Often, if a web application performs well in a garden scenario, it will typically be easier to migrate to a web farm. Session stores the data in the dictionary on the Server and SessionId is used as a key. It is possible to remove a session variable with the Remove method. You can also store user preferences in the Session object, and then access that preference to choose what page to return to the user. A session ends if a user has not requested or refreshed a page in the application for a specified period.

The agent runs a periodic job to purge expired sessions from the database. The main drawback to sticky-sessions for managing InProc session state is that it opens the individual web servers to potential overload. This results in a less scalable solution when compared with distributed session state or session-less web application architectures. In the above example, Session state is first accessed to load an ID variable.

Setting the sessionstate is one of the methods in ASP.NET to manage the session. Yes, but then i had to post a solution with 6 or 7 classes plus unit tests. 2) Normally this should be locked, but IMHO it is not necessary in this case.

Web Gardens, Web Farms, Clouds, And Session State In C# Asp Net

For example, the out-of-process option is a good choice when you want to support multiple Web servers, or when you want to guarantee that session data can survive the Web server process. For example, setting the value to 3 would create three worker processes within the application pool. Of course, this would also mean you would have 3 individual Session states, as each worker process has its own memory, independent of the others. In this article, we’ll take a look at several solutions for scaling a C# ASP .NET web application across a web garden, web farm, and beyond.

The process is shared by multiple worker processes and web servers and servers as a memory-based database for holding session state data. StateServer serves data over a TCP port, typically port 42424, and allows incoming requests from outside servers. However, a drawback is that the usage of memory can grow over-time, potentially over-using the available server resources. Upon executing the web application, now a single magical spell is created and stored within session. Subsequent page refreshes continue to display the same magical spell and increment the view count each time. Since our web application is now loading session state from the 3rd-party StateServer process, all of the worker processes within the web garden can access the same, synchronized, session state data.

It is common to abstract a layer of the web application design for handling data processing and database activity. This layer can be abstracted further into a WCF web service layer, hosted and executed within its own web server, separate from the main web application’s web server. Taking this one step further, the main web application can execute on its own web farm and load balancer, while the WCF web service executes on its own web farm and load balancer.

Cookieless Session

When the page completes execution, the session state module connects to the state store, writes the session state data if it changed, and unlocks the session data. Variables stored in a Session object hold information about one single user, and are available to all pages in one application. Common information stored in session variables are name, id, and preferences. The server creates a new Session object for each new user, and destroys the Session object when the session expires.

Each tier of the solution can be expanded and grown as necessary to serve the users’ needs. The same principle can be applied to migrating the two tiers to web clouds or even multiple web services on multiple tiers, complexity aside. For this example, we’ll create a basic type object, which will be stored and retrieved from the Session. We’ll use this object to test the distribution of the OutOfProc session state and proper performance across the web garden/web farm. It’s important to note that objects stored in the session must be serializable.

• While this is not possible i prefer to only specify the key once and then forget about it whereever i can.
• The main drawback to sticky-sessions for managing InProc session state is that it opens the individual web servers to potential overload.
• The SessionID is randomly generated, and session data—as well as session IDs—do expire.
• As the user’s requests alternate between the two servers in the web farm, Session data will become inconsistent, leading to incomplete, corrupt, and missing data within the web application.
• The HTTP protocol on which all web applications work is a stateless protocol.

All HttpHandlers that implement IRequiresSessionState are locked to one request per session. They enter the lock in SessionStateModule.BeginAcquireState() and leave it in SessionStateModule.OnReleaseState(). If the SessionVariable value is null, and somebody tries to read it (GetInternalValue), while another thread is trying to set a new value.

In IIS 6, either use out-of-process or disable process recycling behavior to avoid data loss. Notice in the first run, upon accessing the page the first time, a new magical spell is created and saved in Session. We’ll define our C# ASP .NET MVC controller to create a new MagicSpell object upon loading the view, and attempt to read the object from the Session on each page refresh. Important It’s important that the programming model is transparent. For example, we don’t have to change how we access or use session state when we change the storage mode.

Remove Session Variables

C# ASP .NET web applications developed for compatibility with a multi-server environment can often be utilized in both web farm and web cloud environments. A web farm is a hosting environment consisting of multiple web servers. The web servers are usually tied together with a load balancer, which routes incoming requests amongst the servers within the web farm. Tip For ASP.NET 1, configure SQL Server for mixed-mode authentication by adding the ASPNET account enabled for the necessary SQL Server permissions for ASP.NET session state. (The ASPNET account is the user that the ASP.NET worker process runs as.) For ASP.NET 1.1 running on IIS 6, configure SQL Server for mixed-mode authentication by adding the NT AUTHORITY\NETWORK SERVICE account. Upon refreshing the page (or clicking the Read Session button to re-load with AJAX), the same magical spell is loaded , this time with the view count incremented to 2, as expected.

It’s because ASP.NET session state is stored in the memory space of an appdomain. Important Using the SessionID as a key for user data is not recommended. The SessionID is randomly generated, and session data—as well as session IDs—do expire. Additionally, although a SessionID might be generated on each request, a SessionID is set only when a Session value is set server side. This means that if no session values are set server side, new SessionIDs are issued on each request. The mode attribute needs to be SQLServer, and the sqlConnectionString attribute must point to a server running SQL Server that has already been configured for ASP.NET SQL session state.

For custom type objects, this requires adding the attribute to the beginning of each class. Out-of-process session state can be used within C# ASP .NET web applications to distribute session data across multiple servers. ASP .NET allows for two types of default OutOfProc session state, including SQLServer and StateServer. A web cloud can scale and reduce resources as needed and throughout the execution of a web application.

