is not much more complex than just executing a bunch of Stored Procedures. Now, if everything works correctly, you don’t have to bother of anything else. You put messages in the queue and your application, invoked by the External Activator, process them. But what happen if for some reason your application fails to process the messages. For examples, it crashes? The message is safe in the queue so you just need to process it again. But your application is invoked by the External Activator application, so now the question is, how do you wake up that app? Service Broker will engage the activation process only if certain conditions are met: http://msdn.microsoft.com/en-us/library/ms171601.aspx But how we can invoke the activation process manually, without having to wait for another message to arrive (the arrival of a new message is a condition that can fire the activation process)? The “trick” is to do manually with the activation process does: sending a system message to a queue in charge of handling External Activation messages: declare @conversationHandle uniqueidentifier; declare @n xml = N' <EVENT_INSTANCE>   <EventType>QUEUE_ACTIVATION</EventType>   <PostTime>' + CONVERT(CHAR(24),GETDATE(),126) + '</PostTime>   <SPID>' + CAST(@@SPID AS VARCHAR(9)) + '</SPID>   <ServerName>[your_server_name]</ServerName>   <LoginName>[your_login_name]</LoginName>   <UserName>[your_user_name]</UserName>   <DatabaseName>[your_database_name]</DatabaseName>   <SchemaName>[your_queue_schema_name]</SchemaName>   <ObjectName>[your_queue_name]</ObjectName>   <ObjectType>QUEUE</ObjectType> </EVENT_INSTANCE>' begin dialog conversation     @conversationHandle from service        [<your_initiator_service_name>] to service          '<your_event_notification_service>' on contract         [http://schemas.microsoft.com/SQL/Notifications/PostEventNotification] with     encryption = off,     lifetime = 6000 ; send on conversation     @conversationHandle message type     [http://schemas.microsoft.com/SQL/Notifications/EventNotification] (@n) ;     end conversation @conversationHandle; That’s it! Put the code in a Stored Procedure and you can add to your application a button that says “Force Queue Processing” (or something similar) in order to start the activation process whenever you need it (which should not occur too frequently but it may happen). PS I know that the “fire-and-forget” (ending the conversation without waiting for an answer) technique is not a best practice, but in this case I don’t see how it can hurts so I decided to stay very close to the KISS principle []

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  • Trouble compiling MonoDevelop 4 on Ubuntu 12.04

    - by Mehran
    I'm trying to compile the latest version of MonoDevelop (4.0.9) on my Ubuntu 12.04 and I'm facing errors I can not overcome. Here are my machine's configurations: OS: Ubuntu 12.04 64-bit Mono: version 3.0.12 And here are the commands that I ran to download MonoDevelop: $ git clone git://github.com/mono/monodevelop.git $ cd monodevelop $ git submodule init $ git submodule update And afterwards to compile: ./configure --prefix=`pkg-config --variable=prefix mono` --profile=stable make Then I faced the following errors (sorry if it's long): ... Building ./Main.sln xbuild /verbosity:quiet /nologo /property:CodePage=65001 ./Main.sln /property:Configuration=Debug /home/mehran/git/monodevelop/main/Main.sln: warning : Don't know how to handle GlobalSection MonoDevelopProperties.Debug, Ignoring. : warning CS1685: The predefined type `System.Runtime.CompilerServices.ExtensionAttribute' is defined in multiple assemblies. Using definition from `mscorlib' /usr/lib/mono/4.0/Microsoft.CSharp.targets: error : Compiler crashed with code: 1. : warning CS1685: The predefined type `System.Runtime.CompilerServices.ExtensionAttribute' is defined in multiple assemblies. Using definition from `mscorlib' Editor/IDocument.cs(98,30): warning CS0419: Ambiguous reference in cref attribute `GetOffset'. Assuming `ICSharpCode.NRefactory.Editor.IDocument.GetOffset(int, int)' but other overloads including `ICSharpCode.NRefactory.Editor.IDocument.GetOffset(ICSharpCode.NRefactory.TextLocation)' have also matched PatternMatching/INode.cs(51,37): warning CS1574: XML comment on `ICSharpCode.NRefactory.PatternMatching.PatternExtensions.Match(this ICSharpCode.NRefactory.PatternMatching.INode, ICSharpCode.NRefactory.PatternMatching.INode)' has cref attribute `PatternMatching.Match.Success' that could not be resolved TextLocation.cs(35,23): warning CS0419: Ambiguous reference in cref attribute `Editor.IDocument.GetOffset'. Assuming `ICSharpCode.NRefactory.Editor.IDocument.GetOffset(int, int)' but other overloads including `ICSharpCode.NRefactory.Editor.IDocument.GetOffset(ICSharpCode.NRefactory.TextLocation)' have also matched TypeSystem/FullTypeName.cs(87,24): warning CS0419: Ambiguous reference in cref attribute `ReflectionHelper.ParseReflectionName'. Assuming `ICSharpCode.NRefactory.TypeSystem.ReflectionHelper.ParseReflectionName(string)' but other overloads including `ICSharpCode.NRefactory.TypeSystem.ReflectionHelper.ParseReflectionName(string, ref int)' have also matched TypeSystem/INamedElement.cs(59,24): warning CS0419: Ambiguous reference in cref attribute `ReflectionHelper.ParseReflectionName'. Assuming `ICSharpCode.NRefactory.TypeSystem.ReflectionHelper.ParseReflectionName(string)' but other overloads including `ICSharpCode.NRefactory.TypeSystem.ReflectionHelper.ParseReflectionName(string, ref int)' have also matched TypeSystem/IType.cs(50,26): warning CS1584: XML comment on `ICSharpCode.NRefactory.TypeSystem.IType' has syntactically incorrect cref attribute `IEquatable{IType}.Equals(IType)' TypeSystem/IType.cs(319,38): warning CS1580: Invalid type for parameter `1' in XML comment cref attribute `GetMethods(Predicate{IUnresolvedMethod}, GetMemberOptions)' TypeSystem/TypeKind.cs(61,17): warning CS1580: Invalid type for parameter `1' in XML comment cref attribute `IType.GetNestedTypes(Predicate{ITypeDefinition}, GetMemberOptions)' TypeSystem/SpecialType.cs(50,52): warning CS1580: Invalid type for parameter `1' in XML comment cref attribute `IType.GetNestedTypes(Predicate{ITypeDefinition}, GetMemberOptions)' /usr/lib/mono/4.0/Microsoft.CSharp.targets: error : Compiler crashed with code: 1.

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  • MySQL Connect 9 Days Away – Optimizer Sessions

    - by Bertrand Matthelié
    72 1024x768 Normal 0 false false false EN-US X-NONE X-NONE /* 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-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Following my previous blog post focusing on InnoDB talks at MySQL Connect, let us review today the sessions focusing on the MySQL Optimizer: Saturday, 11.30 am, Room Golden Gate 6: MySQL Optimizer Overview—Olav Sanstå, Oracle The goal of MySQL optimizer is to take a SQL query as input and produce an optimal execution plan for the query. This session presents an overview of the main phases of the MySQL optimizer and the primary optimizations done to the query. These optimizations are based on a combination of logical transformations and cost-based decisions. Examples of optimization strategies the presentation covers are the main query transformations, the join optimizer, the data access selection strategies, and the range optimizer. For the cost-based optimizations, an overview of the cost model and the data used for doing the cost estimations is included. Saturday, 1.00 pm, Room Golden Gate 6: Overview of New Optimizer Features in MySQL 5.6—Manyi Lu, Oracle Many optimizer features have been added into MySQL 5.6. This session provides an introduction to these great features. Multirange read, index condition pushdown, and batched key access will yield huge performance improvements on large data volumes. Structured explain, explain for update/delete/insert, and optimizer tracing will help users analyze and speed up queries. And last but not least, the session covers subquery optimizations in Release 5.6. Saturday, 7.00 pm, Room Golden Gate 4: BoF: Query Optimizations: What Is New and What Is Coming? This BoF presents common techniques for query optimization, covers what is new in MySQL 5.6, and provides a discussion forum in which attendees can tell the MySQL optimizer team which optimizations they would like to see in the future. Sunday, 1.15 pm, Room Golden Gate 8: Query Performance Comparison of MySQL 5.5 and MySQL 5.6—Øystein Grøvlen, Oracle MySQL Release 5.6 contains several improvements in the query optimizer that create improved performance for complex queries. This presentation looks at how MySQL 5.6 improves the performance of many of the queries in the DBT-3 benchmark. Based on the observed improvements, the presentation discusses what makes the specific queries perform better in Release 5.6. It describes the relevant new optimization techniques and gives examples of the types of queries that will benefit from these techniques. Sunday, 4.15 pm, Room Golden Gate 4: Powerful EXPLAIN in MySQL 5.6—Evgeny Potemkin, Oracle The EXPLAIN command of MySQL has long been a very useful tool for understanding how MySQL will execute a query. Release 5.6 of the MySQL database offers several new additions that give more-detailed information about the query plan and make it easier to understand at the same time. This presentation gives an overview of new EXPLAIN features: structured EXPLAIN in JSON format, EXPLAIN for INSERT/UPDATE/DELETE, and optimizer tracing. Examples in the session give insights into how you can take advantage of the new features. They show how these features supplement and relate to each other and to classical EXPLAIN and how and why the MySQL server chooses a particular query plan. You can check out the full program here as well as in the September edition of the MySQL newsletter. Not registered yet? You can still save US$ 300 over the on-site fee – Register Now!

