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Service Oriented Architecture: A Research Review from the Software and Applications Perspective

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This chapter presents the basic ideas underlying Service Oriented Architecture as well as a brief overview of current research into the phenomena also known as SOA. SOA is defined, and principal components of one proposed SOA framework are discussed. The more relevant historical background behind the move toward SOA is presented, including SOA antecedents such as Web Services, SOAP, and CORBA, and enabling technologies such as XML and EJB. A basis for understanding SOA is presented, based on Krafzig, Banke, and Slama's (2005) three-level hierarchical perspective. The common SOA components including UDDI, Application Programming Interface, Service Bus, Service Contract, Interface, Implementation, Data, and Business Logic are also presented. Finally, relevant research in four categories is presented, including implementation strategies, patterns and blueprints, tool development, standards proposals, or modifications (including middleware), and ontological or meta-model development or modification.
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ABSTRACT
Service-oriented architecture (SOA), Web services, and service-oriented computing (SOC) have become
the buzz words of the day for many in the business world. It seems that virtually every company has imple-
mented, is in the midst of implementing, or is seriously considering an SOA project, a Web services project,
or service-oriented computing. A problem many organizations face when entering the SOA world is that
there are nearly as many denitions of SOA as there are organizations adopting it. Further complicating
the issue is an unclear picture of the value added from adopting the SOA or Web services paradigm. This
article attempts to shed some light on the denition of SOA and the difculties of assessing the value of SOA
or Web services via return on investment (ROI) or nontraditional approaches, examines the scant empirical
body of research that exists on the topic of SOA, and highlights potential research directions in the area.
Keywords: service-oriented architecture; service-oriented computing; Web services
Web Services, Service-Oriented
Computing, and
Service-Oriented Architecture:
Separating Hype from Reality
John Erickson, University of Nebraska - Omaha, USA
Keng Siau, University of Nebraska - Lincoln USA
INTRODUCTION
Service-oriented architecture (SOA); Web ser-
vices; mash-ups; Ajax; Web 2.0; some of their
underlying middleware realization schemas
such as SOAP (simple object access protocol),
UDDI (universal description, discovery, and
integration), XML (extensible markup lan-
guage), and CORBA (common object request
broker architecture); and many other ideas or
approaches to cutting-edge information system
architectures have become the buzzwords of the
day for many in the business world and also in
the IT and IS communities. It has proven quite
difcult, perhaps nearly impossible, to pick up
any relatively current practitioner publication
without encountering an article focusing on at
least one of the above topics. A recent library
database search using keywords service-ori-
ented architecture, Web services, and SOA re-
sulted in 800-plus returns. Further investigation
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revealed that roughly 25 of those 800 articles
were sourced in research journals while the
other (still roughly 800) articles were all from
more practitioner-oriented sources.
When it comes to adopting and imple-
menting SOA, it appears that businesses are
doing it at astounding rates. Of course, what
they are actually doing, even though they may
say that their efforts represent a move toward
service-oriented architecture, may not match
anyone else’s denition of SOA but their own.
Furthermore, how can SOA be dened, and how
can we dene the benets of moving toward
such architectures? It seems that there is little
agreement among practitioners and researchers
alike as to a standard denition of SOA.
Worse still, a growing number of practitio-
ners are now beginning to question the business
return of some of the approaches. For example,
Dorman (2007), Havenstein, (2006), Ricadela
(2006), and Trembly (2007) indicate that there
is doubt emerging as to the real value of SOA
for adopting businesses and organizations.
Perhaps the question of return on investment
(ROI) should not be that surprising since it
sometimes seems that each organization has its
own denition of what SOA really is.
This article attempts to reach for a clearer
understanding of what SOA really is, and pro-
poses some possible areas of research into SOA
that could help clear up some of the denitional
confusion, which could in turn help lead to better
understanding of ROI as it relates to SOA. First
is the introduction. Second, the article provides
existing denitions of SOA, Web services, and
some of the related and underlying technologies
and protocols. The next section combines the
various denitions of SOA into a more coherent
form, while the section after that proposes ideas
about what SOA should be. The fth section
discusses research possibilities and provides
recommendations for future research efforts.
