| Change in EMF Reference Navigability [message #509327] |
Fri, 22 January 2010 00:28  |
 Hemant Kolwalkar
Messages: 17
Registered: July 2009 |
Junior Member |
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Hi,
we have an EMF model in which we had the following reference :
A (1) ----------> (1) B (Older version)
we now changed the reference to be bi-directional as below:
A (1) ----------- (1) B (Current version)
after the change when any existing resource (created using the older version EMF model) is loaded, although both A and B get loaded, the reference between A and B is not created.
i tracked the cause down to the XMLHandler.setValueFromId() method.
if my understanding of the method is right, the reference is created (mustAdd=true) only if the reference is uni-directional or it is a bi-directional with cardinality
of A (1) ------- (*) B.
for our case of A (1) ----------- (1) B, since the reference is bi-directional with cardinality of A (1) ------- (1) B, the reference creation seems to be deferred till B is loaded.
while loading an existing resource (created using the prior EMF model), B does not know about the reference to A as the reference was initially uni-directional. as such, although
B gets loaded the reference to A is not created since the information is absent in the resource.
i would like some guidance on how to solve this issue.
one approach i can think of is to extend the XMLHandler and override the setValueFromId() method. but inorder to do that, i would like to have some insight on the existing implementation rationale and whether it is by intention or an oversight.
a second approach would be to set the option deferIDREFResolution=true while loading the resource.
that would set the mustAdd=true flag and force the creation of the reference.
any other suggestions would be much appreciated.
thanks,
- Hemant
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| Re: Change in EMF Reference Navigability [message #509399 is a reply to message #509327] |
Fri, 22 January 2010 06:34  |
Ed Merks
Messages: 33142
Registered: July 2009 |
Senior Member |
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Hemant,
Comments below.
Hemant Kolwalkar wrote:
> Hi,
>
> we have an EMF model in which we had the following reference :
>
> A (1) ----------> (1) B (Older version)
>
> we now changed the reference to be bi-directional as below:
>
> A (1) ----------- (1) B (Current version)
>
> after the change when any existing resource (created using the older
> version EMF model) is loaded, although both A and B get loaded, the
> reference between A and B is not created.
>
> i tracked the cause down to the XMLHandler.setValueFromId() method.
> if my understanding of the method is right, the reference is created
> (mustAdd=true) only if the reference is uni-directional or it is a
> bi-directional with cardinality
> of A (1) ------- (*) B.
>
> for our case of A (1) ----------- (1) B, since the reference is
> bi-directional with cardinality of A (1) ------- (1) B, the reference
> creation seems to be deferred till B is loaded.
> while loading an existing resource (created using the prior EMF
> model), B does not know about the reference to A as the reference was
> initially uni-directional. as such, although
> B gets loaded the reference to A is not created since the information
> is absent in the resource.
>
> i would like some guidance on how to solve this issue.
> one approach i can think of is to extend the XMLHandler and override
> the setValueFromId() method. but inorder to do that, i would like to
> have some insight on the existing implementation rationale and whether
> it is by intention or an oversight.
>
> a second approach would be to set the option deferIDREFResolution=true
> while loading the resource.
> that would set the mustAdd=true flag and force the creation of the
> reference.
>
> any other suggestions would be much appreciated.
Do these references need to span resources? If not, you should consider
making the B -> A reference transient. Then the other end will be set
and that will populate both ends.
>
> thanks,
>
> - Hemant
>
>
>
Ed Merks
Professional Support: https://www.macromodeling.com/
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| Re: Change in EMF Reference Navigability [message #509747 is a reply to message #509719] |
Mon, 25 January 2010 05:00 |
Ed Merks
Messages: 33142
Registered: July 2009 |
Senior Member |
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Hermant,
Comments below.
Hemant Kolwalkar wrote:
> Hi Ed,
>
> the reference would not need to span resources with our current usage
> but one cannot rule it out the possibility in future.
>
> as you suggested, i did try by setting B -> A reference transient in
> the Rose model. but when i tried to reload the genmodel, i get the
> error message "Cross document bidirectional reference must not be
> transient; reference 'B' -> 'A' ".
>
> also would'nt setting to "transient =true" exclude the reference from
> serialization to the resource? if thats rue then that approach may not
> work for our use-case.
You'd also need to turn off proxy resolving, that's why I was asking
about the need for cross document references.
>
> what is your take on the deferIDREFResolution=true approach?
That won't help the cross document case. In that case you must have a
proxy at both ends and since your older serialization doesn't include
that, you'll have to do more than just fiddle with the model's settings.
> from the documentation, doing so also would help in improving loading
> performance is definitely welcome. any downsides to using the
> deferIDREFResolution?
It has to build a table so will use more memory, but if there are lots
of forward references, it has to do that anyway.
>
> thanks,
>
> - Hemant
>
Ed Merks
Professional Support: https://www.macromodeling.com/
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