Abstract
This paper explores the challenges of constructing a distributed e-business architecture based on the concept of Request Based Virtual OrganiZation (RBVO) and presents a solution based on ebXML, Open Source e-business component framework and Peer-to-Peer (P2P) technologies. RBVO is a value network, which is dynamically formed upon demand to meet identified business opportunities.
The architecture proposed in our work incorporates an innovative approach to discovery and matchmaking of business partners and services that includes usage of Peer-to-Peer (P2P) technology. The increasing maturity of P2P based solutions allow, where applicable, for their implementation in the B2B area. The basic P2P concept fits well with that of highly dynamic Virtual Organizations - to find potential partners and services on demand, to group business entities into communities, to provide added value otherwise unavailable, to assure flexible fail-over scenarios and to increase overall service availability.
The presented work introduces an abstract discovery and matchmaking interface, which can be implemented using both P2P and a more traditional, registry-based approach. Selection of the potential domains of partnership is performed using XML-based meta-data, which describes capabilities of the domains. The particular P2P implementation of interest is Project JXTA. XML-based definitions are used to describe partners' capabilities in order to pre-screen the best candidates to service a client request, using pluggable matchmaking strategies and the data of previous activity. This approach allows maximizing utilization of business partners' resources and increases their competitive advantage.
Keywords
Table of Contents
The traditional B2B techniques, including the modern standards such as the ebXML framework, mostly address the issues of relatively large businesses, even when claiming to be enablers of B2B infrastructure for Small and Medium Enterprises (SME). Larger businesses follow more stable collaboration patterns, have better established partner base and typically much stronger IT capabilities, which is naturally reflected in B2B architectural frameworks. SMEs, on the other hand, often tend to do business in a more ad-hoc manner and constantly look for the best trading options in order to survive and be competitive. For a number of reasons, SMEs do not immediately benefit from the B2B frameworks tailored for larger businesses, however the economic potential of SMEs suggests that they should not be deprived of e-business benefits. The Request based Virtual Organization (RBVO) concept attempts to address the needs of SMEs by introducing on-demand and just-in-time dimensions in addition to other aspects of virtual organizations.
The original motivation of the research discussed in this paper was to ensure suitability of certain e-business concepts, such as RBVO [Svirskas A and Roberts R 2003], for SMEs in several regions (UK, Greece, Germany, Bulgaria) and various industry sectors (food, timber, furniture) of Europe. The concept of Virtual Organization (VO) must be supported by appropriate architectural and technical implementation solutions, as well as suitable operational services, in order to provide its expected value for business partners. In addressing this particular task certain general B2B collaboration aspects were identified which led to the development of a generic architectural framework. Three areas of particular importance were singled out for end-to-end business collaboration; discovery and matchmaking of the business partners, secure and reliable business data transmission and business process specification and enactment. These areas, especially the first two, are addressed in detail along with the description of practical steps for deriving an e-business service solution architecture from the concepts of virtual organization together with the typical business requirements of SMEs that wish to participate in such arrangements.
In order to fully reveal the potential of RBVOs as highly dynamic virtual business formations an innovative approach is taken, which is based on natural trading behaviour pattern, expressing direct interaction between partners. Recent developments in the peer-to-peer (P2P) computing field allow this pattern to be implemented. This approach results in a more flexible topology for virtual formations and bridges the gap between the isolated 'islands' thus forming a business to business grid that widens the possibilities for collaboration and increases their availability to business partners.
The further organization of this paper is as follows: Section 2 introduces the LAURA project as a reference implementation, states the requirements and presents a conceptual solution, Section 3 discusses specific B2B RBVO collaboration aspects and introduces the P2P approach, Section 4 presents the key design decisions based on the architectural requirements and technology needs of the solution, introduces the reference framework and explains its operation and communication between the peers of the LAURA network. Section 5 concludes with a summary of the overall effort and outlines future research.
The proposed e-business environment consists of the two main parts: a business service infrastructure and e-business software system, which supports the infrastructure. In this section we will outline the business requirements for such a solution, later we will examine architectural and technical challenges arising as a result of the business requirements.