Next, we look at ways of measuring and justify-
ing SOA and SOC (service-oriented computing)
success. Finally, we conclude the article.
BACKGROUND AND HISTORY
OF SERVICE-ORIENTED
ARCHITECTURE
A minimum of nine formal denitions of SOA
exist as of this writing, from sources such
as the Organization for the Advancement of
Structured Information Standards (OASIS),
the Open Group, XML.com, Javaworld.com,
Object Management Group (OMG), the World
Wide Web Consortium (W3C), Webopedia,
TechEncyclopedia, WhatIs.com, and Webo-
pedia.org. In addition, many other denitions
put forth by numerous industry experts, such
as those from IBM, further cloud the issue, and
worse yet, other formal denitions might also
exist. In other words, the concept of service-
oriented architecture appears in many ways to
be a virtually content-free description of an
IT-based architecture. It is not our intent here
to add yet another denition to this already
crowded arena of denitions, but to try to cull
the common, base meanings from the various
distinct denitions.
Prior to about 2003, the term service-ori-
ented architecture was not in general use for
the most part, according to Wikipedia (“SOA,”
2007). However, since that time, SOA has
exploded nearly everywhere in the business
and technology world. SOA appears to derive
or develop in many cases from more basic Web
services. These services can include enabling
technologies such as SOAP, CORBA, EJB
(Enterprise Java Beans), DCOM (distributed
component object model), and even SIP (ses-
sion-initiated protocol) among many others;
services may also include other middleware cre-
ated with XML (Lee, Siau, & Hong, 2003; Siau
& Tian, 2004; Sulkin, 2007; Walker, 2007).
Service-Oriented Architecture
Denitions
The Open Group (2007) denes SOA as “an
architectural style that supports service orien-
tation.” The denition goes on to also include
descriptions of architectural style, service
orientation, service, and salient features of
SOA. OASIS denes SOA as “a paradigm for
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organizing and utilizing distributed capabili-
ties that may be under the control of different
ownership domains.” The OASIS denition
includes what they call a “reference model” in
which the details of the denition are expanded
and formalized. The Object Management Group
(2007) denes SOA as “an architectural style
for a community of providers and consumers of
services to achieve mutual value.” OMG adds
that SOA allows technical independence among
the community members, species the standards
that the (community) members must agree to
adhere to, provides business and process value
to the (community) members, and “allows for a
variety of technologies to facilitate (community)
interactions” (OMG, 2007).
W3C (2007) denes SOA as “a form of
distributed systems architecture that is typically
characterized by…a logical view, a message
orientation, a description orientation, granular-
ity and platform neutrality.” W3C adds details
describing what it means by logical view, mes-
sage and description orientations, granularity,
and platform neutrality. XML.com (2007)
denes SOA as follows:
SOA is an architectural style whose goal
is to achieve loose coupling among interacting
software agents. A service is a unit of work done
by a service provider to achieve desired end
results for a service consumer. Both provider
and consumer are roles played by software
agents on behalf of their owners.
The Javaworld.com SOA denition, com-
posed by Raghu Kodali (2005), is as follows:
“Service-oriented architecture (SOA) is an
evolution of distributed computing based on the
request/reply design paradigm for synchronous
and asynchronous applications.” Kodali also
goes on to describe four characteristics of SOA.
First, the interfaces composed in XML, using
WSDL (Web services description language), are
used for self-description. Second, XML schema
called XSD should be used for messaging. Third,
a UDDI-based registry maintains a list of the
services provided. Finally, each service must
maintain a level of quality dened for it via a QoS
(quality of service) security requirement.
Finally, IBM proposes that SOA “describes
a style of architecture that treats software com-
ponents as a set of services” (UNL-IBM System
in Global Innovation Hub, 2007). Furthermore,
it insists that business needs should “drive
denition” of the services, and that the value
proposition be centered on the reusability and
exibility of the dened services.