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  • Single Instance of Child Forms in MDI Applications

    - by Akshay Deep Lamba
    In MDI application we can have multiple forms and can work with multiple forms i.e. MDI childs at a time but while developing applications we don't pay attention to the minute details of memory management. Take this as an example, when we develop application say preferably an MDI application, we have multiple child forms inside one parent form. On MDI parent form we would like to have menu strip and tab strip which in turn calls other forms which build the other parts of the application. This also makes our application looks pretty and eye-catching (not much actually). Now on a first go when a user clicks a menu item or a button on a tab strip an application initialize a new instance of a form and shows it to the user inside the MDI parent, if a user again clicks the same button the application creates another new instance for the form and presents it to the user, this will result in the un-necessary usage of the memory. Therefore, if you wish to have your application to prevent generating new instances of the forms then use the below method which will first check if the the form is visible among the list of all the child forms and then compare their types, if the form types matches with the form we are trying to initialize then the form will get activated or we can say it will be bring to front else it will be initialize and set visible to the user in the MDI parent window. The method we are using: private bool CheckForDuplicateForm(Form newForm) { bool bValue = false; foreach (Form frm in this.MdiChildren) { if (frm.GetType() == newForm.GetType()) { frm.Activate(); bValue = true; } } return bValue; } Usage: First we need to initialize the form using the NEW keyword ReportForm ReportForm = new ReportForm(); We can now check if there is another form present in the MDI parent. Here, we will use the above method to check the presence of the form and set the result in a bool variable as our function return bool value. bool frmPresent = CheckForDuplicateForm(Reportfrm); Once the above check is done then depending on the value received from the method we can set our form. if (frmPresent) return; else if (!frmPresent) { Reportfrm.MdiParent = this; Reportfrm.Show(); } In the end this is the code you will have at you menu item or tab strip click: ReportForm Reportfrm = new ReportForm(); bool frmPresent = CheckForDuplicateForm(Reportfrm); if (frmPresent) return; else if (!frmPresent) { Reportfrm.MdiParent = this; Reportfrm.Show(); }

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  • A few questions about integrating AudioKinetic Wwise and Unity

    - by SaldaVonSchwartz
    I'm new to Wwise and to using it with Unity, and though I have gotten the integration to work, I'm still dealing with some loose ends and have a few questions: (I'm on Unity 4.3 as of now but I think it shouldn't make any difference) The base path: The Wwise documentation implies you set this in the AkGlobalSoundEngineInitializer basePath public ivar, which is exposed to the editor. However, I found that this variable is not really used. Instead, the path is hardcoded to /Audio/GeneratedSoundBanks in AkBankPath. I had to modify both scripts to actually look in the path that I set in the editor property. What's the deal with this? Just sloppyness or am I missing something? Also about paths: since I'm on Mac, I'm using Unity natively under OS X and in tadem, the Wwise authoring tool via VMWare and I share the OS X Unity project folder so I can generate the soundbanks into the assets folder. However, the authoring tool (downloaded the latest one for Windows) doesn't automatically generate any "platform-specific" subfolders for my wwise files. That is, again, the Unity integration scripts assume the path to be /Audio/GeneratedSoundBanks/<my-platform>/ which in my case would be Mac (I set the authoring tool to generate for Mac). The documentation says wwise will automatically generate the platform-specific folders but it just dumps all the stuff in GeneratedSoundBanks. Am I missing some setting? cause right now I just manually create the /Mac folder. The C# methods AkSoundEngine.PostEvent and AkSoundEngine.LoadBank for instance, have a few overloads, including ones where I can refer to the soundbanks or events by their ID. However, if I try to use these, for instance: AkSoundEngine.LoadBank(, AkSoundEngine.AK_DEFAULT_POOL_ID) where the int I got from the .h header, I get Ak_Fail. If I use the overloads that reference the objects by string name then it works. What gives? Converting the ID header to C#: The integration comes with a C# script that seems to fork a process to call Python in turn to covert the C++ header into a C# script. This always fails unless I manually execute the Python script myself from outside Unity. Might be a permissions thing, but has anyone experienced this? The Profiler: I set up the Unity player to run in the background and am using the "Profile" version of the plugin. However, when I start the Unity OS X standalone app, the profiler in VMWare does not see it. This I'm thinking might just be that I'm trying to see a running instance of the sound engine inside an OS X binary from a Windows virtual machine. But I'm just wondering if anyone has gotten the Windows profiler to see an OS X Unity binary. Different versions of the integration plugin: It's not clear to me from the documentation whether I have to manually (or write a script to do it) remove the "Profile" version and install the "Release" version when I'm going to do a Release build or if I should install both version in Unity and it'll select the right one. Thanks!

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  • SQL SERVER – Columnstore Index and sys.dm_db_index_usage_stats

    - by pinaldave
    As you know I have been writing on Columnstore Index for quite a while. Recently my friend Vinod Kumar wrote about  SQL Server 2012: ColumnStore Characteristics. A fantastic read on the subject if you have yet not caught up on that subject. After the blog post I called him and asked what should I write next on this subject. He suggested that I should write on DMV script which I have prepared related to Columnstore when I was writing our SQL Server Questions and Answers book. When we were writing this book SQL Server 2012 CTP versions were available. I had written few scripts related to SQL Server columnstore Index. I like Vinod’s idea and I decided to write about DMV, which we did not cover in the book as SQL Server 2012 was not released yet. We did not want to talk about the product which was not yet released. The first script which I had written was with DMV - sys.column_store_index_stats. This DMV was displaying the statistics of the columnstore indexes. When I attempted to run it on SQL Server 2012 RTM it gave me error suggesting that this DMV does not exists. Here is the script which I ran: SELECT * FROM sys.column_store_index_stats; It generated following error: Msg 208, Level 16, State 1, Line 1 Invalid object name ‘column_store_index_stats’. I was pretty confident that this DMV was available when I had written the scripts. The next reaction was to type ‘sys.’ only in SSMS and wait for intelisense to popup DMV list. I scrolled down and noticed that above said DMV did not exists there as well. Now this is not bug or missing feature. This was indeed something can happen because the version which I was practicing was early CTP version. If you go to the page of the DMV here, it clearly stats notice on the top of the page. This documentation is for preview only, and is subject to change in later releases. Now this was not alarming but my next thought was if this DMV is not there where can I find the information which this DMV was providing. Well, while I was thinking about this, I noticed that my another friend Balmukund Lakhani was online on personal messenger. Well, Balmukund is “Know All” kid. I have yet to find situation where I have not got my answers from him. I immediately pinged him and asked the question regarding where can I find information of ‘column_store_index_stats’. His answer was very abrupt but enlightening for sure. Here is our conversation: Pinal: Where can I find information of column_store_index_stats? Balmukund: Assume you have never worked with CTP before and now try to find the information which you are trying to find. Honestly  it was fantastic response from him. I was confused as I have played extensively with CTP versions of SQL Server 2012. Now his response give me big hint. I should have not looked for DMV but rather should have focused on what I wanted to do. I wanted to retrieve the statistics related to the index. In SQL Server 2008/R2, I was able to retrieve the statistics of the index from the DMV - sys.dm_db_index_usage_stats. I used the same DMV on SQL Server 2012 and it did retrieved the necessary information for me. Here is the updated script which gave me all the necessary information I was looking for. Matter of the fact, if I have used my earlier SQL Server 2008 R2 script this would have just worked fine. SELECT DB_NAME(Database_ID) DBName, SCHEMA_NAME(schema_id) AS SchemaName, OBJECT_NAME(ius.OBJECT_ID) ObjName, i.type_desc, i.name, user_seeks, user_scans, user_lookups, user_updates,* FROM sys.dm_db_index_usage_stats ius INNER JOIN sys.indexes i ON i.index_id = ius.index_id AND ius.OBJECT_ID = i.OBJECT_ID INNER JOIN sys.tables t ON t.OBJECT_ID = i.OBJECT_ID GO Let us see the resultset of above query. You will notice that column Type_desc describes the type of the index. You can additionally write WHERE condition on the column and only retrieve only selected type of Index. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Silverlight Cream for May 20, 2010 -- #866