So on any page, you can store a value in the Session object via the below line of code. The value of stateNetworkTimeout represents the number of seconds that may elapse between the time ASP.NET tries to connect to the state service and the time the request times out. Although the default value for stateNetworkTimeout does not need to be changed, you have the option to make the value higher or lower depending upon your requirements. Now that you’ve had an overview of out-of-process session, let’s discuss the two out-of-process modes, StateServer and SQLServer. So you had to use ValueOrDefault and then check against the default value wich is null for reference types and a specific one per struct or value type. We all know about the problems storing data in untyped dictionaries using some key, so I spare you.

Subsequent page refreshes of the ASP .NET MVC Razor web application would display additional view counts of the same two magical spells and a third magical spell created for the last worker process. After all worker processes have executed at least once, any remaining page refreshes will display at least one of the three previous magical spells already created. In the above code, we’ve created a basic type object for storing in the session.

Store And Retrieve Session Variables

Declare and initialize the session variable in a static field or property in a third class – you could call it “SharedState”, for example. As you can tell in the above execution, running as InProc in this environment is less than ideal. However, we can solve this by re-configuring the web application’s web.config to utilize OutOfProc StateServer storage. For purposes of this example, the MVC Razor markup code has been included above.

Asp Net Session Dataset, Datatable, And net Class Storage

If you’re using OOP modes , one of your major cost is the serialization/deserialization of objects in your ASP.NET session state. ASP.NET performs the serialization/deserialization of certain “basic” types using an optimized internal method. “Basic” types include numeric asp net usage types of all sizes (e.g. Int, Byte, Decimal, … etc), String, DateTime, TimeSpan, Guid, IntPtr and UIntPtr. By default, the values for the validationKey and decryptionKey attributes are set to AutoGenerate, which enables the server to randomly create the values.

Stateserver Session State

However, a down-side to IP affinity is in not taking full advantage of the web farm capability in fully distributing and routing all requests and sessions. In general, web gardens use more resources than typical hosting environments. They may also be slower in performance and add unnecessary complexity. Another scenario may involve unreliable web application processing, which could cause a worker process to halt or freeze. In both cases, a web garden could offer a solution by offloading the single worker process and distributing incoming requests amongst the workers in the application pool. The locking mechanism implemented is a reader-writer lock using the ReaderWriterLock class.

When you apply this strategy for optimizing out-of-process session, you get fewer requests to the out-of-process session store, which increases the scalability and throughput of the site. Once the server designated to run the state server has been properly configured, it is simply a matter of starting the Windows service. The service can be started from either the command line or the Microsoft Management Console for Services. Important Use in-process session state if you have only a single server.

The second option for starting the state service is through the Services MMC snap-in, which you open by navigating to Start\Administrative Tools\Services. Right-click on the ASP.NET State Service option in the list and select Start to start the service. Once the Services MMC is started, you should see a screen similar to Figure 5-2.

Multiple requests can read data simultaneously when the session isn’t locked. If the session is locked, read requests are blocked until the write lock is released. This locking strategy guarantees that the Session object with which the user is interacting is always an accurate reflection of the data. If you attempt to build a site that uses frames, and each page within a frame requires session state, the pages will execute serially. You can configure session state to be read-only on a page-by-page or even application basis. Configuring a page to use session data in a read-only manner allows the page to be requested without locking the session data and prevents serialized access.

However, a drawback is that it is often slower in processing, due to read/write IO. As shown in the above scenario, involving two web servers, the core issue with C# ASP .NET web applications in a Web Garden or Web Farm scenario is the persistence and synchronization of Session State data. As you can imagine, if the above scenario were increased to 10, 100, or even 1,000 web servers, the corruption of data would become even more apparent. As cloud services and cloud hosting becomes more popular, Session state will become even further problematic. Luckily, ASP .NET offers solutions for maintaining Session across gardens and farms. Before we discuss the solutions, let’s define the differences between a garden and farm.

Web farms provide a necessary solution for offloading and expanding high-traffic and demanding C# ASP .NET web applications. When not available during development, web gardens may be utilized to help simulate the demands of a web farm environment by providing multiple worker processes on a multi-core machine. Configuring the web application to use OutOfProc session in a web garden scenario, can help resolve issues prior to application deployment on a web farm. Further abstraction and migration to web clouds can provide on-demand web application sizing and scalability. StateServer session state stores data within a 3rd-party process, aspnet_state.exe.

SQL Server is an enterprise-class database solution optimized for managing, storing, and retrieving data quickly and efficiently. In a clustered environment, SQL Server can be configured to failover. For example, when the clustered production SQL server fails, a backup can take over. When ASP.NET is configured to use state server for out-of-process session, it uses a TCP/IP address and port number to send HTTP requests to the state server . We recommend SQLServer for out-of-process session state because it is just as fast as StateServer and SQL Server is excellent at managing data. Furthermore, ASP.NET can communicate with SQL Server natively (meaning internally, using the System.Data.SqlClient libraries), and SQL Server can be configured to support data failover scenarios.

As mentioned in the web farm topic above, sticky-sessions can be utilized as a quick solution for Session state. By directing incoming requests to the same web server throughout the session, data will always be pulled from memory on the same physical web server. Compatibility and support for configuring sticky sessions can be located within the load balancer settings or web cloud configuration, if available. As shown in the above screenshot, the 3rd refresh of the page results in a new magical spell being created, with a fresh view count of 1.