[jira] Commented: (TUSCANY-1493) Snapshot mapping framework to convert DataObjects to and from Java objects

["Kelvin Goodson (JIRA)" <tu...@ws.apache.org>]

    [ https://issues.apache.org/jira/browse/TUSCANY-1493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12531723 ] 

Kelvin Goodson commented on TUSCANY-1493:
-----------------------------------------

Hi,  Thanks for the code. Sorry to take a while to get back to you.  I have revisited this a few times to make sure I have a reasonably good feel for it before commenting.  I'd love to be able to execute a test program to answer some of the question I have about the code,  or at least to see some code that exercises it. Looking at the SnapshotSerializer code I think I'm OK to make the inference that the Type and Property classes used in there are your implementation classes of the SDO concepts, although of course that implementation code is not available.  So, given that assumption,  I understand that the implementation of your opaque snapshot representation is based on SDOs.  It would be interesting to understand the issues you have encountered in using the code; for example, if there are any lossy round-trip transformations that cause problems.   It would be great to work towards getting some code running inside the Tuscany code base;  it would also be helpful if you could put some more words around any key design concepts and the issues you have encountered and solved, or have yet to solve.  How should we proceed?  Clearly the code is broken at the moment, given the missing aspects, so it's not suitable for including in the nightly build.   I can put it in my sandbox,  or I could set up another project under the SDO project,  but not include it in the main build.   

> Snapshot mapping framework to convert DataObjects to and from Java objects
> --------------------------------------------------------------------------
>
>                 Key: TUSCANY-1493
>                 URL: https://issues.apache.org/jira/browse/TUSCANY-1493
>             Project: Tuscany
>          Issue Type: New Feature
>          Components: Java SDO Implementation
>            Reporter: bert.robben
>             Fix For: Java-SDO-Next
>
>         Attachments: sdo-snapshot.zip, sdo.zip
>
>
> We're developing 3-tier applications with a  swing client, JBoss app server and a couple of databases in the back-end. We use sdo as mechanism to exchange data between our client and our server. On the server side we have a fairly complex implementation based partially on Hibernate pojo's, partially on an inhouse legacy persistency system. The legacy part (although written in Java) is very hard to change. In this environment we often need to convert between data objects and server side objects (typically, but not always at a transition from server to client or vice versa). 
> To support this we developed a mapping framework that allows us to convert data between SDO and ordinary Java objects. This framework defines a number of important concepts.
> - A snapshot is an opaque collection of structured data at a given moment in time. It is opaque in the sense that the data inside can't be accessed directly.
> - A Mapper is an interface that defined how data can be accessed from an object. We have implementations for SDO DataObjects, normal Java POJO's (following java beans convention). hibernate pojos, and support for customizing this to access any kind of object (as we need for instance for our legacy objects).
> - We defined a DataAccessService (sorry for the confusing name) that given a mapper and some objects can create a snapshot. Given a snapshot and a mapper it can instantiate new objects. As such we can convert data to and from data objects very easily.
> This framework is part of our in-house developed implementation of the SDO spec. We want to share our code and experience with the open-source community. As such, Frank Budinsky proposed that we make JIRA request for this to start the discussion. 
> I'll attach the core classes for this feature to this JIRA. At this moment I'm not making the entire code available because we implemented more than one additional feature (I'll add some more JIRA over the next days) and I'd like to have a more focussed discussion. Also, at this moment in time some smaller parts of implementation (for instance the hibernate integration) are still implemented as a specialization of our SDO implementation. As such they can't be built outside of the rest of our application (which is not open-sourced). However this is just a matter of finding enough time to move them to our sdo component.

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