1. Software System for Business Enterprise
Large number of users must be supported
Powerful computers to store data, not to be loadedd with additional application functionality
Users must be able to access entire system
Client PCs must provide only GUI
Three-tier architecture, e.g. SAP/R3
Wine Lover (Wine Cellar Management System)
Small amount of data (Wine cellar containing 300 bottles)
For personal use (Single user)
Single user DBMS, e.g. Access

2. Library Information System
Old fashioned client computers(not much computing power)
Literature search on library database (short queries)
Two-tier architecture, Clients just provide GUI, Fat server,
Sym-multiple server architecture would be ok but not necessary,
Monolithic multithreaded server is also ok (short queries),
Asym-multiple server architecture seems best
(few users, short queries, management of queue is easy).
Banking Application
Money
Huge amount of daily data has to be stored safely and efficiently
High performance xaction processing
High Aavailability
Mainframe computer, multiuser DBMS,
several processes can run in parallel, all services are centrally defined.

3. AP Client 1 Log Writer Process Server Process 1 DA 1 CL
Database Buffer CL
Betriebssystem 1
Betriebssystem n
Netzwerk

4. Line 1 to 9 AP Client 1 our client Log Writer Process Server Process 1
DA 1
our DA
Database Buffer CL CL
Betriebssystem 1
Betriebssystem n
Netzwerk
username:“*****“ password:“********“
db_string:“STUD“
oldterm: newterm: ident:
Line 1 to 9

5. Line 10 AP Client 1 our client Log Writer Process Server Process 1
Our Server Process
CONNECT...
DA 1
our DA
Database Buffer CL CL
Betriebssystem 1
Betriebssystem n
Netzwerk
:username:“*****“ :password:“********“
:db_string:“STUD“
username:“*****“ password:“********“
db_string:“STUD“
oldterm: newterm: ident:
Line 10

6. our x-locked DB page // line 12AP
Client 1
our client
Log Writer Process
Server Process 1
Our Server Process
SELECT...
DA 1
our DA
Database Buffer CL CL
our x-locked DB page // line 12
Betriebssystem 1
Betriebssystem n
Netzwerk
:username:“*****“ :password:“********“
:db_string:“STUD“
:oldterm:“ISK…“ //line 12
:ident: //line 12
username:“*****“ password:“********“
db_string:“STUD“
oldterm:“ISK…“ //line 11 newterm: ident: //line 11
Line 11 to 12

7. our x-locked DB page „ISK…Spass“AP
Client 1
our client
Log Writer Process
Server Process 1
Our Server Process
UPDATE...
DA 1
our DA
Database Buffer CL CL
our x-locked DB page „ISK…Spass“
Betriebssystem 1
Betriebssystem n
Netzwerk
:username:“*****“ :password:“********“
:db_string:“STUD“
:oldterm:“ISK…“
:newterm:“…doof“ //line 14
:ident: //result!
username:“*****“ password:“********“
db_string:“STUD“
oldterm:“ISK…“ newterm:“…doof“ //line 13 ident: //result!
Line 13 to 14

8. our x-locked DB page „ISK…doof“AP
Client 1
our client
Log Writer Process
Server Process 1
Our Server Process
Commit!
COMMIT //line 15
DA 1
our DA
Database Buffer CL CL
our x-locked DB page „ISK…doof“
Betriebssystem 1
Betriebssystem n
Netzwerk
:username:“*****“ :password:“********“
:db_string:“STUD“
:oldterm:“ISK…“
:newterm:“…doof“
:ident:1
username:“*****“ password:“********“
db_string:“STUD“
oldterm:“ISK…“ newterm:“…doof“ ident:1
Line 15