    - by Dave Campbell
    In this Issue: Mike Snow, Victor Gaudioso, Ola Karlsson, Josh Twist(-2-), Yavor Georgiev, Jeff Wilcox, and Jesse Liberty. Shoutouts: Frank LaVigne has an interesting observation on his site: The Big Take-Away from MIX10 Rishi has updated all his work including a release of nRoute to the latest bits: nRoute Samples Revisited Looks like I posted one of Erik Mork's links two days in a row :) ... that's because I meant to post this one: Silverlight Week – How to Choose a Mobile Platform Just in case you missed it (and for me to find it easy), Scott Guthrie has an excellent post up on Silverlight 4 Tools for VS 2010 and WCF RIA Services Released From SilverlightCream.com: Silverlight Tip of the Day #23 – Working with Strokes and Shapes Mike Snow's Silverlight Tip of the Day number 23 is up and about Strokes and Shapes -- as in dotted and dashed lines. New Silverlight Video Tutorial: How to Fire a Visual State based upon the value of a Boolean Variable Victor Gaudioso's latest video tutorial is up and is on selecting and firing a video state based on a boolean... project included. Simultaneously calling multiple methods on a WCF service from silverlight Ola Karlsson details a problem he had where he was calling multiple WCF services to pull all his data and had problems... turns out it was a blocking call and he found the solution in the forums and details it all out for us... actually, a search at SilverlightCream.com would have found one of the better posts listed once you knew the problem :) Securing Your Silverlight Applications Josh Twist has an article in MSDN on Silverlight Security. He talks about Windows, forms, and .NET authorization then WCF, WCF Data, cross domain and XAP files. He also has some good external links. Template/View selection with MEF in Silverlight Josh Twist points out that this next article is just a simple demonstration, but he's discussing, and provides code for, a MEF-driven ViewModel navigation scheme with animation on the navigation. Workaround for accessing some ASMX services from Silverlight 4 Are you having problems hitting you asmx web service with Silverlight 4? Yeah... others are too! Yavor Georgiev at the Silverlight Web Services Team blog has a post up about it... why it's a sometimes problem and a workaround for it. Using Silverlight 4 features to create a Zune-like context menu Jeff Wilcox used Silverlight 4 and the Toolkit to create some samples of menus, then demonstrates a duplication of the Zune menu. You Already Are A Windows Phone 7 Programmer Jesse Liberty is demonstrating the fact that Silverlight developers are WP7 developers by creating a Silverlight and a WP7 app side by side using the same code... this is a closer look at the Silverlight TV presentation he did. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Working with Reporting Services Filters–Part 1

    - by smisner
    There are two ways that you can filter data in Reporting Services. The first way, which usually provides a faster performance, is to use query parameters to apply a filter using the WHERE clause in a SQL statement. In that case, the structure of the filter depends upon the syntax recognized by the source database. Another way to filter data in Reporting Services is to apply a filter to a dataset, data region, or a group. Using this latter method, you can even apply multiple filters. However, the use of filter operators or the setup of multiple filters is not always obvious, so in this series of posts, I'll provide some more information about the configuration of filters. First, why not use query parameters exclusively for filtering? Here are a few reasons: You might want to apply a filter to part of the report, but not all of the report. Your dataset might retrieve data from a stored procedure, and doesn't allow you to pass a query parameter for filtering purposes. Your report might be set up as a snapshot on the report server and, in that case, cannot be dynamically filtered based on a query parameter. Next, let's look at how to set up a report filter in general. The process is the same whether you are applying the filter to a dataset, data region, or a group. When you go to the Filters page in the Properties dialog box for whichever of these items you selected (dataset, data region, group), you click the Add button to create a new filter. The interface looks like this: The Expression field is usually a field in the dataset, so to make it easier for you to make a selection,the drop-down list displays all of the current dataset fields. But notice the expression button to the right, which means that you can set up any type of expression-not just a dataset field. To the right of the expression button, you'll find a data type drop-down list. It's important to specify the correct data type for the field or expression you're using. Now for the operators. Here's a list of the options that you have: This Operator Performs This Action =, <>, >, >=, <, <=, Like Compares expression to value Top N, Bottom N Compares expression to Top (Bottom) set of N values (N = integer) Top %, Bottom % Compares expression to Top (Bottom) N percent of values (N = integer or float) Between Determines whether expression is between two values, inclusive In Determines whether expression is found in list of values Last, the Value is what you're comparing to the expression using the operator. The construction of a filter using some operators (=, <>, >, etc.) is fairly simple. If my dataset (for AdventureWorks data) has a Category field, and I have a parameter that prompts the user for a single category, I can set up a filter like this: Expression Data Type Operator Value [Category] Text = [@Category] But if I set the parameter to accept multiple values, I need to change the operator from = to In, just as I would have to do if I were using a query parameter. The parameter expression, [@Category], which translates to =Parameters!Category.Value, doesn’t need to change because it represents an array as soon as I change the parameter to allow multiple values. The “In” operator requires an array. With that in mind, let’s consider a variation on Value. Let’s say that I have a parameter that prompts the user for a particular year – and for simplicity’s sake, this parameter only allows a single value, and I have an expression that evaluates the previous year based on the user’s selection. Then I want to use these two values in two separate filters with an OR condition. That is, I want to filter either by the year selected OR by the year that was computed. If I create two filters, one for each year (as shown below), then the report will only display results if BOTH filter conditions are met – which would never be true. Expression Data Type Operator Value [CalendarYear] Integer = [@Year] [CalendarYear] Integer = =Parameters!Year.Value-1 To handle this scenario, we need to create a single filter that uses the “In” operator, and then set up the Value expression as an array. To create an array, we use the Split function after creating a string that concatenates the two values (highlighted in yellow) as shown below. Expression Data Type Operator Value =Cstr(Fields!CalendarYear.Value) Text In =Split( CStr(Parameters!Year.Value) + ”,” + CStr(Parameters!Year.Value-1) , “,”) Note that in this case, I had to apply a string conversion on the year integer so that I could concatenate the parameter selection with the calculated year. Pay attention to the second argument of the Split function—you must use a comma delimiter for the result to work correctly with the In operator. I also had to change the Expression value from [CalendarYear] (or =Fields!CalendarYear.Value) so that the expression would return a string that I could compare with the values in the string array. More fun with filter expressions in future posts!

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  • My Package Version Number Appears Greater Yet apt-get Doesn't Select It

    - by nutznboltz
    Backstory: It was determined that when using lxc container VMs the Nagios nrpe shutdown script when run on the host of the containers would kill the nrpe processes inside the containers. This was remediated by changing the script to use pidfiles instead of searching the process table for the nrpe process. Regrettably start-stop-daemon is a C program that resulted from translating a Perl script and it shows. There are far too many global varibles in start-stop-daemon.c and although there are some nice blocks of comments there are far to few comments that explain the intent behind variable names such as "schedule" (the string "schedule" appears in many contexts.) The manual page for start-stop-daemon strongly suggests that unless you use the "--retry" option the start-stop-daemon program may return before the process it sent a signal to actually calls exit() and terminates, however it doesn't actually state this in plain English. The obtuseness of start-stop-daemon is most likely the reason that the "fixed" version of the script includes a dubious comment indicating that sometimes the pid file has not been removed. I can easily see why someone would not understand that he left the --retry option missing. This bug also causes failures when the script is given the "restart" option; the nrpe daemon will shutdown but not start up again. Did I mention that since applying the update our nrpe servers started crashing over and over? Repairing this is why I am doing this work. I have been working on remediating the fix. You can see my current work in this PPA. Actual Question: The upstream version number of nagios-nrpe-server in lucid-updates is 2.12-4ubuntu1.10.04.1 My PPA uses this version number 2.12-4ubuntu1.10.04.1.1~ppa1~lucid1 I check the rules here and use this test program and I am lead to believe that the version number I use in my PPA is greater than the one in lucid-updates yet when I ran: sudo add-apt-repository ppa:nutznboltz/nrpe-unbreak-lp-600941 sudo apt-get update sudo aptitiude dist-upgrade The replacement package was not installed. I was able to install it using sudo aptitude install nagios-nrpe-server=2.12-4ubuntu1.10.04.1.1~ppa1~lucid1 Can anyone explain this behavior? Why didn't my version number appear greater to "aptitude dist-upgrade"? Thanks $ cat /etc/apt/preferences Package: * Pin: release a=lucid-backports Pin-Priority: 400 Package: * Pin: release a=lucid-security Pin-Priority: 990 Package: * Pin: release a=lucid-updates Pin-Priority: 900 Package: * Pin: release a=lucid-proposed Pin-Priority: 400 $ ls /etc/apt/preferences.d/ $ Should not make any difference as a PPA cannot be in any of those pockets. I went ahead and bumped the version number in the PPA to 2.12-4ubuntu1.10.04.2~ppa1~lucid1. I'll see if that makes a difference. I do notice that lintian complains: W: nagios-nrpe-server: debian-revision-not-well-formed 2.12-4ubuntu1.10.04.2~ppa1~lucid1

