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Understanding OutputCacheFilter in Microsoft MVC Preview 4: Does It Really Save Action Invocations?

In the world of web development, performance is crucial. When building applications using Microsoft MVC, developers often seek ways to optimize speed and responsiveness to meet user expectations and contractual obligations. One common performance enhancement technique is caching. A specific question arises regarding the OutputCacheFilter in Microsoft MVC Preview 4: Does it actually save on action invocations?

The Context of Caching in MVC

When we deployed a new, fresh site using MVC Preview 3, we leveraged rigorous stress testing to evaluate its performance under load. Our experience highlighted the importance of page output caching, which proved to be a savior by enabling our application to satisfy its performance goals efficiently.

The Core Questions

  1. Is there a difference between the action OutputCacheFilter and page output caching?
  2. Is action output caching faster than page output caching?

What is Output Caching?

Before delving into the specifics, it’s essential to understand what output caching entails:

  • Output Caching temporarily stores the result of a web request.
  • When the same request is made again, it can be served from the cache rather than re-executing the action, resulting in faster response times.

The Functionality of OutputCacheAttribute

The OutputCacheAttribute, also known as the output cache filter, functions similarly to page output caching:

  • It utilizes the same internal mechanism as the older page output caching feature.

Thus, the performance between the two is largely equivalent, raising the question:

Is Action Output Caching Faster?

The short answer:

  • No, the action output caching is not faster than page output caching.

Why Is That?

  1. MVC Rendering Process:

    • In MVC, the view (or page) is rendered after the action completes.
    • Consequently, using the @OutputCache directive for page output caching doesn’t yield much benefit since the action execution occurs first.

  2. Optimized Execution:

    • With the OutputCacheFilter, if the desired result is already in the output cache, the action code is not executed.
    • This translates to efficient resource utilization, making the application performance smoother without unnecessary processing.

Conclusion

In conclusion, while both action output caching and page output caching operate on the same internal mechanics, the structure of MVC dictates that the output cache filter is more effective in practice. By preventing action invocations when cached results are available, the OutputCacheFilter provides a significant performance boost without actually being faster than traditional page output caching.

So yes, it does save on action invocations by avoiding the execution of the action code altogether if the output is cached.

Takeaway

If you’re working with Microsoft MVC and looking to improve your application’s performance, implementing the OutputCacheFilter is a wise choice, but it’s also important to understand its functionalities and limitations compared to traditional page caching.

Feel free to explore and optimize your applications with this knowledge!