Home » Modeling » EMF » [CDO] Multiple (interface) inheritance issues
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| Re: [CDO] Multiple (interface) inheritance issues [message #768083 is a reply to message #768067] |
Mon, 19 December 2011 14:52   |
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Hi Dan,
This seems to be a mostly HibernateStore-specific question, so I've cc'ed Martin.
I'm currently not aware of DBStore problems with multiple inheritance.
IIRC. the MongoDBStore supports auditing, but it cannot support no auditing because it's a pure "delta store" (due to
the missing transaction semantics of MongoDB).
Cheers
/Eike
----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper
Am 19.12.2011 15:09, schrieb Dan Pollitt:
> Hi all,
>
> I've recently moved to using CDO for an existing EMF model that used multiple inheritance (of interfaces) quite
> heavily (which is nice and powerful from the generated Java perspective). I've been hit by the limitation as mentioned
> on the Teneo/Hibernate/ModelRelational wiki page ("..that references to supertypes do not (always) work correctly.."):
>
> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>
> Mostly this was to allow polymorphism of references, allowing ClassA to have a multi-valued reference to a list of
> InterfaceB where InterfaceB was actually both abstract and an interface, being extended by ClassC & ClassD. ClassC &
> ClassD extend directly both InterfaceB and InterfaceE.
>
> My question is, is this likely to be a fundamental issue of my model that is going to have problems with any
> relational DB store implementation or could I work around it with specific mapping configuration? My starting point is
> the ecore model (as opposed to annotated Java or XSD).
>
> Also does this problem not exist with an Object DB store (i.e. MongoDB)? I'll need a store implementation that
> supports audit eventually so am not tied to using the Hibernate store.
>
> Hope someone can help,
>
> Thanks,
> Dan
Cheers
/Eike
----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper
|
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| Re: [CDO] Multiple (interface) inheritance issues [message #768090 is a reply to message #768083] |
Mon, 19 December 2011 14:58 |
 Martin Taal
Messages: 5468
Registered: July 2009 |
Senior Member |
|
|
Hi Dan, Eike,
Afaics there is no question for the hibernatestore, this is a documented limitation which is practically impossible to
solve. It is a limitation of practically all ORM's I know.
gr. Martin
On 12/19/2011 03:52 PM, Eike Stepper wrote:
> Hi Dan,
>
> This seems to be a mostly HibernateStore-specific question, so I've cc'ed Martin.
>
> I'm currently not aware of DBStore problems with multiple inheritance.
>
> IIRC. the MongoDBStore supports auditing, but it cannot support no auditing because it's a pure "delta store" (due to
> the missing transaction semantics of MongoDB).
>
> Cheers
> /Eike
>
> ----
> http://www.esc-net.de
> http://thegordian.blogspot.com
> http://twitter.com/eikestepper
>
>
> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>> Hi all,
>>
>> I've recently moved to using CDO for an existing EMF model that used multiple inheritance (of interfaces) quite
>> heavily (which is nice and powerful from the generated Java perspective). I've been hit by the limitation as mentioned
>> on the Teneo/Hibernate/ModelRelational wiki page ("..that references to supertypes do not (always) work correctly.."):
>>
>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>
>> Mostly this was to allow polymorphism of references, allowing ClassA to have a multi-valued reference to a list of
>> InterfaceB where InterfaceB was actually both abstract and an interface, being extended by ClassC & ClassD. ClassC &
>> ClassD extend directly both InterfaceB and InterfaceE.
>>
>> My question is, is this likely to be a fundamental issue of my model that is going to have problems with any
>> relational DB store implementation or could I work around it with specific mapping configuration? My starting point is
>> the ecore model (as opposed to annotated Java or XSD).
>>
>> Also does this problem not exist with an Object DB store (i.e. MongoDB)? I'll need a store implementation that
>> supports audit eventually so am not tied to using the Hibernate store.
