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From Jakob Braeuchi <jbraeu...@gmx.ch>
Subject Re: Some (major) Bugs in OJB RC3/4
Date Fri, 29 Aug 2003 19:33:26 GMT
hi carsten,

i had problems with your 'super' references in the ocot sample. you set 
auto-update=false this led to the situation where the subclass was 
inserted _without_ the super class !

<class-descriptor class="Firma" table="FIRMA" >
   <field-descriptor id="1" name="prsId" column="FIRMA_PRS_ID" 
jdbc-type="DECimal" primarykey="true" autoincrement="true" 
   <field-descriptor id="2" name="register" column="FIRMA_REGISTER" 
   <reference-descriptor id="1" name="super" class-ref="Person"  >
     <foreignkey field-id-ref="1"/>

after removing the auto-settings inserts work fine.  with the patch 
provided by kurt hoehn querying a superclass attribute also works !  
i'll do some further tests and will check it in asap.


Jakob Braeuchi wrote:

> hi carsten ,
> see inline
> Spräner, Carsten wrote:
>> Hi all.
>> I thing we found some (major) bugs in OJB or we made something wrong 
>> in the usage of OJB. We are using the new feature of mapping 
>> inheritance to different tables. This feature is new in OJB RC3. 
>> Another Bug is in handling exceptions while there are locks in a 
>> locking table. I listed the errors below. I attached a tgz-File to 
>> this mail where you find a test environment for the Bugs. To run the 
>> test, follow these steps:
>> 0. Excuse my English ;->
>> 1. Extract the tgz to a location of your choice. It will create a new 
>> folder ojbTest. 2. Copy all jars from the OJB-Environment/lib to the 
>> ojbTest/lib directory. Don't forget the db-ojb-1.0.rc3.jar. If you 
>> use db-ojb-1.0.rc4.jar edit the class-path in the build.xml of 
>> ojbTest and replace all name="this" to name="super" in the 
>> repository.xml files. 3. Go to the ojbTest directory and run ant 
>> <testCase> where you can choose <testcase> as generatorGap, ocot, 
>> aiot or opot. Each ant target sets up an environment for the test. 
>> (It copies repository.xml and/or dbCreate.ddl to the ojbTest 
>> directory). 4. The dbCreate.ddl is for db2-Environments. Start a db2 
>> command environment. Create a test database for the tests and connect 
>> to it:
>>   a: db2 create database test and edit the JCDs in all repository.xml 
>> files      so OJB can connect to your database.
>>   b: Do a "db2 connect to <test> user <x> using <y>" to connect
>> your      database
>>   c: do a "db2 -tf dbCreate.ddl" to create the schema.
>> Steps a and b are only needed once. Step c is necessary after each 
>> set up of a new test environment. It will create a new empty 
>> database. Running the script the first time gives a couple of errors 
>> because the drop table statements do not find there tables.
>> 5. Perform a "ant run" to start the test.
>> Step 1-4b are only needed once. You can repeat Step 4c and 5 again 
>> and again. The Test.java uses the ODMG-API and is easy to understand. 
>> It creates several object nets and stores them to the database with 
>> the ODMG API.
>> Now here are the Bugs:
>> 1. (generatorGap)
>> It is not possible to map the following Situation:
>>  AGenarted <|-- A <|-- BGenerated <|-- B
>> You can test the behaviour by doing "ant generatorGap" and "ant run".
>> In this Situation the RepositoryHandler can not load the Repository 
>> because A is not the direct superclass of B. But that should be no 
>> problem to OJB. I thing the algorithm should only check if A is a 
>> superclass of B. Or the next mapped superclass of B is A.
>> 2. Retrieving inheritance trees.
>>   (OneClassOneTable (ocot))
>>   (OnePathOneTable (opot))
>>   (AllInOneTable (aiot))
>> Try the following Situation: There is a Containerclass Container 
>> which references an abstract Class Person. There are two derived 
>> classes of Person. NatuerlichePerson and Firma. Sorry for the german 
>> names. In UML:
>>     Container --->  Person <|-+---NatuerlichePerson
>>                             |
>>                             +---Firma
>> OCOT:
>> The ocot-Example maps Person to a table PRS, NatuerlichePerson to a 
>> table PRSN and Firma to a table FIRMA. Table FIRMA and PRSN 
>> references the PRS table via an FK attribute. The reference is called 
>> this (or super in RC4).
>>>>> BUG?
>> Running this test the first time shows a NullPointerException. The 
>> real reason is that OJB queries a PRS_NAME in the FIRMA-Table. But 
>> PRS_NAME is only in the PRS-Table. This query fails because the 
>> broker implementation in Method getRsIteratorFromQuery tries to load 
>> FIRMA with the same query as PERSON. But table FIRMA does not have 
>> the column for attribute name!!! IMHO the method should perform the 
>> query on PRS as it does. But when it tries to load the extents it has 
>> to analyze how the extension is implemented, create a query for the 
>> extension implementation and perform this query for retreiving the 
>> extents. (See PersistenceBrokerImpl row 2328 to 2345 in RC3 of OJB. 
>> It is the same problem in RC4.) This Bug makes it impossible to 
>> perform any query on an object hierarchy where the objects
> ojb currently does not perform an automatic lookup of a field in the 
> superclass. ths can be forced by using super. prefix (ie. 
> 'super.name') but this would not solve your problem because it fails 
> on the first query. it's quite tricky !
> jakob
>> are mapped on different tables. It only works if ALL attributes for 
>> queries are in all tables with the same value!
>>>>> BUG?
>> If you have a closer look to the output you see that the attributes 
>> of Firma are filled in the retrieved Object but not the attributes of 
>> Person! Also there are two objects in the resulting list?
>>>>> BUG?
>> Running the example a second time shows another Bug. Each run of Test 
>> creates a container referencing to a NatuerlichePerson and another 
>> container referencing to a Firma. But if the test looks up all 
>> Persons the number of NatuerlichePerson and Firma differs?
>> OPOT:
>> Now switch to the opot environment with "ant opot". The first run is 
>> OK. Everything works fine. But after the second run the number of 
>> NatuerlichePerson is not equal to the number of Firma?
>> AIOT:
>> This example works perfect!
>> 3. (Exception during ODMG-Transaction)
>> Using database locking in ODMG-API: If you lock an Object to a 
>> transaction then OJB creates an entry in the locking table with a 
>> special control connection. If an exception is thrown in the 
>> operational code the broker does not use control connection for 
>> removing the locks but the connection for doing the operational work. 
>> Thus when doing the rollBack all locks are there again?!
>> Hope this can help you (and us :->)
>> Carsten Spräner
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