MOBILE APPLICATIONS AND SERVICE-ORIENTED

ARCHITECTURE INTEGRATION

A Practical Approach in Incorporating Mobility with

Enterprise Information System

Guillaume Koum, Augustin Yekel

Ecole Nationale Supérieure Polytechnique, Université de Yaoundé,P.O. Box. 8390 Yaoundé, Cameroon

Tam Sangbong, Raoul M. Tsamo, Arnaud Fosso

Soft-Tech International Inc, P.O. Box. 15412 Douala, Cameroon

Keywords: Mobile Applications, Service-Oriented Architecture, Web Service, Mediator, Gateway, Computer

Reservations System, Java 2 Mobile Edition.

Abstract: Mobile Applications and Service-Oriented Architecture (SOA) are two aspects of Computer Science which

offer to Enterprise Information Systems (EIS) more agility and flexibility in order to follow the constant

evolution of enterprises business. However, the inadequacy of hardware resources and wireless network

availability and bandwidth constitutes a major constraint when developing any mobile application. The

challenge is exacerbated for developers when trying to integrate these applications with EIS which are

naturally heavier. This document presents this integration in the context of an EIS built on SOA. Added to

the basic tools needed for local data storage and communication with the server, a mediator (on the device)

is introduced to facilitate interactions between the application and the service. We also study reasons which

lead us to the choice of implementing a gateway on the server, in order to facilitate the service consumption.

1 INTRODUCTION

The mobile terminal has long served as a

communication tool between people. Its use was

further diversified with the implementation of

gaming, organizer and calculating applications. This

evolution reached a critical point when it was

necessary to allow these applications running on the

mobile to be able to communicate with external

applications, thus granting real mobility to the user.

The object of our work is the integration of the

mobile applications in the global system of the

enterprise, notably in the setting of a SOA.

In this document we present the architecture of

mobile in section 2 which also presents how the

problem of client (on the mobile) and server

(backend system) communication is tackled. After

the description of SOA applications in section 3,

section 4 will present how they are integrated with

mobile applications. Before the concluding remarks

section 5 and 6 respectively show the description of

our prototype and related work in this area.

2 ARCHITECTURE OF MOBILE

APPLICATIONS

Like for other applications describing mobile

applications architecture refers to presenting their

various building blocks and the models which

govern interactions between the blocks. However,

mobile applications are specific primarily because

mobility.

Mobility, the hardware limitation of mobile devices

as well as the fact that devices need to communicate

with backend systems, really influence mobile

applications architecture.

204

Koum G., Yekel A., Sangbong T., M. Tsamo R. and Fosso A. (2007).

MOBILE APPLICATIONS AND SERVICE-ORIENTED ARCHITECTURE INTEGRATION - A Practical Approach in Incorporating Mobility with Enterprise

Information System.

In Proceedings of the Second International Conference on e-Business, pages 204-208

DOI: 10.5220/0002113802040208

 SciTePress

2.1 Types of Mobile Application

The first criterion of distinction between mobile

applications is the application connectivity mode.

Then like other applications they can be layered

from three different perspectives (user interface,

processing, and Data layers). The layered view of

the application is applied to another mobile

applications differentiation according to the

client/server paradigm: the thin client and the fat or

smart client.

The fat client solves most of thin client

disadvantage and improves performance by allowing

data and operations to be executed locally. It

facilitates the interaction with other applications on

the terminal and can be integrated to the existing

infrastructures. The inconvenience is that it requires

more resources (Juntao Y., Michael, 2004).

2.2 Client/Server Communications

The fact that mobile applications are mostly partially

disconnected imposes constraints on the

management of data storage and transfer between

the client application and the enterprise server. That

is why a communication model or data exchange

protocol needs to be define thoroughly. The low

debit and the occasional unavailability of the

wireless network can impede the normal execution

of the application if it interacts with the server in

synchronous mode. So, the use of an asynchronous

communication model is better indicated for mobile

applications.

However, asynchronous communication poses the

problem of data synchronization. This affects most

partially-connected applications which use the store

- and - forward model. (Jourdain, Sébastien, 2002)

To execute the synchronization it is necessary to

implement solutions such as the protocol SyncML

(Crochet-Damais, Antoine, June 2004).

