query builder methods - Page 428

C# 4.0: COM Interop Improvements

- by Paulo Morgado

Dynamic resolution as well as named and optional arguments greatly improve the experience of interoperating with COM APIs such as Office Automation Primary Interop Assemblies (PIAs). But, in order to alleviate even more COM Interop development, a few COM-specific features were also added to C# 4.0. Ommiting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. These parameters are typically not meant to mutate a passed-in argument, but are simply another way of passing value parameters. Specifically for COM methods, the compiler allows to declare the method call passing the arguments by value and will automatically generate the necessary temporary variables to hold the values in order to pass them by reference and will discard their values after the call returns. From the point of view of the programmer, the arguments are being passed by value. This method call: object fileName = "Test.docx"; object missing = Missing.Value; document.SaveAs(ref fileName, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing); can now be written like this: document.SaveAs("Test.docx", Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value); And because all parameters that are receiving the Missing.Value value have that value as its default value, the declaration of the method call can even be reduced to this: document.SaveAs("Test.docx"); Dynamic Import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object form the context of the call, but has to explicitly perform a cast on the returned values to make use of that knowledge. These casts are so common that they constitute a major nuisance. To make the developer’s life easier, it is now possible to import the COM APIs in such a way that variants are instead represented using the type dynamic which means that COM signatures have now occurrences of dynamic instead of object. This means that members of a returned object can now be easily accessed or assigned into a strongly typed variable without having to cast. Instead of this code: ((Excel.Range)(excel.Cells[1, 1])).Value2 = "Hello World!"; this code can now be used: excel.Cells[1, 1] = "Hello World!"; And instead of this: Excel.Range range = (Excel.Range)(excel.Cells[1, 1]); this can be used: Excel.Range range = excel.Cells[1, 1]; Indexed And Default Properties A few COM interface features are still not available in C#. On the top of the list are indexed properties and default properties. As mentioned above, these will be possible if the COM interface is accessed dynamically, but will not be recognized by statically typed C# code. No PIAs – Type Equivalence And Type Embedding For assemblies indentified with PrimaryInteropAssemblyAttribute, the compiler will create equivalent types (interfaces, structs, enumerations and delegates) and embed them in the generated assembly. To reduce the final size of the generated assembly, only the used types and their used members will be generated and embedded. Although this makes development and deployment of applications using the COM components easier because there’s no need to deploy the PIAs, COM component developers are still required to build the PIAs.

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Using Managed Beans with your ADF Mobile Client Applications

- by [email protected]

Did you know it's easy to extend your ADF Mobile Client application with a Managed Bean just like it is with an ADF web application? Here's how: Using the New Gallery (File -> New), create a new Java class. This class should extend oracle.adfnmc.el.utils.BeanResolver. Add this java class as a managed bean: Go to your task flow, select the Overview tab at the bottom and go to the Managed Bean section. Add an entry and name your new Managed Bean and point to the java class you just created. Add your custom methods and properties to your java class Since reflection is not supported in the J2ME version on some platforms (BlackBerry), you need to provide dispatch code if you want to invoke/access any of your methods/properties from EL. Here's a sample: MyBeanClass.java Use Expression Language (EL) to access your properties and invoke your methods on your MCX pages. Here's an sample: <?xml version="1.0" encoding="UTF-8" ?><amc:view xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:amc="http://xmlns.oracle.com/jdev/amc"> <amc:form id="form0"> <amc:menuControl refId="menu0"/> <amc:panelGroupLayout id="panelGroupLayout1" width="100%"> <amc:panelGroupLayout id="panelGroupLayout2" layout="horizontal" width="100%"> <amc:image id="image1" source="logo_sm.png"/> <amc:outputText value="Home" id="outputText1" verticalAlign="center" fontSize="20" fontWeight="bold" foregroundColor="#ff0000"/> </amc:panelGroupLayout> <amc:commandLink text="#{MyBean.property1}" id="commandLink1" actionListener="#{MyBean.doFoo}" foregroundColor="#0000ff" action="patientlist"/> </amc:panelGroupLayout> </amc:form> <amc:menu type="main" id="menu0"> <amc:menuGroup id="menuGroup1"> <amc:commandMenuItem id="commandMenuItem1" action="exit" label="Exit" index="1" weight="0"/> </amc:menuGroup> </amc:menu></amc:view>

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MvcExtensions - ActionFilter

- by kazimanzurrashid

One of the thing that people often complains is dependency injection in Action Filters. Since the standard way of applying action filters is to either decorate the Controller or the Action methods, there is no way you can inject dependencies in the action filter constructors. There are quite a few posts on this subject, which shows the property injection with a custom action invoker, but all of them suffers from the same small bug (you will find the BuildUp is called more than once if the filter implements multiple interface e.g. both IActionFilter and IResultFilter). The MvcExtensions supports both property injection as well as fluent filter configuration api. There are a number of benefits of this fluent filter configuration api over the regular attribute based filter decoration. You can pass your dependencies in the constructor rather than property. Lets say, you want to create an action filter which will update the User Last Activity Date, you can create a filter like the following: public class UpdateUserLastActivityAttribute : FilterAttribute, IResultFilter { public UpdateUserLastActivityAttribute(IUserService userService) { Check.Argument.IsNotNull(userService, "userService"); UserService = userService; } public IUserService UserService { get; private set; } public void OnResultExecuting(ResultExecutingContext filterContext) { // Do nothing, just sleep. } public void OnResultExecuted(ResultExecutedContext filterContext) { Check.Argument.IsNotNull(filterContext, "filterContext"); string userName = filterContext.HttpContext.User.Identity.IsAuthenticated ? filterContext.HttpContext.User.Identity.Name : null; if (!string.IsNullOrEmpty(userName)) { UserService.UpdateLastActivity(userName); } } } As you can see, it is nothing different than a regular filter except that we are passing the dependency in the constructor. Next, we have to configure this filter for which Controller/Action methods will execute: public class ConfigureFilters : ConfigureFiltersBase { protected override void Configure(IFilterRegistry registry) { registry.Register<HomeController, UpdateUserLastActivityAttribute>(); } } You can register more than one filter for the same Controller/Action Methods: registry.Register<HomeController, UpdateUserLastActivityAttribute, CompressAttribute>(); You can register the filters for a specific Action method instead of the whole controller: registry.Register<HomeController, UpdateUserLastActivityAttribute, CompressAttribute>(c => c.Index()); You can even set various properties of the filter: registry.Register<ControlPanelController, CustomAuthorizeAttribute>( attribute => { attribute.AllowedRole = Role.Administrator; }); The Fluent Filter registration also reduces the number of base controllers in your application. It is very common that we create a base controller and decorate it with action filters and then we create concrete controller(s) so that the base controllers action filters are also executed in the concrete controller. You can do the same with a single line statement with the fluent filter registration: Registering the Filters for All Controllers: registry.Register<ElmahHandleErrorAttribute>(new TypeCatalogBuilder().Add(GetType().Assembly).Include(type => typeof(Controller).IsAssignableFrom(type))); Registering Filters for selected Controllers: registry.Register<ElmahHandleErrorAttribute>(new TypeCatalogBuilder().Add(GetType().Assembly).Include(type => typeof(Controller).IsAssignableFrom(type) && (type.Name.StartsWith("Home") || type.Name.StartsWith("Post")))); You can also use the built-in filters in the fluent registration, for example: registry.Register<HomeController, OutputCacheAttribute>(attribute => { attribute.Duration = 60; }); With the fluent filter configuration you can even apply filters to controllers that source code is not available to you (may be the controller is a part of a third part component). That’s it for today, in the next post we will discuss about the Model binding support in MvcExtensions. So stay tuned.

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Implementing features in an Entity System

- by Bane

After asking two questions on Entity Systems (1, 2), and reading some articles on them, I think that I understand them much better than before. But, I still have some uncertainties, and mainly they are about building a Particle Emitter, an Input system, and a Camera. I obviously still have some problems understanding Entity Systems, and they might apply to a whole other range of objects, but I chose these three because they are very different concepts and should cover a pretty big ground, and help me understand Entity Systems and how to handle problems like these myself, as they come along. I am building an engine in Javascript, and I've implemented most of the core features, which include: input handling, flexible animation system, particle emitter, math classes and functions, scene handling, a camera and a render, and a whole bunch of other things that engines usually support. Then, I read Byte56's answer that got me interested into making the engine into an Entity System one. It would still remain an HTML5 game engine with the basic Scene philosophy, but it should support dynamic creation of entities from components. These are some of the definitions from the previous questions, updated: An Entity is an identifier. It doesn't have any data, it's not an object, it's a simple id that represents an index in the Scene's list of all entities (which I actually plan to implement as a component matrix). A Component is a data holder, but with methods that can operate on that data. The best example is a Vector2D, or a "Position" component. It has data: x and y, but also some methods that make operating on the data a bit easier: add(), normalize(), and so on. A System is something that can operate on a set of entities that meet the certain requirements, usually they (the entities) need to have a specified (by the system itself) set of components to be operated upon. The system is the "logic" part, the "algorithm" part, all the functionality supplied by components is purely for easier data management. The problem that I have now is fitting my old engine concept into this new programming paradigm. Lets start with the simplest one, a Camera. The camera has a position property (Vector2D), a rotation property and some methods for centering it around a point. Each frame, it is fed to a renderer, along with a scene, and all the objects are translated according to it's position. Then the scene is rendered. How could I represent this kind of an object in an Entity System? Would the camera be an entity or simply a component? A combination (see my answer)? Another issues that is bothering me is implementing a Particle Emitter. For what exactly I mean by that, you can check out my video of it: http://youtu.be/BObargIMQsE. The problem I have with this is, again, what should be what. I'm pretty sure that particles themselves shouldn't be entities, as I want to support 10k+ of them, and creating that much entities would be a heavy blow on my performance, I believe. Or maybe not? Depends on the implementation, but anyone with experience: please, do answer. The last bit I wan't to talk about, which is also bugging me the most, is how input should be handled. In my current version of the engine, there is a class called Input. It's a handler that subscribes to browser's events, such as keypresses, and mouse position changes, and also it maintains an internal state. Then, the player class has a react() method, which accepts an input object as an argument. The advantage of this is that the input object could be serialized into JSON and then shared over the network, allowing for smooth multiplayer simulations. But how does this translate into an Entity System?

