________________________________________________________________
J.J. Dubray, Yuzo Fujishima, P.
Curtin, A. Chaloori
NEC Systems Boston Technology Center 305 Foster Street Littleton, MA 01460 |
Correspondence should be addressed to: Tel:
(978) 742-8816 |
________________________________________________________________
The
business-to-business eCommerce environment has created new challenges to IT
organizations. In a few months, a corporation success is going to be measured
by its ability to open its systems and transact with several hundreds to
several thousands business partners.
Fig
1. The eBusiness Environment
This
problem can be viewed as another integration problem, but it is actually more
than that. The number of systems to integrate requires the definition and wide
acceptance of standards from middleware to business protocols and semantic.
Unlike application-to-application interactions (A2A), business-to-business
(B2B) interactions are legally binding. In addition to guarantied message
delivery, companies must now acknowledge the validity of the messages and its
acceptance.
Current
IT infrastructures are not ready to address the complexity of
business-to-business eCommerce. They are not designed to support and handle
near-real-time business messages. EDI, CORBA or DCOM were not built to support
large business communities of several thousand partners linking all their systems
together. HTML and the current web-architecture are not well suited to exchange
business information in a reliable and secure fashion. Conventional object technology cannot fit into an e-Business environment:
In
order to address all these issues and provide a framework to design and
implement eBusiness solutions at NEC, our group has developed a generic
web-based architecture for business-to-business eCommerce systems based on the
concepts of:
·
Business Messages
·
Business Services
·
Business Processes
·
Business Documents
The
first part of this presentation focuses on describing an eXtensible Object
Model (XOM) which is using well-formed XML documents to model business objects.
The second presents our eBusiness Architecture (eBusiness Process Engine -
eBPE) that is using XOM as one of the founding technology, and constitutes a
run-time facility for the XOM concepts.
Fig 2. The Object
Oriented Design Metamodel
A
Java or C++ run-time facility needs to constantly refer to the class definition
to handle its instances. Referring to an external entity with proprietary encoding
is an important issue in the development of highly distributed systems.
Objective-C and SmallTalk have partially solved the problem by providing a
semantic based method invocation. However, instance's data structure is still
constrained to a class structure. A key concept in the OMG distributed
component specification [1] is to wrap messages into a rigid request and
marshal all the arguments in the Semantic
Data Object that is passed as a
set of arguments with the request message. The receiver processes the SDO to
extract key value-pairs. The major issue with the approach is the maintenance
of the SDOs code when the business object format evolves.
We
suggest to model business objects after well-formed XML documents [2] (i.e.
not necessarily associated with a schema). The major benefit of this approach
is that now the "instance" carries both data and data structure. This
approach features several benefits in a highly distributed environment like
eBusiness. One of the most innovative is instance evolution or extensibility.
In the OO world once an instance has been created, its structure has been set
in stone. The only evolution possible is to create a new instance of a new |
|
class or subclass, then populate this new
instance with some or all of the content of the original instance and finally
delete the original instance. Well-formed XML documents can be appended with
new data structure and data without loosing the integrity of the original
instance. This makes them both flexible and adaptive.
Instances of well-formed XML documents (XOM
instances) are concept that is hybrid between the concepts of Object and
Documents. You can access the data through a strict semantic, and you can
augment the data at run-time like you would edit a document.
In addition to being distributable
components in the OMG sense [1], XOM instances are also semantically accessible
(as opposed through an interface) [2,3]. You don't need to share the knowledge
of all or part of the data structure to access the data, you only need to share
a common semantic. Furthermore, semantic translator can easily be built in the
access layer, in the case where the two systems would not share the same
semantic.
The extensible object model has also some
major design implications:
The major drawbacks of this approach are the
instance memory model, which is not optimized for space conservation or content
retrieval, and the re-usability of data structure definitions.
We
have designed and implemented a run-time facility that exploits the concepts of
the extensible object model. This work is the basis of an eBusiness
Architecture that we have developed for NEC and its business units to
facilitate the development of business-to-business eCommerce Solutions [5].
Fig 4. eBusiness Process
Engine
From
an architecture perspective, the eBPE is designed with two components:
·
An extended workflow engine (Application Logic
Layer)
·
A business document server (Data layer)
The
extended workflow engine manages users and business partner systems
interactions with the business document server and operational systems
according to a business process definition (Fig. 5). The application logic is
clearly divided into workflow logic and services. A workflow definition
specifies the choreography of service invocation and documents that will be
passed to, modified, or created by the services. The use of well-formed XML
documents as arguments of the service invocation, in combination with the
projection layer greatly simplifies the requirements of a Service Definition
Language compared to IDL.
Fig. 5 A requisition
business process definition (After OBI business process [6])
The
business document server provides a unified view of the data model organized in
well-formed XML business documents. This XML document repository is augmented
with the projection layer that enables the decoupling between our data model
and the various services that consume, create or update business data.
The
eBPE is compliant with XML-based industry standards like RosettaNet, OBI, and
the OAG.
[1]
P. Eeles et al "Building Business
Objects", Wiley Computer Publishing, 1998
[2]
J.J. Dubray et al "Business Object Modeling: an XML-based approach",
Accepted for publication in the Journal of Markup Languages: Theory &
Practice, 1999
[3]
T. Berners-Lee et al "Web
Architecture: Describing and Exchanging Data" W3C Note, 7 June 1999
[4]
J. Boyer et al "Extensible Forms
Description Language (XFDL) 4.0", Submission September 2, 1998
[5]
D. Wiedmer et al "E-Business
Process Engine: A Solution Framework for E-Business Integration", White Paper, August 1999.
[6] Open Buying on the Internet Consortium,
http://www.openbuy.org/