[
https://issues.apache.org/jira/browse/COUCHDB-2052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13894944#comment-13894944
]
Jens Alfke commented on COUCHDB-2052:
-------------------------------------
> An HTTP server is free to ignore an Upgrade request for a protocol it doesn't
> support.
It still seems ugly to me that the server will start generating the changes
feed and sending out changes until the client sees the non-101 response code
and closes the socket.
> That's a bug to fix.
Yeah, but it tells me that it's perhaps not realistic to rely on subtleties of
HTTP negotiation for detecting features.
> I don't see much difference between checking version > foo vs
> features.contains
In this example there are at least three different vendor-and-version tests
involved. Possibly more; for instance I don't know if rcouch has an independent
version numbering scheme, and if so which version merged in the patch that
fixed multipart parsing.
> Add API for discovering feature availability
> --------------------------------------------
>
> Key: COUCHDB-2052
> URL: https://issues.apache.org/jira/browse/COUCHDB-2052
> Project: CouchDB
> Issue Type: Improvement
> Security Level: public(Regular issues)
> Components: HTTP Interface
> Reporter: Jens Alfke
>
> I propose adding to the response of "GET /" a property called "features" or
> "extensions" whose value is an array of strings, each string being an
> agreed-upon identifier of a specific optional feature. For example:
> {"couchdb": "welcome", "features": ["_bulk_get", "persona"]}, "vendor":
> …
> Rationale:
> Features are being added to CouchDB over time, plug-ins may add features, and
> there are compatible servers that may have nonstandard features (like
> _bulk_get). But there isn't a clear way for a client (which might be another
> server's replicator) to determine what features a server has. Currently a
> client looking at the response of a GET / has to figure out what server and
> version thereof it's talking to, and then has to consult hardcoded knowledge
> that version X of server Y supports feature Z.
> (True, you can often get away without needing to check, by assuming a feature
> exists but falling back to standard behavior if you get an error. But not all
> features may be so easy to detect — the behavior of an unaware server might
> be to ignore the feature and do the wrong thing, rather than returning an
> error — and anyway this adds extra round-trips that slow down the operation.)
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)
