TOWARDS VERIFYING SERVICE INTEROPERABILITY

REQUIREMENTS FOR PERVASIVE COMPUTING

ENVIRONMENTS

Yasir Malik and Bessam Abdulrazak

DOMUS Laboratory, University of Sherbrooke, Sherbrooke, Canada

Keywords:

Veriﬁcation, Interoperability, Design by Contract, Service Modeling, Smart Environment.

Abstract:

Service interoperability veriﬁcation is key to enable service continuity among pervasive computing environ-

ments. Pervasive computing is shifting the computing paradigm toward everywhere computing where number

of heterogeneous and autonomous systems offer rich sets of services to assist inhabitants in their daily living.

To support continuity of services these systems must provide seamless and ﬂawless interoperability among

devices and services. In this paper, We present our ongoing project on verifying the service interoperability

in pervasive computing environments. We highlight the potential use of formal methods to verify the interop-

erability requirements and propose using design by contract technique to model and verify the semantic and

pragmatic service interoperability requirements. We also present our veriﬁcation requirement analysis and the

beneﬁts of using this technique with rich support from languages for implementation.

1 INTRODUCTION

Service interoperability veriﬁcation is key to enable

service continuity among pervasive computing en-

vironments. Pervasive computing is shifting the

computing paradigm toward everywhere computing,

where number of heterogeneous and autonomous sys-

tems offer rich set of services to assist its habitants

in their daily living. Mark Weiser envisioned perva-

sive computing where computing devices will be in-

tegrated smartly in their environments to help users

with their everyday living (Weiser, 1999). We foresee

a future, where humans will be directly or indirectly

interacting with number of smart devices and ser-

vices embedded in their physical environments with-

out knowing about them. To support continuity of

such services these systems must provide seamless

interoperability among devices and services. Inter-

operability is the capability of heterogeneous and au-

tonomous systems to interact with each other for efﬁ-

cient service execution (Pokraev et al., 2006b), it can

also deﬁned as transparent & compatible execution

between equipment from different vendors. The for-

mal deﬁnition of interoperability given in IEEE glos-

saries is the ability of two or more networks, systems,

devices, applications or components to exchange in-

formation between them and use the exchanged infor-

mation. Pervasive computing environments are het-

erogeneous with many autonomous systems running

in it. To successfully deploy pervasive computing en-

vironments, it is very important that these environ-

ments support interoperability of services and compo-

nents deployed in the environments to achieve com-

mon goal(Perumal et al., 2008a). There are three

types of interoperability problems that can occur in

pervasive computing environments:

• Syntactic Interoperability: Syntactic interoper-

ability involves a common data format and com-

mon protocol to structure any data so that the

manner of processing the information will be in-

terpretable from the structure

• Semantic Interoperability: Semantic interoper-

ability requires that any two systems will derive

the same inferences from the same information

• Pragmatic Interoperability: Pragmatic interop-

erability is reached when the interoperating sys-

tems are aware of the methods and procedures

that each system is employing. In other words,

the use of the data or the context of its application

is understood by the participating systems

Researchers have presented many approaches to sup-

port interoperability in pervasive computing environ-

http://en.wikipedia.org/wiki/Semantic interoperability

220

Malik Y. and Abdulrazak B..

TOWARDS VERIFYING SERVICE INTEROPERABILITY REQUIREMENTS FOR PERVASIVE COMPUTING ENVIRONMENTS.

DOI: 10.5220/0003907202200223

In Proceedings of the 2nd International Conference on Pervasive Embedded Computing and Communication Systems (PECCS-2012), pages 220-223

ISBN: 978-989-8565-00-6

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

ments (Perumal et al., 2008b; Maestre and Camacho,

2009), however there are very few works done on ver-

ifying service interoperability requirements for these

environments. We address in this paper the problem

of verifying the interoperability requirements of ser-

vices in pervasive environments. We highlighted and

analyzed potential use of formal methods for specify-

ing and verifying services at run-time. We propose to

use Design by Contact technique to model and verify

the semantic and pragmatic service interoperability

requirements at runtime. Our analysis shows promis-

ing beneﬁts of using this technique, also there is rich

support from languages for implementing this tech-

nique.