Along with synchronization, another important facet

of the problem of data transfer between the client

and the server is the format of the data to be

transmitted. Because XML (eXtensible Markup

Language) data is generally “large” (Enrique Ertiz.,

April 2004), WBXML (WAP Binary XML) which is

targeted to mobiles terminals, is preferred.

(WIKIMEDIA Project, January 2006).

We will now examine the architecture of service-

oriented application before looking at its integration

with mobile application.

3 SERVICE ORIENTED

ARCHITECTURES (SOA)

Service oriented architecture is defined as a set of

methods, practices and environments that allow

functionalities of an application to be provided and

used as a set of services at a suitable level of detail

for the consumer of the service. Services can be

invoked, published, and outlined and are separated

from the implementation by a unique and

standardized interface (Gartner Group, April 2005).

A SOA is centred on a principal concept: the

service which is the means by which a supplier

satisfies a consumer's needs.

The SOA puts in place a certain number of

entities that have to interact in order to permit a

comfortable use of the functionalities of the

application by means of services (the service user;

the service supplier, the service directory, the service

contract, the proxy, communication and transport

protocols).

Web services are currently the most widely

implemented service oriented architecture (Keen,

Martin, 2004).

More details on mobile and service oriented

applications architecture can be found in references.

4 INTEGRATION OF A MOBILE

APPLICATION WITH A SOA

4.1 Principles

We present here the integration of a mobile

application on a server whose architecture is service-

oriented. The goal is to enable the application to

integrate the SOA while taking into consideration

the fact that the connection is not guaranteed at all

times and that capacities of the mobile terminal are

limited.

The mediators’ model (Kureshi, Arif, 2004) has

been used to allow the application to reach the

offered services in order to preserve a weak coupling

between the various aspects of the application and

the service. Therefore the mediator will execute the

operations normally reserved for the services. It has

the following roles:

 Intermediary between the application and the

service: It can offer the application to do in

several small actions of operations that the

service asks to make in only one time;

 Local processing unit: it encapsulates

processes and local data which enables,

MOBILE APPLICATIONS AND SERVICE-ORIENTED ARCHITECTURE INTEGRATION - A Practical Approach in

Incorporating Mobility with Enterprise Information System

205

among others, the application to be able to

function in a partially connected environment;

 Scheduling: it must be able to schedule the

resumption of transactions. For this, it needs

to be autonomous;

4.1.1 Mediator–service Association

A mediator can be the mediator of several services if

these have a narrow relation between them. It is the

case if transactions exist in which these services

participate explicitly from the point of view of the

mobile application.

4.1.2 Communication between Mediators

It is possible that mediators need to use data used by

another mediator. To maintain the weakest possible

coupling between the different mediators as is

maintained between services themselves, one

mediator should not directly address another. An

object of the application must be able to take data

from one and transfer it to the other.

4.2 Proposed Architecture

The model presented above is summarised on the

figure 2 and explained in subsections below.

Figure 1: Proposed architecture.

4.2.1 Client Side (Mobile Terminal)

 Basic infrastructure: The basic infrastructure

comprises the set of services enabling the

storage of data on the mobile terminal and

communication network operations. The topic

is not about services offered by the SOA but

of tools that can be implemented by the

developer or placed at his disposal by the

development environment or external

libraries;

 Business logic layer: This layer contains

mediators and possibly entities executing

other processes that are not provided by the

services;

 User Interface: The user-interface comprises

all the components enabling the interaction

with the user. These elements can be visual or

vocal;

4.2.2 Server Side

 Service - oriented architecture: We developed

this work on the basis that the application

server has a service - oriented architecture,

which means that functionalities are

distributed in the form of services that can

eventually be integrated on an enterprise

services bus;

 Gateway: We presented the different

properties of this gateway. It has an optional

role, depending on the capacities of the mobile

terminal and the network on which the

application is going to function.

5 IMPLEMENTATION

OF A FLIGHT INFORMATION

APPLICATION

This section applies the studied concepts in order to

verify their validity. Thus, we have developed a

working prototype, the Flight Info application. The

system provides information on scheduled flights of

various airline companies. The importance of a

flight information application can be recognized by

anybody having had to plan a long distance journey

requiring several stopovers.