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Acr.ExtDirect – Part 1 – Method Resolvers

- by Allan Ritchie

One of the most important things of any open source libraries in my opinion is to be as open as possible while avoiding having your library become invasive to your code/business model design. I personally could never stand marking my business and/or data access code with attributes everywhere. XML also isn’t really a fav with too many people these days since it comes with a startup performance hit and requires runtime compiling. I find that there is a whole ton of communication libraries out there currently requiring this (ie. WCF, RIA, etc). Even though Acr.ExtDirect comes with its own set of attributes, you can piggy-back the [ServiceContract] & [OperationContract] attributes from WCF if you choose. It goes beyond that though, there are 2 others “out-of-the-box” implementations – Convention based & XML Configuration. Convention – I don’t actually recommend using this one since it opens up all of your public instance methods to remote execution calls. XML Configuration – This isn’t so bad but requires you enter all of your methods and there operation types into the Castle XML configuration & as I said earlier, XML isn’t the fav these days. So what are your options if you don’t like attributes, convention, or XML Configuration? Well, Acr.ExtDirect has its own extension base to give the API a list of methods and components to make available for remote execution. 1: public interface IDirectMethodResolver { 2: 3: bool IsServiceType(ComponentModel model, Type type); 4: string GetNamespace(ComponentModel model); 5: string[] GetDirectMethodNames(ComponentModel model); 6: DirectMethodType GetMethodType(ComponentModel model, MethodInfo method); 7: } Now to implement our own method resolver: 1: public class TestResolver : IDirectMethodResolver { 2: 3: #region IDirectMethodResolver Members 4: 5: /// <summary> 6: /// Determine if you are calling a service 7: /// </summary> 8: /// <param name="model"></param> 9: /// <param name="type"></param> 10: /// <returns></returns> 11: public bool IsServiceType(ComponentModel model, Type type) { 12: return (type.Namespace == "MyBLL.Data"); 13: } 14: 15: /// <summary> 16: /// Return the calling name for the client side 17: /// </summary> 18: /// <param name="model"></param> 19: /// <returns></returns> 20: public string GetNamespace(ComponentModel model) { 21: return model.Name; 22: } 23: 24: public string[] GetDirectMethodNames(ComponentModel model) { 25: switch (model.Name) { 26: case "Products" : 27: return new [] { 28: "GetProducts", 29: "LoadProduct", 30: "Save", 31: "Update" 32: }; 33: 34: case "Categories" : 35: return new [] { 36: "GetProducts" 37: }; 38: 39: default : 40: throw new ArgumentException("Invalid type"); 41: } 42: } 43: 44: public DirectMethodType GetMethodType(ComponentModel model, MethodInfo method) { 45: if (method.Name.StartsWith("Save") || method.Name.StartsWith("Update")) 46: return DirectMethodType.FormSubmit; 47: 48: else if (method.Name.StartsWith("Load")) 49: return DirectMethodType.FormLoad; 50: 51: else 52: return DirectMethodType.Direct; 53: } 54: 55: #endregion 56: } And there you have it, your own custom method resolver. Pretty easy and pretty open ended!

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Subterranean IL: Custom modifiers

- by Simon Cooper

In IL, volatile is an instruction prefix used to set a memory barrier at that instruction. However, in C#, volatile is applied to a field to indicate that all accesses on that field should be prefixed with volatile. As I mentioned in my previous post, this means that the field definition needs to store this information somehow, as such a field could be accessed from another assembly. However, IL does not have a concept of a 'volatile field'. How is this information stored? Attributes The standard way of solving this is to apply a VolatileAttribute or similar to the field; this extra metadata notifies the C# compiler that all loads and stores to that field should use the volatile prefix. However, there is a problem with this approach, namely, the .NET C++ compiler. C++ allows methods to be overloaded using properties, like volatile or const, on the parameters; this is perfectly legal C++: public ref class VolatileMethods { void Method(int *i) {} void Method(volatile int *i) {} } If volatile was specified using a custom attribute, then the VolatileMethods class wouldn't be compilable to IL, as there is nothing to differentiate the two methods from each other. This is where custom modifiers come in. Custom modifiers Custom modifiers are similar to custom attributes, but instead of being applied to an IL element separately to its declaration, they are embedded within the field or parameter's type signature itself. The VolatileMethods class would be compiled to the following IL: .class public VolatileMethods { .method public instance void Method(int32* i) {} .method public instance void Method( int32 modreq( [mscorlib]System.Runtime.CompilerServices.IsVolatile)* i) {} } The modreq([mscorlib]System.Runtime.CompilerServices.IsVolatile) is the custom modifier. This adds a TypeDef or TypeRef token to the signature of the field or parameter, and even though they are mostly ignored by the CLR when it's executing the program, this allows methods and fields to be overloaded in ways that wouldn't be allowed using attributes. Because the modifiers are part of the signature, they need to be fully specified when calling such a method in IL: call instance void Method( int32 modreq([mscorlib]System.Runtime.CompilerServices.IsVolatile)*) There are two ways of applying modifiers; modreq specifies required modifiers (like IsVolatile), and modopt specifies optional modifiers that can be ignored by compilers (like IsLong or IsConst). The type specified as the modifier argument are simple placeholders; if you have a look at the definitions of IsVolatile and IsLong they are completely empty. They exist solely to be referenced by a modifier. Custom modifiers are used extensively by the C++ compiler to specify concepts that aren't expressible in IL, but still need to be taken into account when calling method overloads. C++ and C# That's all very well and good, but how does this affect C#? Well, the C++ compiler uses modreq(IsVolatile) to specify volatility on both method parameters and fields, as it would be slightly odd to have the same concept represented using a modifier or attribute depending on what it was applied to. Once you've compiled your C++ project, it can then be referenced and used from C#, so the C# compiler has to recognise the modreq(IsVolatile) custom modifier applied to fields, and vice versa. So, even though you can't overload fields or parameters with volatile using C#, volatile needs to be expressed using a custom modifier rather than an attribute to guarentee correct interoperability and behaviour with any C++ dlls that happen to come along. Next up: a closer look at attributes, and how certain attributes compile in unexpected ways.

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How to write simple code using TDD [migrated]

- by adeel41

Me and my colleagues do a small TDD-Kata practice everyday for 30 minutes. For reference this is the link for the excercise http://osherove.com/tdd-kata-1/ The objective is to write better code using TDD. This is my code which I've written public class Calculator { public int Add( string numbers ) { const string commaSeparator = ","; int result = 0; if ( !String.IsNullOrEmpty( numbers ) ) result = numbers.Contains( commaSeparator ) ? AddMultipleNumbers( GetNumbers( commaSeparator, numbers ) ) : ConvertToNumber( numbers ); return result; } private int AddMultipleNumbers( IEnumerable getNumbers ) { return getNumbers.Sum(); } private IEnumerable GetNumbers( string separator, string numbers ) { var allNumbers = numbers .Replace( "\n", separator ) .Split( new string[] { separator }, StringSplitOptions.RemoveEmptyEntries ); return allNumbers.Select( ConvertToNumber ); } private int ConvertToNumber( string number ) { return Convert.ToInt32( number ); } } and the tests for this class are [TestFixture] public class CalculatorTests { private int ArrangeAct( string numbers ) { var calculator = new Calculator(); return calculator.Add( numbers ); } [Test] public void Add_WhenEmptyString_Returns0() { Assert.AreEqual( 0, ArrangeAct( String.Empty ) ); } [Test] [Sequential] public void Add_When1Number_ReturnNumber( [Values( "1", "56" )] string number, [Values( 1, 56 )] int expected ) { Assert.AreEqual( expected, ArrangeAct( number ) ); } [Test] public void Add_When2Numbers_AddThem() { Assert.AreEqual( 3, ArrangeAct( "1,2" ) ); } [Test] public void Add_WhenMoreThan2Numbers_AddThemAll() { Assert.AreEqual( 6, ArrangeAct( "1,2,3" ) ); } [Test] public void Add_SeparatorIsNewLine_AddThem() { Assert.AreEqual( 6, ArrangeAct( @"1 2,3" ) ); } } Now I'll paste code which they have written public class StringCalculator { private const char Separator = ','; public int Add( string numbers ) { const int defaultValue = 0; if ( ShouldReturnDefaultValue( numbers ) ) return defaultValue; return ConvertNumbers( numbers ); } private int ConvertNumbers( string numbers ) { var numberParts = GetNumberParts( numbers ); return numberParts.Select( ConvertSingleNumber ).Sum(); } private string[] GetNumberParts( string numbers ) { return numbers.Split( Separator ); } private int ConvertSingleNumber( string numbers ) { return Convert.ToInt32( numbers ); } private bool ShouldReturnDefaultValue( string numbers ) { return String.IsNullOrEmpty( numbers ); } } and the tests [TestFixture] public class StringCalculatorTests { [Test] public void Add_EmptyString_Returns0() { ArrangeActAndAssert( String.Empty, 0 ); } [Test] [TestCase( "1", 1 )] [TestCase( "2", 2 )] public void Add_WithOneNumber_ReturnsThatNumber( string numberText, int expected ) { ArrangeActAndAssert( numberText, expected ); } [Test] [TestCase( "1,2", 3 )] [TestCase( "3,4", 7 )] public void Add_WithTwoNumbers_ReturnsSum( string numbers, int expected ) { ArrangeActAndAssert( numbers, expected ); } [Test] public void Add_WithThreeNumbers_ReturnsSum() { ArrangeActAndAssert( "1,2,3", 6 ); } private void ArrangeActAndAssert( string numbers, int expected ) { var calculator = new StringCalculator(); var result = calculator.Add( numbers ); Assert.AreEqual( expected, result ); } } Now the question is which one is better? My point here is that we do not need so many small methods initially because StringCalculator has no sub classes and secondly the code itself is so simple that we don't need to break it up too much that it gets confusing after having so many small methods. Their point is that code should read like english and also its better if they can break it up earlier than doing refactoring later and third when they will do refactoring it would be much easier to move these methods quite easily into separate classes. My point of view against is that we never made a decision that code is difficult to understand so why we are breaking it up so early. So I need a third person's opinion to understand which option is much better.