The rest of article is organized as follows. In the

next section we present state of the art addressing

interoperability and its veriﬁcation process. In sec-

tion 3 we present the potential beneﬁts of using for-

mal method and analysis of design by contract for se-

mantic and pragmatic interoperabilityveriﬁcation. Fi-

nally, in section 4, we conclude the paper and discuss

future work.

2 RELATED WORK

This section presents some presentative work related

to interoperability requirements and solutions in per-

vasive computing environments. Sullivan and col-

leagues highlighted the interoperability requirements

and suggested the potential use of semantic tech-

niques like ontologies in solving the key challenges of

service interoperability(O’Sullivan and Lewis, 2003).

Roussaki and colleagues in (Roussaki et al., 2008)

suggested the use of ontologies and presented an on-

tology based service model for composability of var-

ious available services in pervasive computing en-

vironments. Bromberg and colleagues presented an

event-based parsing technique to provide full service

discovery interoperability to any existing middleware,

their system act as bridge between topological net-

works and discovery technologies to adapt itself to

the environment and its host to offer interoperabil-

ity anytime anywhere (Bromberg and Issarny, 2005).

Later this approach was extended by Bottaro and col-

leagues (Bottaro et al., 2007), they proposed a soft-

ware architecture based on OSGi framework to ad-

dress protocol heterogeneity, interface fragmentation

and device composition among other challenges in

smart home environment. All the aforementioned

approaches have presented solutions for supporting

interoperability requirements in pervasive computing

environments; however they have not provided any

mechanism or approach for its veriﬁcation. Pokraev

and colleagues (Pokraev et al., 2006a; Pokraev et al.,

2006b) addressed the issue of interoperability veriﬁ-

cation and identiﬁed assessment requirements for se-

mantic and pragmatic interoperability. These require-

ments are as summarized below:

R1: A necessary condition for the semantic interoper-

ability of two systems is the existence of a trans-

lation function that maps the entity types, proper-

ties and values of the subject domain model of the

ﬁrst system to the respective entity types, proper-

ties and values of the subject domain model of the

second system.

R2: A necessary condition for pragmatic interoper-

ability of a single interaction is that at least one

result that satisﬁes the constraint of all contribut-

ing systems can be established.

R3: A necessary conditions for pragmatic interoper-

ability of a service is that R2 is met for all of its

interactions and they can occur in a causal order,

allowed by all participating systems.

Based on the above requirements, they proposed a

method to verify composite systems. The limitation

of their approach is the lack of mapping mechanism

for their service model. Baldoni and colleagues in

(Baldoni et al., 2006) suggested formalizing the inter-

action protocols using ﬁnite state automata to deﬁne

and verify properties of a service for the given pro-

tocol. There approach is a static analysis of the sys-

tem which can improve the conﬁdence in the system,

however it require prior knowledge of protocols de-

scription under test. A similar approach is presented

by Wan and colleagues, authors presented a veriﬁca-

tion algorithm and propose to formalize the properties

of service adapted to Pantagruel i.e.(language that de-

scribes and manages services), which will allow pro-

grams to be veriﬁed prior to their execution, however

this approach is limited when used to verify compos-

ite systems on the ﬂy (Wan et al., 2010).

3 VERIFICATION METHOD

Formal methods have been use to specify system and

provide methods such as model checking, theorem

proving for verifying and validating the functional

and behavioral correctness of the systems at early de-

sign stage. Recently the research in formal methods

is moved from off-line veriﬁcation to on demand veri-

ﬁcation (runtime veriﬁcation) which combines formal

speciﬁcation with programming languages to support

the runtime veriﬁcation of software systems. We ana-

lyzed the potential beneﬁts of using formal methods

TOWARDS VERIFYING SERVICE INTEROPERABILITY REQUIREMENTS FOR PERVASIVE COMPUTING

ENVIRONMENTS

221

to verify the interoperability requirements in perva-

sive computing environment. In particular, we studied

and identiﬁed the potential use of Design by Contract

(DbC) technique in systems based on service oriented

architectures.

Design by Contract is the object oriented design

techniques introduces by Meyer (Meyer, 1992), based

on the Hoare’s Correctness Triplets of {P} A {Q}.