SERVICE-ORIENTED
ARCHITECTURE
We begin the SOA discussion with an overview
of SOA provided by Krafzig, Banke, and Slama
(2005). They proposed a three-level hierarchical
perspective on SOA in which Level 1 includes
the application front end, the service, the ser-
vice repository, and the service bus (SB). Ac-
cordingly, only the service child has children,
consisting of the contract, implementation, and
interface. Finally, the last level of the proposed
hierarchy is composed of business logic and
data, children of implementation. The next
subsections will discuss the general ideas of the
elements included in the hierarchy proposed by
Krafzig et al. described previously. This is not
to recommend adoption of the hierarchy and
description as the nal description of SOA, but
rather as a framework for discussing the meaning
of SOA for the remainder of this article.
Application Front End
This part of SOA comprises a source-code in-
terface, and in SOA terminology, it is referred
to as the application programming interface
(API). In accordance with most commonly ac-
cepted design principles, the underlying service
requests, brokerage (negotiation), and provision
should be transparent to the end user.
Service Repository
The service repository could be thought of as
the library of services offered by a particular
SOA. This would likely consist of an internal
system that describes the services, and provides
the means in the user interface to call a particular
service. UDDI could be seen as a realization of
the service repository idea. UDDI is a global
registry that allows businesses to list themselves
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on the Internet. UDDI is platform independent
and XML based. The point of UDDI is for busi-
nesses to list the Web or SOA-type services that
they provide so that other companies searching
for such services can more easily locate and
arrange to use them.
Service Bus
The SB, more commonly referred to as the
enterprise service bus (ESB), provides a
transportation pathway between the data and
the end-user application interface. Using an
ESB does not necessarily mean SOA is being
implemented, but ESB or some sort of SB use
is almost always part of an SOA deployment.
According to Hicks (n.d.), Oracle’s idea of an
ESB includes multiple protocols that “separate
integration concerns from applications and
logic.” What this means is that ESBs have now
become commercialized, and can be licensed for
use much like other UDDI-based services. So,
companies searching for ESB solutions as part
of an SOA effort now have multiple choices and
do not necessarily have to re-create the wheel
by building their own ESB.
Common Services
It seems apparent from many of the SOA deni-
tions that many of the technologies included in
an SOA denition, and by default SOA imple-
mentations, are established and conventional
protocols. To better understand the services
provided in many SOA denitions, a brief
explanation of some of the more commonly
used underlying technologies is provided. A
particular service may or may not be explicitly
Web based, but in the end it matters little since
the services provided by the architecture should
be transparently designed, implemented, and
provided. The general consensus from most
involved in Web services is that the services
are meant to be modular. This means that no
single document encompasses all of them, and
furthermore, that the specications are multiple
and (more or less) dynamic. This results in a
small number of core specications. Those core
services can be enhanced or supported by other
services as “the circumstances and choice of
technology dictate” (“Web Service,” 2007).
XML allows users to dene and specify the
tags used to capture and exchange data, typi-
cally between distinct and usually incompatible
systems from different companies or organiza-
tions. This means that XML is a good example
of middleware; it also means that XML enables
Web services. XML was one of the initial drivers
that provided the ability to conduct e-business
for many businesses in the Internet era. XML
cannot really be considered a service, but as
the language used to write many of the Web
services or service stack protocols.
SOAP, like all protocols, consists of a
set list of instructions detailing the action(s)
to be taken in a given circumstance. SOAP is
designed to call, access, and execute objects.
The original SOAP was typically for com-
munications between computers, and usually
involved XML-based messages. SOAP and
its underlying XML programming comprised
one of the rst Web service communication
stacks. One of the original Web services that
SOAP provided was called remote procedure
call (RPC), which allowed a remote computer
to call a procedure from another computer or
network. More recently, SOAP has taken on a
somewhat modied meaning so that the acro-
nym now means service-oriented architecture
protocol. In both cases, what SOAP does is
to use existing communications protocols to
provide its services. The more common early
SOAP contracts included XML applications
written for HTTP (hypertext transfer protocol),
HTTPS (HTTP over secure socket layer), and
SMTP (simple mail transfer protocol), among
others. It should be apparent from these that
many early SOAP implementations involved
e-commerce or e-business applications, which
means that the concern at the time when many
applications were rst developed was to move
sales and other data collected in Web portals
to back-end data stores.
