T. Traczyk

Electronic Trading on Electricity Markets within a Multi-agent Framework

Specific features of trade on electrical energy markets make the automation of certain negotiation and contracting processes attractive and desirable. Multi-agent systems are a natural solution for automating processes in a distributed environment, where individual market entities posses their own objectives. In the paper we consider a concept of a multi-agent framework for an electronic market trade. Since both energy markets and trade mechanisms are complex and permanently evolving, we require the highest expressiveness from this concept. Development of such a system involves solving several design issues related to embedding the agents in the environment, agent communications schemas, language, and offers modeling, especially in the case of the distributed, multilateral trade. We present a solution for the most important design issues. Our concept, including new information technologies supplementing multi-agent systems and Web services, are capable to support enterprises in the decision processes, to facilitate the buy/sell offers preparation, to select parties and enter into business relations with entities, and to support contract negotiations.

Modeling Multi-commodity Trade: Information Exchange Methods

This book contains revised versions of papers presented on scientific workshop Modeling Multi-commodity Trade: Information exchange methods, which took place in November 2010 atWarsaw University of Technology. It summarizes results of the research work supported so far by scientific grant Methods and architectures of information interchange for electronic trade on infrastructural markets (see page xi), and some earlier research work on multi-commodity markets modeling. Though partial results of the research were published earlier, the book gives the most complete view on results of our research in the field of modeling the trade on complex multi-commodity infrastructural markets.

Information Management in Federated Digital Archives

The chapter describes the problem of resources dislocation among federated archives. In the archive lifetime, the resource can be a subject of format change, relocation, transfer onto another operating system or area, the data carrier can be a subject of magnetic renewal, etc. Some of the operations can be risky, namely the resource can be, in the effect of them, damaged. The federation of archives allows for dislocation of digital resources, i.e. the another method to ensure reliable ability to read it. As the federated archives are usually geographically dispersed, have different operating systems, or storage media, are managed in various ways, the dislocation prevents against the effects of natural disasters, acts of war, etc. The chapter describes acquisition and placement of information about the corresponding resources, archives identification, and communication among the archives. The developed coordination protocol, basing on the state of the art, is described and presented under the assumption, that the archives communicate as they have software agents to communicate with each other. It allows among others, that the archives do not need to be homogeneous. Finally, the implementation proposal of the module responsible for relocation is described.

The CREDO Project

The chapter describes main assumptions of the project Digital Document Repository CREDO, which resulted in design and implementation of a long-term digital archive of significant capacity, conforming to OAIS standard, with packaging preserved resources in archival packages, and metadata management. The archive ensures storage correctness and devices reliability monitoring. Thanks to sophisticated scheduling of archive operations, energy efficiency is also provided. A discussion is presented how the CREDO archive meets the requirements, which are usually applied to long-term digital archives.

Requirements for Digital Preservation

Long-term preservation of digital information differs in many aspects from well-known short-term data storage. The longevity of the preservation causes a lot of little-known and difficult problems, which cannot be completely solved by technologies currently available, and some cannot be solved at all using only technical means. This chapter presents the most important requirements for long-term digital preservation and introduces some basic problems associated with this area.

Metadata in CREDO Long-Term Archive

In long-term archiving stored resources have to be accompanied by information which enables their searching, helps proper preservation and maintenance, and may be used to examine the correctness of the preservation. This information, called metadata, has to be therefore stored and processed in the archive. This chapter describes metadata preservation and processing in the CREDO archive. The archive stores metadata in archival packages. Since we are dealing with a deep archive, this type of storage is usually off-line, and any access to archived data is slow. To enable effective search and efficient maintenance of the archive, copies of selected metadata are stored also in on-line archive database.

Information Processing in CREDO Long-Term Archive

CREDO processes archived information in several types of archival and administrative sessions. This chapter describes these sessions, and logical as well as physical structures that are used to store and process archived resources.

CREDO Repository Architecture

A long-term archive has to be designed in such a way that it can function for decades, despite changes in technology and methods of storage. As the technology rapidly changes, we cannot assume any currently designed module of the archive to be permanent. Therefore, an architecture of the archive has to enable quite easy and safe exchange of system modules and smooth cooperation between older and newer solutions and technologies. The architecture itself should be as stable as possible. The chapter presents assumptions and some details of the architecture of the CREDO archive. Subsystems of the archive are described and currently used technologies are briefly discussed.

Persistence Management in Digital Document Repository

The CREDO Digital Document Repository enables short-and long-term archiving of large volumes of digital resources, ensuring bitstream preservation and providing most of the technical means to ensure content preservation of digital resources. The goal of the paper is to describe the design and implementation an innovative component of the CREDO Repository: the Persistence Management Subsystem (PMS). This subsystem sets guidelines for the file management system on replicas placement, and data relocation. The module responsible for scheduling access to the archive provides energy efficiency by setting suboptimal schedules. The module responsible for diagnose and exchange of data carriers calculates the probabilities of failure, and the information is used by the scheduling module to select appropriate storage areas for reading or writing of data, and for marking the areas as obsolete. Finally, the power management module is responsible for starting-up the storage areas only when necessary.

M3 Data Structures

A detailed data model for multi-commodity trade is presented, based on formal model described in previous chapter. This data model has form of UML class diagrams, and widely uses generic (i.e. metadata driven) constructs. On the basis of the UML model, an XML dialect, called M3-XML, is proposed, which can be used to store formal descriptions of multi-commodity market and offers, or as a content language for market data interchange.