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  • JavaScript in different browsers

    - by PointsToShare
    Adventures with JavaScript rendered in IE 8, Chrome 15, and Firefox 8.0 I have written a little monogram about the advantages of Math and wrote a few JavaScript applications to demonstrate them. I was a bit careless and used elements on the page in my JavaScript without using any of the GetElementsByXXXX methods to identify them.  Say I had a text box named tbSeqNum into which I entered a number to be used in a computation. In my code I simply referred to its value by using it directly. Like here: Function Blah() {                 return tbSeqNum.value; } This ran fine in IE8. In IE, the elements are available as global variables. This is not the case in either Firefox or Chrome. In there one has to create the variable and only then use it. Assuming I also used tbSeqNum as the element’s ID, this works: Function Blah() {                 return GetElementById(“tbSeqNum”).value; } Naturally this corrected function also works in IE, so be warned. Also, coming from windows programming (I am long in the tooth and programmed long before the internet), I have a habit of putting an “Exit” button on my pages and setting their onclick to: onclick=”window.close()”. Again, this works fine in IE. In Firefox and chrome, it does not! There you can only close a window that you opened in the code. A window that was opened by navigation to a URL will not close.  Before I deployed mu code to my website, I painfully removed all my Exit buttons. But my greatest surprise came when I tested my pages in the various browsers. In my code I do a comparison on the performance of two algorithms used to solve the same problem. One is brute force, the other uses a mathematical formula. The compare functions runs each many times and displays the time it took for each and also the ratio. Chrome runs JavaScript between 5 and 10 times faster than Firefox and between 50 and 100 times faster that IE. Wow!!! This difference is especially remarkable when the code uses iteration. I suspect that the JS engines in Chrome and Firefox simply cache the result of a function and if it is called again with the same parameters, it returns the cached result. To see it in action play run the “How Many Squares” page in www.mgsltns.com/games.htm The host is running on Unix, so the link is case sensitive. Last Note: IE9 runs JS a bit faster, but still lags behind almost as badly. That’s All Folks!

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  • Programming and Ubiquitous Language (DDD) in a non-English domain

    - by Sandor Drieënhuizen
    I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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  • Mostrar Imagenes en ListView utilizando ImageList WinForms

    - by Jason Ulloa
    El día de hoy veremos como trabajar con los controles ListView e Imagelist de WindowsForms para poder leer y mostrar una serie de imágenes. Antes de ello debo decir que pueden existir otras formas de mostrar imagenes que solo requieren un control por ejemplo con un Gridview pero eso será en otro post, ahora nos centraremos en la forma de realizarlo con los controles antes mencionados. Lo primero que haremos será crear un nuevo proyecto de windows forms, en mi caso utilizando C#, luego agregaremos un Control ImageList. Este control será el que utilicemos para almacenar todas las imágenes una vez que las hemos leído. Si revisamos el control, veremos que tenemos la opción de agregar la imágenes mediante el diseñador, es decir podemos seleccionarlas manualmente o bien agregarlas mediante código que será lo que haremos. Lo segundo será agregar un control ListView al Formulario, este será el encargado de mostrar las imagenes, eso sí, por ahora será solo mostrarlas no tendrá otras funcionalidades. Ahora, vamos al codeBehind y en el Evento Load del form empezaremos a codificar: Lo primero será, crear una nueva variable derivando DirectoryInfo, a la cual le indicaremos la ruta de nuestra carpeta de imágenes. En nuestro ejemplo utilizamos Application.StartUpPath para indicarle que vamos a buscar en nuestro mismo proyecto (en carpeta debug por el momento). DirectoryInfo dir = new DirectoryInfo(Application.StartupPath + @"\images");   Una vez que hemos creado la referencia a la ruta, utilizaremos un for para obtener todas la imágenes que se encuentren dentro del Folder que indicamos, para luego agregarlas al imagelist y empezar a crear nuestra nueva colección. foreach (FileInfo file in dir.GetFiles()) { try { this.imageList1.Images.Add(Image.FromFile(file.FullName)); }   catch { Console.WriteLine("No es un archivo de imagen"); } }   Una vez, que hemos llenado nuestro ImageList, entonces asignaremos al ListView sus propiedades, para definir la forma en que las imágenes se mostrarán. Un aspecto a tomar en cuenta acá será la propiedad ImageSize ya que está será la que definirá el tamaño que tendrán las imágenes en el ListView cuando sean mostradas. this.listView1.View = View.LargeIcon;   this.imageList1.ImageSize = new Size(120, 100);   this.listView1.LargeImageList = this.imageList1;   Por último y con ayuda de otro for vamos a recorrer cada uno de los elementos que ahora posee nuestro ImageList y lo agregaremos al ListView para mostrarlo for (int j = 0; j < this.imageList1.Images.Count; j++) { ListViewItem item = new ListViewItem();   item.ImageIndex = j;   this.listView1.Items.Add(item); } Como vemos, a pesar de que utilizamos dos controles distintos es realmente sencillo  mostrar la imagenes en el ListView al final el control ImageList, solo funciona como un “puente” que nos permite leer la imagenes para luego mostrarlas en otro control. Para terminar, los proyectos de ejemplo: C# VB

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  • How to Quickly Add Multiple IP Addresses to Windows Servers

    - by Sysadmin Geek
    If you have ever added multiple IP addresses to a single Windows server, going through the graphical interface is an incredible pain as each IP must be added manually, each in a new dialog box. Here’s a simple solution. Needless to say, this can be incredibly monotonous and time consuming if you are adding more than a few IP addresses. Thankfully, there is a much easier way which allows you to add an entire subnet (or more) in seconds. Adding an IP Address from the Command Line Windows includes the “netsh” command which allows you to configure just about any aspect of your network connections. If you view the accepted parameters using “netsh /?” you will be presented with a list of commands each which have their own list of commands (and so on). For the purpose of adding IP addresses, we are interested in this string of parameters: netsh interface ipv4 add address Note: For Windows Server 2003/XP and earlier, “ipv4″ should be replaced with just “ip” in the netsh command. If you view the help information, you can see the full list of accepted parameters but for the most part what you will be interested in is something like this: netsh interface ipv4 add address “Local Area Connection” 192.168.1.2 255.255.255.0 The above command adds the IP Address 192.168.1.2 (with Subnet Mask 255.255.255.0) to the connection titled “Local Area Network”. Adding Multiple IP Addresses at Once When we accompany a netsh command with the FOR /L loop, we can quickly add multiple IP addresses. The syntax for the FOR /L loop looks like this: FOR /L %variable IN (start,step,end) DO command So we could easily add every IP address from an entire subnet using this command: FOR /L %A IN (0,1,255) DO netsh interface ipv4 add address “Local Area Connection” 192.168.1.%A 255.255.255.0 This command takes about 20 seconds to run, where adding the same number of IP addresses manually would take significantly longer. A Quick Demonstration Here is the initial configuration on our network adapter: ipconfig /all Now run netsh from within a FOR /L loop to add IP’s 192.168.1.10-20 to this adapter: FOR /L %A IN (10,1,20) DO netsh interface ipv4 add address “Local Area Connection” 192.168.1.%A 255.255.255.0 After the above command is run, viewing the IP Configuration of the adapter now shows: Latest Features How-To Geek ETC How To Create Your Own Custom ASCII Art from Any Image How To Process Camera Raw Without Paying for Adobe Photoshop How Do You Block Annoying Text Message (SMS) Spam? How to Use and Master the Notoriously Difficult Pen Tool in Photoshop HTG Explains: What Are the Differences Between All Those Audio Formats? How To Use Layer Masks and Vector Masks to Remove Complex Backgrounds in Photoshop Bring Summer Back to Your Desktop with the LandscapeTheme for Chrome and Iron The Prospector – Home Dash Extension Creates a Whole New Browsing Experience in Firefox KinEmote Links Kinect to Windows Why Nobody Reads Web Site Privacy Policies [Infographic] Asian Temple in the Snow Wallpaper 10 Weird Gaming Records from the Guinness Book

