from mainframe to cloud computing: a study of programming paradigms with the evolution of...

8/3/2019 From Mainframe to Cloud Computing: A Study of Programming Paradigms with the Evolution of Client-Server Archit

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From Mainframe to Cloud Computing: A Study ofProgramming Paradigms with the Evolution of Client-Server ArchitectureDost Muhammad Khan1, Nawaz Mohamudally2

1Assistant Professor, Department of Computer Science & IT, The Islamia University of Bahawalpur, Pakistan & PhD student,

School of Innovative Technologies & Engineering, University of Technology, Mauritius

2Associate Professor & Consultancy & Technology Transfer Centre, Manager, University of Technology, Mauritius (UTM)

Abstract

The rapid growth of distributed computing architectures createsnew approaches and opportunities for the software engineers todevelop new programming and structured information processingwithin an organization. New computing architectures provide the

technologies that enable organizations to reengineer theirbusiness processes and the dominant of these new architecturesfor information processing is client-server architectures. Theclient-server systems have evolved in conjunction with advances

in desk-top computing, new storage technologies, improvednetwork communications, and enhanced database technology.New development in client-server is allowing developing on-linebusiness systems with all the possible implementations that was

dream of a few years ago. The wide spread of networks, and inparticular, of networks connected to each other, as the Internet,has imposed new needs that required new paradigms and new

technologies. There are several network technologies availablewhich support user-level communication between processing ashared-memory. The client-server architectures are commonly

used in distributed environment due to optimization, modularly,no wastage of resources, reliability, availability and providesgraphical user interface aid. This paper presents a study of theprogramming paradigms with the evolution of client-server

architecture from mainframe to cloud computing.

Keywords:Agent-Oriented Programming, Object-OrientedProgramming, Lightweight Programming

1. Introduction

Client-Server architecture is an environment that satisfies

the business needs by appropriately allocating the

application processing between the client and the server

processors. The client requests services from the server;

the server processes the request and returns the result to

the client [1][2][3][4][5]. Figure 1 depicts typical client-server architecture.

Fig. 1 A Client-Server Architecture

One of the primary advantages of client-server model is

that as data storage needs grow without affecting clients

the way data is stored can be changed. The middle layer of

system is commonly referred to as the application server

can thus concentrate on centralizing business rule

processing. The client-server model is based on the idea

that one computer specializing in information presentation

displays the data stored and processed on a remote

machine. The client-server environment demands

graphical user interface and network communications. A

multi-user application is a slight variation on the typical

client-server application. The only difference is thatinformation passes from one client through the server to

other clients. On a typical client-server application,

information flows only from the client to the server and

then back. In an ideal environment, the server side of the

application handles all common processing and the client

side handles user-specific processing [3]. Strengths and

weaknesses of client-server architecture are discussed in

table 1.

JOURNAL OF COMPUTING, VOLUME 3, ISSUE 12, DECEMBER 2011, ISSN 2151-9617

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Table 1: Strengths and Weaknesses of Client-Server

Strengths Weaknesses

Highly interactive Fat Client

Graphical User Interface(GUI) aid

High Cost

Modularly Data interaction and business rulesmoved to client

The software process model applied for client-server

systems has closely resemblance with object-oriented

approaches. The developer has to describe objects,

database and application components. In the analysis and

design part of client-server systems, one has to use data-

flow, entity-relationship diagrams, structures charts and

other notations. The testing phase has to be modified by

examine network communication and the relationships

between software that resides both on client and server.

The client-server environment demands dedicated testing

tools that exercise the graphical user interface and the

network requirements for both client and server. The

components namely user interaction and presentation,

application component and database management aremajor parts of testing tools. To access many servers

applications from a client machine, through a common

interface, typically a browser is called a middleware,

which exists in all client-server systems, also known as

nervous system of client-server system. Middleware is

comprised of software elements that exists on both client

and server and includes elements of network operating

system as well as specialized application software that

supports database-specific applications, object-request

broker (ORB) standards group technologies,

communication management and other features that

facilitate the client-server connection. There are different

configurations for the distribution of software components,which are: Distribution presentation, Remote presentation,

Distributed logic, Remote data management and

Distributed databases. The common linking mechanisms

used to connect the various components of the client-

server architecture are: Pipes, Client-Server SQL

interaction, CORBA, RMI, ORB, DEC and many more.