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Node.js Lockstep Multiplayer Architecture

- by Wakaka

Background I'm using the lockstep model for a multiplayer Node.js/Socket.IO game in a client-server architecture. User input (mouse or keypress) is parsed into commands like 'attack' and 'move' on the client, which are sent to the server and scheduled to be executed on a certain tick. This is in contrast to sending state data to clients, which I don't wish to use due to bandwidth issues. Each tick, the server will send the list of commands on that tick (possibly empty) to each client. The server and all clients will then process the commands and simulate that tick in exactly the same way. With Node.js this is actually quite simple due to possibility of code sharing between server and client. I'll just put the deterministic simulator in the /shared folder which can be run by both server and client. The server simulation is required so that there is an authoritative version of the simulation which clients cannot alter. Problem Now, the game has many entity classes, like Unit, Item, Tree etc. Entities are created in the simulator. However, for each class, it has some methods that are shared and some that are client-specific. For instance, the Unit class has addHp method which is shared. It also has methods like getSprite (gets the image of the entity), isVisible (checks if unit can be seen by the client), onDeathInClient (does a bunch of stuff when it dies only on the client like adding announcements) and isMyUnit (quick function to check if the client owns the unit). Up till now, I have been piling all the client functions into the shared Unit class, and adding a this.game.isServer() check when necessary. For instance, when the unit dies, it will call if (!this.game.isServer()) { this.onDeathInClient(); }. This approach has worked pretty fine so far, in terms of functionality. But as the codebase grew bigger, this style of coding seems a little strange. Firstly, the client code is clearly not shared, and yet is placed under the /shared folder. Secondly, client-specific variables for each entity are also instantiated on the server entity (like unit.sprite) and can run into problems when the server cannot instantiate the variable (it doesn't have Image class like on browsers). So my question is, is there a better way to organize the client code, or is this a common way of doing things for lockstep multiplayer games? I can think of a possible workaround, but it does have its own problems. Possible workaround (with problems) I could use Javascript mixins that are only added when in a browser. Thus, in the /shared/unit.js file in the /shared folder, I would have this code at the end: if (typeof exports !== 'undefined') module.exports = Unit; else mixin(Unit, LocalUnit); Then I would have /client/localunit.js store an object LocalUnit of client-side methods for Unit. Now, I already have a publish-subscribe system in place for events in the simulator. To remove the this.game.isServer() checks, I could publish entity-specific events whenever I want the client to do something. For instance, I would do this.publish('Death') in /shared/unit.js and do this.subscribe('Death', this.onDeathInClient) in /client/localunit.js. But this would make the simulator's event listeners list on the server and the client different. Now if I want to clear all subscribed events only from the shared simulator, I can't. Of course, it is possible to create two event subscription systems - one client-specific and one shared - but now the publish() method would have to do if (!this.game.isServer()) { this.publishOnClient(event); }. All in all, the workaround off the top of my head seems pretty complicated for something as simple as separating the client and shared code. Thus, I wonder if there is an established and simpler method for better code organization, hopefully specific to Node.js games.

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How do you report out user research results?

- by user12277104

A couple weeks ago, one of my mentees asked to meet, because she wanted my advice on how to report out user research results. She had just conducted her first usability test for her new employer, and was getting to the point where she wanted to put together some slides, but she didn't want them to be boring. She wanted to talk with me about what to present and how best to present results to stakeholders. While I couldn't meet for another week, thanks to slideshare, I could quickly point her in the direction that my in-person advice would have led her. First, I'd put together a panel for the February 2012 New Hampshire UPA monthly meeting that we then repeated for the 2012 Boston UPA annual conference. In this panel, I described my reporting techniques, as did six of my colleagues -- two of whom work for companies smaller than mine, and four of whom are independent consultants. Before taking questions, we each presented for 3 to 5 minutes on how we presented research results. The differences were really interesting. For example, when do you really NEED a long, written report (as opposed to an email, spreadsheet, or slide deck with callouts)? When you are reporting your test results to the FDA -- that makes sense. in this presentation, I describe two modes of reporting results that I use. Second, I'd been a participant in the CUE-9 study. CUE stands for Comparative Usability Evaluation, and this was the 9th of these studies that Rolf Molich had designed. Originally, the studies were designed to show the variability in evaluation methods practitioners use to evaluate websites and applications. Of course, using methods and tasks of their own choosing, the results were wildly different. However, in this 9th study, the tasks were the same, the participants were the same, and the problem severity scale was the same, so how would the results of the 19 practitioners compare? Still wildly variable. But for the purposes of this discussion, it gave me a work product that was not proprietary to the company I work for -- a usability test report that I could share publicly. This was the way I'd been reporting results since 2005, and pretty much what I still do, when time allows. That said, I have been continuing to evolve my methods and reporting techniques, and sometimes, there is no time to create that kind of report -- the team can't wait the days that it takes to take screen shots, go through my notes, refer back to recordings, and write it all up. So in those cases, I use bullet points in email, talk through the findings with stakeholders in a 1-hour meeting, and then post the take-aways on a wiki page. There are other requirements for that kind of reporting to work -- for example, the stakeholders need to attend each of the sessions, and the sessions can't take more than a day to complete, but you get the idea: there is no one "right" way to report out results. If the method of reporting you are using is giving your stakeholders the information they need, in a time frame in which it is useful, and in a format that meets their needs (FDA report or bullet points on a wiki), then that's the "right" way to report your results.

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3 Incredibly Useful Projects to jump-start your Kinect Development.

- by mbcrump

I’ve been playing with the Kinect SDK Beta for the past few days and have noticed a few projects on CodePlex worth checking out. I decided to blog about them to help spread awareness. If you want to learn more about Kinect SDK then you check out my”Busy Developer’s Guide to the Kinect SDK Beta”. Let’s get started: KinectContrib is a set of VS2010 Templates that will help you get started building a Kinect project very quickly. Once you have it installed you will have the option to select the following Templates: KinectDepth KinectSkeleton KinectVideo Please note that KinectContrib requires the Kinect for Windows SDK beta to be installed. Kinect Templates after installing the Template Pack. The reference to Microsoft.Research.Kinect is added automatically. Here is a sample of the code for the MainWindow.xaml in the “Video” template: <Window x:Class="KinectVideoApplication1.MainWindow" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="480" Width="640"> <Grid> <Image Name="videoImage"/> </Grid> </Window> and MainWindow.xaml.cs using System; using System.Windows; using System.Windows.Media; using System.Windows.Media.Imaging; using Microsoft.Research.Kinect.Nui; namespace KinectVideoApplication1 { public partial class MainWindow : Window { //Instantiate the Kinect runtime. Required to initialize the device. //IMPORTANT NOTE: You can pass the device ID here, in case more than one Kinect device is connected. Runtime runtime = new Runtime(); public MainWindow() { InitializeComponent(); //Runtime initialization is handled when the window is opened. When the window //is closed, the runtime MUST be unitialized. this.Loaded += new RoutedEventHandler(MainWindow_Loaded); this.Unloaded += new RoutedEventHandler(MainWindow_Unloaded); //Handle the content obtained from the video camera, once received. runtime.VideoFrameReady += new EventHandler<Microsoft.Research.Kinect.Nui.ImageFrameReadyEventArgs>(runtime_VideoFrameReady); } void MainWindow_Unloaded(object sender, RoutedEventArgs e) { runtime.Uninitialize(); } void MainWindow_Loaded(object sender, RoutedEventArgs e) { //Since only a color video stream is needed, RuntimeOptions.UseColor is used. runtime.Initialize(Microsoft.Research.Kinect.Nui.RuntimeOptions.UseColor); //You can adjust the resolution here. runtime.VideoStream.Open(ImageStreamType.Video, 2, ImageResolution.Resolution640x480, ImageType.Color); } void runtime_VideoFrameReady(object sender, Microsoft.Research.Kinect.Nui.ImageFrameReadyEventArgs e) { PlanarImage image = e.ImageFrame.Image; BitmapSource source = BitmapSource.Create(image.Width, image.Height, 96, 96, PixelFormats.Bgr32, null, image.Bits, image.Width * image.BytesPerPixel); videoImage.Source = source; } } } You will find this template pack is very handy especially for those new to Kinect Development. Next up is The Coding4Fun Kinect Toolkit which contains extension methods and a WPF control to help you develop with the Kinect SDK. After downloading the package simply add a reference to the .dll using either the WPF or WinForms version. Now you will have access to several methods that can help you save an image: (for example) For a full list of extension methods and properties, please visit the site at http://c4fkinect.codeplex.com/. Kinductor – This is a great application for just learning how to use the Kinect SDK. The project uses MVVM Light and is a great start for those looking how to structure their first Kinect Application. Conclusion: Things are already getting easier for those working with the Kinect SDK. I imagine that after a few more months we will see the SDK go out of beta and allow commercial applications to run using it. I am very excited and hope that you continue reading my blog for more Kinect, WPF and Silverlight news. Subscribe to my feed

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If the model is validating the data, shouldn't it throw exceptions on bad input?