>>
>> Hope someone can help,
>>
>> Thanks,
>> Dan
--
With Regards, Martin Taal
Springsite/Elver.org
Office: Hardwareweg 4, 3821 BV Amersfoort
Postal: Nassaulaan 7, 3941 EC Doorn
The Netherlands
Cell: +31 (0)6 288 48 943
Tel: +31 (0)84 420 2397
Fax: +31 (0)84 225 9307
Mail: mtaal@springsite.com - mtaal@elver.org
Web: www.springsite.com - www.elver.org
|
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| Re: [CDO] Multiple (interface) inheritance issues [message #768099 is a reply to message #768090] |
Mon, 19 December 2011 15:17 |
Dan Pollitt
Messages: 55
Registered: August 2010 |
Member |
|
|
Hi Eike, Martin,
Thanks for your replies - is there a rule of thumb you guys use when
designing models, to avoid multiple inheritance? It's not impossible for
me to take a look back at my ecore and see if I can restructure to only
have one superclass but it feels unnatural and a shame to compromise
what I thought was quite a neat portion of my model.
Thanks,
Dan
On 19/12/2011 14:58, Martin Taal wrote:
> Hi Dan, Eike,
> Afaics there is no question for the hibernatestore, this is a documented
> limitation which is practically impossible to solve. It is a limitation
> of practically all ORM's I know.
>
> gr. Martin
>
> On 12/19/2011 03:52 PM, Eike Stepper wrote:
>> Hi Dan,
>>
>> This seems to be a mostly HibernateStore-specific question, so I've
>> cc'ed Martin.
>>
>> I'm currently not aware of DBStore problems with multiple inheritance.
>>
>> IIRC. the MongoDBStore supports auditing, but it cannot support no
>> auditing because it's a pure "delta store" (due to
>> the missing transaction semantics of MongoDB).
>>
>> Cheers
>> /Eike
>>
>> ----
>> http://www.esc-net.de
>> http://thegordian.blogspot.com
>> http://twitter.com/eikestepper
>>
>>
>> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>>> Hi all,
>>>
>>> I've recently moved to using CDO for an existing EMF model that used
>>> multiple inheritance (of interfaces) quite
>>> heavily (which is nice and powerful from the generated Java
>>> perspective). I've been hit by the limitation as mentioned
>>> on the Teneo/Hibernate/ModelRelational wiki page ("..that references
>>> to supertypes do not (always) work correctly.."):
>>>
>>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>>
>>>
>>> Mostly this was to allow polymorphism of references, allowing ClassA
>>> to have a multi-valued reference to a list of
>>> InterfaceB where InterfaceB was actually both abstract and an
>>> interface, being extended by ClassC & ClassD. ClassC &
>>> ClassD extend directly both InterfaceB and InterfaceE.
>>>
>>> My question is, is this likely to be a fundamental issue of my model
>>> that is going to have problems with any
>>> relational DB store implementation or could I work around it with
>>> specific mapping configuration? My starting point is
>>> the ecore model (as opposed to annotated Java or XSD).
>>>
>>> Also does this problem not exist with an Object DB store (i.e.
>>> MongoDB)? I'll need a store implementation that
>>> supports audit eventually so am not tied to using the Hibernate store.
>>>
>>> Hope someone can help,
>>>
>>> Thanks,
>>> Dan
>
>
|
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| Re: [CDO] Multiple (interface) inheritance issues [message #768104 is a reply to message #768099] |
Mon, 19 December 2011 15:23 |
Martin Taal
Messages: 5468
Registered: July 2009 |
Senior Member |
|
|
Hi Dan,
You can have multiple inheritance with hibernate (all inherited efeatures should be persisted), but there are
limitations to how a multiple inheritance structure can be used in references. See the wiki page you referenced, I don't
have much to add to that page.
