ENGINEERING PROCESS BASED ON GRID USE CASES FOR
MOBILE GRID SYSTEMS
David G. Rosado, Eduardo Fernández-Medina, Mario Piattini
University of Castilla-La Mancha, Alarcos Research Group – Institute of Information Technologies & Systems
Dep. of Information Technologies & Systems – Escuela Superior de Informática, Ciudad Real, Spain
Javier López
Computer Science Department, University of Málaga, 29071, Málaga, Spain
Keywords: Development process, Use cases, Security Use cases, Security Service Oriented Architecture, Grid
computing, Mobile computing.
Abstract: The interest to incorporate mobile devices into Grid systems has arisen with two main purposes. The first
one is to enrich users of these devices while the other is that of enriching the own Grid infrastructure.
Security of these systems, due to their distributed and open nature, is considered a topic of great interest. A
formal approach to security in the software life cycle is essential to protect corporate resources. However,
little attention has been paid to this aspect of software development. Due to its criticality, security should be
integrated as a formal approach into the software life cycle. We are developing a methodology of
development for secure mobile Grid computing based systems that helps to design and build secure Grid
systems with support for mobile devices directed by use cases and security use cases and focused on
service-oriented security architecture. In this paper, we will present one of the first steps of our
methodology consisting of analyzing security requirements of mobile grid systems. This analysis will allow
us to obtain a set of security requirements that our methodology must cover and implement.
1 INTRODUCTION
Grid computing is already a mainstream paradigm
for resource-intensive scientific applications, but it
also promises to become the future model for
enterprise applications. The grid enables resource
sharing and dynamic allocation of computational
resources, thus increasing access to distributed data,
promoting operational flexibility and collaboration,
and allowing service providers to scale efficiently to
meet variable demands (Foster and Kesselman,
1999).
Today, the development of wireless technology
and mobile devices enables us to access the network
service from anywhere at any time (Bruneo, Scarpa
et al., 2003). Provided that mobile devices have
limited computing capacity, the Grid becomes an
important computation service provider that enables
mobile users to perform complicated jobs (Trung,
Moon et al., 2005). On the other hand, the
performances of current mobile devices have
significantly increased, reason why laptops and
PDAs can provide aggregated computational
capability when gathered in hotspots, forming a Grid
on site. Mobile Grid, in relevance to both Grid and
Mobile Computing, is a full inheritor of Grid with
the additional feature of supporting mobile users and
resources in a seamless, transparent, secure and
efficient way (Litke, Skoutas et al., 2004; Guan,
Zaluska et al., 2005; Jameel, Kalim et al., 2005).
Security has been a central issue in grid
computing from the outset, and has been regarded as
the most significant challenge for grid computing
(Humphrey, Thompson et al., 2005). Security over
the mobile platform is more critical due to the open
nature of wireless networks. In addition, security is
more difficult to implement into a mobile platform
due to the limitations of resources in these devices
(Bradford, Grizzell et al., 2007). Therefore, a Grid
infrastructure that supports the participation of
mobile nodes will play a significant role in the
development of Grid computing.
146
G. Rosado D., Fernández-Medina E., Piattini M. and López J. (2008).
ENGINEERING PROCESS BASED ON GRID USE CASES FOR MOBILE GRID SYSTEMS.
In Proceedings of the Third International Conference on Software and Data Technologies - SE/GSDCA/MUSE, pages 146-151
DOI: 10.5220/0001879901460151
Copyright
c
 SciTePress

A Grid system is a software that has been
developed by means of a certain technology and that
fulfills a set of characteristics and own
functionalities of the Grid. As it is a software, the
problems that have arisen and given rise to
numerous researches in the last years are those of
considering and integrating security into the whole
software lifecycle (Baskerville, 1993; Anderson,
2001). In addition, if we add the appearance of a
new technology where security is fundamental and
the advance that mobile computation has
experienced in the last years, it appears the need to
define, consider and develop a methodology or
process of development in which security is
integrated from the first stages of development,
obtaining as a result, a secure, robust and scalable
Mobile Grid system.
In this paper we want to describe a development
process directed by special use cases for mobile grid
systems that will help us to identify the necessities
and requirements of these environments from initial
states and that they will guide us toward the
construction of secure service oriented architecture
supporting mobile devices and offering security grid
services. This methodology has two (general and
security) reusable repositories containing artefacts,
elements, diagrams of use cases, mechanisms,
patterns, templates, and so on, both general and
security aspects, that we can use in any stages or
activities of our methodology making the
development easier.
