2011, Graf, Sebastian, Kramis, Marc, Waldvogel, Marcel

XML underlies the same constant modification scenarios like any other resource especially in flexible environments like the WWW. Therefor intelligent handlings of versioned XML are mandatory. Due to the structural nature of XML, the efficient storage of changes in the data and therefor in the tree needs new paradigms regarding efficient storage and effective retrieval operations. We present a node granular XML versioning approach which relies on the independence of the storage and the versioning system. Different layers which have the ability to satisfy specific aspects of a node-granular versioning storage guarantee this independence. Results prove that our architecture offers efficient handling of consecutive changes within all modification scenarios while not restricting XML regarding its usage. Hence, our prototype system handles even huge XML instances while ensuring equal access to each revision of the data.

2007, Kramis, Marc, Onea, Alexander, Graf, Sebastian

PERFIDIX shows an easy way to benchmark your code. Unlike heavy-load profilers, PERFIDIX comes in an easy-to-use way based on the proven usage of JUnit Testcases. This short paper describes the current work-in progress of the PERFIDIX 1.0 release.

2008, Graf, Sebastian, Kramis, Marc, Waldvogel, Marcel

In contrast to relational databases the distribution of document-centric XML is not well researched. While there are some suggestions on how to split and distribute large XML documents, these approaches do not consider the parallel query evaluation. In this paper, we present and compare five different algorithms to search after suitable split nodes in a large XML document. We then describe how to distribute extractable sub-structures over a fixed number of peers and how to query these peers in parallel to retrieve the final result. In addition, we analyse the impact of our splitting algorithms with respect to scalability for two different XPath expression classes on three well-known XML data sets. We conclude this paper with an outlook on future work, including result ordering during parallel query execution and dynamic re-distribution of XML fragments to new peers due to updates.

2007, Kramis, Marc, Wildi, Volker, Lemke, Bastian, Graf, Sebastian, Janetzko, Halldor, Waldvogel, Marcel

jSCSI represents an initiator implementation of the iSCSI standard. This short paper describes the current work-in-progress of the jSCSI 1.0 release and gives first benchmarks as well as an outlook for upcoming releases.