- by Carlos Campderrós

Reading this SO question it seems that throwing exceptions for validating user input is frowned upon. But who should validate this data? In my applications, all validations are done in the business layer, because only the class itself really knows which values are valid for each one of its properties. If I were to copy the rules for validating a property to the controller, it is possible that the validation rules change and now there are two places where the modification should be made. Is my premise that validation should be done on the business layer wrong? What I do So my code usually ends up like this: <?php class Person { private $name; private $age; public function setName($n) { $n = trim($n); if (mb_strlen($n) == 0) { throw new ValidationException("Name cannot be empty"); } $this->name = $n; } public function setAge($a) { if (!is_int($a)) { if (!ctype_digit(trim($a))) { throw new ValidationException("Age $a is not valid"); } $a = (int)$a; } if ($a < 0 || $a > 150) { throw new ValidationException("Age $a is out of bounds"); } $this->age = $a; } // other getters, setters and methods } In the controller, I just pass the input data to the model, and catch thrown exceptions to show the error(s) to the user: <?php $person = new Person(); $errors = array(); // global try for all exceptions other than ValidationException try { // validation and process (if everything ok) try { $person->setAge($_POST['age']); } catch (ValidationException $e) { $errors['age'] = $e->getMessage(); } try { $person->setName($_POST['name']); } catch (ValidationException $e) { $errors['name'] = $e->getMessage(); } ... } catch (Exception $e) { // log the error, send 500 internal server error to the client // and finish the request } if (count($errors) == 0) { // process } else { showErrorsToUser($errors); } Is this a bad methodology? Alternate method Should maybe I create methods for isValidAge($a) that return true/false and then call them from the controller? <?php class Person { private $name; private $age; public function setName($n) { $n = trim($n); if ($this->isValidName($n)) { $this->name = $n; } else { throw new Exception("Invalid name"); } } public function setAge($a) { if ($this->isValidAge($a)) { $this->age = $a; } else { throw new Exception("Invalid age"); } } public function isValidName($n) { $n = trim($n); if (mb_strlen($n) == 0) { return false; } return true; } public function isValidAge($a) { if (!is_int($a)) { if (!ctype_digit(trim($a))) { return false; } $a = (int)$a; } if ($a < 0 || $a > 150) { return false; } return true; } // other getters, setters and methods } And the controller will be basically the same, just instead of try/catch there are now if/else: <?php $person = new Person(); $errors = array(); if ($person->isValidAge($age)) { $person->setAge($age); } catch (Exception $e) { $errors['age'] = "Invalid age"; } if ($person->isValidName($name)) { $person->setName($name); } catch (Exception $e) { $errors['name'] = "Invalid name"; } ... if (count($errors) == 0) { // process } else { showErrorsToUser($errors); } So, what should I do? I'm pretty happy with my original method, and my colleagues to whom I have showed it in general have liked it. Despite this, should I change to the alternate method? Or am I doing this terribly wrong and I should look for another way?

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Non-blocking I/O using Servlet 3.1: Scalable applications using Java EE 7 (TOTD #188)

- by arungupta

Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. In a typical application, ServletInputStream is read in a while loop. public class TestServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { ServletInputStream input = request.getInputStream(); byte[] b = new byte[1024]; int len = -1; while ((len = input.read(b)) != -1) { . . . } }} If the incoming data is blocking or streamed slower than the server can read then the server thread is waiting for that data. The same can happen if the data is written to ServletOutputStream. This is resolved in Servet 3.1 (JSR 340, to be released as part Java EE 7) by adding event listeners - ReadListener and WriteListener interfaces. These are then registered using ServletInputStream.setReadListener and ServletOutputStream.setWriteListener. The listeners have callback methods that are invoked when the content is available to be read or can be written without blocking. The updated doGet in our case will look like: AsyncContext context = request.startAsync();ServletInputStream input = request.getInputStream();input.setReadListener(new MyReadListener(input, context)); Invoking setXXXListener methods indicate that non-blocking I/O is used instead of the traditional I/O. At most one ReadListener can be registered on ServletIntputStream and similarly at most one WriteListener can be registered on ServletOutputStream. ServletInputStream.isReady and ServletInputStream.isFinished are new methods to check the status of non-blocking I/O read. ServletOutputStream.canWrite is a new method to check if data can be written without blocking. MyReadListener implementation looks like: @Overridepublic void onDataAvailable() { try { StringBuilder sb = new StringBuilder(); int len = -1; byte b[] = new byte[1024]; while (input.isReady() && (len = input.read(b)) != -1) { String data = new String(b, 0, len); System.out.println("--> " + data); } } catch (IOException ex) { Logger.getLogger(MyReadListener.class.getName()).log(Level.SEVERE, null, ex); }}@Overridepublic void onAllDataRead() { System.out.println("onAllDataRead"); context.complete();}@Overridepublic void onError(Throwable t) { t.printStackTrace(); context.complete();} This implementation has three callbacks: onDataAvailable callback method is called whenever data can be read without blocking onAllDataRead callback method is invoked data for the current request is completely read. onError callback is invoked if there is an error processing the request. Notice, context.complete() is called in onAllDataRead and onError to signal the completion of data read. For now, the first chunk of available data need to be read in the doGet or service method of the Servlet. Rest of the data can be read in a non-blocking way using ReadListener after that. This is going to get cleaned up where all data read can happen in ReadListener only. The sample explained above can be downloaded from here and works with GlassFish 4.0 build 64 and onwards. The slides and a complete re-run of What's new in Servlet 3.1: An Overview session at JavaOne is available here. Here are some more references for you: Java EE 7 Specification Status Servlet Specification Project JSR Expert Group Discussion Archive Servlet 3.1 Javadocs

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MVC Communication Pattern

- by Kedu

This is kind of a follow up question to this http://stackoverflow.com/questions/23743285/model-view-controller-and-callbacks, but I wanted to post it separately, because its kind of a different topic. I'm working on a multiplayer cardgame for the Android platform. I split the project into MVC which fits the needs pretty good, but I'm currently stuck because I can't figure out a good way to communicate between the different parts. I have everything setup and working with the controller being a big state machine, which is called over and over from the gameloop, and calls getter methods from the GUI and the android/network part to get the input. The input itself in the GUI and network is set by inputlisteners that set a local variable which I read in the getter method. So far so good, this is working. But my problem is, the controller has to check every input separately,so if I want to add an input I have to check in which states its valid and call the getter method from all these states. This is not good, and lets the code look pretty ugly, makes additions uncomfortable and adds redundance. So what I've got from the question I mentioned above is that some kind of command or event pattern will fit my needs. What I want to do is to create a shared and threadsafe queue in the controller and instead of calling all these getter methods, I just check the queue for new input and proceed it. On the other side, the GUI and network don't have all these getters, but instead create an event or command and send it to the controller through, for example, observer/observable. Now my problem: I can't figure out a way, for these commands/events to fit a common interface (which the queue can store) and still transport different kind of data (button clicks, cards that are played, the player id the command comes from, synchronization data etc.). If I design the communication as command pattern, I have to stick all the information that is needed to execute the command into it when its created, that's impossible because the GUI or network has no knowledge of all the things the controller needs to execute stuff that needs to be done when for example a card is played. I thought about getting this stuff into the command when executing it. But over all the different commands I have, I would need all the information the controller has, and thus give the command a reference to the controller which would make everything in it public, which is real bad design I guess. So, I could try some kind of event pattern. I have to transport data in the event. So, like the command, I would have an interface, which all events have in common, and can be stored in the shared queue. I could create a big enum with all the different events that a are possible, save one of these enums in the actual event, and build a big switch case for the events, to proceed different stuff for different events. The problem here: I have different data for all the events. But I need a common interface, to store the events in a queue. How do I get the specific data, if I can only access the event through the interface? Even if that wouldn't be a problem, I'm creating another big switch case, which looks ugly, and when i want to add a new event, I have to create the event itself, the case, the enum, and the method that's called with the data. I could of course check the event with the enum and cast it to its type, so I can call event type specific methods that give me the data I need, but that looks like bad design too.

