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As it was written above the OBIEE consists of 8 interdependent components. Each of them is described in detail below:
Oracle BI Server is a high-impact query, reporting and analysis server that provides services to the other components of the Business Intelligence Suite such as Answers, Dashboards, Data Mining, Reporting, and Analytic Applications. The Oracle BI Server uses ODBC 2.0 //Open Database Connectivity provides a standard software API method for using database management systems// and JDBC //Java Database Connectivity is an API for the Java programming language that defines how a client may access a database// interfaces to shows its services. The services of the BI server have two primary functions. Firstly, they compile incoming query requests into an executable code and then execute the code. Clients of the BI Server work with a logical data /simplified logical SQL/ independent of the data sources, and they submit them to the BI server. The server translates the data to some combination of physical SQL and sends them to the back-end databases. Server administration functions include facilities such as monitoring, statistics logging, cancellation, session and query management, and others. The administration of the server is managed internally with using standard protocols e.g. AD //Active Directory is an implementation of LDAP services// or LDAP//The Lightweight Directory Access Protocol is an application protocol for querying and modifying directory services running over TCP/IP//.
Query compilation has five phases:
The multi-functional parser accepts the full ANSI SQL92 syntax as its input and its main function is to generate a parse tree//It is a tree data structure that represents the syntactic structure of a string // as its output.
A component of the logical request generation takes the parse tree and makes of it a logical request tree that describes the precise semantics of the requested data in simplified SQL.
The navigation is one of the major phases. The navigator processes the logical request tree to an initial physical execution plan as its output, and it uses a knowledge of content to eliminate the traditional multi-database joins.
The rewrite is also a very important phase and its output is also the execution plan.This phase is responsible for distributed relational query optimization and suitable native SQL generation. The phase of rewriting covers:
A fed for the code generation phase is a native physical execution plan as its input. Code generation produces native query processing language directives to communicate with heterogeneous or remote databases/i.e., physical SQL generation/.It also produces a code for any remaining query processing that has not been function shipped to remote databases. Parallel execution directives are inserted in this code and it is used for the Analytics execution engine.