CORBA is an OMG-developed standard
that allows different software components that
are usually written in different languages and
installed on different computers to work together
(Zhao & Siau, 2007). CORBA was developed in
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the early 1990s, and while not overtly an SOA
at the time, it actually performs many of the
functions in an SOA, using an IIOP- (Internet
inter-orb protocol) based service stack.
EJB is a component typically situated on
the server that “encapsulates the business logic
of an application” (“EJB,” 2007). EJB enables
the creation of modular enterprise (and other)
applications. The intent of EJB is to facilitate
the creation of middleware that acts as a go-be-
tween tying front-end applications to back-end
applications or data sources.
SIP is a signaling protocol designed for use
in telecommunications at the application layer. It
has generally become one of the primary proto-
cols used in VoIP (voice over Internet protocol),
H.323, and other communications standards.
SIP can be seen as a primary provider of Web
services for Internet-based voice communica-
tions such as VoIP (Sulkin, 2007).
Contract (Services)
Components of a service contract typically
include primary and secondary elements.
The primary elements consist of the header,
functional requirements, and nonfunctional re-
quirements. Subelements for the header consist
of the name, version, owner, RACI, and type.
Under functional requirements are functional
requirement descriptions, service operations,
and invocation. Nonfunctional requirements
include security constraints, QoS, transactional
requirements (the service part of a larger trans-
action), service-level agreement, and process
(“SOA,” 2007). The contract generally includes
metadata about itself, who owns it, and how it
is brokered, bound, and executed.
Interface
At this level of service provision, the interface
referred to is a segment of code that connects
the service with the data and/or business logic
(process). The interface describes how data will
be moved into and out of the data source by the
service, and must be designed to comply with
the physical (data, data structures, etc.) and
process (business logic) requirements of the
existing and/or legacy system.
Implementation
The implementation species the contract and
interface to be used for each service requested,
and contains the direct pathway into the data
and business logic.
Architecture
The service component of SOA has been
discussed, though admittedly at a high level.
However, the architecture component has not
yet been addressed and it will be helpful to
speak briey about the architecture segment of
SOA. Architecture in general refers to the art
(or science) behind the design and building of
structures. Alternatively, an architecture may
refer to a method or style of a building or a
computer system. So, if SOA is taken literally
as a description of its function, it could be
taken to mean a structured way of organiz-
ing or arranging the services in a business or
organization.
SOA FRAMEWORK
It is apparent from the existing denitions and
models that service-oriented architecture is
commonly seen as an architecture or way of
assembling, building, or composing the infor-
mation technology infrastructure of a business
or organization. As such, SOA is not a technol-
ogy in itself; rather, it is a way of structuring or
arranging other technologies to accomplish a
number of other tasks. This naturally leads to
the problem of a multiplicity of denitions of
SOA since many relatively similar structural
arrangements of services are possible. Many of
the denitions also indicate that the arrangement
and relationships between modules should be
loosely coupled rather than tightly coupled. This
allows for customization of services based on
need, and on-demand rather than some prede-
termined structure, but the downside is that it
also leads toward a plethora of denitions and
approaches to SOA implementation.
Some of the common features that seem
sensible to include in a formal denition of
SOA would relate to a common framework,
such as that specied by Krafzig et al. (2005)
or one of the other standards bodies. In other
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words, a framework would include metadata
describing the various important features of
SOA, how those features can be arranged, and
the libraries or location of services that allow
adopting organizations to arrange bindings or
contracts between themselves and the service
provider, independent of whether the service
provider is internal or external. We propose the
framework depicted in Figure 1 as a starting
point for visualizing SOA.
Several of the standards bodies have taken
a stance in creating or calling for a metamodel,
at least in some form. Among them are the Open
Group, OASIS, OMG, W3C, and to a lesser ex-
tent industry-related bodies such as Javaworld.
com, XML.com, IBM, and Oracle.
