Decision Tree and Agent-Based Approach to Specify Inter-Company Cooperation Using Offline Services Composition

Transcription

1 Decision Tree and Agent-Based Approach to Specify Inter-Company Cooperation Using Offline Services Composition Meriem Kermani, Mahmoud Boufaida and Emmanuel Paviot-Adet Abstract With the deep development of economic globalization, companies tend now to collaborate closely with each others to improve their competitiveness. The problems of interoperability have recently been the subject of considerable amount of studies. In this paper, we propose a mediation based approach, which allows to a set of heterogeneous companies to cooperate. So, they can form a company network called SoS system of systems. The purpose of this solution is to keep the company architecture and to ask the mediator that is a software-based agent to play an intermediary role between companies, and to make the transformation between companies as well. We define a dynamic and cooperative inter companies model. The dynamic aspect gives the possibility to change the collection of services involved in the collaboration. Our model combines the agent technology and the decision trees paradigm. This last facilitates making decision by selecting the services that best meet customer needs, in order to create a composite service. The realization of the offline composition process by mediator saves the response time. Once the service is executable it will be published to permit its reuse. Keywords Multi agent systems Decision tree Interoperability Cooperative process M. Kermani (&) M. Boufaida LIRE Laboratory, Constantine 2 University, 11 rue des cousins Hamrouch, Constantine 25000, Algéria kermanimeriem@hotmail.fr M. Boufaida mboufaida@umc.edu.dz E. Paviot-Adet LIP6 Laboratory, Pierre and Marie Curie University, Paris, France emmanuel.paviot-adet@lip6.fr K. Mertins et al. (eds.), Enterprise Interoperability VI, Proceedings of the I-ESA Conferences 7, DOI: / _32, Ó Springer International Publishing Switzerland

2 382 M. Kermani et al. 1 Introduction Today the definition of new organization models of companies is driven by the increased competition, the variability of customer demands and the communications performance. In this new context, companies have understood the importance of inter-cooperation and they implement models based on cooperation (virtual companies, companies network..). These forms of organization have a significant impact on information systems. Our research work concerns with the question of the on demand cooperation considering that the information system of company is a central element of this problem. Being given the nature of the on demand cooperation, we consider two principles. The first one is related to the dynamism and the lifetime of the cooperation. The dynamism aims to respond quickly to a business opportunity. Concerning the lifetime, the objective is to reduce the implementation time of the collaborative process by composing services while improving the quality of the obtained composite service. The second principle concerns the openness. In fact, openness has an immediate consequence on increasing the number of potential partners. Therefore, a strong need of an entity that manages firstly the various services offered by partners and secondly, that allows the setting of the security level required by companies. Though it is important that every company can communicate and report what it can offer in terms of services. This does not deny the fact that they can be rivals. Thereafter, the presence of a third entity that provides these features is of paramount importance. To answer to the limitations and issues described above we propose mediation architecture between different companies which participate in the collaboration process. The use of mediator ensures the interoperability between companies, and a certain level of security and allows the interconnection processes of different companies. The dynamic and cooperative autonomous processes required for this interaction must then integrate a representation of the user knowledge and behaviors, and have a real ability to communicate. The multi-agent approach provides an abstraction level suitable for this problem. In fact, multi-agent systems (MAS) allow a coordination of the interacting agents behavior in a company in order to perform tasks or solve problems [1 3]. We focus on the communication capabilities of agents to allow them to be used as basic elements for the design of the complex collaborative systems. In order to facilitate the decision taking and the choice of services that best meet the customer needs in the shortest time, we use the paradigm of the decision trees in the software agents inside the mediator component. This paper is structured as following. Section 2 is dedicated to a comparative study between multiple research works. Sections 3, 4 and 5 are consecrated to the study of our proposal which will be illustrated by an example in Sects. 6 and 7. In Sect. 8, we will give a discussion for positioning our solution compared to the existing work. Finally we will make some conclusions about our work and we will talk about the extension of it.

