ASP.NET View State Caching Properties and Overview

ASP.NET View State is a powerful mechanism that stores pages, controls, and custom values between multiple HTTP requests across the client and the web server. However, it's important to note that ASP.NET applications that utilize View State may experience performance overhead due to the handling and transmission of View State data. Thus, caching View State on web servers sends a much smaller payload to the user's browser containing only a unique ID for the particular View State. As a result, the page uses lesser bandwidth that enhances the performance and the ASP.NET application also scales much better.

Why Cache View State?

View State is an encrypted text string containing the state of web form controls and widgets which is sent to the user's browser to preserve the state across post-backs. For forms with a lot of controls, DataGrid control, or some other complex controls, the View State can become quite large.

Another drawback is heavy ASP.NET View State where the increased bandwidth usage increases the bandwidth cost considerably. For example, if 60-100k of additional ASP.NET View State data is appended to each HTTP request, this multiplied by the total number of transactions results in exceptional bandwidth consumption.

Moreover, there is a security risk with sending confidential data as part of ASP.NET View State. Furthermore, encrypting it before sending is also costly.

Hence, this is why it should be considered to cache the View State:

  1. View State is large (tens of KBs) on large forms and DataGrid.
  2. Large View State slows down page download time.
  3. Large View State slows down post-back request time.
  4. Cache View State on web servers & send only a token to the user.
  5. View State cache is distributed to all web servers in the farm; there is no single point of failure.

NCache's View State Caching resolves these issues, following are some of its features:

  • Increased Performance: NCache reduces the request/response payload which improves the overall request time.

  • Availability and Reliability: NCache is an in-memory cache, it is distributed and synchronized across all web servers, even if the post-back request goes to a different web server in the farm than the original server where the ViewState was created, NCache is able to find the View State value in the cache.

  • View State with its Session: NCache allows View State to be categorized according to its respective session.

  • Limit View State Caching: For longer sessions with abundant amounts of View States, it is now possible to limit View State per session to a configurable number. Metadata is used for limiting. Metadata is also cached. It is also possible to lock metadata. Locking can be configured using Web.config file.

  • Page level Grouping for View State: NCache allows grouping on page level, multiple pages can be coupled to define a group. For each group, different configurations can be set.

  • ViewState.xml is required for the View State grouping feature. This xml can have multiple web app configurations. In each web app configuration, there can be one or more group configurations and different caches can be configured for different groups.

In This Section

ASP.NET View State Content Optimization Configuration
Explains how Content Optimization can be configured and used in NCache applications.

Group ASP.NET View State with Session
Explains how View State can be grouped with sessions in your application.

Limit ASP.NET View State Caching
Provides solution to limit View State Caching per group and per session.

Page Level Grouping for ASP.NET View State
Describes how View State caching can be performed at a micro level, i.e., page level.