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CREATION OFVIRTUALENTERPRISES 571VANBuyer Translator TranslatorVendorVANA2C 3B1Buyers SellersVANA2C 3B1BuyersBuyersVAN
VANA2C 3B1BuyersBuyers SellersSellersVANA2C 3B1BuyersBuyersFigure 3: Buying and selling using EDI.Just as Internet services today are provided by inde-
pendent Internet service providers (ISPs), EDI services
can be obtained through value-added networks (or VANs)
(Figure 3). Companies such as GE, IBM, and AT&T pro-
vide these EDI services, depending on individual and
group needs. EDI frameworks allow for the establish-
ment of electronic bulletin boards where various needs
can be posted and subscribers can respond to the busi-
ness opportunities using EDI. The U.S. Defense Logistics
Agency (DLA) is managing the federal government’s im-
plementation of EDI. In recent years, most of the VANs
have offered a hybrid EDI/Internet-based service where
the World Wide Web has been used to exchange EDI-
based documents between customers and businesses. Ad-
ditional information on EDI can be obtained from a num-
ber of sources, including books and the Internet (ECRC,
2002).Computer Architectures and Technologies
That Support the Realization of VEs
When teams and resources are distributed and linked via
the Internet, as mentioned earlier, the major problem is
the ability to communicate across heterogeneous com-
puter platforms. The various software modules and sys-
tems used to accomplish engineering and business func-
tions can be implemented on various software paradigms
or frameworks. One of the more important (yet basic) con-
cepts in the realm of software computing is the notion of
an “object.” An object-oriented software program (or an
“object”) can be viewed as a discrete software entity that
contains some “data” that can be manipulated using cer-
tain functions or operations. In general, such an object has
several advantages over traditional software entities built
using non-object-oriented languages such as Fortran. Ob-
ject orientation provides three distinct advantages includ-
ing ease of maintenance, ease of change, and less time to
create. Objects can be reused, and in most cases, they pro-
vide a basis that can be extended. Objects can be created
from a template. The template used to create a group of
objects is termed a “class.” In a manufacturing or any
other enterprise, most objects model real-world entities.Software entities can send messages to objects with spe-
cific requests; the objects, in turn, send their responses
through messages.
In an Internet-based VE, the various software entities
that are distributed can be viewed as engines and tur-
bines working together to propel a given enterprise. Us-
ing distributed object-computing methods, communica-
tion among the physically distributed software systems is
possible. Distributed computing allows objects to be dis-
tributed in an heterogeneous manner across the Internet
by extending object-oriented programming concepts so
that these distributed objects behave as a unified whole.
These objects can reside in their own address space out-
side of an application and be distributed on different com-
puter platforms linked via the Internet; however, they will
behave as if they were local objects. There are several
ways to implement a distributed computing environment,
which is a key requisite to realize a fully functional VE.
Three of the most popular paradigms and approaches are
discussed in the following sections: the common object re-
quest broker architecture (CORBA) from the Object Man-
agement Group (OMG), the distributed component ob-
ject model (DCOM) from Microsoft, and Jini technology
from Sun Microsystems. Among these three, CORBA and
DCOM are architectures and can be compared. Jini is built
on top of the Java language and has become popular as it
enables systems to function as a federation of services.The Common Object Request Broker Architecture
(CORBA)
The Object Management Group is the world’s largest com-
puter industry consortium whose mission is to define a
set of interfaces for software to be interoperable. OMG
is a nonprofit organization with around 750 members.
The OMG provides a structure and a process through
which its members can specify technology and then pro-
duce commercial software that meets those specifications.
CORBA is an industry consensus standard that defines
a higher-level facility for distributed computing. The dis-
tributed environment is specified using an object-oriented
approach, which masks the differences relating to object
location, type of operating system or computing platform,