It all depends on the use/business/model case but I personally don't use multiple inheritance that much, but I work
mainly/only in ERP environments. There it makes sense to have something like additional features brought in/injected by
other super types but there is always/at most one primary inheritance structure.
gr. Martin
On 12/19/2011 04:17 PM, Dan Pollitt wrote:
> Hi Eike, Martin,
>
> Thanks for your replies - is there a rule of thumb you guys use when designing models, to avoid multiple inheritance?
> It's not impossible for me to take a look back at my ecore and see if I can restructure to only have one superclass but
> it feels unnatural and a shame to compromise what I thought was quite a neat portion of my model.
>
>
> Thanks,
> Dan
>
> On 19/12/2011 14:58, Martin Taal wrote:
>> Hi Dan, Eike,
>> Afaics there is no question for the hibernatestore, this is a documented
>> limitation which is practically impossible to solve. It is a limitation
>> of practically all ORM's I know.
>>
>> gr. Martin
>>
>> On 12/19/2011 03:52 PM, Eike Stepper wrote:
>>> Hi Dan,
>>>
>>> This seems to be a mostly HibernateStore-specific question, so I've
>>> cc'ed Martin.
>>>
>>> I'm currently not aware of DBStore problems with multiple inheritance.
>>>
>>> IIRC. the MongoDBStore supports auditing, but it cannot support no
>>> auditing because it's a pure "delta store" (due to
>>> the missing transaction semantics of MongoDB).
>>>
>>> Cheers
>>> /Eike
>>>
>>> ----
>>> http://www.esc-net.de
>>> http://thegordian.blogspot.com
>>> http://twitter.com/eikestepper
>>>
>>>
>>> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>>>> Hi all,
>>>>
>>>> I've recently moved to using CDO for an existing EMF model that used
>>>> multiple inheritance (of interfaces) quite
>>>> heavily (which is nice and powerful from the generated Java
>>>> perspective). I've been hit by the limitation as mentioned
>>>> on the Teneo/Hibernate/ModelRelational wiki page ("..that references
>>>> to supertypes do not (always) work correctly.."):
>>>>
>>>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>>>
>>>>
>>>> Mostly this was to allow polymorphism of references, allowing ClassA
>>>> to have a multi-valued reference to a list of
>>>> InterfaceB where InterfaceB was actually both abstract and an
>>>> interface, being extended by ClassC & ClassD. ClassC &
>>>> ClassD extend directly both InterfaceB and InterfaceE.
>>>>
>>>> My question is, is this likely to be a fundamental issue of my model
>>>> that is going to have problems with any
>>>> relational DB store implementation or could I work around it with
>>>> specific mapping configuration? My starting point is
>>>> the ecore model (as opposed to annotated Java or XSD).
>>>>
>>>> Also does this problem not exist with an Object DB store (i.e.
>>>> MongoDB)? I'll need a store implementation that
>>>> supports audit eventually so am not tied to using the Hibernate store.
>>>>
>>>> Hope someone can help,
>>>>
>>>> Thanks,
>>>> Dan
>>
>>
>
--
With Regards, Martin Taal
Springsite/Elver.org
Office: Hardwareweg 4, 3821 BV Amersfoort
Postal: Nassaulaan 7, 3941 EC Doorn
The Netherlands
Cell: +31 (0)6 288 48 943
Tel: +31 (0)84 420 2397
Fax: +31 (0)84 225 9307
Mail: mtaal@springsite.com - mtaal@elver.org
Web: www.springsite.com - www.elver.org
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| Re: [CDO] Multiple (interface) inheritance issues [message #768148 is a reply to message #768104] |
Mon, 19 December 2011 16:55 |
Dan Pollitt
Messages: 55
Registered: August 2010 |
Member |
|
|
Hi Martin,
Thanks for the information - I've taken a look through my model and have
been able to identify, in most cases, for a given entity, a single type
that could be used when referring to general forms of that entity.
I'm hoping this should alleviate my immediate problems but I have a
feeling this will come back to bite in the future... To have a concrete
class that brings together two distinct inheritance hierachies and then
to have references of types that sit in these hierarchies seems like
something I'd expect people to want to do frequently?
