INTELLIGENT DECISION-MAKING TIER IN SOFTWARE

ARCHITECTURES

D. Ong and S. Khaddaj

Faculty of Computing, Information Systems and Mathematics, Kingston University London, Kingston upon Thames, U.K.

Keywords: Software Architectures, Intelligent Decision Making, N-tier Architectures, Control Systems.

Abstract: Despite recent developments there are still many challenges in the application of intelligent control systems,

as intelligent decision-making providers in constructing many software architectures which are required in

many applications particularly in service-oriented computing. In this work we are particularly interested

with the use of intelligent decision making mechanisms for the management of software architectures. Our

research aims at designing and developing an intelligent tier which allows dynamic system architecture

configuration and provisioning. The tier is based on a number of logical reasoning and learning processes

which use historical data and a set of rules for its analysis and diagnosis in its attempt to offer a solution to a

particular problem.

1 INTRODUCTION

The adoption of a service-oriented architecture

(SOA) approach in the software development

lifecycle has increased significantly over recent

years. The SOA approach is an extension of

distributed computing, modular programming and

object-oriented programming concepts, where each

software component in the architecture can be

considered as a service provider. Each service

provider is able to operate as an individual

independent unit, as well as collaborate with other

services to fulfil a particular application objective. A

software package which is based on business

requirements and processes can be assembled via the

manipulation of these services.

For many applications, especially those based on

services, it is very important to have a system that is

able to reconfigure itself dynamically based on its

operational situation. To achieve this dynamism, this

paper proposes an intelligent decision-making

mechanism which can be incorporated into existing

n-tier architecture as i-tier to form new n(i)-tier

architecture.

We start by discussing intelligent decision

making mechanisms and processes. Then, the

different layers in typical software architectures are

described and some problems and challenges are

identified. The intelligent decision making layer is

then presented which offers dynamic optimisation of

the way services (resources) in the n-tier architecture

are utilised. Then, the layer potential use as an

intelligent service provider is discussed. We

conclude with some suggestions for future work.

2 INTELLIGENT DECISION

MAKING MECHANISMS

Most intelligent control systems have some form of

decision making mechanisms build into their

systems, but many obstacles remain as they are

usually built for a specific purpose / scenario,

relying heavily on predetermined algorithms, and

autonomous behaviour that is based on

preconfigured / static configurations (Kramer,

1985), (Sun , 2000), (Satoh, 2002), (Beckert, 2006).

Historically, the control unit of many intelligent

systems is not easily adapted to other architectures /

systems because it is statically designed to solve a

particular problem.

To overcome the above challenges, this work

proposes an intelligent control unit that is capable to

deploy a generic decision-making mechanism across

various software architectures. The intelligent

decision-making unit provides decision-making

functionality for the software architecture in the

form of system configuration and provisioning.

Based on the decision-making scope, the decision-

355

Ong D. and Khaddaj S. (2010).

INTELLIGENT DECISION-MAKING TIER IN SOFTWARE ARCHITECTURES.

In Proceedings of the 12th International Conference on Enterprise Information Systems - Databases and Information Systems Integration, pages

355-358

DOI: 10.5220/0002868103550358

 SciTePress

making unit is expected to make a sensible decision

upon every request, and to learn from its past

decisions via the received feedback.

The main obstacle in developing intelligent

decision-making mechanisms is to understand how

we perceive an “intelligent” entity (Ong and

Khaddaj, 2009). A general concept on how an

intelligent decision-making ability is achieved using

combined functionalities is shown in figure 1. This

is used as a general guideline in constructing the

proposed intelligent control unit where the learning

and logical reasoning processes use historical data

for its analysis and diagnosis as well as sets of rules,

both pre-defined and self-defined, to offer a solution

to a particular problem.

Figure 1: A decision-making ability.

3 SOFTWARE ARCHITETURES

The traditional software architectures have a

tendency toward developing computer applications

as standalone visible software (commodity), where it

can be sold as an off-the-shelf product. Typically, it

is designed for a specific business function (e.g. an

in-house payroll system) or a specialised general-

purpose application such as word processing,

desktop publishing, operating system, etc.

However, continuous growth in the integration

and globalisation of the current computer

infrastructures has offered a new opportunity for a

“next step” in software evolution. A service-oriented

architecture (SOA) has emerged as a popular

architectural platform, where it has moved

significantly from the traditional design (Choset,

2000). This has created a great opportunity for the

full integration of existing applications into one

universal service provider with each software

component capable of acting autonomously as a

service provider. This service provider can range

from a small task (e.g. statistical calculation, sorting

functions, etc.) to a larger enterprise solution, where

it can consist of an integration of various small tasks

to form a complex service such as online banking, e-

store, etc. Furthermore, any improvement or

deployment of this component to other solutions can

be accomplished without any noticeable effect to the

overall infrastructure (Pfister, 2002), (Gyurjyan,

2003), (Soundararajan, 2008), (Bar-Kana, 1989),

(Frankovic, 2009).

An n-tier concept is commonly used in designing

an SOA solution, where it is generally adopted and

implemented as a software development scheme

particularly for web services (e.g. the core design

concept of Microsoft .Net (Microsoft, 2007)).

