From: deudon@feiffel.UUCP (Guillaume Deudon)
Newsgroups: comp.databases,comp.lang.eiffel
Subject: Re: Persistent Eiffel?
Summary: EiffelStore
Keywords: persistence ODBMS Eiffel
Date: 9 Sep 92 08:07:21 GMT


Quoting: 

>Article <1992Sep7.110938.4302@eua.ericsson.se> Mon 13:09
>Subject: Re: Persistent Eiffel?
>Keywords: persistence ODBMS Eiffel
>From: konpar@eua.ericsson.se (Par.Emanuelsson @ Ellemtel Telecom Systems Labs, Stockholm, Swe
den)
>Newsgroups: comp.databases,comp.lang.eiffel
>..
>There is also a class library to interface Eiffel with
>OODBMS's called EiffelStore (Jean-Marc Nerson is designer).

   That's right: our company is currently working on ``EiffelStore'', 
an Eiffel class library providing facilities for interfacing Eiffel 
applications with various data persistency mechanisms.

The library is designed as a virtual layer on top of different 
implementation schemes, ranging from object paging facilities 
to uniform interfaces with relational and
object-oriented data base management systems.

The library interface consists of two clusters (set of classes):

    o A cluster of general classes designed 
   regardless of any data management system used
    o A cluster of specific classes, referred to by general classes, 
   bridging the application to selected data management systems

Several interface levels are provided, 
ranging from a very general set of primitives
available across a wide range of object management systems, 
to more specific primitives, including mechanisms influenced by 
the external data formats.

Three user interface levels are defined:

    - The ``EiffelStore layer'' encapsulates general primitives 
   to manage the object manipulation session, and to deal with 
   high-level persistency primitives.

    - The ``Standard layer'' groups together existing 
   implicit storage mechanisms (class STORABLE) and 
   explicit storage mechanisms (class ENVIRONMENT).

    - The ``DBSM layer'' supports various 
   relational and object-oriented DBMS. This layer also includes
   a RDBMS simulator, called EDBMS. The EDBMS permits the storage
   and retrieval of Eiffel objects, with an implementation
   based on the Standard layer, but offering the RDBMS interface.

Now referring to some recent postings:

>Article <1992Aug31.071631.17765@monu6.cc.monash.edu.au> Aug 31 09:16
>Subject: Storable file format for a Store Browser
>From: gmaughan@monu6.cc.monash.edu.au (Glenn Maughan @ Monash University, Caulfield Campus)
>
>I am implementing a Persistent Object Store Browser for a research project
>and was wondering if anyone knows the format/layout of the store files
>created by classes STORABLE and ENVIRONMENT.

This can be done using EiffelStore-EDBSM. This layer offers SQL-like 
queries such as SELECT, INSERT, UPDATE and DELETE.
Eiffel persistent objects are in this case actually stored in 
an ENVIRONMENT file. Note that a pre-existing ENVIRONMENT may also 
be simply passed to EiffelStore to start with.

>Article <1992Sep1.223008.26778@bony1.bony.com> Wed 00:30
>Subject: Re: Persistent Eiffel?
>Keywords: persistence ODBMS Eiffel
>From: stevef@bony1.bony.com (Steve Faiwiszewski @ Lost in NYC)
>Newsgroups: comp.databases,comp.lang.eiffel
> ...
>There's one OODBMS called O2, which supposedly works with Eiffel.
>Another, Versant, will in the future: ISE and Versant will develop an
>Eiffel interface jointly.  In the meantime, we've been using Versant's
>C interface to build our own Eiffel interface.  While not, completely
>transparent or automatic, our interface is quite usable.

Some OODBMS interfaces with Eiffel have already been 
defined within different organizations and in different
contexts.
We are now working on how to benefit these
experiences and come up with a consistent 
solution in EiffelStore. O2 and Versant are first on our task list.


Regards,
Guillaume.






-- 
Guillaume Deudon
R&D Dpt.
Socie'te' des Outils du Logiciel - Paris
Newsgroups: comp.databases