UDDI has become a very well-known
structured repository for services and service
components, which speaks to the universality of
the library or centralized database of services.
However, more standardization efforts will
be necessary to enhance the interoperability
of UDDI.
It also appears, especially with the in-
dustry denitions of SOA, that the contracts,
bindings, interfaces, service buses, and other
implementation-related portions of SOA are
important elements to be considered when at-
Figure 1. SOA framework
Service
Includes:
1. P hysical Transport Schema
2. A PI (Application Programming Interface)
3. Source (Service Library or Repository;
UDDI
,
internal or external
)
Service Implementation
Includes:
1. C ontract or binding detail
2. C ode Schema
Business Logic
(Process or Activity)
Data
(connection to data source;
internal or external)
Service Oriented Architecture
SOA
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tempting to give an overall denition of SOA.
This unfortunately could easily represent a
stumbling block in garnering consensus on a
denition of SOA since each of these companies
has invested signicant time, human, and other
likely resources toward development of their
specic pieces of the SOA pie. Each company
has invested heavily and thus will likely be less
willing to risk that investment and any potential
return and customer lock-in in order to simply
agree on standards. We can see a similar oc-
currence of this type of behavior in the current
format war going on for the high-denition DVD
market. Similarly, if the standards bodies have
political or industry leanings, agreement on a
common SOA denition and standards could
be difcult to achieve.
Another more recent development comes
from Shah and Kalin (2007). They proposed
that organizations adopting SOA follow a
specic path based on an analysis of business
challenges, including SOA business drivers and
IT barriers. This led them to speculate that a
specic adoption model be used to guide the
SOA implementation process. They indicated
that an ad hoc SOA model is better where the
benets of new services are specic to each
individual service, where the technologies may
be inconsistently applied (different implementa-
tions for the same service in different projects),
where services cannot be reused, and where the
increases in technological complexity translate
into decreased system response times. Shah
and Kalin ended with a call for a strategy- or
program-based SOA adoption model that is
situational.
We propose that a common denition of
SOA is possible and necessary, and call for
negotiations among interested bodies with the
aim of reaching a common denition of SOA.
We realize that in practice it might prove dif-
cult or even nearly impossible to expect such
a consensus to be arrived at, but a common
denition and structure of SOA would go a long
way toward dealing with some of the confusion,
misinformation, and hype regarding the entire
subject. Difcult though it might be to expect
this, a realization that SOAP, CORBA, RPC,
and XML among many other technological
tools have reached a point of relative agreement
amongst users if not ubiquity, at least related
to their underlying standards, should provide
some evidence that agreements can be reached.
Next, we will examine SOA from the research
perspective.
POSSIBILITIES FOR
RESEARCH
Research into SOA is extremely limited at this
point in time. What studies exist can be clas-
sied into several distinct categories. The rst
includes exploratory or recommendation-type
efforts that propose various means to approach
SOA implementation. These investigations
may or may not include proprietary industry
software, but most of these research efforts
propose the use of patterns or blueprints and
a metamodel of SOA as a means to under-
standing the SOA perspective. Second, in this
category are research proposals that examine
company-specic technologies or tools (i.e.,
IBM proposing the use of Rational Software,
including the Rational Unied Process) in rela-
tion to SOA design and implementation. Neither
of the rst two types of SOA research generally
involve ideas on how to measure SOA in terms
of success or failure, or even suggest metrics.
Finally, the third type of research articles focus
on empirical research.
SOA Development or Deployment
Patterns and Blueprints, and the
Meta-Approach
Stal (2006) took a roughly similar approach
to what we are attempting to do in this article;
he advocated using architectural patterns and
blueprints (software engineering patterns) as a
means to enable or foster efcient deployment of
SOA. He supported loose coupling of services in
a registry or library to the extent that he thought
that removing the services’ dependency on the
registry’s or provider’s distinct location would
benet the deployment of SOA. Stal maintained
that this would eliminate, or at least minimize, a
layer in the SOA framework. He also proposed
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a more tightly dened and controlled integration
of middleware using XML or similar tools. Basi-
cally, Stal suggested a metamodel and pattern
approach to dening SOA, but did not suggest
what the research might accomplish or how
the research into SOA would be framed. Kim
and Lim (2007) also proposed a distinct means
to implementing SOA, using in this instance
business process management in addition to
a variant of the SOA framework specically
dealing with the telecommunications industry.
