Erik Wilde

Semantically Extensible Schemas for Web Service Evolution

Web Services are designed for loosely coupled systems, which means that in many cases it is not possible to synchronously upgrade all peers of a Web Service scenario. Instead, Web Service peers should be able to coexist in different versions. Additionally, older software versions often could benefit from upgrades to the service if they were able to understand it. This paper presents a framework for semantically extensible schemas for Web Service evolution. The core idea of is to use declarative semantics to describe extensions to a service’s vocabulary. These declarative semantics can be used by older software versions to understand the semantics of extensions, thus enabling older software to dynamically adapt to newer versions of the service. As long as declarative semantics are sufficient, older software can benefit from the service’s extension.

Mapping XML instances

For XML-based applications in general and B2B applications in particular, mapping between differently structured XML documents, to enable exchange of data, is a basic problem. A generic solution to the problem is of interest and desirable both in an academic and practical sense. We present a case study of the problem that arises in an XML based project, which involves mapping of different XML schemas to each other. We describe our approach to solving the problem, its advantages and limitations. We also compare and contrast our approach with previously known approaches and commercially available software solutions.

SPath: a path language for XML schema

XML is increasingly being used as a typed data format, and therefore it becomes more important to gain access to the type system; very often this is an XML Schema. The XML Schema Path Language (SPath) presented in this paper provides access to XML Schema components by extending the well-known XPath language to also include the domain of XML Schemas. Using SPath, XML developers gain access to XML Schemas and thus can more easily develop software which is type- or schema-aware, and thus more robust.

Merging trees: file system and content integration

XML is the predominant format for representing structured information inside documents, but it stops at the level of files. This makes it hard to use XML-oriented tools to process information which is scattered over multiple documents within a file system. File System XML (FSX) and its content integration provides a unified view of file system structure and content. FSXs adaptors map file contents to XML, which means that any file format can be integrated with an XML view in the integrated view of the file system.

Structuring namespace descriptions

Namespaces are a central building block of XML technologies today, they provide the identification mechanism for many XML-related vocabularies. Despite their ubiquity, there is no established mechanism for describing namespaces, and in particular for describing the dependencies of namespaces. We propose a simple model for describing namespaces and their dependencies. Using these descriptions, it is possible to compile directories of namespaces providing searchable and browsable namespace descriptions.

XPath filename expansion in a Unix shell

Locating files based on file system structure, file properties, and maybe even file contents is a core task of the user interface of operating systems. By adapting XPaths power to the environment of a Unix shell, it is possible to greatly increase the expressive power of the command line language. We present a concept for integrating an XPath view of the file system into a shell, the emphXPath Shell (XPsh), which can be used to find files based on file attributes and contents in a very flexible way. The syntax of the command line language is backwards compatible with traditional shells, and the new XPath-based expressions can be easily mastered with a little bit of XPath knowledge.

Fragment identifiers for plain text files

Hypermedia systems like the Web heavily depend on their ability to link resources. One of the key features of the Webs URIs is their ability to not only specify a resource, but to also identify a subresource within that resource, by using a fragment identifier. Fragment identification enables user to create better hypermedia. We present a proposal for fragment identifiers for plain text files, which makes it possible to identify character or line ranges, or subresources identified by regular expressions. Using these fragment identifiers, it is possible to create more specific hyperlinks, by not only linking to a complete plain text resource, but only the relevant part of it. Along with this proposal, a prototype implementation is described which can be used both as a server-side testbed and as a client-side extension for the Firefox browser.

XML-based XML schema access

XML Schemas abstract data model consists of components, which are the structures that eventually define a schema as a whole. XML Schemas XML syntax, on the other hand, is not a direct representation of the schema components, and it proves to be surprisingly hard to derive a schemas components from the XML syntax. The Schema Component XML Syntax (SCX) is a representation which attempts to map schema components as faithfully as possible to XML structures. SCX serves as the starting point for applications which need access to schema components and want to do so using standardized and widely available XML technologies.

Management and sharing of bibliographies

Managing bibliographic data is a requirement for many researchers. The ShaRef system has been designed to fill the gap between public libraries and personal bibliographies, and provides an open platform for sharing bibliographic data among user groups.

Describing namespaces with GRDDL

Describing XML Namespaces is an open issue for many users of XML technologies, and even though namespaces are one of the foundations of XML, there is no generally accepted and widely used format for namespace descriptions. We present a framework for describing namespaces based on GRDDL using a controlled vocabulary. Using this frame-work, namespace descriptions can be easily generated, har-vested and published in human- or machine-readable form.