These technologies allow the distribution of processing

across multiple processors and platforms [3].

The rest of the paper is organized as: Section 2 is an

overview of client-server architectures, namely, Code-on

Demand, Remote Procedure Call (RPC), Simple Network

Management Protocol (SNMP), Mobile Intelligent Agentand Cloud Computing, section 3 is about the results and

discussion whereas conclusion is drawn in section 4.

2. Overview of Client-Server Architectures

In this section we will discuss commonly used client-

server architectures such as Code-on Demand, Remote

Procedure Call (RPC), Simple Network Management

Protocol (SNMP), Mobile Intelligent Agent and Cloud

Computing.

2.1 Code-on Demand

The Code-on Demand paradigm allows nodes to request

programs from other nodes. An application of this

paradigm is the world wide web where browsers routinely

download code from remote sites. The idea is that a host

is only required to execute a program when it explicitly

demands the program. The best known example of such

functionality is that provided by the JAVA language, as

embedded within HTML. A user with a JAVA-

compatible browser can request HTML pages that contain

applets. These applets are downloaded along with all

other images, text, forms, etc. and once downloaded, are

executed on the users machine. The destination itself

initiates the transfer of the program code. The client

becomes thin, where most of the application resides and

runs on the server. It has no hard disk, it is a networkcomputer and easier to use and more reliable [6]. Figure 2

illustrates the working of code-on demand.

Fig. 2 Function of Code-on Demand Paradigm

The explanation of figure 2 is that client requests to a

server for a code, the server in response acknowledge the

clients request but instead of transferring the code, coderesides and runs on the server.

2.2 Remote Procedure Call (RPC)

A remote procedure call (RPC) also known as remote

method invocation (RMI) is a protocol that allows a

computer program running on one host to cause code to be

executed on another host without the programmer needing

to explicitly code for this. RPC is an easy and popular

paradigm for implementing the client-server model of

distributed computing. An RPC is initiated by the client;

sending a request message to the server, to execute a

certain procedure using arguments supplied, in response to

this message a result message is returned to the client. It is

based on extending the notion of conventional or local

procedure calling, so that the called procedure need not

exist in the same address space as the calling procedure.

The two processes may be on the same system, or they

may be on different systems with a network connecting

them. By using RPC, programmers of distributed

applications avoid the details of the interface with the





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network [7]. The function of Remote Procedure Call

(RPC) is illustrated in figure 3.

Fig. 3 Function of Remote Procedure Call (RPC) Paradigm

The explanation of figure 4 is that local procedures are

executed on Machine A; the remote procedure is actually

executed on Machine B. The program executing onMachine A will wait until Machine B has completed the

operation of the remote procedure and then continue with

its program logic. The remote procedure may have a return

value that continuing program may use immediately.

2.3 Simple Network Management Protocol (SNMP)

Simple Network Management protocol is a standard for

gathering statistical data about network traffic and the

behavior of network components. It is an application layer

protocol that sits above TCP/IP stack. It is a set of

protocols for managing complex networks. It enables

network administrators to manage network performance,find and solve network problems and plan for network

growth. It is a request/response type of protocol,

communicating management information between two

types of SNMP entities, one application is called

Manager, which issue queries to get information about

the status, configuration and performance of external

network devices and the second application is Agent,

which compliant devices; store data about themselves in

MIBs (Each agent in SNMP maintain a local database of

information relevant to network management is known as

the Management Information Base) and return this data to

the SNMP requesters [8][9]. The working of SNMP is

illustrated in figure 4.