Similar to Stal, Kim and Lim did not propose
empirical research into SOA, but rather focused
on implementation and standards in a specic
industry.
Shan and Hua (2006) proposed an SOA
approach for the Internet banking industry.
They also compiled a list of patterns that have
been proven successful for other online service
industries. However, the models they used and
ended up with are very detailed regarding how
SOA should be implemented for rst online
companies in general, and then Internet bank-
ing specically. This again does not propose
or frame specic research but rather suggests
an implementation approach and a structure
for SOA.
The ESB is explained in detail, but from a
general perspective rather than a company-spe-
cic approach in Schmidt, Hutchison, Lambros,
and Phippen’s (2005) expository. The article
is informative regarding ESB implementa-
tion and design patterns, but it is not research
oriented.
Crawford, Bate, Cherbakov, Holley, and
Tsocanos (2005) proposed a different way to
structure SOA, what they called on-demand
SOA. They essentially proposed an even looser
coupling of services and their connecting ele-
ments than in other perspectives of SOA.
They argued that this would allow much more
exibility for the adopting organizations and
the end users.
Company-Specic and
Commercial Tool-Based SOA
Deployment
Brown, Delbaere, Eeles, Johnston, and Weaver
(2005) presented an industry-oriented per-
spective on the SOA puzzle. They suggested
an approach to service orientation using the
proprietary IBM Rational platform. Their rec-
ommendations follow similar paths as some
previous research, but are also ltered through
the IBM Rational lens. The article is primarily
illustrative in nature, suggesting how to best
implement SOA using IBM Rational tools. In
a similar vein, Ferguson and Stockton (2005)
also detailed IBM’s programming model and
product architecture.
De Pauw, Lei, Pring, and Villard (2005)
described the benets of Web Services Navi-
gator, a proprietary tool created to provide a
better visualization of SOA and Web services
in a loosely coupled architecture. The tool can
help with design-pattern, business-logic, and
business-process analysis, and thus help with
SOA architecture design and implementation.
Jones (2005) suggested that SOA, service,
and Web service standards were “on the way”
and provided a list of existing tools, such as
UML (unied modeling language) and/or the
rational unied process that could aid the SOA
(or service) design process. However, he also
advocated the push toward formal denitions
of such SOA basics as services, to the end of
providing a more coherent and cohesive struc-
ture that he thought would enhance the ability
of developers and adopters to understand and
deploy SOA.
Research-Based Perspectives on
SOA
Chen, Zhou, and Zhang (2006) proposed an
ontologically based perspective on SOA, Web
services, and knowledge management. They
attempted, with some success, to integrate
two separate research streams into one. They
presented a solution to show that semantic- and
syntactic-based knowledge representations
could both be depicted with a comprehensive
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ontology that also described Web service com-
position. While their framework represents a
step toward automated (Web) service composi-
tion, more research is still needed.
Borkar, Carey, Mangtani, McKinney, Pate,
and Thatte (2006) suggested a way of handling
XML-based data in an SOA or service environ-
ment. Their idea involved the use of data both
able to be queried and unable to be queried, and
would necessarily also involve XML-formatted
data. This represents empirical research into a
part of SOA, namely, the underlying services,
and is at least a step in the right direction, al-
though it does not enter the realm of research
into the efcacy or ROI of SOA.
Duke, Davies, and Richardson (2005)
recommended and provided details on using
the Semantic Web to organize an organization’s
approach to SOA and Web service orientation.
They suggested that combining the Semantic
Web and SOA into what they called Semantic
SOA would provide benets to adopting orga-
nizations. Then they further proposed an onto-
logical model of the Semantic SOA, attempting
essentially to create a meta-metamodel of SOA
using their experience with the telecommunica-
tions industry as a case example. This is one of
the few high-level articles that can also be seen
as empirical research.