This expression can be interpreted as an execution of

process A is a state where P holds and termination of

process A is a state where Q holds. Here P and Q

are the logical pre and post condition assertions for

the process A respectively. These pre and post con-

ditions are formally known as contracts that software

designers can use to formally deﬁne precise and ver-

iﬁable speciﬁcation for software components. These

contacts can be viewed as rights and obligations of the

class and its client. DbC can be used to support the se-

mantic interoperability. The fundamental idea of DbC

is to attach assertions or ”contracts” with each compo-

nent of the application, which allow the runtime ver-

iﬁcation of the properties that hold. There are three

different kinds of assertions that could be deﬁned for

any service, routine or application component:

1. Pre-condition: As the term is self expressive,

preconditionsare used to specify the assertion that

must hold before the execution of the program, or

component. In this way the programs/services can

be veriﬁed before their executions. For instance it

is possible to verify the arguments or inputs re-

quired for the service.

2. Post-condition: Post-conditions are assertions

that must hold after the execution of the program.

In this way services are veriﬁed after their execu-

tions against respective contracts.

3. Invariants: Invariants are the assertions in the

contract that must hold anytime during the exe-

cution of a program.

3.1 Requirements Analysis

In this section we analyze Design by Contract tech-

nique to verify the semantic and pragmatic interoper-

ability requirements. Contracts can be used to specify

the application requirement that must hold to interop-

erate with other systems. A service contract can spec-

ify semantics, behavioral, functional and non func-

tional requirements associated with the respective ser-

vice. In this way, a service provider makes no as-

sumptions about a service consumer, other than those

speciﬁed in the service contract. Service contract can

act as an interface through which service consumers

communicate with the other services for service com-

position. These service contracts can be speciﬁed in-

dependently of underline technologies to support in-

teroperability. The service model for such implemen-

tation is shown in Figure 1. The use of DbC tech-

nique will help to support and verify semantic inter-

operability requirements in pervasive computing en-

vironments. In the next section we present the anal-

ysis of DbC technique in satisfying the semantic and

pragmatic interoperability requirements identiﬁed in

(Pokraev et al., 2006b). The ﬁrst requirement R1

Figure 1: Service contract model.

for the semantic interoperability is that the system

must have a translation function that maps the en-

tity types, properties and subject domain model of

the systems being integrated. This requires the com-

plete knowledge of the system/service and its rela-

tionships with other components in the environment.

This requirement can be satisﬁed by associating a

contract with each component of the system. Thus

when systems are interacting, they can be veriﬁed

w.r.t to their contracts. This could be the pre or

post-condition that must hold for any communica-

tion. To enrich the contract with the domain knowl-

edge and relations with other components, ontologies

can be used. Ontologies are the description of some

shared concepts and their relationships for the given

domain and they support semantics interoperability

based on the domain knowledge. Requirement R2

and R3 address the problem of pragmatic interoper-

ability. As discussed above, pragmatic interoperabil-

ity can be reached when the inter-operating systems

are aware of each other methods and procedures also

that necessary conditions are met for at least one re-

sult that can satisfy constraint. As a result the context

of its application is understood by the participating

systems. This requirement can be satisﬁed by deﬁn-

ing the invariants of the contract and can be veriﬁed

any anytime during the execution to know the cur-

rent state of the system. DbC can also be applied

to address the service composition and veriﬁcation in

pervasive computing environment. Authors in (Chen

and Huang, 2009) has presented an approach to model

a service behavior represented by concurrent regular

expression and then translate it to labeled transition

system to form a ﬁnite state process notation trace

PECCS 2012 - International Conference on Pervasive and Embedded Computing and Communication Systems

222

to verify the service composition. This approach is

not automatic and does not support service interop-

erability if the composition is between two different

systems. DbC approach can be applied to support

such interoperability and veriﬁcation of service com-

position. The idea is similar as stated above, every

service has its contract which speciﬁcs its behavior,

functional and semantics requirements.

4 CONCLUSIONS

In this paper, we presented the potential beneﬁts of

using formal method for verifying the interoperability

requirements in pervasive computing environments.

In particular, we highlighted the potential beneﬁts of

Design by Contact technique to verify the service in-

teroperability. We analyzed the DbC to satisfy the re-

quirements of semantic and pragmatic interoperabil-

ity. We have also presented a service contract model

that can be used to specify the contracts of the ser-

vice in OSGI framework. The model include behav-

ioral, semantical, functional and non functional con-

tracts associated with respective service. The poten-

tial beneﬁt of DbC can be applied at runtime for ser-

vice veriﬁcation and supporting interoperability at the

same time. In upcoming publications, we will present

the implementation of service contacts developed in

OSGi framework to show the results of our proposed

method.