5.1 General Description of the Use of

the Product

The product will be used by the commercial agents

of travel agencies or any other third parties. The

software comprises two main modules, one for

agents of travel agencies and the other for travellers.

5.2 The Different Functionalities

 Obtain flight information (costs, timetables,

number of available seats, etc.);

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 Determine flight itineraries while specifying

constraints (minimum cost, timetables,

stopovers, etc.)

 Book customer reservations (card number can

be stored since data is isolated);

 Receive and send notifications from and to the

travel agency;

5.3 Application Architecture

The application architecture is the one that we

proposed above. We describe the different services

and mediators who build the application server and

the client application respectively.

5.3.1 The Application Server

It comprises the set of services that offer Flight Info

The identified services are:

 The information service on flights and

accommodation (hotels); offers customers

flight and hotel information

 The booking service; enables the customer to

book a seat on a flight or a room in a hotel.

This service uses the electronic payment

service for confirmation;

 The electronic payment service: enables

electronic payment of a booking;

 The customer management service: enables

registration, modification or deletion of

customer information.

 The agent management service: enables

registration, modification or deletion of agent

information;

 The security service, assures the security of

the application (authentication of users, etc.)

5.3.2 The client Application on the Mobile

Terminal

It comprises all functionalities that are accessible

from the mobile terminal (client of the travel agent

or the traveller). We have the different mediators

and services to which they correspond

 The information and booking mediator: this is

the mediator between the application and the

information service on flights and

accommodation and the booking service;

 The customer management mediator: this is

the mediator between the application and the

customer management service. It will enable

access and modification of customer data;

 The agent management mediator: this

mediator enables the agent management

service, notably for the access and the

modification of information on this agent;

 The notification management mediator, this

mediator permits to manage the sending and

reception of notifications.

5.3.3 The Gateway between

the Client Application and

the Application Server

It is relevant mainly for the functioning of the flight

itineraries search service. It permits to store the

important data in order to send only a tolerable

amount to the application.

5.4 Tools and Technologies used to

develop a flight Information System

Several tools and technologies were used to develop

the prototype. We describe then below.

5.4.1 J2ME and J2EE

J2ME is a Java (language) platform used for

developing mobile applications. The framework

provides three main categories of virtual machines:

the CVM (C-Virtual Machine) which implements

nearly all specifications of the regular JVM but is

optimized for the mobile; the KVM (Kilobyte

Virtual Machine): a very light version of the JVM

(40 - 80 KB) which supports fewer functionalities;

the CardVM (Card Virtual Machine): a version of

the virtual machine for applications on SIM cards.

5.4.2 Simplicity

Simplicity for Mobile Servers is a development

environment especially for mobile Client–Server

applications. This environment permits to develop

enterprise servlets and integrates MIDPS that permit

to develop Midlets applications. It offers some key

components:

 The XML Export component allows to quasi-

automatically export captured data in XML by

a servlet. This module proves to be very useful

for the communication between the client and

the server.

 The Transaction module is available at the

level of the client Midlet application. It

permits to send requests to a servlet via HTTP

and to receive the data in XML format

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5.4.3 JESS

JESS (Java Expert System Shell) is an inference

engine written in Java. It enables inferences based

on rules and conditions defined in a script language.

It permits mainly forward reasoning, but backward

reasoning is possible, both through an algorithm

called RETE. We used JESS to search for itineraries

between cities.

6 RELATED WORK

Found in the literature are the works of (Do Van

Thanh; Jorstad, I., July 2005).and (Duda, I.; Aleksy,

M.; Butter, T., July 2005).

7 CONCLUSIONS

Mobile applications are an opportunity for

enterprises that wish to cover wide areas and at the

same time be closer to the user. However,

developers face challenges because of a certain

number of restrictions in term of material and

network infrastructure. We have examined in this

paper how these problems can be solved in the case

where the mobile application integrates an enterprise

application with a service-oriented architecture. This

work permitted us to propose an architecture

allowing the mobile application to access services

through the intermediary of mediators. However,

two important aspects must be studied in depth:

security and the supply of services.

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