BusinessObjects Board

Universe Linking

building semantic layer
#1

Guys,

Is there any document which lists out all the implications about universe linking? We are in the phase of deciding whether to go with universe linking or not. Any help is greately appreciated. Thanks,

Sreeni

sreeni B (BOB member since 2003-06-19)

Linking Universe
Linked universes
Questions on linked universes
Universe Linking
linked universe-added a new object in master universe
High-level Universe designing in Business Objects
#2

Welcome to Bob! There is no such document, but you should be able to arrive at a decent decision if you read all the threads you can find on this subject here. Personallly, I’m dead against it. What is the thinking behind potentially taking this approach?

Nick Daniels :uk: (BOB member since 2002-08-15)

#3

Thanks for the reply Nick,

Here are the requirements that are making the group to think about linked universes.

  1. The users want only one universe to deal with.
  2. The individual departments are supposed to develop and maintain their part of the universe.
  3. The development speed or pace of the one department specific part of the universe should not effect the other departments.

I have gone through some of the posts that are on this site. But, was just wondering whether there is any other place that I can get more info about the practical issues with linking universes. We have a single security domain here (with multiple universe and doc domains for dev and production). So, I am thinking that at least the migration related issues (from one repository to another) of linked universes (like loosing the objects ID’s ) may not bother me.

Any insight about the other potential issues is greatly appreciated. Thanks,

sreeni B (BOB member since 2003-06-19)

#4

Sreeni

why not maintain 1 universe with some common objects which can be used for linking ( at report level) with other universes. ID and Keys are ideal for this

export this universe with diif connections to diff repositories of each dept. let each dept maintain their universe in the reporsotory along with this common universe. let the linking be done at report level from seperate dataproviders

Thx
Prem

Bo_Bhai :us: (BOB member since 2003-07-11)

#5

I do not trust linked universes at all.

This issue caused me much pain, twice. It has been a few years ago and I have heard that it is better, but you are risking your reputation and your companies business on it. First make sure that this is even possible. In the past is was not.

If you do go this route, make sure your repository is backed up regularly and is easily restorable. I had a client that backed up weekly, but could not restore easily. It cost them a week’s worth of invoicing.

You may consider more, but smaller, universes. If only one or two reports need to be able to span departments, it is easier to link queries in the report. Smaller universes are usually easier to use and maintain.

Lee Drake :us: (BOB member since 2002-08-15)

#6

Prem,

As I mentioned earlier, the end users want only one universe to deal with. My actual question is - What are the major practical issues with linked universes?

While going through the previous posts, I came to know about the following ones.

  1. We still have to open and add any new joins to existing contexts in the “host” universe
  2. The migration of linked universes from one release to the other is not straight forward. etc…

While going through these posts, I found that the Guru’s out there are very unhappy about linked universes and I would like to know more reasons to not go for linked universes. Thanks,

sreeni B (BOB member since 2003-06-19)

#7

You loose custom LOVs

Andreas :de: (BOB member since 2002-06-20)

#8

Tough. :smiley:

The bigger your universe is, whether it is linked or not, the more problems you have. BusinessObjects was not intended to contain your entire ERP system in one single universe. Can you? Well, if you are really looking for punishment. :wink: But it won’t work very well.

You need to go back to your users and get them to enumerate why they are making this requirement… and have they even seen BusinessObjects before? How do they know what the issues are? Once you see their objections then you have something you can work with. But saying that they will only allow one universe… you need to find out why so you can address those concerns.

Trust me, linked universes or no, going into a project with the restriction of only having one universe is not getting off to a good start.

The preceeding comments are of course, only my opinion. And worth everything that you paid for them. 8)

Dave Rathbun :us: (BOB member since 2002-06-06)

#9

Dave,

Thanks for the help. I am sorry for not sounding very clear in explaining my problem. This organization already have more than 40 universes. So, they know what it means to have 5 or 6 more of them. They have already implemented SupplyChain, Sales and Customer analytics here. They actually want to build the smaller universes (Business function specific ones). But, because of the WebI restriction - “No Multiple Dataproviders”, they want to go for one big universe which will host all these 5 or 6 component universes so that the users can do some cross functional queries also from WebI when there is a requirement. It’s the pretext.

I would like to make them aware about the the pros and cons of having one big honking universe Vs 5 or 6 component universes linked with a host universe. I know why is it not good to have very big universes. The same way, I want to know what are the usual issues with linked universe. I have seen the comments of many members of this group saying they don’t like that approach. I am trying to get to the details. Thanks,

Sreeni

sreeni B (BOB member since 2003-06-19)

#10

If the reports are that complex, WebI is not the right answer anyway.

Steve Krandel :us: (BOB member since 2002-06-25)

#11

Hi Sreeni,
I have worked a lot with linked univers.I had a set up in which i had taken out all the dimensions into a single univrse and all the other universes with there individual facts were linked to this .
Some points i have learnt about linked universs.
1)Its a major bother moving them from one repository to another.Its possible but there is long about way of doing it.
2)Once you link a universe the the order in which the object appear at the time of linking is set.Say you change in the order in ur core universe but then this is not reflected in the derived universe.Same thing with adding new objects,they always get added at the end of the class.Can be bothersome if you have to change a hierarchy.
3)But the good thing is maintenance becomes very easy.You have to make changes in one universe only and they get reflected across all universes,in my case as we had taken all dimensions,so all changes went to one universe and consistency was maintained.
4)Another thing is using multiple data providers.In this the users have to be educated about linking dimension but is good in the long run as they get used to the basic concepts faster.
5)Compatablility issues between different grain objects also appears.
hope this helps.Will add more as and when i remember them
abhi

abhi_ruiet (BOB member since 2003-01-20)

#12

Hi Abhi,

Appreciate if you could explain more about the above with practical issues.