Firstly, the solution should be simple and easy to use for business users as simplicity is a crucial factor when attracting SMEs without previous e-business experience. Secondly, the solution should address the most common needs of SMEs. According to a survey, conducted by the LAURA consortium in different regions of Europe (Greece, Bulgaria, Germany), most of the SMEs would like to increase their sales, customer base and reach for the new markets as a result of e-business practice adoption. Increase of the supplier base is considered a little less important, but still a strong driver [LAURA 2003]. The results of this survey are similar to the results of several other surveys, thus enabling us to take them as the basis for the solution design. Thirdly, the solution, as well as capturing the common needs typical for such e-business formations of SMEs will be used to develop a reusable framework that can be used as a reference when building similar solutions. Certain SME-specific collaboration patterns should be distinctively captured and supported by business and technology solutions. Figure 1 presents the conceptual model of the LAURA project from the structural and life-cycle perspectives.
The model builds on the lifecycle and structural concepts of RBVO and introduces a business context dimension, aligned with the business needs and other requirements of SMEs. The following concepts distinguish the LAURA conceptual model:
LAURA Network is an multiple-domain collaboration infrastructure, which defines a set of rules and provides arrangements for inter-regional (inter-domain) business collaboration between the SMEs.
LAURA E-Commerce (EC) Shell (domain) is a set of SMEs belonging to a certain geographical region and registered with the LAURA network via a LAURA support centre. The notion of domain and presence of multiple domains in the LAURA network allows referring to the architecture as distributed.
LAURA EC Kernel is the focal point of an EC Shell. The main component of the kernel is the support centre, which is responsible for provisioning of both commercial and IT services to the SMEs (outsourced to the IT provider, if needed). In a technical context the EC Kernel itself, the Support Centre or the software behind it is also referred to as a LAURA Domain Hub.
LAURA Business Collaboration Service is the software service in charge of communication between the EC Kernels and/or other participants of the LAURA Network.
In this section we will discuss interaction between the business partners from the structural perspective of RBVO, i.e. what entities constitute and facilitate a RBVO, what data and messages are being passed between these entities and what are the options for the most efficient interaction.
Traditionally, modern e-business applications were being built (both technically and conceptually) with a client-server interaction paradigm in mind. There are different flavours of client-server interactions in e-business ranging from fully centralized hub-and-spoke solutions to point-to-point links between the peers. In most cases, the structure of a traditional VO is assumed to be relatively static and the explicit presence of different intermediaries or static knowledge of participants is taken for granted. Examples of such interaction are vertical B2B marketplaces, big vendor sponsored supply/distribution value networks, B2C marketplaces and similar.
However, the true anatomy of interaction within virtual communities, especially highly dynamic ones such as RBVO, is peer-to-peer by its nature. The participants do not seek "a server", a "centre" or a "hub"; they seek partnerships irrespectively of the underlying infrastructure, partner location, etc. This is especially true for SMEs, as their business interactions are often more complex than these of bigger businesses.
This phenomenon, also known as peer-to-peer communication, has been successfully exploited for consumer-oriented purposes [Caviglione 2004], and can be also applied to B2B virtual communities as the necessary technical provisioning becomes widely available. Definitions of P2P vary in emphasis depending on the application. [Milojicic et al. 2002] define P2P as "a class of systems and applications that employ distributed resources to perform a function in a decentralised manner", and go on to explain that these resources can be anything from computing power to data and network bandwidth. In the context of this work we apply the notion of resource to business capabilities of the partners involved in RBVO formations.
In the LAURA network context there are two types of peers:
Domain Hubs, acting on behalf of SMEs, which are not capable of using LAURA business collaboration service themselves
Advanced SMEs, using the LAURA collaboration service connected to their back-office and/or ERP systems
The domain hubs bridge the peering gap for the SMEs without stand-alone collaboration capabilities and also might provide certain services for the advanced SMEs such as authentication/authorization, coordinated regional marketing campaigns, etc. Therefore, a domain hub and a LAURA support centre act together as an e-chamber of commerce for local SME businesses.
Project JXTA [JXTA 2003] provides a simple and generic concept for P2P networking and provides a base P2P infrastructure over which other P2P applications can be built. The JXTA Protocols document describes six XML-based protocols that standardise the methods used by peers to discover each other and interact to form peer groups. JXTA technology has been designed to be independent of programming language, system platform and networking platform and is accessible to a wide range of devices. It uses a virtual network overlay on top of Internet and non-IP networks, allowing traversal of firewalls and NATs using a range of transport methods.
JXTA uses a number of protocols to ensure that a peer can join the network and discover other peers. For any P2P network, the first issue is that the new peer must know how to contact at least one other peer. All resources (e.g. peer, peer-group, pipe, service) within a JXTA network are represented by advertisements containing information about a resource formatted as an XML document following a defined standard. A peer-group is an aggregation of peers with common interests although JXTA does not specify how peer-groups should be created, leaving this to the application developer. Certain well-known peers within the JXTA network maintain large caches of advertisement indices in order to support the peer-group and these are known as rendezvous peers.