Thanks,
Dan
On 19/12/2011 15:23, Martin Taal wrote:
> Hi Dan,
> You can have multiple inheritance with hibernate (all inherited
> efeatures should be persisted), but there are limitations to how a
> multiple inheritance structure can be used in references. See the wiki
> page you referenced, I don't have much to add to that page.
> It all depends on the use/business/model case but I personally don't use
> multiple inheritance that much, but I work mainly/only in ERP
> environments. There it makes sense to have something like additional
> features brought in/injected by other super types but there is always/at
> most one primary inheritance structure.
>
> gr. Martin
>
> On 12/19/2011 04:17 PM, Dan Pollitt wrote:
>> Hi Eike, Martin,
>>
>> Thanks for your replies - is there a rule of thumb you guys use when
>> designing models, to avoid multiple inheritance?
>> It's not impossible for me to take a look back at my ecore and see if
>> I can restructure to only have one superclass but
>> it feels unnatural and a shame to compromise what I thought was quite
>> a neat portion of my model.
>>
>>
>> Thanks,
>> Dan
>>
>> On 19/12/2011 14:58, Martin Taal wrote:
>>> Hi Dan, Eike,
>>> Afaics there is no question for the hibernatestore, this is a documented
>>> limitation which is practically impossible to solve. It is a limitation
>>> of practically all ORM's I know.
>>>
>>> gr. Martin
>>>
>>> On 12/19/2011 03:52 PM, Eike Stepper wrote:
>>>> Hi Dan,
>>>>
>>>> This seems to be a mostly HibernateStore-specific question, so I've
>>>> cc'ed Martin.
>>>>
>>>> I'm currently not aware of DBStore problems with multiple inheritance.
>>>>
>>>> IIRC. the MongoDBStore supports auditing, but it cannot support no
>>>> auditing because it's a pure "delta store" (due to
>>>> the missing transaction semantics of MongoDB).
>>>>
>>>> Cheers
>>>> /Eike
>>>>
>>>> ----
>>>> http://www.esc-net.de
>>>> http://thegordian.blogspot.com
>>>> http://twitter.com/eikestepper
>>>>
>>>>
>>>> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>>>>> Hi all,
>>>>>
>>>>> I've recently moved to using CDO for an existing EMF model that used
>>>>> multiple inheritance (of interfaces) quite
>>>>> heavily (which is nice and powerful from the generated Java
>>>>> perspective). I've been hit by the limitation as mentioned
>>>>> on the Teneo/Hibernate/ModelRelational wiki page ("..that references
>>>>> to supertypes do not (always) work correctly.."):
>>>>>
>>>>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>>>>
>>>>>
>>>>>
>>>>> Mostly this was to allow polymorphism of references, allowing ClassA
>>>>> to have a multi-valued reference to a list of
>>>>> InterfaceB where InterfaceB was actually both abstract and an
>>>>> interface, being extended by ClassC & ClassD. ClassC &
>>>>> ClassD extend directly both InterfaceB and InterfaceE.
>>>>>
>>>>> My question is, is this likely to be a fundamental issue of my model
>>>>> that is going to have problems with any
>>>>> relational DB store implementation or could I work around it with
>>>>> specific mapping configuration? My starting point is
>>>>> the ecore model (as opposed to annotated Java or XSD).
>>>>>
>>>>> Also does this problem not exist with an Object DB store (i.e.
>>>>> MongoDB)? I'll need a store implementation that
>>>>> supports audit eventually so am not tied to using the Hibernate store.
