In response to my thoughts about using DOM as an intermediate representation
for schema elements, for use in lazy re-loading on schema change, Erik Hatcher
argued against (solely) using XML for schema serialization
(<https://issues.apache.org/jira/browse/SOLR-3251?focusedCommentId=13571631&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13571631>):
IMO - The XMLness of the current Solr schema needs to be isolated
to only one optional way of constructing an IndexSchema instance.
We want less XML rather than more. (for example, it should be
possible to have a relational database that contains a model of
a schema and load it that way)
I was hoping to avoid dealing with round-tripping XML comments (of which there
are many in schema.xml). My thought was that an XML->JSON conversion tool
would insert "description" properties on the enclosing/adjacent object when it
encounters comments. But I suppose the same process could be applied to
schema.xml: XML comments could be converted to <description> elements, and then
when serializing changes, any user-inserted comments would be stripped.
The other concern is about schema "ownership": dealing with schemas that mix
hand-editing with Solr modification/serialization would likely be harder than
supporting just one of them. But I suppose there is already a set of validity
checks, so maybe this wouldn't be so bad?
Steve
On Mar 6, 2013, at 1:35 PM, Mark Miller <[email protected]> wrote:
> bq. Change Solr schema serialization from XML to JSON, and provide an
> XML->JSON conversion tool.
>
> What is the motivation for the change? I think if you are sitting down and
> looking to design a schema, working with the XML is fairly nice and fast. I
> picture that a lot of people would start by working with the XML file to get
> it how they want, and then perhaps do future changes with the rest API. When
> you are developing, starting with the rest API feels fairly cumbersome if you
> have to make a lot of changes/additions/removals.
>
> So why not just keep the XML and add the rest API? Do we gain much by
> switching it to JSON? I like JSON when it comes to rest, but when I think
> about editing a large schema doc locally, XML seems much easier to deal with.
>
> - Mark
