2009/12/15 Jo Størset <[email protected]> > > Den 15. des. 2009 kl. 10.54 skrev Bob Jolliffe: > > The real question is a general one; how do we think the api (and the xml >> formats we want to support) will evolve in the future? I don´t think we can >> avoid the rising cost of changes to the domain model, but we should try to >> make a concious choice on where we think we are going, before I create a new >> mapping solution. Some possiblities: >> >> 1) Proposed jaxb mapping, generally not supporting multiple xml versions - >> visible, easy, but no support for old formats >> > > I have for some time been proposing to Lars that the marshalling and > unmarshalling of domain objects should be part of the API. There are lots > of advantages but I have come around to his thinking that decoupling these > is in fact important. Primarily because I think there will be ongoing > tweaks to the domain model. Particularly I expect we will do at least one > more refactor of mcdonalds (categories, combo's etc). > > >> 2) Something like the existing "mapping layer" - low visibility, easier to >> support multiple separate xml versions (but rising uncertainty of entity >> changes for every version) >> 3) jaxb and "versioned" domain models - visible, reflecting the (real) >> complexity of different api versions in the domain model >> >> I don´t think we are at a point yet where we are sold on the approach we >> choose now, but obviously I would prefer not have to rewrite the mapping >> approach in the near future. I haven´t really looked at the feasibility of >> trying to do something like 3, but I think it should be to introduce such a >> model on parts of the domain model when needed, starting from 1. >> >> Personally I prefer to try 1, what do you think? >> > > My thinking was some combination of 2 and 3. A jaxb set of > marshalling/unmarshalling classes which are bound to a namespaced version. > And then mapping these to the domain model. Not as neat as a direct jaxb > mapping but more flexible. > > > I´m not entirely convinced that it will be that much more flexible. I mean, > it really depends on how important backwards compability will be, and > currently the domain model is a bit too changing to warrant it. So, at the > moment I tend to think that planned breaking changes to a single export > format would be preferable. The added complexity and extra resources needed > to maintain a separate mapping layer and multiple versions just seem to > outweigh the benefits. If we don´t have that many concrete use cases in the > short term, the cost of upgrading them seems preferable? >
OK. I would say go with what you are convinced by. We can always pre-process old versions on the way in to massage them into whatever is current if the need arises. Regards Bob > > On another note, I don´t think jaxb makes a lot of sense if we go for a > separate layer. I would tend to favour a solution more like the current > framework, simpler and with less boilerplate overhead. > > Jo >
_______________________________________________ Mailing list: https://launchpad.net/~dhis2-devs Post to : [email protected] Unsubscribe : https://launchpad.net/~dhis2-devs More help : https://help.launchpad.net/ListHelp
