So far, we have discussed the basic concepts of Business Intelligence; however the whole lot of terminologies and concepts might be confusing for the end users, and SAP`s goal is to make BI tools intuitive and easy to use by the end users. In this post, we will talk about some ground work for the set of BI tools SAP offers, and we will summarize the set of tools offered by SAP but we will discuss them in details in future posts.
The Semantic Layer
The Semantic layer is an abstract representation of the business entities (dimensions, measures ... ) enriched with semantics closely related to the business terms so that a mapping is done between the deep entities and the business terms.
- there is a connection to many data sources; the layer is agnostic to data-sources
- it empowers Business users with the autonomy they need to access, analyze, enrich and share information freely and securely using familiar business terms
- It provides a common user experience, best access method for each specific data source and provide access to various data sources, for all front-ends
- users manipulate business terms, they need not to care about data source related technical details
- No ETL , no new data source (use best features for each DB, relational -> SQL, Multidimensional -> MDX .. etc)
- It models data in a "Shared object model"
The collection of abstractions is called a Universe, so in SAP a Universe is a business representation of organization's data that helps end users access data autonomously using common business terms and it isolates business users from the technical details of the databases where source data is stored. Universes are made up of objects and classes that are mapped to the source data in the database and accessed through queries and reports. Users retrieve data using descriptive terms used in the business environment with the company's business terminology. A Universe is a semantic layer that maps complex data into descriptive business terms used across the organization, such as product, customer, region, revenue, margin or costs.
Benefits of using Universes
The main benefits that come with Universes are:
- Separate business and IT responsibilities - only the metadata modeler (universe designer) needs to know SQL and understand the complex database structure.
- The Universe Designer application allows users to create universes in a simple, intuitive graphical environment.
- Data security - data exposed by the universe can be limited to a specific group of users.
- Maintenance of the universe is easy
- End-users can use a simple interface to create reports and analysis and work with consistent business terminology.
- The design and scope of a universe schema should always derive from the end-user requirements as it provides an interface for them to run queries against a source database, create reports and analyze data.
It is absolutely necessary to understand the underlying data prior to starting the universe development process. This might be a data warehouse model (Star, Snowflake or Fact Constellation schema), Data Mart or a production OLTP source system. Every universe contains the following two structures that represent the source data:
- Class - is a logical grouping of objects within a universe which represents a category of objects, indicates the category of the contained objects. Classes can be divided hierarchically into subclasses and represented as folders on a tree hierarchy in the universe pane.
- Object - is a component named with a business naming standard that maps to data in the database or calls a database function or uses other objects from within the same universe. Each objects can be qualified as a Dimension, a Detail or a Measure. Objects represent meaningful entities, facts or calculations used by the business users.
The universe is built using: (Information Design Tool, formerly known as Designer Tool)
- Connectivity: specify how to connect to the data source, SSO, what is the server what is the DB name ... etc.
- Data Foundation: if it is relational, it is the schema of the database we want to use, generally a subset of the DB
- Business layer: the Business representation of the data, it contains the objects, we define what we displayed at the end, for example combine first and last name into full name (define dimensions and measures), change dimensions labels into more understandable format, aggregations can be defined here but they are generally automatically done by Webi on the fly
On top of the universe is the information engine, takes the universe data and exposes it as sdk for other applications, consists of:
- Query technique: translates the list of object into the sql, mdx ... etc (get data back)
- Report data (make calculations over the data)
- Calculator
Federated table: virtual data table that doesn't exist in any database, it is the best representation of your data you can think of .. then ill map these tables with the ones i get from my database -> fact table
Shared Objects
The main idea behind proposing the Shared Objects (SO) was due to the fact that SAP`s BI products were very complex, and there was no way to reuse already created content, so SO is a way to describe BI content according to the different aspects that constitute the BI content. It consists mainly of 6 layers, each tool will that wants to expose a SO from a BI element will have to determine which layer it exposes and which layer it consumes.SO is a suggestion to facilitate consumption of heterogeneous BO content but is not a completely agnostic representation of BI content. 
notes:
- It looks like the SO concept is discontinued now and replaced with a lightweight version.
- A Universe can be referred to sometimes as data foundation model
