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Posted to dev@hc.apache.org by "Jon Moore (JIRA)" <ji...@apache.org> on 2014/06/10 16:48:01 UTC
[jira] [Commented] (HTTPCLIENT-1515) Caching responses to HEAD
requests
[ https://issues.apache.org/jira/browse/HTTPCLIENT-1515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14026520#comment-14026520 ]
Jon Moore commented on HTTPCLIENT-1515:
---------------------------------------
@Tyrone: thanks for this contribution.
I do think adding the request method to the cache entry is a good long-term approach. The short-term issue is that this has some backwards-compatibility issues for HttpCacheStorage implementations that don't use the default serializer, which would not necessarily realize they need to also be storing (and loading) the method. There might also be issues after an upgrade even with the default serializer, especially with cache storage engines that might persist across application restarts.
I might suggest two possible approaches here, and would be interested in hearing others' opinions on these:
1. Go ahead and add this new field, but handle the repercussions. Specifically: add code that catches the resultant java.io.InvalidClassExceptions, deleting that cache entry, and then proceeding as with a cache miss. There's an open question about how to treat a null request method on a cache entry, as I think we can no longer assume that the method was GET. One possible solution would be to test the cache storage implementation at initialization time to see if it is retaining the request methods or not, and to disable caching HEAD requests if it doesn't.
2. Add a configuration option that converts HEAD requests into GETs to the origin; then serve HEAD requests from cache assuming cache entries were always the result of GETs. I'm not crazy about this, as although it is conceptually simpler, it removes the main benefit of issuing HEADs, which is to avoid downloading the bodies.
After writing this out, I'm kind of leaning towards #1, but would be interested in hearing from others (including Tyrone).
> Caching responses to HEAD requests
> ----------------------------------
>
> Key: HTTPCLIENT-1515
> URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1515
> Project: HttpComponents HttpClient
> Issue Type: Improvement
> Components: HttpCache
> Reporter: Tyrone Cutajar
>
> Our system retrieves metadata via HEAD requests using HTTP Client 4.x and would benefit immensely from having the headers in the response cached.
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