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JEP 124: Enhance the Certificate Revocation-Checking API

- by smullan

Revocation checking is the mechanism to determine the revocation status of a certificate. If it is revoked, it is considered invalid and should not be used. Currently as of JDK 7, the PKIX implementation of java.security.cert.CertPathValidator includes a revocation checking implementation that supports both OCSP and CRLs, the two main methods of checking revocation. However, there are very few options that allow you to configure the behavior. You can always implement your own revocation checker, but that's a lot of work. JEP 124 (Enhance the Certificate Revocation-Checking API) is one of the 11 new security features in JDK 8. This feature enhances the java.security.cert API to support various revocation settings such as best-effort checking, end-entity certificate checking, and mechanism-specific options and parameters. Let's describe each of these in more detail and show some examples. The features are provided through a new class named PKIXRevocationChecker. A PKIXRevocationChecker instance is returned by a PKIX CertPathValidator as follows: CertPathValidator cpv = CertPathValidator.getInstance("PKIX"); PKIXRevocationChecker prc = (PKIXRevocationChecker)cpv.getRevocationChecker(); You can now set various revocation options by calling different methods of the returned PKIXRevocationChecker object. For example, the best-effort option (called soft-fail) allows the revocation check to succeed if the status cannot be obtained due to a network connection failure or an overloaded server. It is enabled as follows: prc.setOptions(Enum.setOf(Option.SOFT_FAIL)); When the SOFT_FAIL option is specified, you can still obtain any exceptions that may have been thrown due to network issues. This can be useful if you want to log this information or treat it as a warning. You can obtain these exceptions by calling the getSoftFailExceptions method: List<CertPathValidatorException> exceptions = prc.getSoftFailExceptions(); Another new option called ONLY_END_ENTITY allows you to only check the revocation status of the end-entity certificate. This can improve performance, but you should be careful using this option, as the revocation status of CA certificates will not be checked. To set more than one option, simply specify them together, for example: prc.setOptions(Enum.setOf(Option.SOFT_FAIL, Option.ONLY_END_ENTITY)); By default, PKIXRevocationChecker will try to check the revocation status of a certificate using OCSP first, and then CRLs as a fallback. However, you can switch the order using the PREFER_CRLS option, or disable the fallback altogether using the NO_FALLBACK option. For example, here is how you would only use CRLs to check the revocation status: prc.setOptions(Enum.setOf(Option.PREFER_CRLS, Option.NO_FALLBACK)); There are also a number of other useful methods which allow you to specify various options such as the OCSP responder URI, the trusted OCSP responder certificate, and OCSP request extensions. However, one of the most useful features is the ability to specify a cached OCSP response with the setOCSPResponse method. This can be quite useful if the OCSPResponse has already been obtained, for example in a protocol that uses OCSP stapling. After you have set all of your preferred options, you must add the PKIXRevocationChecker to your PKIXParameters object as one of your custom CertPathCheckers before you validate the certificate chain, as follows: PKIXParameters params = new PKIXParameters(keystore); params.addCertPathChecker(prc); CertPathValidatorResult result = cpv.validate(path, params); Early access binaries of JDK 8 can be downloaded from http://jdk8.java.net/download.html

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Joomla SMTP Configuration Issue

- by msargenttrue

I'm having an issue with the SMTP setup of my Joomla website when trying to send mass emails through the CB Mailing (Mass Email) extension. I receive this error: SMTP Error! The following recipients failed: Number of users to whom e-mail was sent: 0 (Total in list: 1) The old version of this websites mass emailer worked fine, however, in order to add Kunena Forum and maintain compatibility I had to make several upgrades to the site. Both the new version and old verson configurations are outlined below. Server for Website: Mac OS X Server 10.4.11, Apache 1.3.4.1, PHP 5.2.3, MySQL 4.1.22 Server for SMTP: Eudora Internet Mail Server 3.3.9 (EIMS Server X) New Configuration: Joomla 1.5.25, Community Builder 1.7.1, CB Paid Subscriptions (CB Subs) 1.2.2, CBMailing 2.3.4, Kunena Forum 1.7.0, Legacy 1.0 plug-in disabled Mail Settings (New Config): Mailer: SMTP Server Mail from: [email protected] From Name: CASPA Sendmail Path: /usr/sbin/sendmail SMTP Authentication: Yes SMTP Security: None SMTP Port: 25 SMTP Username: [email protected] SMTP Password: xxxxxxx SMTP Host: 209.48.40.194 Old Configuration (Working SMTP Configuration): Joomla 1.5.9, Community Builder 1.2, CB Paid Subscriptions (CB Subs) 1.0.3, CB Mailing 2.1, Legacy 1.0 plug-in enabled Mail Settings (Old Config): Mailer: SMTP Server Mail from: [email protected] From Name: CASPA Sendmail Path: /usr/sbin/sendmail SMTP Authentication: Yes SMTP Username: [email protected] SMTP Password: xxxxxxx SMTP Host: 209.48.40.194 (Notice how the older version of Joomla is missing the 2 fields: SMTP Security and SMTP Port) Thanks in advance!

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How To Delete Top 100 Rows From SQL Server Tables

- by Gopinath

If you want to delete top 100/n records from an SQL Server table, it is very easy with the following query: DELETE FROM MyTable WHERE PK_Column IN( SELECT TOP 100 PK_Column FROM MyTable ORDER BY creation ) Why Would You Require To Delete Top 100 Records? I often delete a top n records of a table when number of rows in the are too huge. Lets say if I’ve 1000000000 records in a table, deleting 10000 rows at a time in a loop is faster than trying to delete all the 1000000000 at a time. What ever may be reason, if you ever come across a requirement of deleting a bunch of rows at a time, this query will be helpful to you. Join us on Facebook to read all our stories right inside your Facebook news feed.

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TFS 2008 Web Access Report 100 record limitation

- by HosamKamel

By default TFS 2008 Web Access has the limit of 100 record when you open any query in report mode. Even if you tried to export the query to excel or PDF you will only get first 100 record exported. To overcome this issue, you have to reconfigure this count in the web.config file Navigate to web access files C:\Program Files\Microsoft Visual Studio 2008 Team System Web Access\Wiwa Open web.config modify maxWorkitemsInReportList count to whatever count you need. You need to do modify the same configuration in web.config located here C:\Program Files\Microsoft Visual Studio 2008 Team System Web Access\Web A full discussion thread exists here Team Foundation Server - Team System Web Access

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EBS: OPP Out of memory issue...

- by ashish.shrivastava

FO Processor is little more hungry for memory compare to other Java process. If XSLT scalable option is not set and the same time your RTF template is not well optimized definitely you are going to hit Out of memory exception while working with large volume of data. If the memory requirement is not too bad, you can set the OOP Heap size using following SQL queries. Check the current OPP JVM Heap size using following SQL query SQL select DEVELOPER_PARAMETERS from FND_CP_SERVICES where SERVICE_ID = (select MANAGER_TYPE from FND_CONCURRENT_QUEUES where CONCURRENT_QUEUE_NAME = 'FNDCPOPP' DEVELOPER_PARAMETERS ----------------------------------------------------- J:oracle.apps.fnd.cp.gsf.GSMServiceController:-mx512m Set the JVM Heap size using following SQL query SQL update FND_CP_SERVICES set DEVELOPER_PARAMETERS = 'J:oracle.apps.fnd.cp.gsf.GSMServiceController:-mx2048m' where SERVICE_ID = (select MANAGER_TYPE from FND_CONCURRENT_QUEUES where CONCURRENT_QUEUE_NAME = 'FNDCPOPP'); SQLCommit; . You need to restart the Concurrent Manager to make it effective. If this does not resolve the issue, You need to optimize RTF template and set the XSLT scalable option true.

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LLBLGen Pro v3.5 has been released!