Zhang (2004) explored the connection
between Web services and business process
management, and described the modular nature
of the service (and Web service) perspective.
He detailed the software industry’s approach
to Web services and provided evidence that
standards development would quickly mature,
beginning in 2005. He maintained that once
standards were agreed upon, a connection to
business process management would be easier
to sell to businesses. Zhang also developed a
prototype e-procurement system that composed
external services to operate.
Malloy, Kraft, Hallstrom, and Voas (2006)
developed an extension to WSDL. They insisted
that Web services’ specications were “typically
informal and not well-dened,” and proposed
what they called an intermediate step between
requiring more formal and rigorous service
specications and the informal nature of the
existing service specications. They accom-
plished this balance by extending WSDL to
include support for application arguments that
would help automate and expand the ability of
services to operate in multiple environments.
They provided an example of how their WSDL
extension could allow a single service to func-
tion successfully in different applications using
multiple zip code formats (ve vs. nine digits,
and hyphens vs. no hyphens).
Verheecke, Vanderperren, and Jonckers
(2006) proposed and developed a middleware
level that they called the Web services manage-
ment layer (WSML). They saw the primary
advantage of their approach in that it provided
a reusable framework. They further believed
that the use of their framework would enable
“dynamic integration, selection, composition,
and client-side management of Web Services
in client applications” (p. 49). They were aware
that their approach could cause some problems
in a distributed system since implementation of
it resulted in a centralized architecture.
Hutchinson, Henzel, and Thwaits (2006)
described a case in which an SOA-based system
was deployed for a library extension collabora-
tion project. Much of the case details the SOA
approach itself, and explains the experiences
of the project developers and implementers.
They noted that while the SOA architecture
could be expected to reduce the operational
maintenance costs overall, the way the system
was specied and delivered in this particular
case might require more work from IT to keep
some services, such as ash players, up to date.
While the authors did not specically mention
it in the article, perhaps a more loosely coupled
architecture might alleviate some of those op-
erational maintenance costs.
Li, Huang, Yen, and Cheng (2007) proposed
a methodology to migrate the functionality of
legacy systems to a Web services or SOA archi-
tecture. They used a case study to investigate
the efcacy of their proposed methodology,
nding that while it was possible to make
such a migration from legacy systems to SOA
(or Web services), the changes that it required
Journal of Database Management, 19(3), 42-54, July-September 2008 51
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is prohibited.
from the organization were considerable, and
some process reengineering would likely be
necessary.
MEASURING SOA AND SOC
SUCCESS
Another tricky issue in SOA and SOC imple-
mentation is the measurement or evaluation
of success. Traditionally, software (or system)
successes and failures have been estimated by
the usual suspects: traditional measures such
as ROI, net present value (NPV), breakeven,
internal rate of return (IRR), or other similar -
nancially based approaches. Similarly, software
itself has usually been measured in terms of er-
rors or productivity via numeric methodologies
such as lines of code, COCOMO (constructive
cost model), and similar estimation techniques.
These approaches are all based rmly on the
idea that if we can assign some number to a
system, then we can compare them across proj-
ects, systems, or organizations. The problem is
analogous to the question often asked regarding
enterprise resource planning (ERP) systems: If
all of the Fortune 100 companies implement
the same piece of software, such as SAP, then
what allows one organization to differentiate
itself from another if they have standardized
on SAP’s best processes and best practices?
One way to answer that question is to examine
other measures of success such as competitive
advantages (Siau, 2003), competitive neces-
sity, exibility, agility (Erickson, Lyytinen, &
Siau, 2005), nimbleness, responsiveness, and
other relevant intangibles. We would even
propose that the best way to evaluate SOA or
SOC implementation is not ROI. Intangible but
critical factors such as competitive necessity,
agility, on-demand abilities, and responsiveness
should be the decisive factors.
Nah, Islam, and Tan (2007) proposed a
framework and critical success factors for es-
timating the success of ERP implementations.
