SIQXC: Schema Independent Queryable XML Compression for Smartphones

The explosive growth of XML use over the last decade has led to a lot of research on how to best store and access it. This growth has resulted in XML being described as a de facto standard for storage and exchange of data over the web. However, XML has high redundancy because of its self-­‐ describing nature making it verbose. The verbose nature of XML poses a storage problem. This has led to much research devoted to XML compression. It has become of more interest since the use of resource constrained devices is also on the rise. These devices are limited in storage space, processing power and also have finite energy. Therefore, these devices cannot cope with storing and processing large XML documents. XML queryable compression methods could be a solution but none of them has a query processor that runs on such devices. Currently, wireless connections are used to alleviate the problem but they have adverse effects on the battery life. They are therefore not a sustainable solution. This thesis describes an attempt to address this problem by proposing a queryable compressor (SIQXC) with a query processor that runs in a resource constrained environment thereby lowering wireless connection dependency yet alleviating the storage problem. It applies a novel simple 2 tuple integer encoding system, clustering and gzip. SIQXC achieves an average compression ratio of 70% which is higher than most queryable XML compressors and also supports a wide range of XPATH operators making it competitive approach. It was tested through a practical implementation evaluated against the real data that is usually used for XML benchmarking. The evaluation covered the compression ratio, compression time and query evaluation accuracy and response time. SIQXC allows users to some extent locally store and manipulate the otherwise verbose XML on their Smartphones

Retrieving information from compressed XML documents according to vague queries

XML has become the standard way for representing and transforming data over the World Wide Web. The problem with XML documents is that they have a very high ratio of redundancy, which makes these documents demanding large storage capacity and high network band-width for transmission. Because of their extensive use, XML documents could be retrieved according to vague queries by naive users with poor background in writing XPath query. The aim of this thesis is to present the design of a system named “XML Compressing and Vague Querying (XCVQ)” which has the ability of compressing the XML document and retrieving the required information from the compressed version with less decompression required according to vague queries. XCVQ first compressed the XML document by separating its data into containers and then compress these containers using the GZip compressor. The compressed file could be retrieved if a vague query is submitted without the need to decompress the whole file. For the purpose of processing the vague queries, XCVQ decomposes the query according to the relevant documents and then a second decomposition stage is made according to the relevant containers. Only the required information is decompressed and submitted to the user. To the best of our knowledge, XCVQ is the first XML compressor that has the ability to process vague queries. The average compression ratio of the designed compressor is around 78% which may be considered competitive compared to other queriable XML compressors. Based on several experiments, the query processor part had the ability to answer different kinds of vague queries ranging from simple exact match queries to complex ones that require retrieving information from several compressed XML documents.EThOS - Electronic Theses Online ServiceGBUnited Kingdo