3 Decision Tree and Agent-Based Approach to Specify Inter-Company Some Related Works Several authors and approaches have focused on resolving the issue of intercompany cooperation offering tools and approaches for the design of information systems. The proposed works have the information system at the center of their concerns and qualify it as an indispensable support for the implementation of the company strategy. Research works such as [4 6] were attached to the analysis and design domain of process-oriented information systems. Several methods and tools of information systems engineering have emerged such as component-based approaches, (MDE) Model Driven Engineering. These methods have been proposed to meet the evolution of the current information system context: evolution in terms of the information system architecture (heterogeneous and distributed), and evolution in its use (open and accessible for different users). Since a few years the concept of (SOA) Service Oriented architecture has been rapidly spread and widely accepted as a supporting architecture of the company information system. Although many project such as shape [12], that have studied the aspects of companies cooperation and have proposed solutions to the different heterogeneities that may exist, but the problem still remains an open domain of research. During our bibliographical study we note that researchers in this field have different views. We will present a panorama of solutions. We studied the overall work according to the used approaches and technologies, the nature of collaborative processes if it is static or dynamic, and the field possible for the use of the proposed solution. Touzi et al. [7] adopted a non-standardization approach, which proposes the design of a mediation system between information systems. A mediator is considered as a vector for the interoperability of heterogeneous information systems. She decomposed the proposed approach on its business, logical and technical projections. The proposed practices are similar to the MDA and allow one to anticipate the tooling of a model transformation workshop. This method was also adopted in [8] by Truptil et al. to solve a crisis management problem. The approach used in [11] is a standardization approach which consists on the proposition of a framework where all the participating company must respect it. Among the works that have used the agent paradigm for solving the intercompany cooperation problems, the authors of [3, 9] have proposed global architectures, integrating the technology of web services. The difference that Namin et al. [3], proposed, is the integration of web services and software agents within the internal structure of the company and by adopting software agents within the UDDI registry, they introduced some agent components to help service requesters to select the most appropriate service provider. Few studies have treated the notion of dynamic cooperation or the on demand cooperation. For instance, the work of Boukadi et al. [2] offers such a mechanism of cooperation based on important concepts that are: description, publication, discovery, and the composition of services and the adaption of the services to the context.

4 384 M. Kermani et al. Mallek et al. [10] have a different vision. They proposed an approach to detect problems before a real collaboration, then analyzing and finding solutions to each partner. After studying the achieved research of the inter-company cooperation context, we note that these works are still unable to provide a model of cooperation that can mask the heterogeneity of ISs (information systems) of companies. In addition the few studies that have used software agents have not addressed the decision-making of these agents. We also note that these studies have not taken into account the dynamic aspect, so the process is fixed from the beginning and the addition or deletion of a company disrupts the entire system. In this paper, we propose a mediation architecture, which allows the creation of a dynamic process between companies. We adopted the mediation in order to involve companies that offer interesting services without using standard tools. To allow the reuse of the composite service, we propose its publication in a network. 3 Our Proposal In this section, we propose a mediation architecture between services of companies that are participating to the cooperation. According to Lascoux [13] the mediator provides a framework with its own benchmarks, consisting of operating and communication rules, and steps process. It begins with the acknowledgement of the parts position in terms of legitimacy, to the formalization of an agreement as satisfactory as possible for the parts. In this context, the source and the need of mediator between information systems is their heterogeneity, even making their interoperability complicated. Mediation must successfully make them interoperate following a well defined steps process and operating rules. Specificities acknowledgement of each information system in the network is essential. It is on the basis of the specificities that the mediator of the information systems will offer satisfying solutions. In our architecture the mediator is used to perform a dynamic intercompany process, offering the possibility to change the collection of services involved in the collaboration. The intercompany process will be published to be used as a web service, to permit the visibility as well and to be reused by other customers. Figure 1 shows an overview of the architecture. The different parts of this architecture are: Companies or Partners of collaboration: A set of companies participating in the collaboration. These companies offer accessible services via the public part of their information system. The informations about each service is stored in a services directory. Mediator: is the core of the architecture, it is acting as an intermediate between the requester and the partners. It is composed of: Interface agent: it receives and makes the processing of the applicant request to build a decision tree, which will be sent to the coordinator agent.

