XML has been applied to numerous information processing application areas for various objectives and has earned excellent reputation for simplicity, extensibility, and openness. Researchers and developers in the network and system management area have begun to investigate the use of XML technologies in order to solve the problems that exist in Internet management standards such as SNMP. However, the methods on how to apply XML technologies to network management are not yet clearly defined. This

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... chapter attempts to provide a guideline for applying XML technologies to developing XML-based management systems and to provide an architectural framework for XML-based network management. We first examine XML technologies that can be applied to network management and how they can be applied to common network management tasks. We then present a detailed architecture of the XML-based management that can be used in developing management systems. We have validated this architecture by implementing it and using it in managing network devices and systems. What is XML-based Network Management? In this section, we first explain the definition of XML-based network management (XNM) and illustrate merits and demerits of XNM. We also introduce previous research effort on XNM as a related work. XML [1] is an extensible markup language, with which one can define own set of tags for describing data. It is also regarded as a meta-language, which describes information about data. XML enables data to carry its meta information in the form of an XML document. The meta information is used for searching, filtering, and processing efficiently. The main benefits of XML are simplicity, extensibility, and openness. Definition of XNM The simplicity of XML relies on tree structured text-based encoding of data, so one can easily create, read and modify XML documents with even the most primitive text processing tools. Although simple, XML is extensible enough to express complex data structures. The extensibility of XML allows different applications to represent their own structures of data. Because XML is an open standard, there is a wide selection of both freely available and commercial tools for handling and processing it. By supplementing XML with several advanced features such as 1 XML Schema [2], XSL [3], DOM [4], XPath [5], XQuery [6], and SOAP [7], XML technology is not only emerging as the language of choice, but also as the universal information-processing platform. XNM is a kind of network management methods that applies XML technologies to network management. Therefore, XNM achieves the advantages of XML technologies and one can easily develop network management system using XML technologies. In the next subsection, advantages and disadvantages of XNM are examined. Merits and Demerits of XNM The application area of XML is very broad: data presentation on the Internet, multimedia presentation, data saving of specific programs, electronic commerce, academic uses, and etc. In all these areas, XML proves itself to be an excellent solution to solve technical challenges. Using XML in network management presents the following advantages [8]: • The XML Schema defines the structure of management information in a flexible manner. • Widely deployed protocols such as HTTP can reliably transfer management data. • DOM APIs easily access and manipulate management data from applications. • XPath expressions efficiently address the objects within management data documents. • XSL processes management data easily and generates HTML documents for a variety of user interface views. • Web Service Description Language (WSDL) [9] and SOAP [7] define web services for powerful high-level management operations. However, the current XML-based network management has some weaknesses as well. The current efforts to apply XML to network management are accomplished in a limited network management area, such as configuration management, or performed in the development process of a network management system using a few simple XML technologies. Also the previous XML-based network management does not properly provide a general architecture of XML-based network management system (XNMS) from the aspect of manager and agent. Network bandwidth of transferring XML data is large because XML is text-based. The processing of XML is considered heavy, so it is not yet proven that XML is applicable to embedded systems. Many are curious whether the XML-based manager can process information delivered from multiple managed devices. The development experience of an XNMS is insufficient. Integration efforts of XML-based network management with existing SNMP agents are the first step towards the integrated network management. The specification translation from SNMP SMI to XML DTD or XML Schema is widely in progress. The XML/SNMP gateway approach between an XML-based manager and SNMP agents is also considered to manage the legacy SNMP agents. Therefore, to provide an integrated network management of the XML manager and existing SNMP agents, the architecture and implementation of the gateway need to be provided.