Session Management in Web Garden Using Custom Components

using System.Collections;
public class SessionManager : ISessionManager
{
//Hashtable to store the list of sessions allocated.
Hashtable hsSession = new Hashtable();
static SessionManager objSM; //static SINGLETON object
//a timer to manage the session timeouts
private static Timer tmrSessionTimeout;
//Private Constructor - To prevent creating instaces explicitly
private SessionManager()
{
}
//Create a new object of session manager.
public static SessionManager getInstance()
{
if (objSM == null)
{
objSM = new SessionManager();
//create a new objectof the timer class and associte //a timer call back delegate. The removesession
//method will be invoked by the timer object for //every 1000 milliseconds (change it as u like).
tmrSessionTimeout = new Timer(new TimerCallback (objSM.removesession) , null, 0, 100);
return objSM;
}
return objSM;
}
//This method will be invoked by the timer call back for every 1000 milliseconds.
private void removesession(object state)
{
IDictionaryEnumerator objSesEnum = hsSession.GetEnumerator();
//A temporary session object.
ISession tmpSesObj;
ArrayList arrExpiredKeys = new ArrayList();
//for each session, check the last used datetime.
while (objSesEnum.MoveNext())
{
//The session will be removed, if the user is idle for 2 hours. (change it as u like).
tmpSesObj = (ISession) objSesEnum.Value;
DateTime dt = DateTime.Parse(tmpSesObj.getAttribute ("lastAccessedDatetime").ToString());
TimeSpan ts = dt.Subtract(DateTime.Now);
//If the difference between the last accessed //datetime and current date time is equal to 2 hours //then the session id will be added to the arraylist.
//(ie., left idle for 2 hours)
if (dt.Subtract(DateTime.Now).Hours >= 2)
{
arrExpiredKeys.Add(objSesEnum.Key);
}
//remove the list of keys added to the array list.
int i =0;
while (arrExpiredKeys.Count > i)
{
//remove the session from the hashtable.
hsSession.Remove(arrExpiredKeys[i]);
}
}
}
public string createSessionId()
{
//Create a new guid which will act as the session id
string newSessionId = Guid.NewGuid().ToString;
//create a new session object and store the object in the //hashtable against the new session id (GUID).
Session objS = new Session();
hsSession.Add(newSessionId, objS);
//Set the session id into the session object.
objS.setAttribute("SessionId", newSessionId);
//return the session id,
return newSessionId;
}
public ISession getSession(string strSesId)
{
ISession objS = (ISession) hsSession[strSesId];
//everytime when the session object is retried, update the //lastaccesseddate variable with the latest datetime
objS.setAttribute("lastAccessedDatetime", DateTime.Now);
return objS; //return the session object
}
public ISession removeSession(string strSesId)
{
ISession objS = (ISession) hsSession[strSesId];
//remove the sessionid from the hash table.
hsSession.Remove(strSesId);
return objS; //return the removed session
}
}

Step 3: Implement the ISession interface

At any time there will be only one instance of the session manager class (as it is declared as static). It must always remain as a singleton object, as persistent storage and maintenance of multiple sessions cannot be achieved otherwise. A new static method getInstance is added into the SessionManager class to create a new instance of the SessionManager class. The constructor of the class is made private to prevent creating objects of the SessionManager component explicitly.

Testing the Session Manager component

Now we can test the session manager component. Create a new console application project and add a reference of the SessionManager component. The following code snippet creates an object of the session manager class (using the getInstance method) and assigns a value in the session object. The WriteLine method prints the value in the session object.

using NpSessionManager; //add the namespace
class SessionManagerTest
{
static string strid;

[STAThread]
static void Main(string[] args)
{
//Create a new session and assign values to the session object.
SessionManager sm = SessionManager.getInstance();
//store the session id in some global variable.
strid = (string) sm.createSessionId();
//get the session
ISession objS = (ISession) sm.getSession(strid);
objS.setAttribute ("website", "c-sharpcorner");
Console.WriteLine(objS.getAttribute("website").ToString());
Console.ReadLine();
}
}

Scalibility and deploying the component

Due to the object oriented design of the session manager component, any amount of flexibility and scalability is achievable.

• The session manager component can be deployed in the following ways
• In-process version (will run the Asp.Net Process / w3wp.exe process, just dll reference is enough)
• Out-process version (Using .net Remoting).