Apollo 13 - Tao Liu's blog: January 2013

Monday, January 28, 2013

Decide to use TypeScript on HTML5 + JavaScript

I decide to give my big data project a new face. A HTML5 face, not WPF or SilverLight.

Continue from the previous post about HTML5/JavaScript, I decide to spend several hours on a new tool to write JavaScript. I compared Dart and TypeScript. As a long time C# developer, I feel it will be easier to follow another Andres's language. One advance for TypeScript can host the JavaScript code and this can help me to learn JavaScript as well.

After I install the TypeScript in VS2012, I have to reboot my computer. It was a little surprise as I did not expect a preview language needs reboot my computer while VS SP1 does not requires a reboot. But anyway, it does not take long.

I created the first TypeScript project and the sample code helps me understand what is going on. The first small project I did is a small animation on the Canvas. The following code is located in app1.ts which will be compiled to app1.js. In the HTML page, I have a canvas whose id is "canvas0".

 var c = <HTMLCanvasElement> document.getElementById("canvas0");  
 var ctx = c.getContext("2d");  
 setInterval(() =>  
 {  
   var i = new Date().getSeconds() % 10 / 10;  
   var width = c.width  
   var height = c.height  
   // Create gradient  
   var grd = ctx.createLinearGradient(0, 0, width, 0);  
   grd.addColorStop(0, "red");  
   grd.addColorStop(i, "yellow");  
   // Fill with gradient  
   ctx.fillStyle = grd;  
   ctx.fillRect(0, 0, width, height);  
 }, 500)

In order to make the debug work, you have to use IE as default browser. Adding a new item does not work well, I have to manually add a .ts file and fix the project file.

Sunday, January 27, 2013

HTML5 First Day

My first HTML5 pages. I believe the big data needs a way to render. And I decide to use HTML5 as the way to go. The sample shows how to put script and call javaScript function.

 <!DOCTYPE html>  
 <html lang="en" xmlns="http://www.w3.org/1999/xhtml">  
 <head>  
   <meta charset="utf-8" />  
   <title>Hello HTML5</title>  
 </head>  
 <body>  
   <button title="Click Me" onclick="Javascript:alert('clicked')">Click Me!</button>  
   <button title="Click Me2" onclick="click2()">Click Me2</button>  
 </body>  
 <script type="text/javascript">  
   function click2() {  
     alert('Clicked Me2');  
   }  
 </script>  
 </html>

Saturday, January 26, 2013

Generated Type Provider and Code Generation

Let me finish the generated type provider and 100% move to Hadoop and big data area. In previous postings (1 and 2), I explained how to write generated type provider. The following are some pain points you might encountered when write your own generated type provider.

I currently use generated type provider to generate DLL. This is my main task. Currently, there is not so many document about generated type provider available, especially how to use F# expression to generate the binary. C# provides TypeBuilder to create types in a dynamic DLL, I use F# type provider to generate DLL.

Define a field and property.

let providedField = ProvidedField("field", typeof<System.Func<string, string, string, obj, obj>>)  
let providedProperty = ProvidedProperty("Property", typeof<System.Func<string, string, string, obj, obj>>,   
                   GetterCode = (fun [this] -> Expr.FieldGet (this, providedField)),  
                   SetterCode = (fun [this;v] -> Expr.FieldSet(this, providedField, v)))

ProvidedField is a FieldInfo, ProvidedMethod is a MethodInfo, so everywhere you can to pass in standard .NET type, you can use Provided types.
Constructor code needs to be modified to generate the your code. This piece needs to be added to the .fs. For generated code type provider, you do not have to return < @@ baseClass() @@ > in your constructor code.

         let expr = pcinfo.GetInvokeCodeInternal true parameters  
         let locals = Dictionary<Quotations.Var,LocalBuilder>()  
         let expectedState = ExpectedStackState.Empty  
         emitExpr (ilg, locals, parameterVars) expectedState expr

NewDelegate has not been implemented yet. The bypass is to create a module with your function and pass in the function as expression.
Specify the generated DLL path, where cfg is TypeProviderConfig. You can use any reflector tool to check the generated DLL.

 let providedAssembly = new ProvidedAssembly(System.IO.Path.Combine(cfg.ResolutionFolder, "GeneratedBinary.dll"))

Get C# lambda from F# function.

