What is View State Chunking?
View State Chunking is a feature introduced in ASP.NET 4.0 that allows the ViewState to be split into smaller chunks rather than being stored as a single, monolithic string. This chunking mechanism helps mitigate the limitations associated with large ViewState and improves performance in certain scenarios.
When View State Chunking is enabled, the ViewState is divided into smaller chunks and sent to the client as multiple separate hidden fields ('__VIEWSTATE', '__VIEWSTATE1', '__VIEWSTATE2', and so on). Each hidden field contains a portion of the ViewState data.
Here's how View State Chunking works:
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ViewState Size Threshold: A threshold value is set to determine when chunking should be applied. By default, this threshold is set to 256 KB, meaning if the ViewState size exceeds this value, chunking is automatically applied.
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ViewState Division: When the ViewState size exceeds the threshold, it is split into multiple chunks. Each chunk is assigned a unique identifier (e.g., '__VIEWSTATE', '__VIEWSTATE1', '__VIEWSTATE2', and so on).
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Chunk Transmission: The ViewState chunks are transmitted to the client as separate hidden fields within the HTML output. The client receives and sends back all the ViewState chunks during postbacks.
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Chunk Reassembly: On the server, during postback processing, the ViewState chunks are reassembled and combined to reconstruct the complete ViewState. This allows the server to restore the control state and other data as usual.
The main benefit of View State Chunking is that it helps mitigate the limitations associated with large ViewState. By splitting the ViewState into smaller chunks, the overall size of each individual hidden field is reduced, minimizing the impact on network bandwidth and page load times.
View State Chunking also provides a more efficient approach for transmitting ViewState data when the ViewState exceeds the threshold. Instead of sending a single, large ViewState string in a single hidden field, chunking distributes the data across multiple smaller hidden fields.
It's worth noting that View State Chunking is automatically applied when the ViewState size exceeds the threshold, and developers don't need to enable it explicitly. However, it can be disabled or customized by configuring the 'maxPageStateFieldLength' attribute in the '<pages<' element of the web.config file.
Overall, View State Chunking helps optimize the handling of large ViewState, reduces the impact on performance, and enhances the user experience in ASP.NET applications.