The rest of paper is organized as follows: In
section 2, we will show an overview of our
development methodology for secure mobile grid
systems. Section 3 will present the main contribution
of the paper, which is the analysis process of our
methodology of development. We will explain the
analysis stage and we will describe in detail one of
the activities of this analysis stage, the activity of
building security use cases. We will finish by putting
forward our conclusions as well as some research
lines for our future work in section 4.
2 METHODOLOGY OF
DEVELOPMENT
Our objective is to provide developers with firstly, a
methodology or development systematic process that
will include the complete development of Mobile
Grid systems of whatever complexity and
magnitude, and secondly, an architecture that helps
them to develop a secure mobile Grid system in an
ordered and systematic way. The systematic process
that we have developed is an iterative, incremental
and reusable process. This methodology has been
modified and improved with regard to a first
approach (Rosado, Fernández-Medina et al., 2008),
and it will consist of 3 phases (see Figure 1):
planning, development and maintenance of a secure
mobile Grid system. In all of them we use elements
of the repositories for completing each phase or
stage. We briefly describe the phases of our
methodology emphasizing the features of mobile
grid that are necessary in each phase:
Figure 1: Methodology of development for secure mobile
grid systems.
The planning phase is composed of the Secure
Mobile Grid System Planning stage, where it is
important to understand exactly which components
of the grid must be rigorously secured to detect any
kind of attack. Technology considerations are
important in deploying a grid and it is essential to
understand how the departments within an
organization interact, operate, and contribute to the
whole.
The development phase is composed of three
stages: analysis, design and construction.
 The Secure Mobile Grid System Analysis stage
is centred in building diagrams of use cases
and security use cases of our system
identifying and analyzing requirements and
security requirements of our systems to build.
These use cases must be defined for mobile
grid applications (stereotypes, constraints,
relations, behaviour, etc.). This stage will be
described in detail in section 3.
 In the Secure Mobile Grid System Design stage,
we must build a security architecture offering
the necessary security services that fulfill and
cover the security requirements identified in
the previous stage. This architecture will be a
service-oriented architecture where we define
a collection of basic security services
ENGINEERING PROCESS BASED ON GRID USE CASES FOR MOBILE GRID SYSTEMS
147

supporting the security requirements of mobile
devices in Grid environments. Moreover, we
need to identify what security mechanisms,
protocols and policies will be used for
designing the basic security services.
 In the Secure Mobile Grid System Construction
stage, we must implement the basic security
services together with security mechanisms
and protocols for our secure service-oriented
architecture. We must study the Grid Security
Infrastructure (GSI) that provides methods for
authentication of Grid users and secure
communication. It is based on SSL (Secure
Sockets Layer), PKI (Public Key
Infrastructure) and X.509 Certificate
Architecture. The system to be developed is
composed of mobile devices and resources
which altogether set up a mobile grid system.
The wireless technology will be essential for
the communication between devices.
The maintenance phase is composed of the
Secure Mobile Grid System Maintenance stage,
where a plan of maintenance of the system for its
later modification is defined according to the new
necessities of the client. If a new organization want
to take part of system, or if someone wants to add or
to eliminate resources of Grid, the viability of the
proposed change must be studied identifying which
part of the system is affected and who must take part
in its correction, being this change able to be
accepted or denied depending on the reach of it.
3 SECURE MOBILE GRID
SYSTEM ANALYSIS STAGE
In this section, we will analyze the most common
security requirements and challenges associated with
the above-defined mobile grids. Applications and
their requirements should be analyzed to understand
how they could be designed and developed to reap
the benefits of a mobile grid. We propose an
analysis stage oriented by Grid use cases which are
special use cases (stereotypes) where we define
constraints and properties that are necessary to
define when we are working with mobile devices in
Grid environments. This analysis stage will use a
reuse repository where diagrams of Grid use cases
for Grid applications (CPU intensive, data intensive,
collaborative, and so on) are defined and prepared to
be used in the design of the diagram of use cases for
any mobile Grid application. We define six types:
<<Grid: sch>> indicating that the use case belong to
the scheduler package; <<Grid: res>> indicating that
the use case belong to the resource package; <<Grid:
data>> indicating that the use case belong to the data
package; <<Grid: manage>> indicating that the use
case belong to the management package; <<Grid:
secur>> indicating that the use case belong to the
security package; and <<Grid: info>> indicating that
the use case belong to the information package. The
relations between use cases are defined in the
repository and we can add new relations or add new
actors or constraints for building our own diagram
for our application.