Thanks in adv.

suntra (BOB member since 2003-02-06)

#13

Hi suntra,
BO does not support moving linked universes across different repositories.
Because once u move a linked universe from one repository to another and open the dervied universe ,you will get an error message saying that unable to find the linked universe.
The reason for that is that the linking is based on the repository id of the linked universe as the basic requirement for linking a universe is that it shud have been exported once to the universe.Hence when you move the linked universe as well as the derived universe to a new repository they are both given new repository id’s.Thus when u open the derived universe you get the error message saying that unable to find the linked universe as BO is looking for the old repository id.
If you want more clarification and the way to get it done you can get back to me.
bye
abhi

abhi_ruiet (BOB member since 2003-01-20)

#14

Guys.

Having read all the comments on Universe Linking, I have come to the conclusion that it is a widely mis-trusted concept :frowning:

I am a General Supervisor who maintains multiple universes: a copy of our live database, a warehouse (backed up at month end) and a UAT Universe to name but a few. Needless to say, I really do not want to have to maintain all these universes (with regard to object creation etc.,)

I was wondering if anyone had an alternative solution to Universe Linking - or if all avenues had been discussed in the past and there is just no excuse for laziness?? :mrgreen: :mrgreen: :mrgreen:

IAIN75 (BOB member since 2004-03-24)

#15

Let me put my two cents in … :mrgreen:

Couple projects back I took a “Linked” Universe approach. It worked pretty well. In a nutshell here is what I did and the benefits…

I had a classic Star Schema Data warehouse… Dimension Tables and multiple Grain Fact tables. The fact tables all shared the common Dimensions…so I cobbled all the dimensions…e.g. Customer, Product, Time, blah blah blah… and put them into the master Dimension Universe…

Then I created derived universes for each grain fact table… which also had some aggregate awareness…but that is another ball of wax…These derived universes then linked back to the common dimension universe. In total I had like 10 derived universes and one Dimension universe.

This design made maintenance pretty easy… so when I introduced a new object into the dimension universe…it automatically linked to the derived fact table universes. e.g. Had to add a new time element… thus is was able to be used for data provider automatic linking across the 9~10 derived universes in my different reports.

Now maintenance from development to test to production was tough … but the trick was updating the linking when moving the code from one universe domain to another. Just had to know the trick. The success of this universe design realy fell upon my database design… made Universe Linking and aggregate awareness real handy and a workable solution for the client.

-Dave

David Smith :us: (BOB member since 2002-07-10)

#16

Dave,
I have the same situation as yours. I have around 6-7 derived universes linked to a master universe which has the common dimensions. I am having trouble moving these universe from TEST to PROD. First time move works fine. But there after I am getting the message that the universe already exists so please change the name.
Your help is greatly appreciated.

Thanks in Advance,
Sandeep.

chinnu (BOB member since 2002-11-22)

#17

Sandeep,
Couple things that I remember were critical were:

1> When you move the Derived Universe from TEST to PROD, and then open in designer the derived universe it still points back to the TEST source master Universe… so You’ll get errors… So You need to relink to the master universe in prodcution.

This is done in Designer in the derived universe, select the file menu , select parameters, links tab, select the linked universe and hit change source. Your metedata in the Description field should give you a hint that it is pointing toward the incorrect Universe… Assuming that you code in the metadata a Description like “This is a TEST Universe”?!?

So with that in mind you also need to make sure you first move from test to prod the master univese first… assuming that you are promotiong code in both the master and derived universe…

2> MY COMMENT I’m a little fuzzy about this advise… dont have my notes handy here at my client site… so when I get home I will verify…END COMMENT

Anyhow… The second piece of advice is that when you move from TEST TO PROD I think I remember having to delete the copy of the master and derived universe in prod first… then move the new TEST version over… This gets rid of the message that the universe already exists so change the name. I have a document that I did for a client that details all these steps to promote the code with a linked universe… but I dont have it handy right now. But I will review it and update this post when I get a chance.

Also…Make sure you backup and make copies of any universe code before you delete anything…do it in your version control software or just make a copy on your local hard drive.

Hope this helps.

David Smith :us: (BOB member since 2002-07-10)

#18

thanks for the info which u have given.
we r having problem in exporting linked unv .

i have developed in dev domain and exported it to devlopment domain with secured connection.

when my manager tried to open it in same repository and same domain it is giving error
saying that unable to find the linked universe .

even we tried importing the universe from designer/supervisor
but the unverses were not shown in that domain to import.

i have sucessfully exported both the derived and linked unv to dev domain

can u please help us in this and the way to get it done.

thanks in advance

mailanuv (BOB member since 2005-11-27)

#19

Are the universes new? Has your General Supervisor assigned them to you and your supervisor? It sounds like it may just be a simple security issue.

djenkins (BOB member since 2002-12-12)

#20

I still need a little clarification on knowing “the trick” to link when migrating from one universe domain to the next.
What is the “trick” ? When you migrate derived universes, you have to re-create the links as id of the universe changes in the new universe. Right?

anushajq (BOB member since 2005-02-22)