Forum OpenACS Development: named objects

Problem: When displaying all objects categorized in a particular category, I need to list all the object names. I could use acs_object.name, but it's evident that this proc does not scale at all and thus should never used for more than a few objects.

I added another object-type 'named_objects' derived from acs_objects. All displayable objects (i.e. not like acs_rels) should then be derived from named_objects, no longer from acs_objects.

I also added a table acs_named_objects with the columns object_id, object_name and package_id.

Is this the way we want to do this or should we place this information in the acs_objects table (package_id should certainly go there - why not object_name, too?) ? Storing all data in the acs_objects table would have the advantage of not having to join two potentially large tables everytime we want to get the names of some objects.

One disadvantage does this solution have: We could only store an object_name in one language - so this is not multilingual. But I don't see this as a real difficulty since it probably won't happen too often that an object gets entered in more than one language - if it does, it will be package's responsibility to figure out which name to store as the official object_name. And: acs_object.name is unilingual, too. I strongly oppose of adding another column like locale or something similar since that would make queries a lot lot harder and would be a huge scalability threat (unless someone can come up with a real clever way to do it so queries can run fast), which is exactly what should be avoided by introducing named objects in the first place.

I'm not sure about scenarios either, but my gutfeel is that if you don't have a translation for a particular language+category, you don't have a categorization!!

It should be properly thought through - that's my wish. I I don't like the current solution with acs_objects.name - see my previous postings on it - , however replacing the PL/SQL proc with a simple columns fails another design goal: we'd be replacing a *really* bad solution performance-wise (which seems to have affected only a few sites yet) with a really bad solution I18N-wise.

Localized content needs to be stored somewhere. Why not pull out all user-facing textual information from acs_objects - maybe into a table called acs_objects_description - and make this table locale-dependant. An index on object_id+locale on acs_object_description will make an access relatively light-weight. (Long lists may lead to expensive joins)

To me it seems natural to let the table acs_names_objects have the columns (object_id, name, locale) and potentially others that might be needed. Do we want to add description as well?

Concerning package_id that is a denormalization that probably belongs in acs_objects. The proposal by Don, that I agree with, is to drop the context_id (no longer needed by permissions) column from acs_objects and introduce a parent_id column instead. I'm not sure what exactly that upgrade will involve.

How do you intend to support I18N then? Not only for categorization, but also for *every* other package in the system?

In a document called "Best Practices for Globalization using the Oracle 9i Internet Application Server" to which I was pointed at by Mohan, Oracle suggests this:

-- fallback language is English which is abbreviated as 'US'.
CREATE VIEW default_message_view 
  AS SELECT msgid, message 
  FROM messages 
  WHERE langid = 'US'; 
/

-- create view for services, with fall-back mechanism
CREATE VIEW messages_view AS
SELECT d.msgid,
  CASE WHEN t.message IS NOT NULL 
    THEN t.message 
    ELSE d.message 
  END AS message
FROM default_view d,
  translation t
WHERE t.msgid (+) = d.msgid AND
t.langid (+) = sys_context('USERENV', 'LANG');

SELECT message FROM message_view where msgid = 'hello';

Looks kinda slick: If you don't find a translation with the first index lookup, you need a second one. Shouldn't be that much of a performance impediment: If an average index lookup takes 5 I/O accesses (that's already for a huge table), you add a maximum of 10 I/Os per row.

It *clearly* is much more expensive than returning the name from a row that Oracle has touched anyway (access costs amount to zero there).

The current I18N solution sacrifices performance for tight coupling of related objects. Is it good? I dunno. Is lose coupling - every translated object gets its own row in acs_objects - better. I dunno.

As I said: at the moment (!) I am leaning towards not showing anything if a user can neither be shown something in his chosen language nor in the default language. I wouldn't want to promise a site translated into a user's language that falls back all the while into some other random language.

Maybe someone who is running (Greenpeace) or intends to run (Heidelberg) a multilingual site can give us some "real-life" input on that.