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  • Open the SQL Server Error Log with PowerShell

    - by BuckWoody
    Using the Server Management Objects (SMO) library, you don’t even need to have the SQL Server 2008 PowerShell Provider to read the SQL Server Error Logs – in fact, you can use regular old everyday PowerShell. Keep in mind you will need the SMO libraries – which can be installed separately or by installing the Client Tools from the SQL Server install media. You could search for errors, store a result as a variable, or act on the returned values in some other way. Replace the Machine Name with your server and Instance Name with your instance, but leave the quotes, to make this work on your system: [reflection.assembly]::LoadWithPartialName("Microsoft.SqlServer.Smo") $machineName = "UNIVAC" $instanceName = "Production" $sqlServer = new-object ("Microsoft.SqlServer.Management.Smo.Server") "$machineName\$instanceName" $sqlServer.ReadErrorLog() Want to search for something specific, like the word “Error”? Replace the last line with this: $sqlServer.ReadErrorLog() | where {$_.Text -like "Error*"} Script Disclaimer, for people who need to be told this sort of thing: Never trust any script, including those that you find here, until you understand exactly what it does and how it will act on your systems. Always check the script on a test system or Virtual Machine, not a production system. Yes, there are always multiple ways to do things, and this script may not work in every situation, for everything. It’s just a script, people. All scripts on this site are performed by a professional stunt driver on a closed course. Your mileage may vary. Void where prohibited. Offer good for a limited time only. Keep out of reach of small children. Do not operate heavy machinery while using this script. If you experience blurry vision, indigestion or diarrhea during the operation of this script, see a physician immediately. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • const vs. readonly for a singleton

    - by GlenH7
    First off, I understand there are folk who oppose the use of singletons. I think it's an appropriate use in this case as it's constant state information, but I'm open to differing opinions / solutions. (See The singleton pattern and When should the singleton pattern not be used?) Second, for a broader audience: C++/CLI has a similar keyword to readonly with initonly, so this isn't strictly a C# type question. (Literal field versus constant variable in C++/CLI) Sidenote: A discussion of some of the nuances on using const or readonly. My Question: I have a singleton that anchors together some different data structures. Part of what I expose through that singleton are some lists and other objects, which represent the necessary keys or columns in order to connect the linked data structures. I doubt that anyone would try to change these objects through a different module, but I want to explicitly protect them from that risk. So I'm currently using a "readonly" modifier on those objects*. I'm using readonly instead of const with the lists as I read that using const will embed those items in the referencing assemblies and will therefore trigger a rebuild of those referencing assemblies if / when the list(s) is/are modified. This seems like a tighter coupling than I would want between the modules, but I wonder if I'm obsessing over a moot point. (This is question #2 below) The alternative I see to using "readonly" is to make the variables private and then wrap them with a public get. I'm struggling to see the advantage of this approach as it seems like wrapper code that doesn't provide much additional benefit. (This is question #1 below) It's highly unlikely that we'll change the contents or format of the lists - they're a compilation of things to avoid using magic strings all over the place. Unfortunately, not all the code has converted over to using this singleton's presentation of those strings. Likewise, I don't know that we'd change the containers / classes for the lists. So while I normally argue for the encapsulations advantages a get wrapper provides, I'm just not feeling it in this case. A representative sample of my singleton public sealed class mySingl { private static volatile mySingl sngl; private static object lockObject = new Object(); public readonly Dictionary<string, string> myDict = new Dictionary<string, string>() { {"I", "index"}, {"D", "display"}, }; public enum parms { ABC = 10, DEF = 20, FGH = 30 }; public readonly List<parms> specParms = new List<parms>() { parms.ABC, parms.FGH }; public static mySingl Instance { get { if(sngl == null) { lock(lockObject) { if(sngl == null) sngl = new mySingl(); } } return sngl; } } private mySingl() { doSomething(); } } Questions: Am I taking the most reasonable approach in this case? Should I be worrying about const vs. readonly? is there a better way of providing this information?

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  • Justifiable Perks.

    - by Phil Factor
        I was once the director of a start-up IT Company, and had the task of recruiting a proportion of the management team. As my background was in IT management, I was rather more familiar with recruiting Geeks for technology jobs, but here, one of my early tasks was interviewing a Marketing Director.  The small group of financiers had suggested a rather strange Irishman called  Halleran.  From my background in City of London dealing-rooms, I was slightly unprepared for the experience of interviewing anyone wearing a pink suit. Many of my older City colleagues would have required resuscitation after seeing his white leather shoes. However, nobody will accuse me of prejudging an interviewee. After all, many Linux experts who I’ve come to rely on have appeared for interview dressed as hobbits. In fact, the interview went well, and we had even settled his salary.  I was somewhat unprepared for the coda.    ‘And I will need to be provided with a Ferrari  by the company.’    ‘Hmm. That seems reasonable.’    Initially, he looked startled, and then a slow smile of victory spread across his face.    ‘What colour would you like?’ I asked genially.    ‘It has to be red.’ He looked very earnest on this point.    ‘Fine. I have to go past Hamleys on the way home this evening, so I’ll pick one up then for you.’    ‘Er.. Hamley’s is a toyshop, not a Ferrari Dealership.’    I stared at him in bafflement for a few seconds. ‘You’re not seriously asking for a real Ferrari are you?’     ‘Well, yes. Not for my own sake, you understand. I’d much prefer a simple run-about, but my position demands it. How could I maintain the necessary status in the office without one? How could I do my job in marketing when my grey Datsun was all too visible in the car Park? It is a tool of the job.’    ‘Excuse me a moment, but I must confer with the MD’    I popped out to see Chris, the MD. ‘Chris, I’m interviewing a lunatic in a pink suit who is trying to demand that a Ferrari is a precondition of his employment. I tried the ‘misunderstanding trick’ but it didn’t faze him.’     ‘Sorry, Phil, but we’ve got to hire him. The VCs insist on it. You’ve got to think of something that doesn’t involve committing to the purchase of a Ferrari. Current funding barely covers the rent for the building.’    ‘OK boss. Leave it to me.’    On return, I slapped O’Halleran’s file on the table with a genial, paternalistic smile. ‘Of course you should have a Ferrari. The only trouble is that it will require a justification document that can be presented to the board. I’m sure you’ll have no problem in preparing this document in the required format.’ The initial look of despair was quickly followed by a bland look of acquiescence. He had, earlier in the interview, argued with great eloquence his skill in preparing the tiresome documents that underpin the essential corporate and government deals that were vital to the success of this new enterprise. The justification of a Ferrari should be a doddle.     After the interview, Chris nervously asked how I’d fared.     ‘I think it is all solved.’    ‘… without promising a Ferrari, I hope.’    ‘Well, I did actually; on condition he justified it in writing.’    Chris issued a stream of invective. The strain of juggling the resources in an underfunded startup was beginning to show.    ‘Don’t worry. In the unlikely event of him coming back with the required document, I’ll give him mine.’    ‘Yours?’ He strode over to the window to stare down at the car park.    He needn’t have worried: I knew that his breed of marketing man could more easily lay an ostrich egg than to prepare a decent justification document. My Ferrari is still there at the back of my garage. Few know of the Ferrari cultivator, a simple inexpensive motorized device designed for the subsistence farmers of southern Italy. It is the very devil to start, but it creates a perfect tilth for the seedbed.