- by FransBouma

Last weekend we released LLBLGen Pro v3.5! Below the list of what's new in this release. Of course, not everything is on this list, like the large amount of work we put in refactoring the runtime framework. The refactoring was necessary because our framework has two paradigms which are added to the framework at a different time, and from a design perspective in the wrong order (the paradigm we added first, SelfServicing, should have been built on top of Adapter, the other paradigm, which was added more than a year after the first released version). The refactoring made sure the framework re-uses more code across the two paradigms (they already shared a lot of code) and is better prepared for the future. We're not done yet, but refactoring a massive framework like ours without breaking interfaces and existing applications is ... a bit of a challenge ;) To celebrate the release of v3.5, we give every customer a 30% discount! Use the coupon code NR1ORM with your order :) The full list of what's new: Designer Rule based .NET Attribute definitions. It's now possible to specify a rule using fine-grained expressions with an attribute definition to define which elements of a given type will receive the attribute definition. Rules can be assigned to attribute definitions on the project level, to make it even easier to define attribute definitions in bulk for many elements in the project. More information... Revamped Project Settings dialog. Multiple project related properties and settings dialogs have been merged into a single dialog called Project Settings, which makes it easier to configure the various settings related to project elements. It also makes it easier to find features previously not used by many (e.g. type conversions) More information... Home tab with Quick Start Guides. To make new users feel right at home, we added a home tab with quick start guides which guide you through four main use cases of the designer. System Type Converters. Many common conversions have been implemented by default in system type converters so users don't have to develop their own type converters anymore for these type conversions. Bulk Element Setting Manipulator. To change setting values for multiple project elements, it was a little cumbersome to do that without a lot of clicking and opening various editors. This dialog makes changing settings for multiple elements very easy. EDMX Importer. It's now possible to import entity model data information from an existing Entity Framework EDMX file. Other changes and fixes See for the full list of changes and fixes the online documentation. LLBLGen Pro Runtime Framework WCF Data Services (OData) support has been added. It's now possible to use your LLBLGen Pro runtime framework powered domain layer in a WCF Data Services application using the VS.NET tools for WCF Data Services. WCF Data Services is a Microsoft technology for .NET 4 to expose your domain model using OData. More information... New query specification and execution API: QuerySpec. QuerySpec is our new query specification and execution API as an alternative to Linq and our more low-level API. It's build, like our Linq provider, on top of our lower-level API. More information... SQL Server 2012 support. The SQL Server DQE allows paging using the new SQL Server 2012 style. More information... System Type converters. For a common set of types the LLBLGen Pro runtime framework contains built-in type conversions so you don't need to write your own type converters anymore. Public/NonPublic property support. It's now possible to mark a field / navigator as non-public which is reflected in the runtime framework as an internal/friend property instead of a public property. This way you can hide properties from the public interface of a generated class and still access it through code added to the generated code base. FULL JOIN support. It's now possible to perform FULL JOIN joins using the native query api and QuerySpec. It's left to the developer to check whether the used target database supports FULL (OUTER) JOINs. Using a FULL JOIN with entity fetches is not recommended, and should only be used when both participants in the join aren't the target of the fetch. Dependency Injection Tracing. It's now possible to enable tracing on dependency injection. Enable tracing at level '4' on the traceswitch 'ORMGeneral'. This will emit trace information about which instance of which type got an instance of type T injected into property P. Entity Instances in projections in Linq. It's now possible to return an entity instance in a custom Linq projection. It's now also possible to pass this instance to a method inside the query projection. Inheritance fully supported in this construct. Entity Framework support The Entity Framework has been updated in the recent year with code-first support and a new simpler context api: DbContext (with DbSet). The amount of code to generate is smaller and the context simpler. LLBLGen Pro v3.5 comes with support for DbContext and DbSet and generates code which utilizes these new classes. NHibernate support NHibernate v3.2+ built-in proxy factory factory support. By default the built-in ProxyFactoryFactory is selected. FluentNHibernate Session Manager uses 1.2 syntax. Fluent NHibernate mappings generate a SessionManager which uses the v1.2 syntax for the ProxyFactoryFactory location Optionally emit schema / catalog name in mappings Two settings have been added which allow the user to control whether the catalog name and/or schema name as known in the project in the designer is emitted into the mappings.

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Performance considerations for common SQL queries

- by Jim Giercyk

Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results. There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set. Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient. For the queries below, I downloaded the test database from SQLSkills: http://www.sqlskills.com/sql-server-resources/sql-server-demos/. There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554. Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table. /*************/ /* Sub Query */ /*************/ SELECT a.[Member Number] , m.lastname , m.firstname , a.[Number Of Payments] , a.[Average Payment] , a.[Total Paid] FROM ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 ) a JOIN dbo.member m ON a.[Member Number] = m.member_no /***************/ /* Cross Apply */ /***************/ SELECT ca.[Member Number] , m.lastname , m.firstname , ca.[Number Of Payments] , ca.[Average Payment] , ca.[Total Paid] FROM dbo.member m CROSS APPLY ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment WHERE member_no = m.member_no GROUP BY member_no HAVING COUNT(Payment_No) > 1 ) ca /********/ /* CTEs */ /********/ ; WITH Payments AS ( SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 ), MemberInfo AS ( SELECT p.[Member Number] , m.lastname , m.firstname , p.[Number Of Payments] , p.[Average Payment] , p.[Total Paid] FROM dbo.member m JOIN Payments p ON m.member_no = p.[Member Number] ) SELECT * FROM MemberInfo /************************/ /* SELECT with Grouping */ /************************/ SELECT p.member_no 'Member Number' , m.lastname , m.firstname , COUNT(Payment_No) 'Number Of Payments' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' FROM dbo.payment p JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no , m.lastname , m.firstname HAVING COUNT(Payment_No) > 1 We can see what is going on in SQL’s brain by looking at the execution plan. The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes. SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan. We can settle this once and for all. Here is what SQL did with these queries: Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them. Everybody is right…..I guess we can all finally go to lunch together! But wait a second, I may not be a fighter, but I AM an instigator. Let’s see how a table variable stacks up. Here is the code I executed: /********************/ /* Table Variable */ /********************/ DECLARE @AggregateTable TABLE ( member_no INT , AveragePayment MONEY , TotalPaid MONEY , NumberOfPayments MONEY ) INSERT @AggregateTable SELECT member_no 'Member Number' , AVG(payment_amt) 'Average Payment' , SUM(payment_amt) 'Total Paid' , COUNT(Payment_No) 'Number Of Payments' FROM dbo.payment GROUP BY member_no HAVING COUNT(Payment_No) > 1 SELECT at.member_no 'Member Number' , m.lastname , m.firstname , at.NumberOfPayments 'Number Of Payments' , at.AveragePayment 'Average Payment' , at.TotalPaid 'Total Paid' FROM @AggregateTable at JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query. Here’s what I got: Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps. BUT, the combination of the 2 steps is only 22% of the batch. It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan. The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan. While this is true, the estimate does not come in to play until you read from the table variable. In this case, the table variable had 6,706 rows, but it still outperformed the other queries. People argue that table variables should only be used for hash or lookup tables. The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results. My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style. If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate. If you have a company standard, I strongly recommend you follow it. If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule. Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment. Download the database and try it!

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Using LogParser - part 2

- by fatherjack

PersonAddress.csv SalesOrderDetail.tsv In part 1 of this series we downloaded and installed LogParser and used it to list data from a csv file. That was a good start and in this article we are going to see the different ways we can stream data and choose whether a whole file is selected. We are also going to take a brief look at what file types we can interrogate. If we take the query from part 1 and add a value for the output parameter as -o:datagrid so that the query becomes LOGPARSER "SELECT top 15 * FROM C:\LP\person_address.csv" -o:datagrid and run that we get a different result. A pop-up dialog that lets us view the results in a resizable grid. Notice that because we didn't specify the columns we wanted returned by LogParser (we used SELECT *) is has added two columns to the recordset - filename and rownumber. This behaviour can be very useful as we will see in future parts of this series. You can click Next 10 rows or All rows or close the datagrid once you are finished reviewing the data. You may have noticed that the files that I am working with are different file types - one is a csv (comma separated values) and the other is a tsv (tab separated values). If you want to convert a file from one to another then LogParser makes it incredibly simple. Rather than using 'datagrid' as the value for the output parameter, use 'csv': logparser "SELECT SalesOrderID, SalesOrderDetailID, CarrierTrackingNumber, OrderQty, ProductID, SpecialOfferID, UnitPrice, UnitPriceDiscount, LineTotal, rowguid, ModifiedDate into C:\Sales_SalesOrderDetail.csv FROM C:\Sales_SalesOrderDetail.tsv" -i:tsv -o:csv Those familiar with SQL will not have to make a very big leap of faith to making adjustments to the above query to filter in/out records from the source file. Lets get all the records from the same file where the Order Quantity (OrderQty) is more than 25: logparser "SELECT SalesOrderID, SalesOrderDetailID, CarrierTrackingNumber, OrderQty, ProductID, SpecialOfferID, UnitPrice, UnitPriceDiscount, LineTotal, rowguid, ModifiedDate into C:\LP\Sales_SalesOrderDetailOver25.csv FROM C:\LP\Sales_SalesOrderDetail.tsv WHERE orderqty > 25" -i:tsv -o:csv Or we could find all those records where the Order Quantity is equal to 25 and output it to an xml file: logparser "SELECT SalesOrderID, SalesOrderDetailID, CarrierTrackingNumber, OrderQty, ProductID, SpecialOfferID, UnitPrice, UnitPriceDiscount, LineTotal, rowguid, ModifiedDate into C:\LP\Sales_SalesOrderDetailEq25.xml FROM C:\LP\Sales_SalesOrderDetail.tsv WHERE orderqty = 25" -i:tsv -o:xml All the standard comparison operators are to be found in LogParser; >, <, =, LIKE, BETWEEN, OR, NOT, AND. Input and Output file formats. LogParser has a pretty impressive list of file formats that it can parse and a good selection of output formats that will let you generate output in a format that is useable for whatever process or application you may be using. From any of these To any of these IISW3C: parses IIS log files in the W3C Extended Log File Format. NAT: formats output records as readable tabulated columns. IIS: parses IIS log files in the Microsoft IIS Log File Format. CSV: formats output records as comma-separated values text. BIN: parses IIS log files in the Centralized Binary Log File Format. TSV: formats output records as tab-separated or space-separated values text. IISODBC: returns database records from the tables logged to by IIS when configured to log in the ODBC Log Format. XML: formats output records as XML documents. HTTPERR: parses HTTP error log files generated by Http.sys. W3C: formats output records in the W3C Extended Log File Format. URLSCAN: parses log files generated by the URLScan IIS filter. TPL: formats output records following user-defined templates. CSV: parses comma-separated values text files. IIS: formats output records in the Microsoft IIS Log File Format. TSV: parses tab-separated and space-separated values text files. SQL: uploads output records to a table in a SQL database. XML: parses XML text files. SYSLOG: sends output records to a Syslog server. W3C: parses text files in the W3C Extended Log File Format. DATAGRID: displays output records in a graphical user interface. NCSA: parses web server log files in the NCSA Common, Combined, and Extended Log File Formats. CHART: creates image files containing charts. TEXTLINE: returns lines from generic text files. TEXTWORD: returns words from generic text files. EVT: returns events from the Windows Event Log and from Event Log backup files (.evt files). FS: returns information on files and directories. REG: returns information on registry values. ADS: returns information on Active Directory objects. NETMON: parses network capture files created by NetMon. ETW: parses Enterprise Tracing for Windows trace log files and live sessions. COM: provides an interface to Custom Input Format COM Plugins. So, you can query data from any of the types on the left and really easily get it into a format where it is ready for analysis by other tools. To a DBA or network Administrator with an enquiring mind this is a treasure trove. In part 3 we will look at working with multiple sources and specifically outputting to SQL format. See you there!