5 Decision Tree and Agent-Based Approach to Specify Inter-Company 385 Fig. 1 Overview of the our proposed architecture Services directory: in this directory we have services agents; each of these agent is related to a service proposed by a company. These agents represent information about each service, the information is organized as: a local decision tree in each agent service, and service address, communication protocol, and the details of the service purpose. Coordination Agent: it allows creating a composite service to meet the client request. It has a global decision tree that is created from the set of local decision trees. This tree is used to make a decision which allows choosing the best services to meet customer demand. Applicant service: it represents the launch process. We have proposed the general architecture of the coordination agent, respecting the three properties of independence, communication and intelligence. This architecture is inspired from the modular theory of Fodor [15] (Fig. 2). Communication Module is messages support between the agent and its coordinator. All interactions between the coordination agent and the services agent or the interface agent pass through this module. Mailbox is used to submit messages. This queue box type FIFO (First In First Out) is used for storing messages in order to process them asynchronously. Representation module receives the request sent by the agent service as a tree, and then reformulates the global tree (the tree that includes all local trees published by the different service agents) following the order of criteria sent by interface agent. Information Management Module contains information related to the service published by partners (protocol, address, message structure, description of the

6 386 M. Kermani et al. Fig. 2 Structure of the coordinator agent roles of services). Each service agent uses a local ontology to represent vocabulary and concepts in its application domain. Ontology module this module deals with the search for correspondences between agents to perform a cooperative task. 4 Cooperation Mechanism Based on Decision Trees To mask the heterogeneity of the participating companies in the cooperation, and to facilitate decision making we propose the use of decision trees as a learning mechanism in our agent. A decision tree can be used to clarify and find an answer to a complex problem. The structure allows our coordinator agent to take a problem with multiple possible solutions and display it in a simple and easily understandable format that shows the relationship between different events or decisions [14]. We propose the use of two types of trees, with the following format: Model decision tree (Initial node, Branches, Intermediate node, Leaf) Local tree: shows the details of the services offered by the participating companies to cooperation. This tree is used by the service agents. Global Tree: is created from the fusion of local trees, and used by the coordinator to quickly select the services that best meet customer needs. Each service in the composition is defined by a path to the global tree of the coordinator agent.

7 Decision Tree and Agent-Based Approach to Specify Inter-Company 387 Fig. 3 Internal structure of the global tree The Fig. 3 shows the structure of the global tree. Initial node: each initial node of a global tree located in coordinator agent represents the global service which includes the services representation of different companies. Branches: they connect parent internal node to a child node. They represent the variable value tested in the intermediate parent node to the child node. Each branch corresponding to a question, allows choosing the path to follow. Intermediate node: represents the deals offered by services, with a sort of category, it means that each path or branche belongs to the same service of the same category. Leaf: each leaf refers to a class; this class identifies a service company which means that the path from the root to a leaf of this tree gives details of one or more service. Rule: the conjunction of all tests that have been taken during the tree paths, from the root to the leaf identifies the service C1 or multiple services [C1 C n]; each test is either the predicate P associated with intermediate node if we go on the left after the node or the complement of the predicate : P if we go on the right. 5 Offline Services Composition Process In this section we will explain the construction of dynamic intercompany process. Its creation is based primarily on the selection of multiple services and then specifies the sequence flow between them. The Fig. 4 shows the selection steps and the offline services composition. We show in this figure the entities responsible for each action, and the operations that we propose for the passage from an action to another. Our process is divided into three principal parts.

8 388 M. Kermani et al. Fig. 4 Process of the offline services composition Structuring part: It includes the submission stages of the offers, by companies participating to the cooperation, the creation of the local decision tree for each offer by Service agents, and the creation of the global tree by the coordinator agent. Offline Composition part: this part of the process is triggered by customer demand, we follow each stage of this part from the process to arrive to the generation of an executable orchestration diagram. Web service creation part: After creating the composite service we follow the publishing step of executable service to permit its reuse. 6 Example We will treat in this part the realization of a response process of an emergency case which is an accident, using three existing entities named: Hospital, SAMU and Police. The Hospital service: each hospital proposes a description including its position, the free operating rooms and the laboratory, thus all the available tests, in our case we need the GPS data of the hospital. The description of each hospital is published in a service agent and represented by a local decision tree. All hospitals will be formalized by a global decision tree stored in the coordination agent.