>>>>>
>>>>> Hope someone can help,
>>>>>
>>>>> Thanks,
>>>>> Dan
>>>
>>>
>>
>
>
|
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| Re: [CDO] Multiple (interface) inheritance issues [message #768181 is a reply to message #768148] |
Mon, 19 December 2011 17:49 |
Martin Taal
Messages: 5468
Registered: July 2009 |
Senior Member |
|
|
Hi Dan,
I myself more and more turn away from inheritance hierarchies, I work in the ERP domain and have never had the need for
anything deeper than 3 levels in an inheritance structure and never for multiple inheritance. The multiple inheritance I
can think of in my domain is very similar to java, have a single inheritance hierarchy but annotate/enrich objects with
additional features using interfaces for cross cutting concerns.
But I want to stress that I speak only based on my own limited experience in my own limited world... there are many
different situations/choices/decisions possible..
gr. Martin
On 12/19/2011 05:55 PM, Dan Pollitt wrote:
> Hi Martin,
>
> Thanks for the information - I've taken a look through my model and have been able to identify, in most cases, for a
> given entity, a single type that could be used when referring to general forms of that entity.
>
> I'm hoping this should alleviate my immediate problems but I have a feeling this will come back to bite in the future...
> To have a concrete class that brings together two distinct inheritance hierachies and then to have references of types
> that sit in these hierarchies seems like something I'd expect people to want to do frequently?
>
>
> Thanks,
> Dan
>
> On 19/12/2011 15:23, Martin Taal wrote:
>> Hi Dan,
>> You can have multiple inheritance with hibernate (all inherited
>> efeatures should be persisted), but there are limitations to how a
>> multiple inheritance structure can be used in references. See the wiki
>> page you referenced, I don't have much to add to that page.
>> It all depends on the use/business/model case but I personally don't use
>> multiple inheritance that much, but I work mainly/only in ERP
>> environments. There it makes sense to have something like additional
>> features brought in/injected by other super types but there is always/at
>> most one primary inheritance structure.
>>
>> gr. Martin
>>
>> On 12/19/2011 04:17 PM, Dan Pollitt wrote:
>>> Hi Eike, Martin,
>>>
>>> Thanks for your replies - is there a rule of thumb you guys use when
>>> designing models, to avoid multiple inheritance?
>>> It's not impossible for me to take a look back at my ecore and see if
>>> I can restructure to only have one superclass but
>>> it feels unnatural and a shame to compromise what I thought was quite
>>> a neat portion of my model.
>>>
>>>
>>> Thanks,
>>> Dan
>>>
>>> On 19/12/2011 14:58, Martin Taal wrote:
>>>> Hi Dan, Eike,
>>>> Afaics there is no question for the hibernatestore, this is a documented
>>>> limitation which is practically impossible to solve. It is a limitation
>>>> of practically all ORM's I know.
>>>>
>>>> gr. Martin
>>>>
>>>> On 12/19/2011 03:52 PM, Eike Stepper wrote:
>>>>> Hi Dan,
>>>>>
>>>>> This seems to be a mostly HibernateStore-specific question, so I've
>>>>> cc'ed Martin.
>>>>>
>>>>> I'm currently not aware of DBStore problems with multiple inheritance.
>>>>>
>>>>> IIRC. the MongoDBStore supports auditing, but it cannot support no
>>>>> auditing because it's a pure "delta store" (due to
>>>>> the missing transaction semantics of MongoDB).
>>>>>
>>>>> Cheers
>>>>> /Eike
>>>>>
>>>>> ----
>>>>> http://www.esc-net.de
>>>>> http://thegordian.blogspot.com
>>>>> http://twitter.com/eikestepper
>>>>>
>>>>>
>>>>> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>>>>>> Hi all,
>>>>>>
>>>>>> I've recently moved to using CDO for an existing EMF model that used
>>>>>> multiple inheritance (of interfaces) quite
>>>>>> heavily (which is nice and powerful from the generated Java
>>>>>> perspective). I've been hit by the limitation as mentioned
>>>>>> on the Teneo/Hibernate/ModelRelational wiki page ("..that references
>>>>>> to supertypes do not (always) work correctly.."):
>>>>>>
>>>>>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>>>>>
>>>>>>
>>>>>>
>>>>>> Mostly this was to allow polymorphism of references, allowing ClassA
>>>>>> to have a multi-valued reference to a list of
>>>>>> InterfaceB where InterfaceB was actually both abstract and an
>>>>>> interface, being extended by ClassC & ClassD. ClassC &
>>>>>> ClassD extend directly both InterfaceB and InterfaceE.