Fig. 4 Function of SNMP Paradigm

The explanation of figure 4 is that the agent is software

that enables a device to respond to manager requests toview or update MIB data and send traps reporting

problems or significant events. It receives messages and

sends a response back. An Agent does not have to wait for

order to act, if a serious problem arises or a significant

event occurs, it sends a TRAP (a message that reports a

problem or a significant event) to the manager (software in

a network management station that enables the station to

send requests to view or update MIB variables, and to

receive traps from an agent). The Manager software which

is in the management station sends message to the Agent

and receives a trap and responses. It uses User Data

Protocol (UDP, a simple protocol enabling an application

to send individual message to other applications. Deliveryis not guaranteed, and messages need not be delivered in

the same order as they were sent) to carry its messages.

Finally, there is one application that enables end user to

control the manager software and view network

information [8][9].

2.4 Mobile Intelligent Agent

The term Mobile Intelligent Agent is derived from two

different disciplines, term agent is created from Artificial

Intelligence and code mobility is defined from the

distributed systems. An agent is an object which has

independent thread of control and can be initiated. Every

agent looks like an object, when an agent is implementedin its frame work, it works as an independent thread and

can be initiated from the server for execution according to

its execution plan. This makes an Agent different from an

ordinary object. Mobile intelligent agents are program that

can be dispatched from one computer and delivered to a

remote computer for execution. They are capable of

autonomous actions in pursuit of a specific goal.

Autonomy in agents implies that the software agent has





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the ability to perform its tasks without supervision, or at

least with minimum supervision, in which it will be a

semiautonomous software agent. Its autonomy

distinguishes it from general software programs. Mobile

agents are capable to perform concurrency, client-server

asynchrony, reduce network usage (bandwidth +

frequency), installation of client-specific interfaces and

dynamic interface upgrades. The client becomes smart,an Internet-connected device that allows the users local

applications to interact with server-based applications

through the use of web services. It supports work offline.

It can be deployed and updated in real time over the

network from a centralized server. It supports multiple

platforms and languages because of web services. It runs

on any device that has Internet connectivity, including

desktop, workstations, note books, PDAs and mobile

phones [10][11][12][13]. The basic working of a mobileagent is depicted in figure 5.

Fig. 5 Function of Mobile Intelligent Agent

The explanation of figure 5 is that Computer A and

Computer B are connected via a network. In step 1 a

mobile agent is going to be dispatched from Computer A

towards Computer B. In the mean time Computer A will

suspend its execution. Step 2 shows this mobile Agent is

now on network with its state and code. In step 3 this

mobile Agent will reach to its destination, computer B,

which will resume its execution.

The following are areas but not limited to where mobileintelligent agents can be applied:

1. Distributed Computing: Mobile agents can beapplied in a network using free resources for their

own computations.

2. Collecting Data: A mobile agent travels aroundthe net. On each computer it processes the data

and sends the results back to the central server.

3. Software Distribution and Maintenance: Mobileagents could be used to distribute software in a

network environment or to do maintenance tasks.

4. Mobile agents and Bluetooth: Bluetooth is atechnology for short range radio communication.

Originally, the companies Nokia and Ericsson

came up with the idea. Bluetooth has a nominal

range of 10 m and 100 m with increased power.

The applications for mobile agents are myriads.

5. Mobile agents as Pets: Mobile agents are theideal pets. Imagine something like creatures.

What if you could have some pets wandering

around the internet, choosing where they want to

go, leaving you if you dont care about them or

coming to you if you handle them nicely? People

would buy such things wont they?

6. Mobile agents and offline tasks: Mobile agentscould be used for offline tasks such as, an agent is

sent out into the internet to do some task, and the

agent performs its task while the home computer

is offline and returns with its results. Mobileagents could be used to simulate a factory,

machines in factory are agent driven, agents

provide realistic data for a simulation, e.g.

uptimes and efficiencies, and simulation results

are used to improve real performance or to plan

better production lines [14][15].