In the context of this project, JXTA provides a framework that would allow developers to concentrate on providing high level, business-oriented functionality, rather than implementing the underlying infrastructure. The slogan "JXTA Technology: Creating Connected Communities" captures the essence of JXTA technology, and also particularly matches the essence of the RBVO concept. The proposed LAURA virtual network is structurally similar to the general JXTA virtual network [JXTA2 2004].
Having explained the LAURA business case, the RBVO concept, the architectural requirements and the relevant technologies we can summarize our ideas by providing an architectural reference framework (depicted in Figure 2), which could serve as a basis for a B2B solution implementation. The rest of this section provides an explanation of this framework.
The presented framework reflects the main RBVO realization principles and their solutions, namely the concepts of a domain, its hub, inter-domain collaboration, federated e-business network, lightweight SME client and managed public business processes. The current principal decisions we made are the following:
WWW interface and HTTP(S) protocol is used for SME end-user access to the LAURA network.
Open Source e-business component framework from The Open For Business Project - OFBiz [OFBiz 2003] is used for the basic functionality such as catalogue management, user registration, business transaction monitoring, reporting, etc. [Roberts et al. 2003] elaborate on OFBiz usage for the LAURA project.
Discovery of the remote domains by a domain hub is encapsulated into a generic interface, which allows different discovery techniques. For example, one of them is based on emerging Peer-to-Peer (P2P) technology and its Java implementation in particular - JXTA (JXTA 2003). Domain hubs use JXTA to exchange their meta-data and build lists of remote domains for subsequent product search within the selected domains.
Domain hubs perform search of products and partners on behalf of SMEs by propagating the queries to the selected remote domains. Secure and reliable messaging is needed in this case to ensure the required degree of accuracy and, inherently, trust in the system. The transport option chosen for this task and subsequent business conversations is ebXML messaging [EBMS 2003]. In order to be able to use other business messaging options a generic interface is also used here.
Business processes specify the choreography of business transactions in collaborations between the partners and these are modelled and specified using ebXML BPSS [EBXML 2003].
Business documents are modelled according to the Open Applications Group Integration Specification - OAGIS [Dubray 2001], [Flebowitz 2002], [Rowell 2002].
The next section explains the structure and the basic operational principles of the LAURA Domain Hub. As it was briefly explained earlier, the domain hub is one of the key elements of our solutions architecture. Introduction of this concept was influenced by the context of the LAURA project - limited IT resources and capabilities of many European SMEs, which led to a decision to host electronic catalogues of SMEs and to provide them with the necessary B2B functionality using a portal-type solution.
An explanation of the peer implementation can be made by dividing it functionally into the following parts, (as depicted in Figure 2):
Business Logic Service
Conversation/Messaging Service
Discovery Service
These services work together to fulfil the overall task of a peer.
The discovery service does not have direct exposure to the end user nor any business-oriented purpose. However it is important as it glues together the whole LAURA network. The discovery service is responsible for:
Discovery of other peers of the LAURA network
Obtaining the peer meta-data
Maintaining a registry of other peers, including messaging endpoint information
Periodic communication with other peers to determine their availability (ping-pong), utilization, message round-trip time, etc.
Selecting the best peers to forward a particular product/service search request from a local SME, based on the peer meta-data and the historical business transaction data
Answering requests from other peers
The discovery service has a generic API, which encapsulates the mentioned functions and, therefore, shields other parts of the peer implementation from the underlying specific protocols. The traditional approach used for discovery of services and other objects in Web Services and ebXML environments is registry-based - UDDI and ebXML registry, respectively. Our solution innovates in this case and uses a P2P based approach, JXTA in particular, in order to accommodate more dynamic needs of the LAURA network participants and eliminate single points of failure of the network.
The conversation/messaging service is the main communication instrument used by peers to transfer business messages. This service uses the results provided by the discovery service, such as messaging endpoints and is responsible for business message delivery between the peers for:
Searching for products/services
Conducting business collaborations
Maintaining traceable information about transferred messages in order to provide the necessary information in case of any problem
The conversation/messaging service is relatively straightforward and ensures point-to-point communication between the peers and uses ebXML messaging. One issue with this service is the absence of a standard API which has a negative impact on ebXML interoperability by leaving only the "external" part of it. In other words, two different ebMS implementations can communicate with each other (if fully compliant) but there is no a standard way for an application to interact with the Message Service Interface (MSI). We address this issue by introducing a generic messaging API, which encapsulates the specifics of different ebXML Messaging implementation or other business messaging protocols.
