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From Johs Ensby <j...@b2w.com>
Subject Re: [PROPOSAL] Allow rewrites to be JS function
Date Sat, 17 Oct 2015 15:32:47 GMT
Andy,
I will make my first use case for function in _rewrite a high level one:
to create a standalone server that is an all-in-one DB server, application server, api server
and web server.

I have played with the build of CouchDB 2 with rewrite function implemented that  ermouth
put up on the irish AWS community AMI list and the new use cases are endless.
First, I find that there are a few things that people fail to notice about ddocs.
you need a tool to build a ddoc, editing JSON is not a viable option. The Ddoc Lab of ermouth
is in a class of its own. If you havent tried it yet, do so from http://ddoc.me/ <http://ddoc.me/>.
Installing on your own couch it is as easy as storing the application, all included as one
document in any database. Ddoc Lab is a component oriented IDE with syntax checking, less
preprosessor and other build tools that let you keep a well organized ddoc as a source project
(in one couchdb document) and you publich a ddoc to any target db.
with this tool you can organize your js modules and templates etc and basically...
set up the API of your application in a ddoc. You can switch between databases and their ddoc
functionality based on username, role or geolocation and limit access to parts of the Couch
API as needed

This is the method I would recommend to explore powerful simplicity with function in rewrites
redirect port 80 directly to couch
set up 2 vhosts, one for public access pointing to youdb/_design/api and one for sysadm pointing
to /
for admin use Fauxton and Ddoc Lab on the sysadm vhost
you are set to develop great systems, no big tool stack to learn, just bring in whatever js
modules you like, the template engine you like, the router you like, the HTML5 stuff you like..
.. or just write some very compact js code in one place where you ealier had to mess around
with a whole stack of tools and systems

below is the req object that the function takes

Johs



The rewrite function has this syntax
function(req) {
	.. your code that will
	return
		path
		// optional
		headers
		method // you can change this on the fly
		code
		body
}

the function receives this req object
method
path
raw_path
query
headers
	Accept
	Accept-Encoding
	Connection
	Host
	Upgrade-Insecure-Requests
	User-Agent
	x-couchdb-vhost-path
body
peer
cookie
userCtx
db
name
roles
secObj

> On 1. okt. 2015, at 13.40, Andy Wenk <andywenk@apache.org> wrote:
> 
> Johs,
> 
> Yes for sure! That's always great. Maybe you can also write some user stories (given
when then) or scribble some graphics. Everything is useful and will fasten the process ;-)
> 
> Cheers
> 
> Andy
> 
> On 1 Oct 2015 12:38, "Johs Ensby" <johs@b2w.com <mailto:johs@b2w.com>> wrote:
> Thanks for this Andy,
> 
> I can contribute to the discussion of the feature seen from a user perspective.
> Would it be appropriate to present some use cases?
> 
> best
> Johs
> 
> > On 1. okt. 2015, at 12.33, Andy Wenk <andywenk@apache.org <mailto:andywenk@apache.org>>
wrote:
> >
> > Johs,
> >
> > Let me please show the steps needed.
> >
> > * discuss the feature very clearly on the dev@. Please make sure that core
> > developers as committers with commit bits are involved
> >
> > * code the feature. Make sure to implement tests
> >
> > * send a pull request and show it to dev@
> >
> > * finally the community will accept or decline the feature (this will
> > involve refactoring and changes)
> >
> > As Alex said. The PMC or Jan do not decide about the feature.
> >
> > All the best
> >
> > Andy
> > On 1 Oct 2015 11:21, "Alexander Shorin" <kxepal@gmail.com <mailto:kxepal@gmail.com>>
wrote:
> >
> >> On Thu, Oct 1, 2015 at 12:07 PM, Johs Ensby <johs@b2w.com <mailto:johs@b2w.com>>
wrote:
> >>> will you welcome ermouths rewrite contribution?
> >>
> >> The decision is depends on the implementation. If it will be good, why
> >> not? Finally, CouchDB is open source project: we cannot forbid people
> >> right for contributions, we only welcome them.
> >>
> >>> Arguments against couchapps has to do with performance and the folly in
> >> competing with node.js.
> >>
> >> Performance question for the new _rewrite implementation is very
> >> depends on query server. Once it can process this kind of functions,
> >> you may use something better than JS to gain better performance. That
> >> could be Erlang native query server, or luerl-based one, or else you
> >> like.
> >>
> >> --
> >> ,,,^..^,,,
> >>
> 


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