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CQRS – Questions and Concerns

- by Dylan Smith

I’ve been doing a lot of learning on CQRS and Event Sourcing over the last little while and I have a number of questions that I haven’t been able to answer. 1. What is the benefit of CQRS when compared to a typical DDD architecture that uses Event Sourcing and properly captures intent and behavior via verb-based commands? (other than Scalability) 2. When using CQRS what do you do with complex query-based logic? I’m going to elaborate on #1 in this blog post and I’ll do a follow-up post on #2. I watched through Greg Young’s video on the business benefits of CQRS + Event Sourcing and first let me say that I thought it was an excellent presentation that really drives home a lot of the benefits to this approach to architecture (I watched it twice in a row I enjoyed it so much!). But it didn’t answer some of my questions fully (I wish I had been there to ask these of Greg in person!). So let me pick apart some of the points he makes and how they relate to my first question above. I’m completely sold on the idea of event sourcing and have a clear understanding of the benefits that it brings to the table, so I’m not going to question that. But you can use event sourcing without going to a CQRS architecture, so my main question is around the benefits of CQRS + Event Sourcing vs Event Sourcing + Typical DDD architecture Architecture with Event Sourcing + Commands on Left, CQRS on Right Greg talks about how the stereotypical architecture doesn’t support DDD, but is that only because his diagram shows DTO’s coming up from the client. If we use the same diagram but allow the client to send commands doesn’t that remove a lot of the arguments that Greg makes against the stereotypical architecture? We can now introduce verbs into the system. We can capture intent now (storing it still requires event sourcing, but you can implement event sourcing without doing CQRS) We can create a rich domain model (as opposed to an anemic domain model) Scalability is obviously a benefit that CQRS brings to the table, but like Greg says, very few of the systems we create truly need significant scalability Greg talks about the ability to scale your development efforts. He says CQRS allows you to split the system into 3 parts (Client, Domain/Commands, Reads) and assign 3 teams of developers to work on them in parallel; letting you scale your development efforts by 3x with nearly linear gains. But in the stereotypical architecture don’t you already have 2 separate modules that you can split your dev efforts between: The client that sends commands/queries and receives DTO’s, and the Domain which accepts commands/queries, and generates events/DTO’s. If this is true it’s not really a 3x scaling you achieve with CQRS but merely a 1.5x scaling which while great doesn’t sound nearly as dramatic (“I can do it with 10 devs in 12 months – let me hire 5 more and we can have it done in 8 months”). Making the Query side “stupid simple” such that you can assign junior developers (or even outsource it) sounds like a valid benefit, but I have some concerns over what you do with complex query-based logic/behavior. I’m going to go into more detail on this in a follow-up blog post shortly. He also seemed to focus on how “stupid-simple” it is doing queries against the de-normalized data store, but I imagine there is still significant complexity in the event handlers that interpret the events and apply them to the de-normalized tables. It sounds like Greg suggests that because we’re doing CQRS that allows us to apply Event Sourcing when we otherwise wouldn’t be able to (~33:30 in the video). I don’t believe this is true. I don’t see why you wouldn’t be able to apply Event Sourcing without separating out the Commands and Queries. The queries would just operate against the domain model instead of the database. But you’d still get the benefits of Event Sourcing. Without CQRS the queries would only be able to operate against the current state rather than the event history, but even in CQRS the domain behaviors can only operate against the current state and I don’t see that being a big limiting factor. If some query needs to operate against something that is not captured by the current state you would just have to update the domain model to capture that information (no different than if that statement were made about a Command under CQRS). Some of the benefits I do see being applicable are that your domain model might end up being simpler/smaller since it only needs to represent the state needed to process commands and not worry about the reads (like the Deactivate Inventory Item and associated comment example that Greg provides). And also commands that can be handled in a Transaction Script style manner by the command handler simply generating events and not touching the domain model. It also makes it easier for your senior developers to focus on the command behavior and ignore the queries, which is usually going to be a better use of their time. And of course scalability. If anybody out there has any thoughts on this and can help educate me further, please either leave a comment or feel free to get in touch with me via email:

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Troubleshooting High-CPU Utilization for SQL Server

- by Susantha Bathige

The objective of this FAQ is to outline the basic steps in troubleshooting high CPU utilization on a server hosting a SQL Server instance. The first and the most common step if you suspect high CPU utilization (or are alerted for it) is to login to the physical server and check the Windows Task Manager. The Performance tab will show the high utilization as shown below: Next, we need to determine which process is responsible for the high CPU consumption. The Processes tab of the Task Manager will show this information: Note that to see all processes you should select Show processes from all user. In this case, SQL Server (sqlserver.exe) is consuming 99% of the CPU (a normal benchmark for max CPU utilization is about 50-60%). Next we examine the scheduler data. Scheduler is a component of SQLOS which evenly distributes load amongst CPUs. The query below returns the important columns for CPU troubleshooting. Note – if your server is under severe stress and you are unable to login to SSMS, you can use another machine’s SSMS to login to the server through DAC – Dedicated Administrator Connection (see http://msdn.microsoft.com/en-us/library/ms189595.aspx for details on using DAC) SELECT scheduler_id ,cpu_id ,status ,runnable_tasks_count ,active_workers_count ,load_factor ,yield_count FROM sys.dm_os_schedulers WHERE scheduler_id See below for the BOL definitions for the above columns. scheduler_id – ID of the scheduler. All schedulers that are used to run regular queries have ID numbers less than 1048576. Those schedulers that have IDs greater than or equal to 1048576 are used internally by SQL Server, such as the dedicated administrator connection scheduler. cpu_id – ID of the CPU with which this scheduler is associated. status – Indicates the status of the scheduler. runnable_tasks_count – Number of workers, with tasks assigned to them that are waiting to be scheduled on the runnable queue. active_workers_count – Number of workers that are active. An active worker is never preemptive, must have an associated task, and is either running, runnable, or suspended. current_tasks_count - Number of current tasks that are associated with this scheduler. load_factor – Internal value that indicates the perceived load on this scheduler. yield_count – Internal value that is used to indicate progress on this scheduler. Now to interpret the above data. There are four schedulers and each assigned to a different CPU. All the CPUs are ready to accept user queries as they all are ONLINE. There are 294 active tasks in the output as per the current_tasks_count column. This count indicates how many activities currently associated with the schedulers. When a task is complete, this number is decremented. The 294 is quite a high figure and indicates all four schedulers are extremely busy. When a task is enqueued, the load_factor value is incremented. This value is used to determine whether a new task should be put on this scheduler or another scheduler. The new task will be allocated to less loaded scheduler by SQLOS. The very high value of this column indicates all the schedulers have a high load. There are 268 runnable tasks which mean all these tasks are assigned a worker and waiting to be scheduled on the runnable queue. The next step is to identify which queries are demanding a lot of CPU time. The below query is useful for this purpose (note, in its current form, it only shows the top 10 records). SELECT TOP 10 st.text ,st.dbid ,st.objectid ,qs.total_worker_time ,qs.last_worker_time ,qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC This query as total_worker_time as the measure of CPU load and is in descending order of the total_worker_time to show the most expensive queries and their plans at the top: Note the BOL definitions for the important columns: total_worker_time - Total amount of CPU time, in microseconds, that was consumed by executions of this plan since it was compiled. last_worker_time - CPU time, in microseconds, that was consumed the last time the plan was executed. I re-ran the same query again after few seconds and was returned the below output. After few seconds the SP dbo.TestProc1 is shown in fourth place and once again the last_worker_time is the highest. This means the procedure TestProc1 consumes a CPU time continuously each time it executes. In this case, the primary cause for high CPU utilization was a stored procedure. You can view the execution plan by clicking on query_plan column to investigate why this is causing a high CPU load. I have used SQL Server 2008 (SP1) to test all the queries used in this article.

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Syncing Data with a Server using Silverlight and HTTP Polling Duplex

- by dwahlin

Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex. Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going. In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume. What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions. A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2). [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server. [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call. The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property. This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available. Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor. [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players. GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data. Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>(). This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData(). Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint. <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync(). Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed. As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it. Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible. Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice. Sample Application Download

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Alert visualization recipe: Get out your blender, drop in some sp_send_dbmail, Google Charts API, add your favorite colors and sprinkle with html. Blend till it’s smooth and looks pretty enough to taste.