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  • Sniffing out SQL Code Smells: Inconsistent use of Symbolic names and Datatypes

    - by Phil Factor
    It is an awkward feeling. You’ve just delivered a database application that seems to be working fine in production, and you just run a few checks on it. You discover that there is a potential bug that, out of sheer good chance, hasn’t kicked in to produce an error; but it lurks, like a smoking bomb. Worse, maybe you find that the bug has started its evil work of corrupting the data, but in ways that nobody has, so far detected. You investigate, and find the damage. You are somehow going to have to repair it. Yes, it still very occasionally happens to me. It is not a nice feeling, and I do anything I can to prevent it happening. That’s why I’m interested in SQL code smells. SQL Code Smells aren’t necessarily bad practices, but just show you where to focus your attention when checking an application. Sometimes with databases the bugs can be subtle. SQL is rather like HTML: the language does its best to try to carry out your wishes, rather than to be picky about your bugs. Most of the time, this is a great benefit, but not always. One particular place where this can be detrimental is where you have implicit conversion between different data types. Most of the time it is completely harmless but we’re  concerned about the occasional time it isn’t. Let’s give an example: String truncation. Let’s give another even more frightening one, rounding errors on assignment to a number of different precision. Each requires a blog-post to explain in detail and I’m not now going to try. Just remember that it is not always a good idea to assign data to variables, parameters or even columns when they aren’t the same datatype, especially if you are relying on implicit conversion to work its magic.For details of the problem and the consequences, see here:  SR0014: Data loss might occur when casting from {Type1} to {Type2} . For any experienced Database Developer, this is a more frightening read than a Vampire Story. This is why one of the SQL Code Smells that makes me edgy, in my own or other peoples’ code, is to see parameters, variables and columns that have the same names and different datatypes. Whereas quite a lot of this is perfectly normal and natural, you need to check in case one of two things have gone wrong. Either sloppy naming, or mixed datatypes. Sure it is hard to remember whether you decided that the length of a log entry was 80 or 100 characters long, or the precision of a number. That is why a little check like this I’m going to show you is excellent for tidying up your code before you check it back into source Control! 1/ Checking Parameters only If you were just going to check parameters, you might just do this. It simply groups all the parameters, either input or output, of all the routines (e.g. stored procedures or functions) by their name and checks to see, in the HAVING clause, whether their data types are all the same. If not, it lists all the examples and their origin (the routine) Even this little check can occasionally be scarily revealing. ;WITH userParameter AS  ( SELECT   c.NAME AS ParameterName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  t.name + ' '     + CASE     --we may have to put in the length            WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.max_length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.name IN ('nchar', 'nvarchar')                      THEN c.max_length / 2 ELSE c.max_length                    END)                END + ')'         WHEN t.name IN ('decimal', 'numeric')             THEN '(' + CONVERT(VARCHAR(4), c.precision)                   + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = c.XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType]  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'   AND parameter_id>0)SELECT CONVERT(CHAR(80),objectName+'.'+ParameterName),DataType FROM UserParameterWHERE ParameterName IN   (SELECT ParameterName FROM UserParameter    GROUP BY ParameterName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY ParameterName   so, in a very small example here, we have a @ClosingDelimiter variable that is only CHAR(1) when, by the looks of it, it should be up to ten characters long, or even worse, a function that should be a char(1) and seems to let in a string of ten characters. Worth investigating. Then we have a @Comment variable that can't decide whether it is a VARCHAR(2000) or a VARCHAR(MAX) 2/ Columns and Parameters Actually, once we’ve cleared up the mess we’ve made of our parameter-naming in the database we’re inspecting, we’re going to be more interested in listing both columns and parameters. We can do this by modifying the routine to list columns as well as parameters. Because of the slight complexity of creating the string version of the datatypes, we will create a fake table of both columns and parameters so that they can both be processed the same way. After all, we want the datatypes to match Unfortunately, parameters do not expose all the attributes we are interested in, such as whether they are nullable (oh yes, subtle bugs happen if this isn’t consistent for a datatype). We’ll have to leave them out for this check. Voila! A slight modification of the first routine ;WITH userObject AS  ( SELECT   Name AS DataName,--the actual name of the parameter or column ('@' removed)  --and the qualified object name of the routine  OBJECT_SCHEMA_NAME(ObjectID) + '.' + OBJECT_NAME(ObjectID) AS ObjectName,  --now the harder bit: the definition of the datatype.  TypeName + ' '     + CASE     --we may have to put in the length. e.g. CHAR (10)           WHEN TypeName IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN MaxLength = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN TypeName IN ('nchar', 'nvarchar')                      THEN MaxLength / 2 ELSE MaxLength                    END)                END + ')'         WHEN TypeName IN ('decimal', 'numeric')--a BCD number!             THEN '(' + CONVERT(VARCHAR(4), Precision)                   + ',' + CONVERT(VARCHAR(4), Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0 --tush tush. XML         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT TOP 1 QUOTENAME(ss.name) + '.' + QUOTENAME(sc.Name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType],       DataObjectType  FROM   (Select t.name AS TypeName, REPLACE(c.name,'@','') AS Name,          c.max_length AS MaxLength, c.precision AS [Precision],           c.scale AS [Scale], c.[Object_id] AS ObjectID, XML_collection_ID,          is_XML_Document,'P' AS DataobjectType  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  AND parameter_id>0  UNION all  Select t.name AS TypeName, c.name AS Name, c.max_length AS MaxLength,          c.precision AS [Precision], c.scale AS [Scale],          c.[Object_id] AS ObjectID, XML_collection_ID,is_XML_Document,          'C' AS DataobjectType            FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID   WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'  )f)SELECT CONVERT(CHAR(80),objectName+'.'   + CASE WHEN DataobjectType ='P' THEN '@' ELSE '' END + DataName),DataType FROM UserObjectWHERE DataName IN   (SELECT DataName FROM UserObject   GROUP BY DataName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY DataName     Hmm. I can tell you I found quite a few minor issues with the various tabases I tested this on, and found some potential bugs that really leap out at you from the results. Here is the start of the result for AdventureWorks. Yes, AccountNumber is, for some reason, a Varchar(10) in the Customer table. Hmm. odd. Why is a city fifty characters long in that view?  The idea of the description of a colour being 256 characters long seems over-ambitious. Go down the list and you'll spot other mistakes. There are no bugs, but just mess. We started out with a listing to examine parameters, then we mixed parameters and columns. Our last listing is for a slightly more in-depth look at table columns. You’ll notice that we’ve delibarately removed the indication of whether a column is persisted, or is an identity column because that gives us false positives for our code smells. If you just want to browse your metadata for other reasons (and it can quite help in some circumstances) then uncomment them! ;WITH userColumns AS  ( SELECT   c.NAME AS columnName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  REPLACE(t.name + ' '   + CASE WHEN is_computed = 1 THEN ' AS ' + --do DDL for a computed column          (SELECT definition FROM sys.computed_columns cc           WHERE cc.object_id = c.object_id AND cc.column_ID = c.column_ID)     --we may have to put in the length            WHEN t.Name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.Max_Length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.Name IN ('nchar', 'nvarchar')                      THEN c.Max_Length / 2 ELSE c.Max_Length                    END)                END + ')'       WHEN t.name IN ('decimal', 'numeric')       THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'       ELSE ''      END + CASE WHEN c.is_rowguidcol = 1          THEN ' ROWGUIDCOL'          ELSE ''         END + CASE WHEN XML_collection_ID <> 0            THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                THEN 'DOCUMENT '                ELSE 'CONTENT '               END + COALESCE((SELECT                QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM                sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE                sc.xml_collection_ID = c.XML_collection_ID),                'NULL') + ')'            ELSE ''           END + CASE WHEN is_identity = 1             THEN CASE WHEN OBJECTPROPERTY(object_id,                'IsUserTable') = 1 AND COLUMNPROPERTY(object_id,                c.name,                'IsIDNotForRepl') = 0 AND OBJECTPROPERTY(object_id,                'IsMSShipped') = 0                THEN ''                ELSE ' NOT FOR REPLICATION '               END             ELSE ''            END + CASE WHEN c.is_nullable = 0               THEN ' NOT NULL'               ELSE ' NULL'              END + CASE                WHEN c.default_object_id <> 0                THEN ' DEFAULT ' + object_Definition(c.default_object_id)                ELSE ''               END + CASE                WHEN c.collation_name IS NULL                THEN ''                WHEN c.collation_name <> (SELECT                collation_name                FROM                sys.databases                WHERE                name = DB_NAME()) COLLATE Latin1_General_CI_AS                THEN COALESCE(' COLLATE ' + c.collation_name,                '')                ELSE ''                END,'  ',' ') AS [DataType]FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys')SELECT CONVERT(CHAR(80),objectName+'.'+columnName),DataType FROM UserColumnsWHERE columnName IN (SELECT columnName FROM UserColumns  GROUP BY columnName  HAVING MIN(Datatype)<>MAX(DataType))ORDER BY columnName If you take a look down the results against Adventureworks, you'll see once again that there are things to investigate, mostly, in the illustration, discrepancies between null and non-null datatypes So I here you ask, what about temporary variables within routines? If ever there was a source of elusive bugs, you'll find it there. Sadly, these temporary variables are not stored in the metadata so we'll have to find a more subtle way of flushing these out, and that will, I'm afraid, have to wait!

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  • Simple heart container script for 2D game (Unity)?

