ASP.NET State Management

ASP.NET State Management in ASP.NET 2.0

In this tutorial you will learn about new features included in ASP.NET 2.0 for State Management. The Control State, differences in handling View State and Control State, Implementing the control state. Initialization and loading of a controls private state.

Web pages are constantly constructed and destroyed with round trips to the server. However, state maintenance is an essential aspect of deploying web pages on a stateless protocol such as HTTP. State management is defined as a process of maintaining state and page information over multiple page requests.

State maintenance could be a feature of a client side or a server side process. The approach to state maintenance within an application will depend on a number of factors such as sensitivity of data, storage of data, performance goals and so on. ASP.NET 2.0 state maintenance can be enforced from both the client and the server effectively.

On the client side the developer has options of View state, hidden fields and cookies. The ViewState property provides a dictionary object for retaining values between multiple requests for the same page. The Hidden field stores a variable in its value property and is explicitly added to the page. The HTMLInputHidden control provides the hidden field property to the page. A cookie is a small amount of data that is stored in the client machine or in the memory of a client browser session. It contains site specific information that the server sends to the client along with a page output. Cookies can be temporary or have specific expiration dates. Client side storage would imply weakened security and a limitation on the amount of data that can be stored but better performance.

The server side options would include Application, session and Cache. Application state is a key value dictionary structure that is created during the page request to a URL. Application specific information can be added to this structure and stored between page requests. The session state is scoped to the current browser session and the number of session states will be determined by the number of users using the application. The session can be different for each visit by the user. The Cache is a hashtable used to store frequently accessed data. It is global to the application and is visible from within each currently active session. The Cache can be accessed using the name/value properties. While session is a block of memories set aside for each user, cache manages globally accessible data. Server side storage would provide for greater security but would have issues of scalability if size of information is large.

The entire state management therefore, will have to be a balance between security and performance.

ASP.NET 2.0 has introduced several new features to help the developer.

1. Custom controls with Control state which are more reliable than View State. This control is independent of the view state and customizable.

2. Custom session state management options which are persistent in the data storage medium and a session state provider object can be created.

3. Mechanism for handling custom cache dependencies, including SQL Server database dependencies in with a feature to invalidate cache results when one of the records displayed gets updated.

The control state

All controls in ASP.NET inherit the View State property from the Control Class. The state is stored in Name/value pairs and the view state property returns an instance of the StateBag class which is a specialized dictionary object. At a level of abstraction the Control state and the View state are similar but have several differences in handling.

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