>>>>>>
>>>>>> My question is, is this likely to be a fundamental issue of my model
>>>>>> that is going to have problems with any
>>>>>> relational DB store implementation or could I work around it with
>>>>>> specific mapping configuration? My starting point is
>>>>>> the ecore model (as opposed to annotated Java or XSD).
>>>>>>
>>>>>> Also does this problem not exist with an Object DB store (i.e.
>>>>>> MongoDB)? I'll need a store implementation that
>>>>>> supports audit eventually so am not tied to using the Hibernate store.
>>>>>>
>>>>>> Hope someone can help,
>>>>>>
>>>>>> Thanks,
>>>>>> Dan
>>>>
>>>>
>>>
>>
>>
>
--
With Regards, Martin Taal
Springsite/Elver.org
Office: Hardwareweg 4, 3821 BV Amersfoort
Postal: Nassaulaan 7, 3941 EC Doorn
The Netherlands
Cell: +31 (0)6 288 48 943
Tel: +31 (0)84 420 2397
Fax: +31 (0)84 225 9307
Mail: mtaal@springsite.com - mtaal@elver.org
Web: www.springsite.com - www.elver.org
|
|
|
| Re: [CDO] Multiple (interface) inheritance issues [message #768561 is a reply to message #768083] |
Tue, 20 December 2011 11:21 |
Dan Pollitt
Messages: 55
Registered: August 2010 |
Member |
|
|
Hi Eike,
I switched the Hibernate store out for DBStore and yes it looks like
DBStore doesn't have a problem with multiple inheritance as it uses the
cdo_objects table (when in MySQL) to store a mapping between the cdo_id
of an object to the concrete class (type).
Cool!
Thanks,
Dan
On 19/12/2011 14:52, Eike Stepper wrote:
> Hi Dan,
>
> This seems to be a mostly HibernateStore-specific question, so I've
> cc'ed Martin.
>
> I'm currently not aware of DBStore problems with multiple inheritance.
>
> IIRC. the MongoDBStore supports auditing, but it cannot support no
> auditing because it's a pure "delta store" (due to the missing
> transaction semantics of MongoDB).
>
> Cheers
> /Eike
>
> ----
> http://www.esc-net.de
> http://thegordian.blogspot.com
> http://twitter.com/eikestepper
>
>
> Am 19.12.2011 15:09, schrieb Dan Pollitt:
>> Hi all,
>>
>> I've recently moved to using CDO for an existing EMF model that used
>> multiple inheritance (of interfaces) quite heavily (which is nice and
>> powerful from the generated Java perspective). I've been hit by the
>> limitation as mentioned on the Teneo/Hibernate/ModelRelational wiki
>> page ("..that references to supertypes do not (always) work
>> correctly.."):
>>
>> http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Inheritance_Mapping
>>
>>
>> Mostly this was to allow polymorphism of references, allowing ClassA
>> to have a multi-valued reference to a list of InterfaceB where
>> InterfaceB was actually both abstract and an interface, being extended
>> by ClassC & ClassD. ClassC & ClassD extend directly both InterfaceB
>> and InterfaceE.
>>
>> My question is, is this likely to be a fundamental issue of my model
>> that is going to have problems with any relational DB store
>> implementation or could I work around it with specific mapping
>> configuration? My starting point is the ecore model (as opposed to
>> annotated Java or XSD).
>>
>> Also does this problem not exist with an Object DB store (i.e.
>> MongoDB)? I'll need a store implementation that supports audit
>> eventually so am not tied to using the Hibernate store.
>>
>> Hope someone can help,
>>
>> Thanks,
>> Dan
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