- by Maria Zakourdaev

I really like database monitoring. My email inbox have a constant flow of different types of alerts coming from our production servers with all kinds of information, sometimes more useful and sometimes less useful. Usually database alerts look really simple, it’s usually a plain text email saying “Prod1 Database data file on Server X is 80% used. You’d better grow it manually before some query triggers the AutoGrowth process”. Imagine you could have received email like the one below. In addition to the alert description it could have also included the the database file growth chart over the past 6 months. Wouldn’t it give you much more information whether the data growth is natural or extreme? That’s truly what data visualization is for. Believe it or not, I have sent the graph below from SQL Server stored procedure without buying any additional data monitoring/visualization tool. Would you like to visualize your database alerts like I do? Then like myself, you’d love the Google Charts. All you need to know is a little HTML and have a mail profile configured on your SQL Server instance regardless of the SQL Server version. First of all, I hope you know that the sp_send_dbmail procedure has a great parameter @body_format = ‘HTML’, which allows us to send rich and colorful messages instead of boring black and white ones. All that we need is to dynamically create HTML code. This is how, for instance, you can create a table and populate it with some data: DECLARE @html varchar(max) SET @html = '<html>' + '<H3><font id="Text" style='color: Green;'>Top Databases: </H3>' + '<table border="1" bordercolor="#3300FF" style='background-color:#DDF8CC' width='70%' cellpadding='3' cellspacing='3'>' + '<tr><font color="Green"><th>Database Name</th><th>Size</th><th>Physical Name</th></tr>' + CAST( (SELECT TOP 10 td = name,'', td = size * 8/1024 ,'', td = physical_name FROM sys.master_files ORDER BY size DESC FOR XML PATH ('tr'),TYPE ) AS VARCHAR(MAX)) + '</table>' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject ='Top databases', @body = @html, @body_format = 'HTML' This is the result: If you want to add more visualization effects, you can use Google Charts Tools https://google-developers.appspot.com/chart/interactive/docs/index which is a free and rich library of data visualization charts, they’re also easy to populate and embed. There are two versions of the Google Charts Image based charts: https://google-developers.appspot.com/chart/image/docs/gallery/chart_gall This is an old version, it’s officially deprecated although it will be up for a next few years or so. I really enjoy using this one because it can be viewed within the email body. For mobile devices you need to change the “Load remote images” property in your email application configuration. Charts based on JavaScript classes: https://google-developers.appspot.com/chart/interactive/docs/gallery This API is newer, with rich and highly interactive charts, and it’s much more easier to understand and configure. The only downside of it is that they cannot be viewed within the email body. Outlook, Gmail and many other email clients, as part of their security policy, do not run any JavaScript that’s placed within the email body. However, you can still enjoy this API by sending the report as an email attachment. Here is an example of the old version of Google Charts API, sending the same top databases report as in the previous example but instead of a simple table, this script is using a pie chart right from the T-SQL code DECLARE @html varchar(8000) DECLARE @Series varchar(800),@Labels varchar(8000),@Legend varchar(8000); SET @Series = ''; SET @Labels = ''; SET @Legend = ''; SELECT TOP 5 @Series = @Series + CAST(size * 8/1024 as varchar) + ',', @Labels = @Labels +CAST(size * 8/1024 as varchar) + 'MB'+'|', @Legend = @Legend + name + '|' FROM sys.master_files ORDER BY size DESC SELECT @Series = SUBSTRING(@Series,1,LEN(@Series)-1), @Labels = SUBSTRING(@Labels,1,LEN(@Labels)-1), @Legend = SUBSTRING(@Legend,1,LEN(@Legend)-1) SET @html = '<H3><font color="Green"> '+@@ServerName+' top 5 databases : </H3>'+ '<br>'+ '<img src="http://chart.apis.google.com/chart?'+ 'chf=bg,s,DDF8CC&'+ 'cht=p&'+ 'chs=400x200&'+ 'chco=3072F3|7777CC|FF9900|FF0000|4A8C26&'+ 'chd=t:'+@Series+'&'+ 'chl='+@Labels+'&'+ 'chma=0,0,0,0&'+ 'chdl='+@Legend+'&'+ 'chdlp=b"'+ 'alt="'+@@ServerName+' top 5 databases" />' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject = 'Top databases', @body = @html, @body_format = 'HTML' This is what you get. Isn’t it great? Chart parameters reference: chf Gradient fill bg - backgroud ; s- solid cht chart type ( p - pie) chs chart size width/height chco series colors chd chart data string 1,2,3,2 chl pir chart labels a|b|c|d chma chart margins chdl chart legend a|b|c|d chdlp chart legend text b - bottom of chart Line graph implementation is also really easy and powerful DECLARE @html varchar(max) DECLARE @Series varchar(max) DECLARE @HourList varchar(max) SET @Series = ''; SET @HourList = ''; SELECT @HourList = @HourList + SUBSTRING(CONVERT(varchar(13),last_execution_time,121), 12,2) + '|' , @Series = @Series + CAST( COUNT(1) as varchar) + ',' FROM sys.dm_exec_query_stats s CROSS APPLY sys.dm_exec_sql_text(plan_handle) t WHERE last_execution_time > = getdate()-1 GROUP BY CONVERT(varchar(13),last_execution_time,121) ORDER BY CONVERT(varchar(13),last_execution_time,121) SET @Series = SUBSTRING(@Series,1,LEN(@Series)-1) SET @html = '<img src="http://chart.apis.google.com/chart?'+ 'chco=CA3D05,87CEEB&'+ 'chd=t:'+@Series+'&'+ 'chds=1,350&'+ 'chdl= Proc executions from cache&'+ 'chf=bg,s,1F1D1D|c,lg,0,363433,1.0,2E2B2A,0.0&'+ 'chg=25.0,25.0,3,2&'+ 'chls=3|3&'+ 'chm=d,CA3D05,0,-1,12,0|d,FFFFFF,0,-1,8,0|d,87CEEB,1,-1,12,0|d,FFFFFF,1,-1,8,0&'+ 'chs=600x450&'+ 'cht=lc&'+ 'chts=FFFFFF,14&'+ 'chtt=Executions for from' +(SELECT CONVERT(varchar(16),min(last_execution_time),121) FROM sys.dm_exec_query_stats WHERE last_execution_time > = getdate()-1) +' till '+ +(SELECT CONVERT(varchar(16),max(last_execution_time),121) FROM sys.dm_exec_query_stats) + '&'+ 'chxp=1,50.0|4,50.0&'+ 'chxs=0,FFFFFF,12,0|1,FFFFFF,12,0|2,FFFFFF,12,0|3,FFFFFF,12,0|4,FFFFFF,14,0&'+ 'chxt=y,y,x,x,x&'+ 'chxl=0:|1|350|1:|N|2:|'+@HourList+'3:|Hour&'+ 'chma=55,120,0,0" alt="" />' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject ='Daily number of executions', @body = @html, @body_format = 'HTML' Chart parameters reference: chco series colors chd series data chds scale format chdl chart legend chf background fills chg grid line chls line style chm line fill chs chart size cht chart type chts chart style chtt chart title chxp axis label positions chxs axis label styles chxt axis tick mark styles chxl axis labels chma chart margins If you don’t mind to get your charts as an email attachment, you can enjoy the Java based Google Charts which are even easier to configure, and have much more advanced graphics. In the example below, the sp_send_email procedure uses the parameter @query which will be executed at the time that sp_send_dbemail is executed and the HTML result of this execution will be attached to the email. DECLARE @html varchar(max),@query varchar(max) DECLARE @SeriesDBusers varchar(800); SET @SeriesDBusers = ''; SELECT @SeriesDBusers = @SeriesDBusers + ' ["'+DB_NAME(r.database_id) +'", ' +cast(count(1) as varchar)+'],' FROM sys.dm_exec_requests r GROUP BY DB_NAME(database_id) ORDER BY count(1) desc; SET @SeriesDBusers = SUBSTRING(@SeriesDBusers,1,LEN(@SeriesDBusers)-1) SET @query = ' PRINT '' <html> <head> <script type="text/javascript" src="https://www.google.com/jsapi"></script> <script type="text/javascript"> google.load("visualization", "1", {packages:["corechart"]}); google.setOnLoadCallback(drawChart); function drawChart() { var data = google.visualization.arrayToDataTable([ ["Database Name", "Active users"], '+@SeriesDBusers+' ]); var options = { title: "Active users", pieSliceText: "value" }; var chart = new google.visualization.PieChart(document.getElementById("chart_div")); chart.draw(data, options); }; </script> </head> <body> <table> <tr><td> <div id="chart_div" style='width: 800px; height: 300px;'></div> </td></tr> </table> </body> </html> ''' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject ='Active users', @body = @html, @body_format = 'HTML', @query = @Query, @attach_query_result_as_file = 1, @query_attachment_filename = 'Results.htm' After opening the email attachment in the browser you are getting this kind of report: In fact, the above is not only for database alerts. It can be used for applicative reports if you need high levels of customization that you cannot achieve using standard methods like SSRS. If you need more information on how to customize the charts, you can try the following: Image Based Charts wizard https://google-developers.appspot.com/chart/image/docs/chart_wizard Live Image Charts Playground https://google-developers.appspot.com/chart/image/docs/chart_playground Image Based Charts Parameters List https://google-developers.appspot.com/chart/image/docs/chart_params Java Script Charts Playground https://code.google.com/apis/ajax/playground/?type=visualization Use the above examples as a starting point for your procedures and I’d be more than happy to hear of your implementations of the above techniques. Yours, Maria

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