BY: GROUP 6

A system which its basic specifications and design

correctness arguments have ability to meet its time

constraints.

Correctness depend on both logical correctness

and timeliness of its actions

Deal with temporal data

Response must be produced within a specific

time , otherwise data become out dated

A database system which uses real time processing to handle workloads whose state isconstantly changing.

Timely execution of transactions with the ACID properties.

Operations execute with predictable response , and with application-acceptable levels of logical and temporal consistency of data

Transaction :sequence of read and write

operations.

ACID properties:

Atomicity : transaction is done either completely or not at all

Consistency :transactions are executed in a given sequence

Isolation : actions of a transaction are not visible to any other transactions until it is committed

Durability : transactions of a database are permanent

Timing constraint associated with transactions with deadlines.

Timing constraint types: Hard : must execute before deadline Firm: abort if not completed by deadline Soft: diminished value if completed after deadline

As the complexity of Real Time Systems going up ,

the amount of transactions to be handled by real

time systems increases.

Conventional databases do not support timing and

temporal requirements.

Design objectives of

conventional databases

are not appropriate

for real time applications.

Soft real time database systemsThese are databases used in non-critical real time systems where missed transactions only degrade system quality.

E.g. databases in banking, stock market, and airline reservation systems

Hard real time database systemsThese are databases used in critical real-time systems used in places such as nuclear power plants.

E.g. databases in early warning systems, Emergency alarm systems, MDARTS

MDARTS stands for multiprocessor database architecture for real time systems. This is used mainly in control applications, such as controlling machine tools and robots etc

Has The ACID properties

Has timing constraints

Timeliness is more important than correctness

Queries to the database should have soft or hard deadlines

Data returned must have both absolute consistency and relative consistency

Deal with temporal data that become outdated after a certain time

Not all data are permanent but temporal, e.g., sensor data or stock prices

Both real-time scheduling & database technologies can be applied to real-time data management

Data items reflects the state of environment.

Data from sensors. e.g. temperature,

humidity, pressure etc

Derived data. e.g. rate of reaction

Input to actuators. e.g. amount of chemical

Archival data. e.g. history of(interaction

with) environment

Static data(as in conventional data bases)

Real time databases have to deal with temporal

data compared to static data as the case of

traditional databases.

Unlike traditional databases , timing constraints

are associated with the different operations carried

out on real time databases.

Main objective of conventional databases is to

provide fast “average” responce.But RTDBs focus

on average transactions miss their deadlines(also

the cost incurred for late transactions).

More efficient way of

handling large amount

of data.

Specification of time

constraints.

Improved overall

timeliness.

Reduce development

cost.

Avoid redundant data.

Dealing with time

constraints and violations.

Get the maximum benefit

from results which generate

from actions completed in

time.

Minimize the damage which

occurs from actions that

delayed or not executed in

time.

Telecommunication systems

Routers and network management systems

Telephone switching systems

Control systems

Automatic tracking and object positioning

Engine control in automobiles

Multimedia servers for real-time streaming

E-commerce and e-business

Stock market: program stock trading

Financial services: e.g. credit card transactions

Web based data services

Presented by:

Nipuna Hewamaddumage

Thilina

Dinushika Rathnayaka

Nilshani Jayakodi

Yana Yonitha