9 Decision Tree and Agent-Based Approach to Specify Inter-Company 389 Fig. 5 Generalization of the local decision tree from Excel using Sipina Version 3.2 The SAMU service: It provides a description of its services such as the emergency care team, the possible route and the expected duration of each route. We have service agents representing the SAMU by a local decision trees and the coordination agent representing the global tree. The Police service: It provides the position of the police stations and available patrols, which will be represented by decision trees in the local services agent. All the police stations are represented by the global decision trees stored in the coordination agent. Using these three entities, we will create a composite service to respond to an emergency which is called 333. This service will allow users to report an accident at a given position. The service will take the necessary steps and return to the user the expected intervention delay in seconds. The internal scenario which will lead the interactions between services is the following: The coordination agent will firstly ask the accident base to determine whether the reported accident is known, if so a negative value is simply returned to the service requester. Otherwise, we will first find the nearest hospital to the accident position, we use the hospital GPS data and we determine both the SAMU and the police to be sent. We then add this to the accidents base before returning to the user the intervention time that was given by the SAMU. The scenario here is voluntarily simplified, staying inspired by a real-life case. The aim is indeed to facilitate understanding and to demonstrate the feasibility of our development proposal through a simple but a realistic example. We have chosen to use the SIPINA method for the generalization of our local trees, SIPINA is software but it is also a training method. It generalizes trees by introducing an additional operation which is the fusion, during the induction of the prediction model. The Fig. 5 shows the generalization of the local tree from Excel files. After following all the method steps we obtain the following tree.

10 390 M. Kermani et al. Fig. 6 Communication between agents JADE 7 Some Implementation Aspects Currently we are implementing a model of our dynamic inter-company process to examine the feasibility of the offline services composition. The behavior of agents is created with the jade platform, Fig. 6 shows the structure of agents, and some exchanged messages between our agents, for example a coordinator agent of SAMU service named CA-SAMU sends a request to the service agents SA- SAMU the representatives of the different SAMU, then this services respond with a messages inform given their position, the coordinator agent select the service that best meets the needs and sends a message confirm to the service agent concerned, the traces of exchanged messages between agents are made with the help of sniffer agent. The third part of the figure shows the structure of a message request sent by the agent CA-SAMU to the CA-SAMU agent. 8 Discussion Our solution is a distributed system evolves in a dynamic environment where the partners of cooperation change, and when it comes to designing this type of system, agent technology is suitable, because MAS not only allow the sharing or distribution of knowledge, but also the achievement of a common goal. Agents in our work learn the decision from the user in certain situations to support him in other situations. The decision problem in the case of the cooperative distributed systems is a complex problem. Also we must divide our decision problem into

11 Decision Tree and Agent-Based Approach to Specify Inter-Company 391 several problems. In our case, we choose to use decision trees, because they can model simply graphically and quickly a complex measured phenomenon. Their readability, time processing and the lack of a priori necessary assumptions explain their current popularity. The aim of using training agents with the paradigm of decision trees is to select the best services that meet customer needs. Our contribution has four originalities that distinguish it from the existing works, firstly it takes into account the dynamic aspect, in this case our partners change and so do the service composition according to the request, then we can have a composed service for each request. Secondly the offline achievement of a large part of the composition computing saves the response time by defining an execution order of services. The third thing is the learning of agents by the decision tree. Finally the non-standardization approach or the use of mediator allows a better cooperation between the heterogeneous companies. 9 Conclusion In this paper, we discussed the problems of interoperability of the intercompany collaboration process. Trying to respond to these problems, we studied and analyzed the existing approaches and mechanisms in the literature. Then we discussed the creation problem of dynamic process. We have proposed an offline services interconnection of different companies and to make it, we used a mediator based on software agents that learn decision making by the decision trees. Our future work includes refinement of our model by definition of an algorithm to merge the local trees according to a test on each arc. We will define a transformation model to create matches between decision trees created with SIPINA and agents implemented in Java. References 1. Hoeta, S., & Saboureta, N. (2010) Simplification de la mémoire des agents en utilisant des FMDP. In 18th Journées Francophones sur les Systèmes Multi-Agents (JFSMA 10) (pp ). 2. Boukadi, K., Vincent, L., Ghedira, C., & Maamar, Z. (2010). CSMA: Context-based, serviceoriented modeling and analysis method for modern enterprise applications. International Journal of Organizational & Collective Intelligence, 1(2), Namin, A. S., Shen, W., & Ghenniwa, H. (2006). Implementing enterprise collaboration using web services and software agents. International Journal of Networking and Virtual Organizations: Special Issue on Organizing Collaborative Supply Chains and Networks, 3(2), Indulska, M., Green, P., Recker, J., & Rosemann, M. (2009). Business process modeling: Perceived benefits. ER2009 ( ) Gramado, Brazil. 5. Henderson, S., Gonzalez, S. P., & Ralyté, J. (2007). Situational method engineering: Chunks or fragments. The CAiSE Forum, Trondheim.

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