They empirically assessed a variety of imple-
mentation success factors including top-man-
agement support, project team competence, and
interdepartmental cooperation, among many
others. While the study answered a number of
important questions regarding ERP implementa-
tions, the issue of assessing intangibles in terms
of success factors remains a problem, not only
for ERP-type implementations but also for other
system types as well, especially for SOA since
the SOA approach can be seen as an alternative
in many ways to ERP.
Langdon (2007) noted that while many
economic-based studies indicate that IT projects
add value at the macrolevel, little has been done
to assess how value is added at the more micro or
individual project level. Specically, Langdon
proposed and evaluated a research model that
included (IS) integration and exibility as capa-
bilities that could lead to IT business value. Of
course, exibility and integration are only two
components of a larger IT capabilities structure,
but the study indicates that the rst steps have
been taken to study intangibles in the context
of an IT systems development project.
Two intangibles in the IT success-factor
context are the oft-cited agility or nimbleness
of a company or organization. An entire genre
of systems development has emerged based on
the principle of agility. However, there is little
empirical evidence supporting the value added
from such development approaches (Erickson
et al., 2005). Since a growing number of SOA
installations are constructed as ad hoc, which
is in a basic sense agile, we propose that in
environments where agility and nimbleness
are important, so in turn are SOA and SOC
important.
CONCLUSION
From the literature, it appears that only a few
efforts can be said to be empirical research. A
majority of the research efforts involved cre-
ated tools or language extensions that would
increase the interoperability of services, while
other research proposed standards modica-
tions. Many of the remaining articles published
proposed new tools or the use of existing pro-
prietary tools, described an approach to SOA
from specic perspectives, or proposed model
or metamodel changes. A limited number of case
studies detailing SOA, Web services, or service
deployments or implementation efforts provide
52 Journal of Database Management, 19(3), 42-54, July-September 2008
Copyright © 2008, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global
is prohibited.
experience reports on how best to implement
such systems.
As far as we can determine, virtually no
research has been formally done regarding the
benets and drawbacks of SOA or Web services.
Two problems with this are likely to revolve
around the nebulous nature of SOA and Web
services in terms of the widely varying denition
and the emerging standards issue. An effort to
identify SOA and Web services metrics would
help to get research into this area started.
Another area of interest involving SOA and
Web services adoption is the cultural and struc-
tural impacts on the organization or business. A
number of articles note the importance of those
elements, but little has been accomplished in
terms of research specically connecting SOA
or Web services with cultural and structural
changes in organizations.
A variety of standards bodies are working
separately toward formal denitions including
metamodels, and a number of SOA vendors,
among them some of the very large and estab-
lished software industry players, have emerged.
While the effort toward standardization is direly
needed and commendable, a more collabora-
tive approach would, in our opinion, benet
the industry and implementing companies and
organizations as well. The seeming result of the
rather haphazard approach to SOA appears to
indicate that an increasing number of imple-
menting organizations are nding it difcult
to assess the cost benet of the entire services
approach. Research efforts at this point appear
to be in a similar state of disarray. Until a more
coherent picture of SOA emerges, its image is
likely to remain slightly out of focus, and re-
search in the area is likely to remain somewhat
unfocused as a result.
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John Erickson is an assistant professor in the College of Business Administration at the University of
Nebraska at Omaha. His research interests include UML, software complexity and Systems Analysis and
design issues. He has published in journals such as the CACM, JDM, and in conferences such as AMICIS,
ICIS WITS, EMMSAD, and CAiSE. He has also co-authored several book chapters.
Keng Siau is the E. J. Faulkner professor of management information systems (MIS) at the University
of Nebraska, Lincoln (UNL). He is the director of the UNL-IBM Global Innovation Hub, editor-in-chief
of the Journal of Database Management, and co-editor-in-chief of the Advances in Database Research
series. He received his PhD degree from the University of British Columbia (UBC), where he majored in
management information systems and minored in cognitive psychology. Dr. Siau has over 200 academic
publications. His research has been funded by NSF, IBM, and other IT organizations. Professor Siau has
received numerous research, teaching, and service awards. His latest award is the International Federa-
tion for Information Processing (IFIP) Outstanding Service Award in 2006.
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