The business logic service is a part of the peer implementation responsible for:
Enactment of business collaborations between the partners
Interacting with conversation/messaging service for sending of business messages as necessary
The business logic service is the most complex part of the peer implementation and its details are not covered in this paper due to the lack of space. In essence the Business logic service is used by the application, which is the bridge between the business logic service and the end-user or another application. In our domain hub case, this application is the modified OFBiz framework, an open source e-business component framework, which also serves as a portal for the SMEs and the LAURA network operators.
The main e-business collaboration issues crucial to the success of RBVOs are business partner matchmaking and the subsequent partner-to-partner collaboration. This paper concentrates mainly on matchmaking which can be decomposed into discovery of the most suitable domains of interest and then a later search for the best business opportunities within the domains for pursuing the formation of inter-domain virtual communities, specifically RBVO in our case. The discovery and selection aspect of the most relevant domains is especially crucial in virtual communities of SMEs, due the vast number of participants, geographic spread, lack of knowledge about each other and potential capabilities. All these factors tend to cause business value dispersion and decreased business competitiveness of the participants. Our solution makes an attempt to innovate using modern virtual organization concepts, such as RBVO architectural approaches in order to enable added value on-demand concentration. Therefore, a distributed e-business architecture solution suitable for SMEs has been designed in the framework of the LAURA project.
One of the main results of the paper is the introduction of a reference framework, which could serve as a basis for a B2B solution implementation. The presented framework is based on the principles of Service Oriented Architecture and provides a modular set of services that together form the LAURA Business Collaboration Service. This Business Collaboration Service can be embedded into various environments, such as LAURA domain hubs or the B2B software systems of advanced SMEs. The LAURA domain hubs and the SMEs using LAURA Collaboration service are together referred to as LAURA peers. This implementation based on a P2P approach provides a means of aligning the structure of the IT architecture to the flexible and loosely federated structure of an RBVO while the P2P approach has a good potential to make B2B e-business more accessible and attractive for SMEs.
As part of the LAURA project a prototype e-business system for participating SMEs in the selected regions is being undertaken with a view to gauging the viability of using such a system to support collaboration for RBVOs through full regional and inter-regional implementations.
[Caviglione 2004] Caviglione, L., The "Dark Side" And The "Force" Of The Peer-to-Peer Computing Saga. P2P Journal. January 2004. http://p2pjournal.com/issues/Jan04.pdf
[Dubray 2001] Dubray, J.J. (2001). OAGIS Implementation Using the ebXML CPP, CPA and BPSS specifications v1.0. http://www.openapplications.org/downloads/whitepapers/frameworks
[EBMS 2003] OASIS ebXML Messaging Services TC. http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=ebxml-msg
[EBXML 2003] ebXML Framework.http://www.ebxml.org
[Flebowitz 2002] Flebowitz, M. OAGIS 8.0: Practical Integration meets XML Schema. XML Journal, Volume 03, Issue 09. http://www.openapplications.org/news/articles/XMLJ-Sept02-OAGIS8PracticalIntegrationMeetsXMLSchema.pdf
[JXTA 2003] Project JXTA. http://www.jxta.org/
[JXTA2 2004] JXTA Technology: Creating Connected Communities.http://www.jxta.org/project/www/docs/JXTA-Exec-Brief.pdf
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[OFBiz 2003] The Open For Business Project.http://www.ofbiz.org
[Roberts et al. 2003] Roberts, B., Svirskas, A., Yancheva and S., Ignatiadis, I. Service Oriented Architecture, Open Source Software and ebXML as the Foundation for the Virtual Organizations of SMEs. CollECTeR (LatAm) conference. Santiago, Chile. http://ing.utalca.cl/CollECTeR/
[Rowell 2002] Rowell, M. (2002). OAGIS: A Canonical Business Language. XML Journal, Volume 03, Issue 09.
[Svirskas A and Roberts R 2003] Svirskas A. and Roberts R. Towards Business Quality of Service in Virtual Organizations through Service Level Agreements and ebXML. 10th ISPE international conference on concurrent engineering: research and applications. Madeira, Portugal. http://isg.uninova.pt/ce2003/
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