RPDbeginner
Presentation Layer Design & Subject Areas
Explain best practices for organizing the Presentation layer into intuitive subject areas, folders, and columns for business users.
The presentation layer is what users actually see. A perfect BMM model behind a badly organised presentation layer is a BI tool nobody uses.
It's the difference between a well-organized supermarket with clear aisle signs ("Dairy," "Produce," "Bakery") versus a warehouse where everything is stacked by arrival date — the same products exist in both, but only one lets a shopper find what they need without help.
Key Concepts
1
Organise by business question, not by model.
bad: one subject area mirroring the BMM, every logical table
exposed, named as the modeller named them
good: "Sales", "Inventory", "HR Headcount" -- each holding what
somebody answering that kind of question needs2
One BMM can feed several subject areas, and a subject area can expose part of the model. Those two
freedoms are the whole reason the layer exists.
3
Inside a subject area, folders group columns the way users think.
Sales
Time Year, Quarter, Month, Date
Customer Name, Segment, Region
Product Name, Category, Brand
Sales Facts Revenue, Units, Margin, Margin %4
Dimensions first, facts last, is the convention — because that is the order people build an analysis in.
5
Rename everything into business language. CUST_SEGMENT_CD becomes "Customer Segment". The user should
never see a column name that came from a database.
CUST_SEGMENT_CD
6
Hide what they should not use. Keys, technical columns, staging attributes and anything only present to
make the model work. Every column exposed is a column somebody will put in a report and ask about.
7
The renaming trap. Deleting a presentation column and creating a replacement breaks every saved analysis
using it. Renaming it in place does not — OBIEE tracks the object rather than the name.
8
So a tidy-up done by deleting and re-adding costs the business every report they had built, which is a
mistake made once.
9
Descriptions are worth writing. A presentation column's description appears as a tooltip. "Revenue"
against "Revenue: net of discounts and returns, excluding tax, in reporting currency" is the difference
between two people producing the same number and two people arguing about it.
10
The test of a good layer. A business analyst who has not been trained builds a correct report without
asking anybody what a column means. If they need a data dictionary, the layer is not finished.
11
What the interviewer is probing.1. "What makes a good subject area?" Probing: the user angle. Stalls: "All the columns."
Moves up: business names, a sensible folder structure, no technical keys, and only what that
audience needs — an exposed everything is unusable.
12
2. "Should one subject area cover everything?" Probing: judgement. Stalls: "Yes." *Moves
up:* no — separate ones by business process, since combining unrelated facts in one subject area
invites meaningless cross-joins.
13
3. "How do you handle two audiences needing different views?" Probing: the technique.
Stalls: "One for all." Moves up: separate presentation subject areas over the same business
model, with permissions on each.
14
4. "What is the renaming discipline?" Probing: the practical angle. Stalls: "Rename freely."
Moves up: renaming a presentation column after it is used breaks saved analyses unless the rename
history is preserved.