    - by N1ghtshade3
    I'm attempting to create a simple mobile game (C#) that involves a simple three-heart life system. After searching for hours online, many of the solutions use OnGUI (which is apparently horrible for performance) and the rest are too complicated for me to understand and add to my code. The other solutions involve using a single texture and just hiding part of it when damage is taken. In my game, however, the player should be able to go over three hearts (for example, every 100 points). Sebastian Lague's Zelda-Style Health is what I'm looking for, but even though it's a tutorial there is way too much going on that I don't need or can't customize to fit in mine. What I have so far is a script called HealthScript.cs which contains a variable lives. I have another script, PlayerPhysics.cs which calls HealthScript and subtracts a life when an enemy is hit. The part I don't get is actually drawing the hearts. I think I understand what needs to happen, I just am not experienced enough with Unity to know how. The Start function should draw three (or whatever lives is set to) hearts in the top right corner. Since the game should be resolution-independent to accommodate the various sizes of Android devices, I'd rather use scaling rather than PixelInset. When the player hits an enemy as detected by PlayerPhysics.cs, it should subtract from lives. I think that I have this working using this.GetComponent<HealthScript>().lives -= 1 but I'm not sure if it actually works. This should trigger a redraw of the hearts so that there are now two hearts. The same principle would apply for adding hearts when a score is reached, except when lives > maxHeartsPerRow, the new hearts should be drawn below the old ones. I realise I don't have much code to show but believe me; I've tried for quite some time to figure this out and have little to show for it. Any help at all would be welcome; it seems like it shouldn't take that much code to put an image on the screen for each life there is, but I haven't found anything yet. Thanks!

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  • SSIS Expression Editor & Tester

    Published today on CodePlex is the SSIS Expression Editor & Tester project. If you want to try it just pop over to CodePlex and download it. About five years ago I developed my own expression editor control. It first got used in our custom tasks as the MS editor didn’t become available until SQL 2005 SP1, but even then it had some handy features I preferred. For example resizable panes so that if your expression result was more than two lines you could see them all. It also meant I could change the functions available in the tree view, the most obvious use being to add some handy snippets and samples that I used a lot. This quickly developed into a small expression testing tool. I’d develop complex expressions using my editor and then copy it back into the package itself. I have been meaning to make the tool available for some time and finally made the effort, the code is checked-in and the signed downloads are published on CodePlex. There are two flavours, SQL 2005 or 2008, and just a simple zip file to download and extract. The tool doesn’t need installing, and is completely portable. It does need SSIS to be installed on the local machine though. Each zip file contains two files: ExpressionTester.exe – The tool itself, run this. ExpressionEditor.dll – The reusable editor control. A while ago the gentlemen behind BIDS Helper noticed the editor on a task and asked about using it. This became incorporated into their variable window extensions feature. To try and help them and anyone else that wants to use the editor control, it is available as a single assembly that you can reference yourself, and of course all the source code is on CodePlex too. Just add a reference to the ExpressionEditor.dll assembly and you should be up and running in no time. There is a sample project Package Test in the source code which shows how to use the editor control form in it’s simplest form, or if you want to host control directly then the tester tool is a perfect example.

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  • Time passage arithmetic explanation

    - by Cyber Axe
    I ported this from http://www.effectgames.com/effect/article.psp.html/joe/Old_School_Color_Cycling_with_HTML5 some time ago. However i'm now wanting to modify it for the purpose of changing it from floating point to fixed point maths for enhanced efficiency (for those who are going to talk about premature optimization and what not, i want to have my entire engine in fixed point both as a learning process for me and so i can port code more easily to systems in the future that dont have native floating points such as arm cpus) My initial conversion to fixed points just resulted in the cycling stuck on either the first or last frame of cycling. Plus it would be nice to understand better how it works so i can add more options and so forth in the future, my maths however sucks and the comments are limited so i don't really know how the maths work for determining the frame it shoud use (cycleAmount) I was also a beginner when i ported it as i had no idea between floating points and integers and what not. So in summary my question is, can anyone give an explination of the arithmatic used for determining the cycleAmount (which determings the "frame" of the cycle) This is the working floating point maths version of the code: public final void cycle(Colour[] sourceColours, double timeNow, double speedAdjust) { // Cycle all animated colour ranges in palette based on timestamp. sourceColours = sourceColours.clone(); int cycleSize; double cycleRate; double cycleAmount; Cycle cycle; for (int i = 0, len = cycles.length; i < len; ++i) { cycle = cycles[i]; cycleSize = (cycle.HIGH - cycle.LOW) + 1; cycleRate = cycle.RATE / (int) (CYCLE_SPEED / speedAdjust); cycleAmount = 0; if (cycle.REVERSE < 3) { // Standard Cycle cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); if (cycle.REVERSE < 1) { cycleAmount = cycleSize - cycleAmount; // If below 1 make sure its not reversed. } } else if (cycle.REVERSE == 3) { // Ping-Pong cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize << 1); if (cycleAmount >= cycleSize) { cycleAmount = (cycleSize * 2) - cycleAmount; } } else if (cycle.REVERSE < 6) { // Sine Wave cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); cycleAmount = Math.sin((cycleAmount * 3.1415926 * 2) / cycleSize) + 1; if (cycle.REVERSE == 4) { cycleAmount *= (cycleSize / 4); } else if (cycle.REVERSE == 5) { cycleAmount *= (cycleSize >> 1); } } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } if (USE_BLEND_SHIFT) { blendShiftColours(sourceColours, cycle, cycleAmount); } else { shiftColours(sourceColours, cycle, cycleAmount); } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } } colours = sourceColours; } // This utility function allows for variable precision floating point modulus. private double DFLOAT_MOD(final double d, final double b) { return (Math.floor(d * PRECISION) % Math.floor(b * PRECISION)) / PRECISION; }

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  • User-Defined Customer Events & their impact (FA Type Profile)

    - by Rajesh Sharma
    CC&B automatically creates field activities when a specific Customer Event takes place. This depends on the way you have setup your Field Activity Type Profiles, the templates within, and associated SP Condition(s) on the template. CC&B uses the service point type, its state and referenced customer event to determine which field activity type to generate.   Customer events available in the base product include: Cut for Non-payment (CNP) Disconnect Warning (DIWA) Reconnect for Payment (REPY) Reread (RERD) Stop Service (STOP) Start Service (STRT) Start/Stop (STSP)   Note the Field values/codes defined for each event.   CC&B comes with a flexibility to define new set of customer events. These can be defined in the Look Up - CUST_EVT_FLG. Values from the Look Up are used on the Field Activity Type Profile Template page.     So what's the use of having user-defined Customer Events? And how will the system detect such events in order to create field activity(s)?   Well, system can only detect such events when you reference a user-defined customer event on a Severance Event Type for an event type Create Field Activities.     This way you can create additional field activities of a specific field activity type for user-defined customer events.   One of our customers adopted this feature and created a user-defined customer event CNPW - Cut for Non-payment for Water Services. This event was then linked on a Field Activity Type Profile and referenced on a Severance Event - CUT FOR NON PAY-W. The associated Severance Process was configured to trigger a reconnection process if it was cancelled (done by defining a Post Cancel Algorithm). Whenever this Severance Event was executed, a specific type of Field Activity was generated for disconnection purposes. The Field Activity type was determined by the system from the Field Activity Type Profile referenced for the SP Type, SP's state and the referenced user-defined customer event. All was working well until the time when they realized that in spite of the Severance Process getting cancelled (when a payment was made); the Post Cancel Algorithm was not executed to start a Reconnection Severance Process for the purpose of generating a reconnection field activity and reconnecting the service.   Basically, the Post Cancel algorithm (if specified on a Severance Process Template) is triggered when a Severance Process gets cancelled because a credit transaction has affected/relieved a Service Agreement's debt.   So what exactly was happening? Now we come to actual question as to what is the impact in having a user-defined customer event.   System defined/base customer events are hard-coded across the entire system. There is an impact even if you remove any customer event entry from the Look Up. User-defined customer events are not recognized by the system anywhere else except in the severance process, as described above.   There are few programs which have routines to first validate the completion of disconnection field activities, which were raised as a result of customer event CNP - Cut for Non-payment in order to perform other associated actions. One such program is the Post Cancel Algorithm, referenced on a Severance Process Template, generally used to reconnect services which were disconnected from other Severance Event, specifically CNP - Cut for Non-Payment. Post cancel algorithm provided by the product - SEV POST CAN does the following (below is the algorithm's description):   This algorithm is called after a severance process has been cancelled (typically because the debt was paid and the SA is no longer eligible to be on the severance process). It checks to see if the process has a completed 'disconnect' event and, if so, starts a reconnect process using the Reconnect Severance Process Template defined in the parameter.    Notice the underlined text. This algorithm implicitly checks for Field Activities having completed status, which were generated from Severance Events as a result of CNP - Cut for Non-payment customer event.   Now if we look back to the customer's issue, we can relate that the Post Cancel algorithm was triggered, but was not able to find any 'Completed' CNP - Cut for Non-payment related field activity. And hence was not able to start a reconnection severance process. This was because a field activity was generated and completed for a customer event CNPW - Cut for Non-payment of Water Services instead.   To conclude, if you introduce new customer events that extend or simulate base customer events, the ones that are included in the base product, ensure that there is no other impact either direct or indirect to other business functions that the application has to offer.  

