Why are people continuing to use xml mapping files instead of annotations? [closed]

Answer 1

I have a new one : http://www.summerofnhibernate.com/

Very nice screencast series not yet covering annotations. I have written some apps with it to learn the basics, not for my job but out of curiosity, but never migrated to annotations yet. The series where suggested as still relevant on SO. I still will migrate to annotations if I have some more spare time but for the time being I could be one of the persons asking questions about it.

Answer 2

I feel that it makes the code much more readable if we donot use Annotations.Use of Annotations can really help if the configuration info changes frequently, but take the case of web.xml, how many times does the info in that change, so why use annotations for Servlets.

Answer 3

I've switched to annotations, but sometimes I miss the XML mappings, mainly because the documentation was so much more comprehensive, with examples of many scenarios. With annotations, I stick to pretty basic mappings (which is great if you control the data and object model), but I've done some very complex things in the XML that I don't know if I could replicate in the annotations.

Answer 4

I initially found the annotation syntax very weird. It looks like line noise and mixes in with where I usually put comments. It's vastly better than dealing with the XML files though, because all of the changes are in one place, the model file. Perhaps one limitation of annotation is possible collision with other annotations, but I haven't seen that yet.

I think the real reason that it isn't used more is that it isn't really considered the default. You have to use an additional jar file. It should be part of core and the XML approach should be the optional one.

Answer 5

We continue to use XML because typically for deployed sites, getting a patch (binary code) approved for installation takes time that you may not have. Updates to ASCII files (e.g. xml files) are considered configuration changes and not patches...

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Answer 6

So if you want to deploy your class to multiple datastores. And you want to annotate column definitions into it do you ? Different datastores have different conventions etc and using XML is the only sane place in that situation, being able to have one for MySQL, and one for Derby, and one for Oracle or whatever. You can still put the basic persistence/relation annotations in if you wish, but the schema-specific stuff would go into XML in that case.

--Andy (DataNucleus)