Monday, December 15, 2008

ServiceController Class for Managing a service

You can use the ServiceController class (System.ServiceProcess) to connect to and control the behavior of existing services.

Enumerating services

using System.ServiceProcess;

private void Form1_Load(object sender, EventArgs e)
{
foreach (ServiceController s in ServiceController.GetServices())
listBox1.Items.Add(s.DisplayName );
}

You can then use the class to start, stop, and otherwise manipulate the service.

Here I am using ServiceController class to start and stop Sql Server 2000 Service.

using System.ServiceProcess;
ServiceController sc = new ServiceController();
private void Form1_Load(object sender, EventArgs e)
{
sc.ServiceName = "MSSqlServer";
}

private void btnStart_Click(object sender, EventArgs e)
{
if (sc.Status == ServiceControllerStatus.Stopped sc.Status == ServiceControllerStatus.Paused )
{
sc.Start();
MessageBox.Show("Service started");
}
else
MessageBox.Show("Service already started");
}

private void btnStop_Click(object sender, EventArgs e)
{
if (sc.Status == ServiceControllerStatus.Running )
{
sc.Stop();
MessageBox.Show("Service stopped");
}
else
MessageBox.Show("Service alredy in stopped state");
}
}

Friday, December 12, 2008

Isolated Storage (Code Snippets)

using System.IO;
using System.IO.IsolatedStorage;

private void button1_Click(object sender, EventArgs e)
{
this.Text = textBox1.Text;
IsolatedStorageFile f = IsolatedStorageFile.GetMachineStoreForDomain();
IsolatedStorageFileStream i = new IsolatedStorageFileStream("co.col", System.IO.FileMode.Create, f);
StreamWriter sw = new StreamWriter(i);
sw.Write(this.Text);
sw.Flush();
sw.Close();
}


private void Form1_Load(object sender, EventArgs e)
{
IsolatedStorageFile f1 = IsolatedStorageFile.GetMachineStoreForDomain();
IsolatedStorageFileStream i1 = new IsolatedStorageFileStream("co.col", FileMode.Open, f1);
StreamReader sr = new StreamReader(i1);
this.Text = sr.ReadToEnd();
sr.Close();
}

Courtesy : Saji P Babu, IndiaOptions, Kochi.

Related Blog
System.IO Namespace in .Net

Wednesday, December 10, 2008

Linq to Xml (Code Snippets)

Linq to Xml enables you to query an Xml document using the familiar LINQ syntax. Linq to Xml features and found within System.Xml.Linq namespace.
System.Xml.Linq introduces a series of objects such as XDocument, XElement and XAttributes which makes creating XML document a breeze.

XAttribute
private void btnXElement_Click(object sender, RoutedEventArgs e)
{
XElement xe = new XElement(new XElement("Shalvin",
new XElement("Students",
new XElement("Name", "Shalvin"))));
textBox1.Text = xe.ToString();

}


XElement


using System.Xml.Linq;

private void Form1_Load(object sender, EventArgs e)
{
XElement xml = new XElement("contacts",
new XElement("contact",
new XAttribute("contactId", "2"),
new XElement("firstName", "Shalvin"),
new XElement("lastName", "PD")
),
new XElement("contact",
new XAttribute("contactId", "3"),
new XElement("firstName", "Praseed"),
new XElement("lastName", "Pai")
)
);
textBox1.Text = xml.ToString();
}


XDocument

using System.Xml.Linq;

protected void Page_Load(object sender, EventArgs e)
{
XDocument xd = new XDocument();
XElement contacts =
new XElement("contacts",
new XElement("contact",
new XElement("name", "Shalvin"),
new XElement("Location", "Kochi")
),
new XElement("contact",
new XElement("name", "Viju"),
new XElement("Location", "Trichur")
)
);
xd.Add(contacts);
xd.Save("c:\\Shalvin.xml");
System.Diagnostics.Process.Start("iexplore", "c:\\Shalvin.xml");
}

Output

<?xml version="1.0" encoding="utf-8"?>
<contacts>
<contact contactId="2">
<firstName>Shalvin</firstName>
<lastName>P D</lastName>
</contact>
<contact contactId="3">
<firstName>Praseed</firstName>
<lastName>Pai</lastName>
</contact>
</contacts>

XDocument Parse

private void button3_Click(object sender, RoutedEventArgs e)
{
XDocument xd = XDocument.Parse(@"<contacts>
<contact contactId='2'>
<firstName>Shalvin</firstName>
<lastName>P D</lastName>
</contact>
<contact contactId='3'>
<firstName>Praseed</firstName>
<lastName>Pai</lastName>
</contact>
</contacts>");

textBox1.Text = xd.ToString();

}


Querying an Xml Document














using System.Xml.Linq;
private void Form1_Load(object sender, EventArgs e){
XDocument xmlFile = XDocument.Load("c:\\Shalvin.xml");
var query = from c in xmlFile.Elements("contacts").Elements("contact").Elements("name")

select c;
foreach (XElement nam in query)

