Client/Server Application Components

Faculty:
CS&IT
Department:
Information Technology
Subject:
Data Communication & Computer Network
Assignment:
Client/Server Application components
Lecturer:
Abdijabar Awais Osman

Group Names ID Number Title
Abdisamad Yusuf Omar 17386 5.1 Introduction
5.2 Technologies for
Client/Server Application
5.3 Service of a Client/Server
Application
Sharmake Ahmed Mohamed 17564 5.4 Categories of
Client/Server Applications
5.5 Client Services
5.5.1 Inter Process
Communication
5.5.2 Remote Services
5.5.3 Window Services
Ilham Abubakar Hirabe 18027 Client Services
5.5.4 Dynamic Data Exchange
(DDE)
5.5.5 Object Linking and
Embedding (OLE)
5.5.6 Common Object Request
Broker Architecture (CORBA)
Mohamed Hassan Mohamed 17515 Client Services
5.5.7 Print/Fax Services
5.5.8 Database Services
5.6 Server Services
Abshir Muse Hussein 17460 5.7 Client/Server
Application: Connectivity
5.7.1 Role and Mechanism of
Middleware
Abdihakin Hassan Mohamud 17844 5.8 Client/Server
Application: Layered
Architecture
5.8.1 Design Approach
5.8.2 Interface in Three Layers
Chapter Summary
Group B: CLIENT/SERVER APPLICATION COMPONENTS

5.1 INTRODUCTION
A Client/Server application stand at a new threshold brought on by the exponential increase
Of low cost bandwidth on Wide Area Networks, for example, the Internet and CompuServe;
And shows a new generation of network enabled, multi-threaded desktop operating systems,
Some key technologies are needed at the Client/Server
application level to make all this happen, including:
 Rich transaction processing: In addition to supporting
the venerable flat transaction, the new environment
requires nested transactions that can span across multiple
servers, long-lived transactions that execute over long
periods of time as they travel from server to server, and queued transactions that can be
used in secure business-to-business dealings. Most nodes on the network should be able
to participate in a secured transaction; super server nodes will handle the massive
transaction loads.
 Roaming agents: The new environment will be populated with electronic agents of all
types. Consumers will have personal agents that look after their interests; businesses will
deploy agents to sell their wares on the network; and sniffer agents will be sitting on the
network, at all times, collecting information to do system management or simply looking
for trends. Agent technology includes cross-platform scripting engines, workflow, and
Java-like mobile code environments that allow agents to live on any machine on the
network.
 Rich data management: This includes active multimedia compound documents that you
can move, store, view, and edit in-place anywhere on the network. Again, most nodes on
the network should provide compound document technology — for example, OLE or
OpenDoc – for doing mobile document management. Of course, this environment must
also be able to support existing record-based structured data including SQL databases.
 Intelligent self-managing entities: With the introduction of new multi-threaded, high-
volume, network-ready desktop operating systems; we anticipate a world where millions
5.2
TECHNOLOGIES
FOR
CLIENT/SERVER
APPLICATION

of machines can be both clients and servers. However, we can’t afford to ship a system
administrator with every $99 operating system. To avoid doing this, we need distributed
software that knows how to manage and configure itself and protect itself against threats.
 Intelligent middleware: The distributed environment must provide the semblance of a
single-system-image across potentially millions of hybrid Client/Server machines.
The middleware must create this Houdini-sized illusion by making all servers on the
global network appear to behave like a single computer system. Users and programs
should be able to dynamically join and leave the network, and then discover each other.
You should be able to use the same naming conventions to locate any resource on the
network.
In this section, the discussion is about most widely used five
types of Client/Server applications. In no way is this meant to
cover all Client/Server applications available today. The truth,
there is no agreement within the computer industry as to what
constitutes Client/Server and therefore, what one expect or
vendor may claim to be Client/Server may not necessarily fit the
definition of others.
In general, Client/Server is a system. It is not just hardware or software. It is not necessarily a
program that comes in a box to be installed onto your computer’s hard drive (although many
software manufacturers are seeing the potential market for Client/Server products, and therefore
are anxious to develop and sell such programs). Client/Server is a conglomeration of computer
equipment, infrastructure, and software programs working together to accomplish computing
tasks which enable their users to be more efficient and productive. Client/Server applications can
be distinguished by the nature of the service or type of solutions they provide. Among them five
common types of solutions are as given below.
5.3 SERVICE
OF A
CLIENT/SER
VER
APPLICATIO
N

 File sharing.
 Database centered systems.
 Groupware.
 Transactional processing.
 Distributed objects.
• File sharing: File sharing is Client/Server in its most primitive form. It is the earliest form of
computing over a network. Some purists would deny that file sharing is Client/Server
technology. In file sharing, a client computer simply sends a request for a file or records to a file
server. The server, in turn, searches its database and fills the request. Usually, in a file sharing
environment, the users of the information have little need for control over the data or rarely have
to make modifications to the files or records. File sharing is ideal for organizations that have
shared repositories of documents, images, large data objects, read-only files, etc.
• Database centered systems: The most common use of Client/Server technology is to provide
access to a commonly shared database to users (clients) on a network.
This differs from simple file sharing in that a database centered system not only allows clients to
request data and data-related services, but it also enables them to modify the information on file
in the database. In such systems, the database server not only houses the database itself; it helps
to manage the data by providing secured access and access by multiple users at the same time.
Database-centered systems utilize SQL, a simple computer language which enables data request
and fulfillment messages to be understood by both clients and servers. Database-centered
Client/Server applications generally fall into one of two categories:
(i) Decision-Support Systems (DSS) or
(ii) Online Transaction Processing (OLTP).
Both provide data on request but differ in the kinds of information needs they fulfill.
(i) Decision-support systems (DSS): Decision-Support Systems (DSS) are used when clients on
the system frequently do analysis of the data or use the data to create reports and other
documents. DSS provides a “snapshot” of data at a particular point in time. Typically, DSS
might be utilized for a library catalog,
WWW pages, or patient records in a doctor’s office.

(ii) Online transaction processing: Online Transaction Processing (OLTP) provides current,
up-to-the-minute information reflecting changes and continuous updates.
Users of an OLTP system typically require mission-critical applications that perform data access
functions and other transactions with a one to two seconds response time.
Airline reservations systems, point-of-sale tracking systems (i.e., “cash registers” in large
department stores or super markets), and a stockbroker’s workstation are
OLTP applications.
• Groupware: Groupware brings together five basic technologies multimedia document
management, workflow, scheduling, conferencing, and electronic mail, in order to facilitate work
activities.
One author defines groupware as “software that supports creation, flow, and tracking of non-
structured information in direct support of collaborative group activity.” Groupware removes
control over documents from the server and distributes it over a network, thus enabling
collaboration on specific tasks and projects. The collaborative activity is virtually concurrent
meaning that clients on the network, wherever they may be, can contribute, produce, and modify
documents, and in the end, using the management and tracking features, synchronizes everything
and produces a collective group product.
Multimedia Document Managements (MMDM)
With groupware, clients can have access to documents and images as needed. Multimedia
document management (MMDM) allows them to take those documents and modify them.
The modifications can take place in real time with several clients making changes and
modifications simultaneously, or they can be modified, stored on the server for review or future
action by other clients. MMDM is, in essence, an electronic filing cabinet that holds documents
in the form of text, images, graphics, voice clips, video, and other media.
• Transactional Processing
To create truly effective Client/Server solutions, the various components within the system (the
application software, the network operating system, utilities, and other programs) need to work
together in unison. If infrastructure and software which enable Client/Server computing are
musicians in a symphony, transaction processing would be the conductor.