CH 3 - Database Architecture Flashcards
draw the ANSI-SPARC 3 Level architecture , teleprocessing topolgy, file server topology , client server architectures and topolgies.,
What are the objectives of the Three-Level Architecture in databases?
-provides data independence
- ensures all users can acces the same data
- hide physical storage details from users
-ensures the internal database structure is unaffected by changes in physical storage.
-ensure s how data is stored and retrieved at the internal level.
What is Logical Data Independence?
refers to the immunity of external schemas to changes in the conceptual schema.
Changes to the conceptual schema (e.g., adding or removing entities) should not require changes to the external schema or application programs.
The ANSI SPARC (1975) architecture specifies 3 levels
External – user views of the data
Conceptual – the ‘data model’ view of the data
Internal – how the data is physically stored
What is Physical Data Independence?
refers to the immunity of the conceptual schema to changes in the internal schema.
Changes to the internal schema (e.g., different file organizations, storage structures, or devices) should not require changes to the conceptual or external schemas.
Describe the Teleprocessing (traditional architecture) architecture in a multi-user DBMS.
there is a single mainframe with multiple terminals attached. The DBMS and the database both reside in the mainframe.
What is the File-server architecture in a multi-user DBMS?
A file-server is connected to several workstations across a network.
The database resides on the file-server.
The DBMS and applications run on each workstation.
What are the disadvantages of the File-server architecture?
Significant network traffic.
A copy of the DBMS is required on each workstation.
Concurrency, recovery, and integrity control are more complex.
What are the responsibilities of the client in a Client-Server architecture?
Manages the user interface.
Accepts and checks the syntax of user input.
Generates database requests and transmits them to the server.
Passes the results back to the user.
What are the responsibilities of the server in a Client-Server architecture?
Accepts and processes requests from clients.
Checks authorization.
Ensures integrity constraints are not violated.
Performs query processing.
Maintains the system catalog.
Provides concurrent access and recovery control.
What are the four major components of Client-Server architectures?
The database.
Transaction logic.
Business and data application logic.
User interface.
Describe the Two-Tier Client-Server architecture.
First Tier (Client): Provides the presentation tier (interface) and business logic.
Second Tier (Database Server): Handles server-side validation and database access.
Describe the Three-Tier Client-Server architecture.
Client: Manages the user interface.
Application Server: Handles business logic and data processing logic.
Database Server: Performs data validation and database access.
Describe the N-Tier Client-Server architecture.
The architecture includes multiple layers such as:
Client: Manages user interface. Web Server: Handles web-based requests. Application Server: Manages business logic and data processing. Database Server: Performs data validation and database access.
What are the different Client-Server Topologies?
Single Client, Single Server
Multiple Clients, Single Server
Multiple Clients, Multiple Servers