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 5

    - by MarkPearl
    Learning Outcomes Describe the operation of a memory cell Explain the difference between DRAM and SRAM Discuss the different types of ROM Explain the concepts of a hard failure and a soft error respectively Describe SDRAM organization Semiconductor Main Memory The two traditional forms of RAM used in computers are DRAM and SRAM DRAM (Dynamic RAM) Divided into two technologies… Dynamic Static Dynamic RAM is made with cells that store data as charge on capacitors. The presence or absence of charge in a capacitor is interpreted as a binary 1 or 0. Because capacitors have natural tendency to discharge, dynamic RAM requires periodic charge refreshing to maintain data storage. The term dynamic refers to the tendency of the stored charge to leak away, even with power continuously applied. Although the DRAM cell is used to store a single bit (0 or 1), it is essentially an analogue device. The capacitor can store any charge value within a range, a threshold value determines whether the charge is interpreted as a 1 or 0. SRAM (Static RAM) SRAM is a digital device that uses the same logic elements used in the processor. In SRAM, binary values are stored using traditional flip flop logic configurations. SRAM will hold its data as along as power is supplied to it. Unlike DRAM, no refresh is required to retain data. SRAM vs. DRAM DRAM is simpler and smaller than SRAM. Thus it is more dense and less expensive than SRAM. The cost of the refreshing circuitry for DRAM needs to be considered, but if the machine requires a large amount of memory, DRAM turns out to be cheaper than SRAM. SRAMS are somewhat faster than DRAM, thus SRAM is generally used for cache memory and DRAM is used for main memory. Types of ROM Read Only Memory (ROM) contains a permanent pattern of data that cannot be changed. ROM is non volatile meaning no power source is required to maintain the bit values in memory. While it is possible to read a ROM, it is not possible to write new data into it. An important application of ROM is microprogramming, other applications include library subroutines for frequently wanted functions, System programs, Function tables. A ROM is created like any other integrated circuit chip, with the data actually wired into the chip as part of the fabrication process. To reduce costs of fabrication, we have PROMS. PROMS are… Written only once Non-volatile Written after fabrication Another variation of ROM is the read-mostly memory, which is useful for applications in which read operations are far more frequent than write operations, but for which non volatile storage is required. There are three common forms of read-mostly memory, namely… EPROM EEPROM Flash memory Error Correction Semiconductor memory is subject to errors, which can be classed into two categories… Hard failure – Permanent physical defect so that the memory cell or cells cannot reliably store data Soft failure – Random error that alters the contents of one or more memory cells without damaging the memory (common cause includes power supply issues, etc.) Most modern main memory systems include logic for both detecting and correcting errors. Error detection works as follows… When data is to be read into memory, a calculation is performed on the data to produce a code Both the code and the data are stored When the previously stored word is read out, the code is used to detect and possibly correct errors The error checking provides one of 3 possible results… No errors are detected – the fetched data bits are sent out An error is detected, and it is possible to correct the error. The data bits plus error correction bits are fed into a corrector, which produces a corrected set of bits to be sent out An error is detected, but it is not possible to correct it. This condition is reported Hamming Code See wiki for detailed explanation. We will probably need to know how to do a hemming code – refer to the textbook (pg. 188 – 189) Advanced DRAM organization One of the most critical system bottlenecks when using high-performance processors is the interface to main memory. This interface is the most important pathway in the entire computer system. The basic building block of main memory remains the DRAM chip. In recent years a number of enhancements to the basic DRAM architecture have been explored, and some of these are now on the market including… SDRAM (Synchronous DRAM) DDR-DRAM RDRAM SDRAM (Synchronous DRAM) SDRAM exchanges data with the processor synchronized to an external clock signal and running at the full speed of the processor/memory bus without imposing wait states. SDRAM employs a burst mode to eliminate the address setup time and row and column line precharge time after the first access In burst mode a series of data bits can be clocked out rapidly after the first bit has been accessed SDRAM has a multiple bank internal architecture that improves opportunities for on chip parallelism SDRAM performs best when it is transferring large blocks of data serially There is now an enhanced version of SDRAM known as double data rate SDRAM or DDR-SDRAM that overcomes the once-per-cycle limitation of SDRAM

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  • Java Dynamic Binding

    - by Chris Okyen
    I am having trouble understanding the OOP Polymorphic principl of Dynamic Binding ( Late Binding ) in Java. I looked for question pertaining to java, and wasn't sure if a overall answer to how dynamic binding works would pertain to Java Dynamic Binding, I wrote this question. Given: class Person { private String name; Person(intitialName) { name = initialName; } // irrelevant methods is here. // Overides Objects method public void writeOutput() { println(name); } } class Student extends Person { private int studentNumber; Student(String intitialName, int initialStudentNumber) { super(intitialName); studentNumber = initialStudentNumber; } // irrellevant methods here... // overides Person, Student and Objects method public void writeOutput() { super.writeOutput(); println(studentNumber); } } class Undergaraduate extends Student { private int level; Undergraduate(String intitialName, int initialStudentNumber,int initialLevel) { super(intitialName,initialStudentNumber); level = initialLevel; } // irrelevant methods is here. // overides Person, Student and Objects method public void writeOutput() { super.writeOutput(); println(level); } } I am wondering. if I had an array called person declared to contain objects of type Person: Person[] people = new Person[2]; person[0] = new Undergraduate("Cotty, Manny",4910,1); person[1] = new Student("DeBanque, Robin", 8812); Given that person[] is declared to be of type Person, you would expect, for example, in the third line where person[0] is initialized to a new Undergraduate object,to only gain the instance variable from Person and Persons Methods since doesn't the assignment to a new Undergraduate to it's ancestor denote the Undergraduate object to access Person - it's Ancestors, methods and isntance variables... Thus ...with the following code I would expect person[0].writeOutput(); // calls Undergraduate::writeOutput() person[1].writeOutput(); // calls Student::writeOutput() person[0] to not have Undergraduate's writeOutput() overidden method, nor have person[1] to have Student's overidden method - writeOutput(). If I had Person mikeJones = new Student("Who?,MikeJones",44,4); mikeJones.writeOutput(); The Person::writeOutput() method would be called. Why is this not so? Does it have to do with something I don't understand about relating to arrays? Does the declaration Person[] people = new Person[2] not bind the method like the previous code would?

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  • Issues with touch buttons in XNA (Release state to be precise)

    - by Aditya
    I am trying to make touch buttons in WP8 with all the states (Pressed, Released, Moved), but the TouchLocationState.Released is not working. Here's my code: Class variables: bool touching = false; int touchID; Button tempButton; Button is a separate class with a method to switch states when touched. The Update method contains the following code: TouchCollection touchCollection = TouchPanel.GetState(); if (!touching && touchCollection.Count > 0) { touching = true; foreach (TouchLocation location in touchCollection) { for (int i = 0; i < menuButtons.Count; i++) { touchID = location.Id; // store the ID of current touch Point touchLocation = new Point((int)location.Position.X, (int)location.Position.Y); // create a point Button button = menuButtons[i]; if (GetMenuEntryHitBounds(button).Contains(touchLocation)) // a method which returns a rectangle. { button.SwitchState(true); // change the button state tempButton = button; // store the pressed button for accessing later } } } } else if (touchCollection.Count == 0) // clears the state of all buttons if no touch is detected { touching = false; for (int i = 0; i < menuButtons.Count; i++) { Button button = menuButtons[i]; button.SwitchState(false); } } menuButtons is a list of buttons on the menu. A separate loop (within the Update method) after the touched variable is true if (touching) { TouchLocation location; TouchLocation prevLocation; if (touchCollection.FindById(touchID, out location)) { if (location.TryGetPreviousLocation(out prevLocation)) { Point point = new Point((int)location.Position.X, (int)location.Position.Y); if (prevLocation.State == TouchLocationState.Pressed && location.State == TouchLocationState.Released) { if (GetMenuEntryHitBounds(tempButton).Contains(point)) // Execute the button action. I removed the excess } } } } The code for switching the button state is working fine but the code where I want to trigger the action is not. location.State == TouchLocationState.Released mostly ends up being false. (Even after I release the touch, it has a value of TouchLocationState.Moved) And what is more irritating is that it sometimes works! I am really confused and stuck for days now. Is this the right way? If yes then where am I going wrong? Or is there some other more effective way to do this? PS: I also posted this question on stack overflow then realized this question is more appropriate in gamedev. Sorry if it counts as being redundant.

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