3.1 N-tier Architecture

The n-tier architecture’s aim is to provide an

approach that unifies business, technical and data

access logics into one single flexible software

infrastructure. Business logic provides aims and

purposes of the software (e.g. content management

for different types of user, on-line payment and

billing solutions, etc.). Technical logic gives a

technical integration of the business logic into a

viable technical solution (e.g. interpretation and

transformation of screen display according to level

of information or privileges set by the business

logic). Lastly, data access logic provides a data

management solution for the software such as data

access solution, data storage solution, data

translation solution, etc.

The n-tier architecture utilises a component-

based approach in its design practices. This

approach permits the architecture to be more flexible

and acceptable to any changes with a minimal

impact to its structural integrity. The flexibility

offered by this approach enables the architecture to

reuse existing components, which has led to a large

reduction in the redundancy of functions (codes).

In general, n-tier architecture can be divided into

three main components – “User Interface”,

“Application Structure” and “Data Storage” (figure

2). The “user interface” component provides a

physical medium for a software solution to engage

with an end-user. The “application structure”

component incorporates business, technical and data

access logics into three integrated tiers to provide a

software solution. The “data storage” component

gives a data storage and management facility to an

“application structure” component.

Figure 2: General concept of n-tier architecture.

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4 AN INTELLIGENT DECISION-

MAKING LAYER

Earlier, it was indicated that there is a requirement to

design a system that can reconfigure itself

dynamically based on its operational situation. In

order to achieve this dynamism, a new n(i)-tier

architecture is proposed as an enhancement to the

current n-tier architecture, where a newly proposed

intelligent decision-making layer (i-tier) is

introduced. This i-tier is expected to take over the

responsibility of handling the architecture’s

communication medium (figure 3) by managing

every communication requirement autonomously

through an intelligent resources delivery and

management facility.

Figure 3: General concept of n(i)-tier architecture.

The fundamental characteristics of the i-tier in

n(i)-tier architecture could be described as follows: -

a) To be capable of detecting and adapting to

different communication protocols used by the

architecture’s tiers.

b) To be capable of adapting to any changes

occurring in the infrastructure.

c) To be capable of optimising and fixing any

faulty elements detected within its infrastructure.

d) To be capable of initiating its own

investigation when there is a problem discovered or

a new element introduced to the infrastructure.

e) To be capable of recovering from any failures.

The intelligent resources delivery and

management facility is based on a dynamic decision-

making mechanism. The role of intelligent tier

would be to make the best possible decision to

reflect the current situation of the whole

architecture. Integration of these decision-making

processes into one independent tier enables a wider

identification and evaluation of the architecture’s

overall operating status that inadvertently

contributes to the formation of a better final

outcome. This process is determined by pattern

identification methods and types of logical reasoning

in the tier’s decision-making mechanism (Ong and

Khaddaj, 2009).

Initially, the presentation tier sends an end user’s

requests to the data access tier. The data access tier

needs to access information provided by the business

tier, in order to evaluate which type of information is

required by the presentation tier. If the business tier

almost reaches the breaking point in its processing

capacity, a performance degradation of the overall

architecture will slowly emerge (i.e. a snowball

effect) because the presentation tier is still

continually sending requests to the data access level

and is not aware of any problems in the business tier.

The intelligent tier, which oversees the status of the

overall architecture, instructs (co-ordinates) the

presentation tier to reduce the frequency of requests

sent to the data access tier. It will therefore alleviate

the processing pressure from the business tier and

the overall architecture in general, thus facilitating

optimum processing of the data and an improvement

in the performance of the n(i)-tier as a whole.

4.1 Intelligent Service Provider

As mentioned earlier the current n-tier architecture

has three tiers, which are capable of interacting with

each other to achieve a software solution for the end

user. Moreover, it relies heavily on a static

configuration to achieve its functioning goals. This

configuration often requires manual modification to

reflect its current operational relevancy. However, a

dynamic decision-making process in n-tier

architecture is essential, as any software solutions

produced must reflect the current operating

environment.

In order to achieve this dynamic process, the

intelligent tier was proposed earlier to provide the

intelligent decision-making mechanism for the

architecture tiers. The i-tier layer can be deployed as

an n(i)-tier based solution for an intelligent service

provider where it is taking over the decision-making

responsibilities from other tiers (figure 4). The

intelligent service provider can be used in service-

oriented architectures where many services need to

interact to produce a workable application.

Figure 4: intelligent service provider.

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357

The dynamic decision-making process in each

tier is delegated to the intelligent tier, where the best

possible decision is made to reflect the current

situation in the whole architecture. Integration of

these decision-making processes into one

independent tier enables a wider identification and

evaluation of the architecture’s overall operating

status that inadvertently contributes to the formation

of a better final outcome. This process is determined

by pattern identification methods and types of

logical reasoning in the tier’s decision-making

mechanism.

5 CONCLUSIONS

In this paper an intelligent control system framework

for the dynamic configuration and operation of

software architectures has been presented. To

achieve a high flexibility and dynamism in the

framework design, the paper has looked into an

intelligent decision-making layer which can be

adopted as a control unit of the intelligent control

system. This was then applied into the current

development of n-tier software architecture. The

need of introducing an intelligent decision-making

layer that is capable of acting instantaneously in

response to any changes to its requirements and

environment was also discussed. The paper

attempted to offer a viable technical design and

solution to constructing an n(i)-tier infrastructure for

software development environments. It is suggested

that the introduction of an intelligent decision-

making layer in the n-tier design would enable

software architectures such as the service-oriented

architecture to be more flexible and adoptable.

However, the realisation of the proposed architecture

to its full potential would be considered in future

work.

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