Performance of distributed information systems

There is an increasing use of distributed computer systems to provide services in both traditional telephony as well as in the Internet. Two main technologies are Distributed Object Computing (DOC) and Web based services. One common DOC architecture investigated in this thesis is the Common Object Request Broker Architecture (CORBA), specified by the Object Management Group. CORBA applications consist of interacting software components called objects. Two other DOC architectures investigated are the Telecommunications Information Net- working Architecture (TINA) and a CORBA based Intelligent Network (IN/CORBA) system. In a DOC environment, the objects of an application are distributed on mul- tiple nodes. A middleware layer makes the distribution transparent to the application. However, the distributed nature creates a number of potential performance problems. Three problems in DOC systems are examined in this thesis: object distribution, load balancing and overload protection. An object distribution describes how objects are distributed in the network. The objective is to distribute the objects on the physical nodes in such a way that intern-node communication overhead is as small as possible. One way to solve the object distribution problem is to use linear programming. The constraints for the problem are then given by both ease of management of the system and performance concerns. Load balancing is used when there are multiple objects that can be used at a particular time. The objective of load balancing is to distribute the load e±ciently on the available nodes. This thesis investigates a number of de- centralized load balancing mechanisms, including one based on the use of intelligent agents. Finally, overload protection mechanisms for DOC systems are investigated. While overload protection is well-researched for telecom networks, only little work has been performed previously concerning DOC and overload protection. Also, this thesis examines the use of overload protection in e-commerce web servers. Two schemes are compared, one which handles admission to the e-commerce site on request basis, and another which handles admission on session basis. The session based mechanism is shown to be better in terms of user-experienced performance

Building strategic enterprise context models with i*: a pattern-based approach

Modern enterprise engineering (EE) requires deep understanding of organizations and their interaction with their context. Because of this, in early phases of the EE process, enterprise context models are often built and used to reason about organizational needs with respects to actors in their context and vice versa. However, far from simple, this task is usually cumbersome because of knowledge and communication gaps among technical personnel performing EE activities and their administrative counterparts. In this paper, we propose the use of strategic patterns expressed with the i* language aimed to help bridging this gap. Patterns emerged from several industrial applications of our DHARMA method, and synthesize knowledge about common enterprise strategies, e.g. CRM. Patterns have been constructed based on the well-known Porter’s model of the 5 market forces and built upon i* strategic dependency models. In this way technical and administrative knowledge and skills are synthesized in a commonly agreeable framework. The use of patterns is illustrated with an industrial example in the telecom field.Postprint (author’s final draft

The Impact of the Internet on Telecommunication Architectures

The ever-growing popularity of the Internet is dramatically changing the landscape of the communications market place. The two separate worlds of the Internet and Telecommunications are converging. The respective advantages of the two environments are being integrated to fulfill the promise of the information super-highways. In this paper, we examine the impact of the Internet on the main telecommunication architectures, namely the IN, the TMN and TINA. There are two new tendencies for implementing telephony services in combination with the Internet: running part of the control sys tem over the Internet, or conveying both the user data and the control information over the Internet. We examine these two trends, and elaborate on possible ways of salvaging the best parts of the work achieved by the TINA-Consortium in the Internet context

Ubiquitous Sensor Networks in IMS: an Ambient Intelligence Telco Platform

Ubiquitous Sensor Network (USN) concept describes the integration of heterogeneous and geographically dispersed Wireless Sensor and Actuator Networks (WS&AN) into rich information infrastructures for accurate representation and access to different dynamic user’s physical contexts. This relatively new concept envisions future Sensor-Based Services leading to market disruptive innovations in a broad range of application domains, mainly personal (lifestyle assistants), community (professional users) and industrial domains. The support for this broad range of innovative Ambient Intelligence services urgently demands a standardized access to different WS&AN, and Telco Operators have an opportunity to lead this technological challenge as they evolve towards future Next-Generation Networks. Telefónica Research and Development is a leading innovation company that provides communication services for businesses and consumers. Networks and Service Platforms is a major Telefónica I+D innovation area where new Service Architectures and Platforms concepts are essential for the development of services with a high differentiation value. This contribution describes Telefónica I+D activities directed to the design of an Ambient Intelligence Platform integrating USN concepts over NGN architectures. In our view IP Multimedia Subsystem (IMS) concepts can enable and promote a first generation of Sensor-Based Services where multimedia interactive sessions are enriched with contextual information from WS&ANs. To this end three major design criteria are addressed at three different levels. At the application layer, OMA Service Environment and OGC Sensor Web Enablement are combined to define a specific USN Service Enabler. At the communication, management and control level WS&AN Gateways are defined for integrating WS&ANs infrastructures into all-IP IMS environments. While at the lower level, data and meta-data exchanges with different WS&ANs entities are homogeneously represented using OGC® SensorML standard. Finally this paper concludes by discussing some preliminary business opportunities we foresee for the proposed Platform

A framework for abstracting complexities in service delivery platforms

The telecommunication (telco) and Information Technology (IT) industries are converging into a single highly competitive market, where service diversity is the critical success factor. To provide diverse services, the telco network operator must evolve the traditional voice service centric network into a generic service centric network. An appropriate, but incomplete, architecture for this purpose is the Service Delivery Platform (SDP). The SDP represents an IT-based system that simplifies access to telco capabilities using services. SDP services offer technology independent interfaces to external entities. The SDP has vendor-specific interpretations that mix standards-based and proprietary interfaces to satisfy specific requirements. In addition, SDP architectural representations are technology-specific. To be widely adopted the SDP must provide standardised interfaces. This work contributes toward SDP standardisation by defining a technology independent and extendable architecture, called the SDP Framework. To define the framework we first describe telecom-IT convergence and a strategy to manage infrastructure integration. Second, we provide background on the SDP and its current limitations. Third, we treat the SDP as a complex system and determine a viewpoint methodology to define its framework. Fourth, we apply viewpoints by extracting concepts and abstractions from various standard-based telecom and IT technologies: the Intelligent Network (IN), Telecommunication Information Networking Architecture (TINA), Parlay, enhanced Telecommunications Operations Map (eTOM), Service Oriented Architecture (SOA) and Internet Protocol Multimedia Subsystem (IMS). Fifth, by extending the concepts and abstractions we define the SDP framework. The framework is based on a generic business model and reference model. The business model shows relationships between SDP, telco and external entities using business relationships points. The reference model extends the business model by formalising relationships as reference points. Reference points expand into interfaces exposed by services. Applications orchestrate service functions via their interfaces. Service and application distribution is abstracted by middleware that operates across business model domains. Services, interfaces, applications and middleware are managed in Generic Service Oriented Architectures (GSOA). Multiple layered GSOAs structure the SDP framework. Last, we implement the SDP framework using standard-based technologies with open service interfaces. The implementation proves framework concepts, promotes SDP standardisation and identifies research areas