1. On-Line Transaction Processing

2. On-Line Transaction Processing
On-Line Processing
Immediate processing as the events occur
Show the current state of the business
Transaction
Unit of computations having ACID properties
ACID properties
Atomicity
Consistency
Isolation
Durability

3. TP (transaction processing) Systems
TP systems typically involve
Operating systems
Database management systems
Data communications
Programming languages
Application development
TP systems
A set of software modules that ease and automate application programming, execution, and administration for online TP applications
Best TP systems require the least amount of code to be written for application development !
Transaction processing is a prerequisite for mastering the complexity of distributed, heterogeneous system (J.Gray)

4. Transaction Processing Services
( in addition to, but incooperation with a DB system )
Manage Heterogeneity
Presentation Service
Control Communication
Context Management
Terminal Management
Program Management
Load Balancing
Start / Restart

5. User’s / Programmer’s Views of a TP System (1/2)
Each transaction is an independent unit of work that executes once and produces permanent result
Transaction : the execution of a program that
Gets a request from a terminal
Performs the request by accessing a database and executing application programs
Returns a response to the terminal

6. User’s / Programmer’s Views of a TP System (2/2)
A simple TP application consists of
A form and menu definitions
Input data validation
Mapping of request types into application program names
Application programs to execute requests
User
Shared
data
Transaction
Application
Program
File Manager
( or DBMS )
Read,Write
Read …
Start-trans
Commit-trans
Abort-trans
Write
User

7. Implementer’s (system’s) View of a TP System (1/2)
A collection of various modules and resources
On-line : user waits for response (seconds, not days)
The bleeding edge
100,000 terminals
1,000 disks
3,000 transactions per second

8. Implementer’s (system’s) View of a TP System (2/2)
TP SUB SYSTEM
User
Application
Program
Start_trans, Commit_trans, Abort_trans …
User
Transaction
Manager
Shared
data
Access
Method
Undo, Redo
Recovery
Manager
Read_log
Write_log
Log
Scheduler
(Lock Manager)
File Manager
( or DBMS )
Write_log
Commit Manager

9. OLTP Applications Communications Travel Finance Manufacturing
Setting up and billing for telephone calls, electronic mail, etc
Travel
Reservations and billing for airlines, cars, hotels, etc
Finance
Banking, stock trading, ATM, POS (point of sale)
Manufacturing
Order entry, job and inventory planning and scheduling, accounting
Processing Control
Control of factories, warehouses, plants, etc

10. Characteristics of OLTP Applications
Large number of simple and pre-defined transacrions
Predictable input
Huge terminal users concurrently
Fast response
Large shared databases

11. Terminal-User Requirements
High Performance
Measured in transactions per second
90% of transactions get 2 second response time !
High Availability
Can always run transactions (no downtime)
Atomicity
A virtual sequential transaction processor
Persistence
Never loses results of transactions

12. OLTP Monitor
Coordinates the flow of requests between terminals and application programs that perform transactions
Helps transaction application development
Administration and management of a TP system
Why TP Monitor ?
Performance
Ease of use

13. General Features of a TP Monitor
Transaction Execution
Scheduling
Load balancing
Failure isolation and recovery
System Administration
Authentication and authorization
Status monitoring
Performance tuning
Application Development
Forms editor / compiler
Client / Server development tools