Binding dynamic XML objects to Silverlight Grids

Recently we had an requirement to bind the content of dynamic XML to Silverlight Grids.This is straightforward in ASP.NET with the help of DataSet. But we do not have DataSet in Silverlight or WPF. To achieve this we used the following approach;


The code is self-explanatory with the comments explaining each step;


public string Result
{
get
{
return _result;
}
set
{
System.Windows.Deployment.Current.Dispatcher.BeginInvoke(() =>
{
//Load the xml string to XDocument
XDocument doc = XDocument.Load(new StringReader(value));
MemoryStream str = new System.IO.MemoryStream();
doc.Save(str);


//Finding the Name of the class
string objName = doc.Descendants().First().Name.LocalName.Replace("ArrayOf", "");


//Making it a fully qualified name by appending the corresponding
//namespace
objName = "MyCompany.MyApplication." + objName;


//Loading the assembly that contains the Entity which
//we are trying to de-serialize
//NOTE: To be able to do the below 3 steps, you need to ensure that
//the entities dll reference is added in Deployment.Parts of the
//App Manifest file
StreamResourceInfo sri = Application.GetResourceStream(new Uri("MyApplication.SL.Entities.dll",UriKind.Relative));
AssemblyPart myPart = new AssemblyPart();
System.Reflection.Assembly assm = myPart.Load(sri.Stream);


//Using reflection to build the List<T>
var pageToShowType = assm.GetType(objName);
Type t = typeof(List<>);
Type [] args = {pageToShowType};
Type r = t.MakeGenericType(args);


//De-serializing and assigning to the property to show in the grid
str.Position = 0;
DataContractSerializer serializer = new DataContractSerializer(r);
//Bind the ResultObject to the SL Grid
//NOTE: Ensure that SL Grid has AutoGenerateColumns = TRUE
ResultObject = serializer.ReadObject(str);
str.Close();


});


}


}

Workaround to Button using MVVM ICommand and IsEnabled issue

When you are using the Command Button in MVVM pattern with ICommand, you will not be able to use the IsEnabled property to enable/disable the command button. As a workaround to enable/disable the command button, you can put the Command Button inside the group control like StackPanel and set the IsEnabled property of StackPanel to TRUE/FALSE.

i++ kind of functionality in F#

As F# is immutable language, we will not be able to use i++ kind of functionality directly. You will have to combine the "mutable" and "module" feature of F# to achieve the i++ kind of functionality. Below here is the simple demonstration of this;

module Foo
       let mutable m_field = 0
       let next () =
             m_field <- m_field + 1; m_field

Just use Foo.next () whereever you need i++ kind of functionality.

Consume WCF REST service in F#

Today I successfully implemented the code for consuming WCF REST service in F#. Funny part here is that, this is my first program in F#.. LOL

Ok.. Here is the code for consuming WCF REST in F#.

module FSModule

#light

open System
open System.Text
open System.Net
open System.IO
open System.Web

// F# uses indenting to define scope. So ensure that you indent properly to get it working
let GetDataFromRest =
     let buffer = Encoding.ASCII.GetBytes("<HelloService_SayHello><input>Hello from F#</input></HelloService_SayHello>") //This is needed if its a POST call
     let req = WebRequest.Create(new Uri("http://localhost/HelloService.svc/SayHello")) :?> HttpWebRequest
     req.Method <- "POST"
     req.ContentType <- "application/xml" //Use accordingly XML or JSON
     req.ContentLength <- int64 buffer.Length
     let reqSt = req.GetRequestStream()
     reqSt.Write(buffer,0,buffer.Length)
     reqSt.Flush()
     req.Close()

     let res = req.GetResponse () :?> HttpWebResponse
     let resSt = res.GetResponseStream()
     let sr = new StreamReader(resSt)
     let x = sr.ReadToEnd()
     sr.Close()
     x.ToString()

Done... To invoke this, you can either use F# or C# or even VB.NET :)

F#

let result = GetDataFromRest()
printfn result

C#

string result = FSModule.GetDataFromRest()

Smartphone App for Mainframe systems - A thought

Recently I submitted this idea for one of the competition. The competition was for design approaches for smartphone app for mainframe systems.
Mainframe application provides functionality for uploading the JCL jobs via FTP and executing them. And iPhone SDK supports FTP functionality. Hence we can leverage these functionalities for running the Mainframe jobs from the iPhone or iPad Apps (even we can extend further to Android as well).



Here is the simple demonstration how this can be achieved

1) User keys in the instructions to be run in the mainframe application

2) Clicks Submit button

3) Using the iPhone SDK create the Commands.jcl file

4) Open the FTP connection to the IBM mainframe (FTP details will be pre-configured using the Settings screen)

5) Run the following commands

        a. quote site filetype=jes

        b. quote site jeslrecl=80

        c. put commands.jcl

This will kicks of the job and execute the instructions in the commands.jcl file.

6) Once the instructions are executed, the response will be available in the spooled output file “JOB#####.n” where ‘n’ is the dataset number. (The challenge here will be when to read this response file)

I am yet to hear the result from the competition. Hope this idea wins me an iPad2.. LOL