2.5 Cloud Computing Paradigm

It is a new type of distributed computing still emerging

field in computer science. The remote machines owned by

other company which will run everything for the user is

called cloud computing. It will change entire computerindustry. The only thing the user has to run interface

software of cloud computing system. There is a significant

workload shift i.e. the users computer will not run the

applications. It will decrease the demand of hardware and

software. There is no limit of its applications. Everything

can be done through cloud computing. The major

advantage of this is the client can access his data any

where at any time. It will reduce the need for advanced

hardware which will bring the cost of hardware down. The

client can take the advantage of network processing power

if the cloud computing is using a grid at its back end. This

is a step backward to early computers having only

keyboard and terminal. The major issues in cloud

computing are: Data governance: Enterprises have

sensitive data that requires proper monitoring and

protection, moving data into cloud enterprise will lose

their governance on own data. Manageability, Monitoring,

Compliance, Cross-country Data migration, Reliability,

availability and recovery and Security and privacy: are

major concerns and issues in cloud computing. Figure 6

depicts the cloud computing paradigm.





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Fig. 6 Cloud Computing Paradigm

The followings are the advantages of cloud computing

paradigm:1. It provides small and medium businesses a

break to access web based advance tools as aresource. By grace of cloud, technology accessis no more a prime expenditure, as it is sameas your other utility services (Electricity,Telephone) you are going to pay just for whatyou have utilized, nothing more. Thats howcloud saves cost on important businessapplications and managed by SLA.

2. On one hand where the cloud makes bettersecurity and observation within a central dataaccess, besides, it provides usage of automatedsystem interfaces. User does not need to careabout backend engineering, maintenance andtroubleshooting of ongoing operations.

3. The idea is flourishing every coming day withgreat success in the upcoming time, as nowoffshore services are well-liked more than everand industrialists are putting their money inthe low capable countries in term oftechnology advancement and then sending offtheir cloud computing environment worldwide.

4. In cloud computing, customers using webapplications, access the environment andservices retained by a third party. As a result,the idea of offshore software development inleast economic IT countries is running atenormous pace as developers can access theutility worldwide, at any time from a handhelddevice, PC, or a laptop, history making.

5. Cloud computing is a thought that is based ontransforming the stack of IT away from firmsinto the hands of cloud providers. It buttressesa culture of modernization by eradicating amajor fraction of the economic risks linkedwith bearing out archetype of new ideas[16][17[18].

3. Results and Discussion

In code-on demand based client-server architecture, the

client becomes thin; which has no hard disk, a network

computer, easier to use, reliable and it supports the

centralized and synchronous with no autonomy network

management. In simple network management protocol, theclient becomes fat; which has its local databases, harder to

deploy, runs slowly and it also supports centralized

network management. In remote procedure call, the client

is fat; which consume heavy network bandwidth and it

supports distributed, synchronous and less autonomous

network management. In mobile agent based client-server

architecture, the client becomes smart; which supports

work offline, can be deployed and updated in real time

over the network from a centralized server, supports

multiple platforms and languages because of web services

and runs on any device that has Internet connectivity,

including desktop, workstations, note books, PDAs and

mobile phones. The cloud computing is a new and

emerging paradigm which although supports smart clientbut also consume heavy bandwidth, which has only the

user interface to interact with the cloud and has no

processing power and no storage capacity, all the data is

processed and stored in the cloud. It supports centralized

network, uses both synchronous and asynchronous mode

of communications and also uses both TCP and UDP as

transport protocols. Table 2 presents a comparison of

client-server architectures discussed in this paper.

CORBA and Microsofts (OLE, COM, DCOM and

ActiveX, and many more) objects are around for years.The concept of mobile agent is over a decade old, the

technology proves not to be perfect yet; researchers are

now developing methods for improving the technology,

with more standardization, better programming

environments, as well as design patterns that allow mobile

agents to be used in products. It is obvious that the more

an application gets intelligence, the more it also gets

unpredictable, dangerous and uncontrollable. The mobile





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agents in most aspects are also considered to be a new

programming paradigm. The concept of cloud computing

is very new, there are some privacy and security issues

that put a stop to widespread use of cloud. The center of

attention in cloud development is the evolving of the cloud

from the indoors (private cloud) to outdoors (public cloud).

