SOA based Integration of Telecommunication Services and Verification using Petri-nets” Amar Nath Dsilva1 , Rajdeep Niyogi2 , Santanu K u ma r Rath3 Department of Computer S c ie nc e , Indian Institute of Technology Roorkee1 ,2 National Institute of Technology Rourkela3 , India
[email protected] , rajdeepniyogi@gma il.com2
[email protected]
Abstract In response to high competition, telecommunicatio n service providers aim to provide a wide range of faster value-added services in a cost effective manner. Hence, telecommunication players adopt Service Oriented Architecture (SOA) paradigm to cater to the requirements of various services. SOA helps in rationalizing the Operational Support System (OSS) and Business Support System (BSS) infrastructure, introducing selfservice systems and managing 3r d party business-to-business interactions. This paper investigates as to how SOA can be extended into the domain of telecommunication services and further verification of the SOA based system using a formal model called Petri net. An approach for automatic billing system through service orchestration is detailed and its verification of the process by Petri net has been discussed. This study aims at constructing the integration of OSS/BSS services to make automated billing process of telecommunication and further verifying the Business Process Execution Language (BPEL) process of telecommunication billing process using Petri net model. Keyword: BPEL, BPEL2PNML, OSS/BSS, PIPE2, SOA, Telecommunication.
1. Introduction Telecommunication management has been the most challenging research-bet in the present day software development because of its character of ubiquitousness. The telecommunication services may have complex schemes to manage as they require correct setting among multiple independent network elements. Many services are even outsourced from third parties, which are not under the control of network operators. Because of this, communication service providers intend to bring new products and services to the global market, and respond quickly to the changing demand. Future demand comes from a wider variety of smaller volume of services, which are often relatively shor tlived. In order to maximize the capability to meet the changing demand, the services need to be brought into use as quickly as possible. Hence different services need to be implemented with minimal manual involvement by the operators. This research work aims to composition of different services using the concept of orchestration of services using BPEL and verifying this process using formal verification method i.e. Petri Net Markup Language (PNML) [1]. PNML allows the definition of Petri net types to facilitate different
versions of Petri net. Due to this flexibility, PNML acts as a starting point for a standard interchange format for Petri nets [2].
2. Overview of Methodology A. Telecommunication System SOA based subsystems for telecommunication system is primarily associated with Operations Support System (OSS)/Business Support System (BSS). OSS is a software application which supports various processes. The process may be a maintaining network inventory, provisioning services, configuring network components, service quality monitoring, or managing faults, network and server performance, logical and physical resource management.
B. Overview of Telecommunication Billing Process Telecommunication billing process is associated with a group of sub-processes of OSS/BSS services that are responsible to collect consumption data, calculate charging, produce bills to customers, process their payments and manage debt collection.
C. Service Oriented Architecture (SOA) A Service-Oriented Architecture (SOA) is the underlying structure supporting communications between services. SOA defines as to how two computing entities, i.e. programs, interact in such a way that it enables one entity to perform a unit of work on behalf of another entity. Service interactions are defined using a description language i.e. Web Service Description Language (WSDL). Services of telecommunication system are identified and deployed at their corresponding components (OSS/BSS). To provide the automatic billing system these services need to orchestrated and in this study, BPEL module of OpenESB [3] is used for this purpose. This fully furnished service can be integrated with any other service if required. SOA makes it possible to integrate the applications running at heterogeneous environments. The depiction of OSS/BSS services’ orchestration is shown in Figure 1.
Figure 1. Architecture of a Billing Automation Platform
D. Petri Nets Petri nets are one of the several formal models used extensively for verification and validation. A Petri net is a bipartite directed graph which contains three types of entities such as places, transitions, and directed arcs [4].
3. Experiment Details A. Development of BPEL Process for Telecommunication Billing System There are three layers OSS, BSS and network in telecommunication system, to make automatic billing system where the services from OSS and BSS need to be integrated. The services of OSS and
BSS are developed individually and then these service are Orchestrated using BPEL. In this process first web services i.e. CustomerInfo, TimerInfo, CallNWinfoService and GnerateBillService are identified and subsequently developed and orchestrated in BPEL process using OpenESB tool.
B. Transforming BPEL Process to Petri net The BPEL process of telecommunication billing system is based on (XML) and this is to be converted into Petri net model to analyze formal correctness of the process.
C. Results and Analysis BPEL lacks mathematical semantics, and therefore BPEL specifications are translated into Petri nets to facilitate to draw logical conclusion. After transforming the BPEL process into Petri nets, the performance analysis of the Petri nets model is carried out using PIPE tool. The PIPE tool analyzes the steady state distribution of tangible states, average number of tokens in each place, token probability density, and throughput of timed transition and sojourn time of tangible states. PIPE tool also examines the boundedness, safeness and presence of deadlock in the model. The following tables illustrate the performance analysis result of the BPEL process. Table I shows the average number of tokens present in a place. Table II specifies the token probability density and Table III shows the throughput of timed transition.
Figure 5 shows the reachability graph of the model, which provides a visual representation of all the possible firing sequences for the given Petri net. It also gives information about boundedness safeness and deadlock-free properties. The result of state-space analysis of BPEL process of billing service is shown in Figure 6.
Figure 5. Reachability Graph of Telecommunication Billing BPEL Process
4. Conclusion This study is made on SOA based integration of OSS and BSS services for generating the real time bill of telecommunication customers. In this study, it is observed that SOA ensures interoperability among heterogeneous components of telecommunication i.e. OSS and BSS. The loosely coupled and reusable services are created and orchestrated for generating the customer’s bill in real time, and further the orchestration process is formally verified for correctness using a Petri net tool i.e. PIPE. By this method, telecommunication service providers can provide more and more services in real time and they can handle the agility of demand in the global telecommunication market.
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