Hi Erik,
I've not done much with JSON but it looks like it might be an interesting
approach.
>>Is it possible to introduce a new serialization format without rewriting the
>>whole parser?
Unfortunately, the XML DOM permeates it's way throughout the existing parser
design.
Some initial observations:
1) I suspect JSON offers simpler programmatic construction of queries for
clients rather than having to construct XML using the DOM api
2) XML does have the nice option of being able to use XSLT to populate query
templates with user input. Having the query templates as an externalized .xsl
file held on the server is quite nice. QueryTemplateManager offers support for
this mode of working.
3) Adding JSON will presumably introduce a dependency on some third party
library with the usual license hassles.
4) XML or JSON, it makes sense to avoid making the serialization format mirror
exactly the existing Lucene query/filter objects because this could either make
the serialization format ugly or require changes to the existing Lucene objects
to make them "serialization friendly". The XML parser addresses this with a
suite of "Builder" classes which parse different parts of the idealised XML
syntax and constructs the appropriate Lucene queries/filters. I imagine a JSON
variant would address this by supplying a set of "criteria" classes used to
construct a complex set of query criteria which can then be serialized on the
client as JSON and then deserialized by the Lucene server. Maybe these
"criteria-only" classes could be serialized to XML too as a more convenient way
of constructing XML?
5) I think we need to think about what we are trying to achieve before picking
a technology. Lightweight clients? Readable query representations? Size? Speed
of parsing? Ease of query construction in clients? Checking of valid queries?
Broadest support for different clients? Option of templates?
Cheers
Mark
----- Original Message ----
From: Erik Hatcher <[EMAIL PROTECTED]>
To: solr-dev@lucene.apache.org
Cc: java-dev@lucene.apache.org
Sent: Tuesday, 30 January, 2007 3:21:52 AM
Subject: "xml" query parser, except with JSON
I'm curious, Mark, what you think about the XMLQueryParser being
morphed into a JSON query parser. Is it possible to introduce a new
serialization format without rewriting the whole parser? Or is it
intimately tied to XML throughout?
Solr could really benefit from allowing queries to be pushed down to
the client. XML works, for sure, but I have a feeling Yonik's JSON
parser would be faster than an XML parser. Thoughts?
Thanks,
Erik
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