Table 3 shows different programming paradigms with the

evolution of client-server architecture.

The first generation of programming was machine

programming, the structural unit was called a program,

it was an era of mainframe computers where one machine

was connected with many users having dump terminals atthe same time i.e. it was one-to-many interface. The next

generation was structured programming, the structural

unit was known as subroutine, it was an era of personal

computers where one user could connect with one

computer at a time i.e. it was one-to-one communication.

The succeeding next generation was object-oriented

programming (OOP), the structural unit was identified as

an object, it was an era of networked computers where

many users having personal computers could connect with

one main server at a time i.e. it was many-to-one

interaction. The subsequent next generation was agent-

oriented programming (AOP), the structural unit was

known as agent, the agent has the same properties like an

object but only differ in its autonomous, proactive,

intelligence and mobile behavior, it is an era of the people

where many users are interacting with many intelligent

devices at the same time i.e. it is many-to-many

communication. There are not many applications that use

mobile agents, so it hard for this technology to become

widely adopted. Most work had been around the agents

framework instead of developing the real applications. The

client-server architecture and paradigm is well understood

and quite mature as a technology, but the area of

distributed control of mobile agent systems is still the

subject of many research efforts. An agents envisioned

autonomous behavior, involving collaboration with other

agents at various network locations, creates a dynamic

environment that requires new design methodologies and

modeling tools to properly formulate and construct agent-

based system. The latest generation of programming is

lightweight programming, the structural unit is called a

lightweight program and we are in the era of the people

where many people can interact with many intelligent

devices at the same time i.e. it is many-to-many

communication. The codes to add two integer numbers are

shown as an example in table 3 in all five programming

paradigms. These lines of code are a program in

Assembly Language, subroutines in FORTRAN 77, a

class in Java, an agent in Kaariboga Java based Agent

framework and finally a lightweight program in Phobos

framework. This shows the changes in codes one

programming paradigms to other.

4. Conclusion

In this paper, we discuss five different client-server

architectures namely code-on demand, remote procedure

call, simple network management protocol, mobile

intelligent agent and cloud computing, and finally draw a

comparison of these client-server architectures and their

corresponding programming paradigms. First three

architectures are based on centralized network, they are

less autonomous, synchronous and use heavy network

bandwidth, mobile intelligent agent architecture is basedon distributed, asynchronous execution and autonomy,

robust and fault-tolerance behaviour, works in

heterogeneous environment, reduces network traffic and

overcomes network latency and the cloud computing is

based on centralized network and supports both

synchronous and asynchronous communications. The

increasing popularity of distributed heterogeneous network

and the Internet has created new technologies that lead a

system to be based on some form of mobile agent and

cloud computing. The ever growing amount of data that

are stored in distributed form over network of

heterogeneous and autonomous sources poses several

problems such as communication minimization, autonomy

preservation, scalability and privacy protection, therefore,

mobile intelligent agents are autonomous, capable of

adaptive and deliberative in nature are the best choice to

solve these problems of distributed systems. Now the trend

that every thing will be in a cloud increases the popularity

and usage of cloud computing. We conclude our paper that

with the advent of new client-server architecture based

technologies require the changes in programming





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paradigms. At the evolutionary stage of each paradigm and

then continuing to deploy applications will reach at critical

mass before it becomes effectively main stream but that

day is coming.

Acknowledgment

The authors are thankful to The Islamia University of

Bahawalpur, Pakistan for providing financial assistance to

carry out this research activity under HEC project 6467/F

II.

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Dost Muhammad Khan: M.Sc.(Computer Science) from B.Z.University, Multan, Pakistan. Currently PhD Student at SITE, UTM,Mauritius. Assistant Professor Department of Computer Science &IT, The Islamia University of Bahawalpur, Pakistan. Published 5research papers in International Conferences & Journals. Fields ofinterest are Data Mining, Intelligent Agent, and Object RelationalDatabase Management.

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