2. Agenda Introduction Logical Layers Presentation layer
Application layer Data layer Client / Server Models Distributed
presentation Remote presentation Distributed logic Remote data
Distributed data
3. Introduction The Client-Server model is the most prevalent
model for distributed computing protocols. It is the basis of all
distributed computing paradigms at a higher level of abstraction.
It is service-oriented, and employs a request- response
protocol.
4. Introduction Client A client is an individual users computer
or a user application that does a certain amount of processing on
its own. It also sends and receives requests to and from one or
more servers for other processing and/or data. Server A server
consists of one or more computers that receive and process requests
from one or more client machines. A server is typically designed
with some redundancy in power, network, computing and file
storage.
5. The Client / Server Model A server process, running on a
server host, provides access to a service. A client process,
running on a client host, accesses the service via the server
process. The interaction of the process proceeds according to a
protocol. An application based on the client-server model is a
client-server application.
6. Logical Layers In general, application software can be
divided into 3 logical layers: Presentation layer Application layer
Data layer
7. Presentation Layer Presentation layer is responsible for
displaying the information and interacting with the user . It must
make the information available in a suitable form to the user and
must respond appropriately to input from the user.
8. Application Layer Application layer processes commands,
makes logical decisions, performs calculations, and coordinates the
application It also moves and processes data between the
presentation layer and data layer
9. Data Layer Data layer refers to the management of underlying
databases It is responsible for storing and retrieving the data
according to the requirements of the application layer.
10. Client Server Models Distributed presentation Remote
presentation Distributed logic Remote data Distributed data
11. Distributed Presentation Only presentation management
function shared between client and server everything else remains
on the server Dummy terminals GUI placed in front of existing
character based interface, E.g. Windows 3.1.
12. Presentation Application Layer Data Layer LayerClient Side
Server Side
13. Remote presentation Presentation manager entirely on client
Application layer, data layer and data manager on server Web
applications where clients are Web browsers, Unix through
Putty
14. Presentation Application Layer Data LayerLayerClient Side
Server Side
15. Distributed Logic Application is split into presentation
layer and data layer component All presentation management
activities on client All data management activities on the
server
16. Presentation Application Layer Data LayerLayer Client Side
Server Side
17. Remote Data Database manager resides on server Presentation
management and data logic reside on client Typical of client/server
DBMSs (DB2, Oracle, Informix, etc.)
18. Presentation Application Layer Data LayerLayer Client Side
Server Side
19. Distributed Data Portions of the database reside on client
Portions of the database reside on server DBMS manages
communication involved Limited implementation of full-fledged DDBMS
functionality
20. Presentation Application Layer Data LayerLayer Client Side
Server Side