REFERENCES

Baldoni, M., Baroglio, C., Martelli, A., and Patti, V. (2006).

A priori conformance veriﬁcation for guaranteeing in-

teroperability in open environments. In In Proc. of

ICSOC 2006, volume 4294 of LNCS, pages 339–351.

Springer.

Bottaro, A., Gerodolle, A., and Lalanda, P. (2007). Per-

vasive service composition in the home network. In

Proceedings of the 21st International Conference on

Advanced Networking and Applications, AINA ’07,

pages 596–603, Washington, DC, USA. IEEE Com-

puter Society.

Bromberg, Y.-D. and Issarny, V. (2005). Indiss: interop-

erable discovery system for networked services. In

Proceedings of the ACM/IFIP/USENIX 2005 Interna-

tional Conference on Middleware, Middleware ’05,

pages 164–183, New York, NY, USA. Springer-Verlag

New York, Inc.

Chen, J. and Huang, L. (2009). Formal veriﬁcation of

service composition in pervasive computing envi-

ronments. In Proceedings of the First Asia-Paciﬁc

Symposium on Internetware, Internetware ’09, pages

19:1–19:5, New York, NY, USA. ACM.

Maestre, J. M. and Camacho, E. F. (2009). Smart home

interoperability: the domoesi project approach. Inter-

national Journal of Smart Home, 3:31–44.

Meyer, B. (1992). Applying ”design by contract”. Com-

puter, 25:40–51.

O’Sullivan, D. and Lewis, D. (2003). Semantically driven

service interoperability for pervasive computing. In

Proceedings of the 3rd ACM international workshop

on Data engineering for wireless and mobile access,

MobiDe ’03, pages 17–24, New York, NY, USA.

ACM.

Perumal, T., Ramli, A. R., Leong, C. Y., Mansor, S., and

Samsudin, K. (2008a). Interoperability among het-

erogeneous systems in smart home environment. In

Proceedings of the 2008 IEEE International Confer-

ence on Signal Image Technology and Internet Based

Systems, SITIS ’08, pages 177–186, Washington, DC,

USA. IEEE Computer Society.

Perumal, T., Ramli, A. R., Leong, C. Y., Mansor, S., and

Samsudin, K. (2008b). Interoperability for smart

home environment using web services. International

Journal of Smart Home, 2:1–16.

Pokraev, S., Quartel, D. A. C., Steen, M. W. A., and Re-

ichert, M. (2006a). A method for formal veriﬁcation

of service interoperability. In Proceedings of 2006

IEEE International Conference on Web Services 18-

22 September 2006, Chicago, Illinois, USA, pages

895–900. IEEE Computer Society.

Pokraev, S., Quartel, D. A. C., Steen, M. W. A., and Re-

ichert, M. (2006b). Requirements and method for as-

sessment of service interoperability. In Proceedings of

the 2006 4th International Conference on Service Ori-

ented Computing, ICSOC ’06, December 4-7, 2006,

Chicago, USA, volume 4294 of Lecture Notes in Com-

puter Science, pages 1–14. Springer.

Roussaki, I., Papaioannou, I., Tsesmetzis, D., Kantorovitch,

J., Kalaoja, J., and Poortinga, R. (2008). Ontol-

ogy based service modelling for composability in

smart home environments. In Mhlhuser, M., Ferscha,

A., and Aitenbichler, E., editors, Constructing Am-

bient Intelligence, volume 11 of Communications in

Computer and Information Science, pages 411–420.

Springer Berlin Heidelberg.

Wan, H., Drey, Z., You, Z., and Liu, L. (2010). Formal

Modeling and Veriﬁcation of Services Managements

for Pervasive Computing Environment. In Proceed-

ings of The 7th International Conference on Service

Systems and Service Management, Tokyo Japan.

Weiser, M. (1999). The computer for the 21st century. SIG-

MOBILE Mob. Comput. Commun. Rev., 3(3):3–11.

TOWARDS VERIFYING SERVICE INTEROPERABILITY REQUIREMENTS FOR PERVASIVE COMPUTING

ENVIRONMENTS

223