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From: Jens Alfke <jens@mooseyard.com>
To: user@couchdb.apache.org
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Subject: Replicating partial databases, and validation
Date: Sun, 15 Feb 2009 11:10:58 -0800

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I'm interested in using CouchDB in a peer-to-peer fashion to propagate =20=

content between nodes that don't necessarily trust each other. The =20
available documentation sort of runs out before getting to many of the =20=

aspects I'm interested in [I am eagerly awaiting more chapters of the =20=

book!] but from reading the list archives and people's blog posts, it =20=

sounds like it should be do-able. I'm just not clear on the details.

=95 Is it possible to pull part of a database? For example, I might to =20=

pull only nodes whose names start with a particular prefix, or whose =20
content contains a particular key/value pair.

=95 Can the server validate the content of documents being pulled from =20=

another DB? I may want to disallow updates that modify an "author:" =20
property, or whose "date:" property isn't in a valid format. Or I =20
might want to check a digital signature[1] on each incoming entry.

=95 Likewise, can the server validate docs being posted directly, =20
outside of replication?

Some sort of generic validator hook that got called on all docs being =20=

added to the db, and could give thumbs up or down, would suffice. One =20=

of jchris's blog posts[2] implies this exists, but he's deciphering =20
its functionality from a unit test, and as a total newbie I couldn't =20
follow the details of what this hook is capable of.

=97Jens

[1] Speaking of digital signatures, above =97 how would I perform =
public-=20
key crypto operations from within a JS handler running in CouchDB? =20
Would this require writing glue libraries for SpiderMonkey, to call =20
into e.g. OpenSSL?
[2] http://jchris.mfdz.com/posts/132=

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