Does anybody know of or have access to any documentation on recommended strategies for linking universes ? BO White papers, etc ?
We’re looking for some guidance before the design stage, so there are no specific questions yet, just a general heads up on the subject required…
Thanks
pete10 (BOB member since 2005-01-18)
I haven’t seen any documents on universe linking. It’s really quite simple and straight forward. Keep the following in mind:
Linked universes must use the same connection.
Custom LOVs in the kernel will not be accessible in the derived universe.
All joins from the kernel will need to be included in contexts in the derived universe, if contexts are being used.
If you have any specific questions, let us know.
MichaelWelter 
(BOB member since 2002-08-08)
I might be wrong, but the best practice seems to be not to do this if you can avoid it. 
Seriously, linked universes are OK, but some of the issues have caused people to not use them.
Steve Krandel 
(BOB member since 2002-06-25)
I agree with Steve on this one, I tend to advise my clients against this approach due to the limitations.
IMHO - I find the linking data provider approach provides a similar functionality with more flexability, although there is a greater overhead on the end user…
Mak 1 
(BOB member since 2005-01-06)
There are some scenarios where one should at least consider linked universes, for example:
Set of common objects, which should be used in many universes, keywords: consistency, re-using building blocks (universes) and maintenance
Multi-lingual universes, high initial development effort, but lower maintenance
…
Andreas 
(BOB member since 2002-06-20)
Linked universes where you only have one universe domain are fairly straight-forward. Once you export them, you don’t have to move them around. It’s scenarios where you have multiple universe domains (DEV -> TEST -> PROD) or even worse multiple security domains where managing linked universes becomes problematic.
What problems do linked universes solve? Redundant objects don’t have to be rebuilt. That’s probably the best argument for using them. The limitations of linked universes include:
[list][:8e8c7f4ab4]May only use one connection
[:8e8c7f4ab4]Getting objects to show up in the right order can be problematic
[:8e8c7f4ab4]Certain items from the base universe are not inherited (passed through) to the combined universe [list][:8e8c7f4ab4]contexts [:8e8c7f4ab4]hierarchies [:8e8c7f4ab4]custom LOV queries[/list]
[:8e8c7f4ab4]Supervisor cannot be used to manage linked universes, meaning you must use Designer to migrate universes from one domain to another
[:8e8c7f4ab4]Links are managed in the repository, therefore you cannot use linked universes on a non-exported universe[/list]
What you have to do is determine if the benefits of linked universes (reduced maintenance) outweigh the potential costs. I have several clients that are using linked universes very successfully.
Dave Rathbun (BOB member since 2002-06-06)
See this post for another BOB user’s comments on this issue. 8)
Dave Rathbun (BOB member since 2002-06-06)
I have been exposed to linked universes for the first time at my current client and I’ve been very impressed with how well they work! They really do cut down significantly on the amount of maintenance required for highly repetitious objects.
One of the known bugs that had existed was that in 6.5 the index awareness did not work with linked universes. I found out recently that there is supposed to be a patch for that problem. We haven’t implemented it yet…
Eileen King (BOB member since 2002-07-10)
So Eileen… how many domains does your client have? How do they manage the migration process? That’s generally the biggest issue with using linked universes in my experience.
Dave Rathbun (BOB member since 2002-06-06)
Three domains…move all the pieces together between the domains. Keeping everything together seems to prevent the problems. 8)
Eileen King (BOB member since 2002-07-10)
Has anyone dealt with linked universes in XI? I would like to create a base universe for all dimensions and than link it to facts in seperate universes as needed. The question I have is how XI security will deal with it. I am in an ods environment and having all of these areas together in one universe will not give the users a “easy” reporting environment. Even with contexts. Thanks.
maverick976 (BOB member since 2004-07-06)
The way that my current client is doing things really makes sense and seems to be working well. We find the occasional glitch because of linked universes, but I’d almost say that the pros outweight the cons!
There is a kernel universe for dimensions. That is the basis for most of the other universes and that way it’s all in one place and maintenance is all done in that universe.
There is another kernel universe for systems stuff. It’s where the keys, hyperlinks, literals and misc objects are maintained.
The rest of the universes are master universes that are more subject matter oriented and are linked to the dimension and system universes.
At first I was really nervous…I’d always heard not to use linked universes. They really seem to make a lot of sense and I think the designers here have done a great job. Right now, I’m a big fan of linked universes!!! 
I haven’t worked with them in XI yet…
Eileen King (BOB member since 2002-07-10)
Hi Eileen, I was wondering if you were still a big fan of linked universe and if you upgrade to XI recent version. I’ve also done the linked universe design you have seen and I had the same favorable opinion. I am now at a new customer and I am wondering if that approach is good for them. They currently have over 130 universes and there’s a lots of duplicate objects/dimensions.
thanks
patrick.lavallee 
(BOB member since 2005-07-20)
I haven’t working with them in XI so I really can’t give you an answer. I’ve heard that many things work better with them in XI…but I’ve heard early on that there were a lot of problems with migration. Maybe somebody else will have a more recent opinion…
Eileen King (BOB member since 2002-07-10)
Hi, I am not really expert in BO as a designer however I have been using it since couple of years.
Can some one tell me in a complex universe, how many approximate maximum number of tables can be used.?
s_iska (BOB member since 2009-08-21)
I’m a fan of linked universes in XI. Mine are organised in a data warehouse kind of way - with universes representing the conformed dimensions - people, vehicles etc and universes representing the facts - events etc.
Not had any problems yet and it makes maintenance quiet straightforward, especially as we have frequent source-system upgrades.
debbie
Debbie (BOB member since 2005-03-01)
More than you should ever need. 
Dave Rathbun (BOB member since 2002-06-06)
Is the view that user x in universe X then necessarily the same as user y in universe Y? Does user x necessarily need to see every dimension in the same way as user y?
Damocles (BOB member since 2006-10-05)
In our case, yes. We have very few standard reports - most are ad-hoc queries and we never know from one day to the next what dimension will be flavour of the month with the government. So we have lots of fiddly dimensions that everybody needs to access.
Most of our users have the same level of access to all universes. There are a few universes (such as HR) that can only be accessed by certain users and we have security defined at the oracle logon layer which restricts access to certain records, but otherwise it’s a free-for-all.
debbie
Debbie (BOB member since 2005-03-01)
Debbie, this sounds like a great setup 
Conformed dimension in a kernel universe for linking, plus row-level security implemented directly at the database layer (instead of using BusObjects row-level security).
When can I come to work for your company?
Andreas (BOB member since 2002-06-20)