This stage analyzes security requirements
through grid use cases that we must build for our
application using the diagrams of grid use cases of
the repository and defining the interfaces and
relations between use cases until a full diagram of
grid use cases for our application is built. We will
describe the analysis stage in a general way and we
will study in depth one of the activities of this stage
related to the analysis of security requirements that
will be explained in the following subsection. Now
we will explain the most important (see Figure 2):
Figure 2: Activities of the Secure Mobile Grid System
Analysis stage
• Definition of Mobile Grid Use Cases
(MGUC). The purpose of this activity is to
build a diagram of use cases where we can
identify the necessities and requirements of
both users and the mobile Grid environment.
• Mobile Grid System Requirements Analysis. It
specifies both functional and non-functional
(excluding security) requirements from
MGUC. Also, it specifies security
requirements from MGSUC and integrates
them into a specification of requirements of
the final application.
• Validation and Verification of Results. During
the course of some designs, requirements can
change at the last minute or may go
undiscovered. This activity validates the
results obtained from the analysis as well as
approves the analysis of the system.
Once we have described the activities of the
analysis stage, we will explain activity 3, which is in
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charge of defining security use cases for the mobile
grid system.
3.1 Definition of Mobile Grid Security
Use Cases (MGSUC)
The analysis stage of our methodology has a set of
activities (see Figure 2) analyzing the requirements
of mobile grid systems. One of them (activity 3) is
devoted to define and build a diagram of security use
cases that will serve to specify the security
requirements for this kind of systems. A study of
security requirements in the analysis stage is
necessary for building a secure system, identifying
and analyzing security from early stages of life
cycle. Once the diagram is built, we can formally
specify the security requirements that we can extract
from the security use cases. A set of tasks will serve
us as a guide for defining and building the security
use cases and misuse cases for mobile grid systems:
3.1.1 Identify Security Assets: Task 3.1
The security assets for a grid with mobile devices
depend on the characteristics and type of system to
build, but the most important assets to protect will
be exchanged data, resources of each participant
organization, communication between mobile
devices and the grid, and personal information. The
CPU-intensive applications will consider resources
as main assets while data-intensive applications will
consider data as main assets to protect.
3.1.2 Identify Threats, Vulnerabilities and
Risks: Task 3.2
We can consider the security threats related to any
open network and others related to the mobile
communications. The security threats that are
usually present in the mobile and open networks are
the following: eavesdropping, communication
jamming, injection and modification of data,
interruption, unauthorized access, repudiation,
shoulder surfing, lost mobile terminal, stolen mobile
terminal, unprepared communication shutdown,
misreading and input error. The most important
security attacks for Grid are as follows: user
credentials attacks, man in the middle, credentials
compromise and/or replay, session hijack, SOAP
routing detour, attributes/credentials probing and
brute force attacks, improper key and privileges
management and control, etc.
In the security repository there are a set of
threats, vulnerabilities and risks either identified
from the beginning or that have been added during
the development. These vulnerabilitities and risks
are well-known for mobile computing and Grid
computing. If there are new threats for this
application, we must define them and update the
repository with these new threats extending and
improving the security repository for future
developments.
3.1.3 Build Diagrams of Security Use Cases
and Misuse Cases: Task 3.3
Once we have identified the threats and
vulnerabilities for Grid environments and mobile
computation, we can build, using security use cases
and misuse cases, a diagram of mobile Grid security
use cases where threats, attacks and security are
expressed and represented in the diagram indicating
the assets to protect, the security objectives to
achieve and the security requirements that the
system must fulfill.
In this task, we can use artifacts from our
security repository such as reference diagrams of
security use cases and misuse cases for Mobile Grid
system that have been built in initial phases of
development or updated in several activities and
tasks of our methodology. These reference diagrams
are general diagrams for any mobile Grid application
therefore, we must adapt them to our necessities
modifying, adding or deleting relations, constraints
and security cases until obtaining a diagram of
security use cases for our application that serves for
specifying security requirements in next tasks or
activities of this stage.
Figure 3: Grid Security Use Cases inside of the security
repository
In figure 3, we can see the general diagram for
Mobile Grid security use cases with the external
ENGINEERING PROCESS BASED ON GRID USE CASES FOR MOBILE GRID SYSTEMS
149

actors implicated and the security use cases that we
believe fundamental. Based on this information, we
use the use cases and their relations and constraints
for building our diagram of security use cases
covering the initial necessities and requirements, and
the resultant diagram integrates them into the final
diagram of use cases for the secure mobile Grid
application.