{
listBox1.Items.Add(nam);
}

}

Related Blogs
Linq to Objects
Linq to Sql
.Net Working with Xml

Monday, December 8, 2008

Linq to Objects

Linq (Language Integrated Query) enables you to have queries within the language.
This blog assumes that you are know Type Inference in C#, Generics and Collection Initializer.

private void Form1_Load(object sender, EventArgs e)
{
List<string> interests = new List<string>{"Music", "Singing", "Swimming"};
var result = from w in interests
where w.Contains("ing")
select w;

foreach (string s in result)
listBox1.Items.Add(s);
}


Lambda
protected void btnLambda_Click(object sender, EventArgs e)
{
   List<string> interests = new List<string>{"Music", "Singing", "Swimming"};
   var result = interests.Where(p => p.Contains("ing"));
        
   foreach (string s in result)
     ListBox1.Items.Add(s);
}


The Linq query retrives all values form Generic List that ends with "ing". You can use Linq with any objects that implements IEnumerable or Generic IEnumerable interface.

StartsWith
private void btnStartsWith_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = from p in interests
            where p.StartsWith("M")
            select p;
foreach (string s in ms)
    listBox1.Items.Add(s);
}

EndsWith
private void btnEndWith_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = from p in interests
            where p.EndsWith("g")
            select p;
foreach (string s in ms)
    listBox1.Items.Add(s);
}


Equals
private void btnEquals_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = from p in interests
            where p.Equals("Music")
            select p;
foreach (string s in ms)
    listBox1.Items.Add(s);
}


First
First can be used to extract only the first item in the collection.
private void btnFirst_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = (from p in interests
            select p).First();
listBox1.Items.Add(ms);
}

Last
private void btnLast_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = (from p in interests
            select p).Last();
listBox1.Items.Add(ms);
}

Count
Using the Count operator I am taking a counts of items inside the Generic List. I will get a value 3.

private void btnCount_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = (from p in interests
            select p).Count();
listBox1.Items.Add(ms);
}

Count of EndsWith
Here I am taking a count of items ending with "ing". I will get an output of 2 ie. the count of "Swimming" and "Singing".

private void btnCountEndWithIng_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = (from p in interests
          where p.EndsWith("ing")  
          select p).Count();
listBox1.Items.Add(ms);
}

Count Equals

private void btnCountEquals_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var ms = (from p in interests
where p.Equals("Music")
          select p).Count();
listBox1.Items.Add(ms);
}

Linq and Generic List of Integer
Having seen working with Generic List of string let's turn out attention to Generic List of Inteters. 


List<int> gliMarks = new List<int> { 98, 56, 88, 79, 96 };

GreaterThan Operator

private void btnShowGreaterThan90_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var G90 = from p in gliMarks
    where p > 90
    select p;
listBox1.ItemsSource = G90;
}


Sum

private void btnSum_Click(object sender, RoutedEventArgs e)
{
    listBox1.Items.Clear();
           
    var vSum = (from p in gliMarks
                select p).Sum();
    listBox1.Items.Add(vSum);
}



Average

private void btnAverage_Click(object sender, RoutedEventArgs e)
{
    listBox1.Items.Clear();
    var Avg = (from p in gliMarks
                    select p).Average();
    listBox1.Items.Add(Avg);
}

Max

private void btnMaximum_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var Maxi = (from p in gliMarks
            select p).Max();
listBox1.Items.Add(Maxi);
}

Or

private void btnSOr_Click(object sender, RoutedEventArgs e)
{
listBox1.Items.Clear();
var vOr = from p in gliMarks
    where p== 98 | p == 88 
    select p;
listBox1.ItemsSource = G90;
}



Linq on Collection of Objects

class Session
{
public string Speaker { get; set; }
public string SessionName { get; set; }
}

List<Session> glSessions = new List<Session>{
new Session{Speaker = "Shalvin P D", SessionName= "Entity Framework 4"},
new Session{Speaker="Praseed Pai", SessionName="Powershell"}};

var G = from p in glSessions
where p.Speaker == "Shalvin P D"
select new { p.Speaker, p.SessionName };


dataGrid1.ItemsSource = G.ToList();
}

Type Inference in C# (Implicitly Typed Local Variable)

Type inference is a new feature in C# 3.0. With Type Inference you allow compiler to determine the type of a local variable at compile time.

private void Form1_Load(object sender, EventArgs e)
{
var strName = "Shalvin";
MessageBox.Show(strName.GetType().ToString());

var intPoints = 67;
MessageBox.Show(intPoints.GetType().ToString());

var dblBalance = 110.50;
MessageBox.Show(dblBalance.GetType().ToString());
}


The first batch of statements creates a memory variable of type System.String. The Second batch of statements (intPoints) creates a memory variable of type System.Int32. The third batch of statments (dblBalance) creates a memory variable of type System.Double.

Related Blog
Generics and Collection Initializer in .Net