Very simple, you can just do System.Fun(fun i -> i+1).

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Tuesday, January 22, 2013

SelfNote: Convert rendered location to actual value

Learn something new everyday. :-)

Today I got a solution to get the rendered location for an object which has be RenderTransform-ed.

The trick is to use MatrixConverter to perform the conversion.

Sunday, January 20, 2013

Fakes Framework Replace Function Implementation

Visual Studio 2012 introduces Fakes Framework. Currently I need to find a testing framework and Fakes is one of my choice. I cannot find any good tutorial, hopefully this one can give a quick start.

First the C# code for testing is:

 public interface IStock  
   {  
     int F();  
     int F1(int i);  
   }  
   public class Stock : IStock  
   {  
     public int F()  
     {  
       return 1;  
     }  
     public int F1(int i)  
     {  
       return i + 1;  
     }  
   }

After creating the Test Project from Visual Studio, you can replace the F1 implementation with a new function.

 using (var context = ShimsContext.Create())  
       {  
         System.Fakes.ShimDateTime.NowGet = () => new DateTime();  
         var dt = DateTime.Now;  
         var shim = new ClassLibrary1.Fakes.ShimStock();  
         shim.F = () => 7;  
         var x = shim.Instance.F(); //x is 7 instead of 1  
       }

Wednesday, January 16, 2013

SelfNote: Data Transform in SSIS

I created the table in SQL and SQL Azure using the exact same script. When I tried to use Ado.net data source and OLE data destination in the SSIS package, the SSIS complains about "cannot covert unicode and non-unicode". I do not really have time to figure out why this can happen. Instead, I use the DataConversion solved this problem.

Tuesday, January 15, 2013

Replication health and error

The script below is used to check the replication error.

 use distribution;  
 go  

 select   
    case   
       when COUNT(*)>0 then 'there are error for replication during the last half hour'  
       else 'no error found'  
    end  
 from msrepl_errors   
 where [time] > DATEADD(MINUTE, -30, GETDATE())  
 go  

 declare @errorCount int  
 select @errorCount = COUNT(*) from MSrepl_errors  
 if @errorCount <> 0   
    begin  
       select top 2000 * from MSrepl_errors order by time desc  
    end  
 else  
    select 'NO ERROR'

Monday, January 14, 2013

Generated Type Provider Sample Published on Codeplex

Steffen asked me to provide a generated type provider sample to help understand the type provider API change and generated type provider itself. Changeset 19125 is made minutes ago to FSharp 3.0 Sample pack. The sample shows how to write a generated type provider.

In the solution, there are three projects:

GeneratedTypeProvider project is the one generating the type provider using the new API. The generated type provides only one function which return a constant value 1.
ConsoleApplication2, which is F# project, references to GeneratedTypeProvider project to expose the generated type from type provider
ConsoleApplication1 references to ConsoleApplication2 project to reference type from C# code.

The way I use generated type provider is to generated DLL. I will start several post to help interested user to explore this area more after my sinus infection is getting better.

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Friday, January 11, 2013

Generated Type Provider API Changes

Erased type provider is not a new idea for many F# users, but the problem I am facing is to generate a really DLL which can be consumed by C# project. I use type provider as a code generation tool. If you are thinking about the same thing. Here is how to make your erased type provider to be a generated type provider. The MSDN document does not reflect the recent change in the type provider API's.

you need to declare the ProvidedAssembly.

let providedAssembly = new ProvidedAssembly(System.IO.Path.ChangeExtension(System.IO.Path.GetTempFileName(), ".dll"))

For the generated type, for example the regexTy, invoke the following statements (you have to remove the space between < and -)

regexTy.IsErased < - false

regexTy.SuppressRelocation < - false

providedAssembly.AddTypes([regexTy])

Hopefully this can save you 10 minutes.. :-)

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