3.1.4 Assessment of Security (Threats, Risks
and Countermeasures): Task 3.4
It is necessary to assess whether the threats are
relevant according to the security level specified by
the security objectives. Then, we have to estimate
the security risks based on the relevant threats, their
likelihood and their potential negative impacts, in
other words, we have to estimate the impact (what
may happen) and risk (what will probably happen)
which the assets in the system are exposed to. We
have to interpret the meaning of impact and risk. In
order to carry out this task, we will use a technique
proposed by the guide of techniques of MAGERIT
(MAP, 2006) and which is based on tables to
analyze impact and risk of threats.
For example, if an alteration of information
occurs, we must analyze if the information that has
been modified implies low impact and risk, or on the
contrary it implies high impact and risk.
3.2 Analysis/Integration of Mobile
Grid Systems Requirements
This activity will have as result a security
requirements specification for our application and
they have been obtained from use cases and security
use cases that we have build using components and
models of repositories (general and security) where
we can update and add with news elements that we
believe important for future developments of this
kind of applications. So, for example, we must
obtain a set of security requirements that will be
some of the most important security requirements
and challenges associated with grids and mobile
computing (ITU, 2004; Trusted Computing Group
Administration, 2006; Vivas, López et al., 2007):
Authentication, Confidentiality, Integrity,
Authorization and access control, Trust, Single sign-
on, privilege delegation, Non-repudiation,
interoperability, Usability, Availability, and so on.
All these factors are at play in the Grid, wireless
and mobile device world. There are many shared
security requirements both grid environments and
mobile computing, and there are others one that are
exclusives and depend of our application, depending
of the point of view that we consider (see Table 1).
Table 1: Security requirements from several points of
view.
Points of View
Security
Requirements
Grid Mobile
computing
Mobile
user
Grid
service
provider
Authentication X X X
Confidentiality X X X X
Message Integrity X
Data Integrity X X X
Access Control X X X X
Single sign-on X
Delegation X
Non-repudiation X X X X
Trust X X
Availability X X X
Anonymity X
Privacy X X
Identity
Management
X X
Accounting X X
Credentials X
Interoperability X X
Usability X X
We have the purpose of developing and building
a secure mobile grid system, we must consider these
security factors within our methodology, identifying
and analyzing them in the analysis stage, which will
be shown below, extracting them from the security
use cases and integrating security mechanisms,
protocols and policies into our security architecture
that covers all these requirements. ITU_T X.800
Recommendation provides not only a general
description of security services but also the related
mechanisms that may be used to provide these
services. These services will be the security services
of our service-oriented architecture (design stage of
our methodology) where are well-defined obtaining
a reference security architecture that offers security
services to mobile users aimed at using grid services
sharing and coordinating mobile resources for all
members of the Grid.
4 CONCLUSIONS
In mobile environments the context is extremely
dynamic and it cannot be managed by a priori
assumptions. A methodology is necessary to build
this mobile software incorporating security from the
first phases of the life cycle obtaining a secure
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150

mobile grid system. It is difficult to incorporate
safely existing mobile devices into the Grid, so that
the impact is minimum and transparent to the user.
That’s the reason why the necessity to elaborate and
define a process of development of a system based
on the Grid and mobile technology and, considering
the peculiarities and necessities of this type of
systems arises. This process must be always flexible,
scalable and dynamic, so that it adapts itself to the
necessities, always changing, of the mobile Grid
systems.
An important phase of the methodology is the
security requirements analysis which we have
proposed with a set of task identifying assets to
protect, threat and vulnerabilities of our application
and building a diagram of security use cases and
misuse cases from which we can specify security
requirements for our application in next stages of
our methodology. These security requirements must
be analyzed, specified and validated ensuring that all
requirements obtained are complete, consistent and
easily understandable and analyzable by the
different actors involved in the development.
As a future work we will analyze in depth the
proposed methodology making a special effort in
describing each stage in detail and applying all the
stages to a case study to obtain a real mobile grid
system. Also, we will complete our initial
repositories with all use cases and security use cases,
relations, constraints, actors, and any other
information important and we will specify them
formally.
ACKNOWLEDGEMENTS
This research is part of the following projects:
MISTICO (PBC-06-0082) financed by FEDER and
by the “Consejería de Educación y Ciencia de la
Junta de Comunidades de Castilla-La Mancha”
(Spain), and ESFINGE (TIN2006-15175-C05-05)
granted by the “Dirección General de Investigación
del Ministerio de Educación y Ciencia” (Spain).
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