TypEx : a type based approach to XML stream querying

We consider the topic of query evaluation over semistructured information streams, and XML data streams in particular. Streaming evaluation methods are necessarily eventdriven, which is in tension with high-level query models; in general, the more expressive the query language, the harder it is to translate queries into an event-based implementation with finite resource bounds

Scalable Indexing for Reachability Problem on Directed Graphs

本研究では，有向グラフ上の任意の2ノード間の距離を高速に計算できる規模耐性の高い索引構造を提案する．本研究で提案する手法は，有向グラフ上の最短距離計算として，ノード間の距離計算の結果をあらかじめ隣接行列に格納しておく方法がある．しかしながら，この方法では時間計算量と領域計算量の両方のコストが高く，大規模なグラフ構造に適用する事は困難である．そこで本研究では，一般の有向グラフに適用可能な距離計算のためのラベル付けを提案し，その有効性を実験により検証する．特に, XMLデータにおいて，前処理に必要な主記憶量，計算時間および索引サイズを示す．We propose an efficient algorithm which reports the length of a shortest path between any two nodes of a directed graph in constant time. In usual method, we can obtain the constant time response for any query in this problem by using an adjacent matrix for the graph. However, this method requires huge memory space and it is difficult to apply it to lage database. So we introduce more practical method for this problem and evaluated the efficency by experiments

Lower Bounds for Multi-Pass Processing of Multiple Data Streams

This paper gives a brief overview of computation models for data stream processing, and it introduces a new model for multi-pass processing of multiple streams, the so-called mp2s-automata. Two algorithms for solving the set disjointness problem wi th these automata are presented. The main technical contribution of this paper is the proof of a lower bound on the size of memory and the number of heads that are required for solvin g the set disjointness problem with mp2s-automata

XQuery Streaming by Forest Transducers

Streaming of XML transformations is a challenging task and only very few systems support streaming. Research approaches generally define custom fragments of XQuery and XPath that are amenable to streaming, and then design custom algorithms for each fragment. These languages have several shortcomings. Here we take a more principles approach to the problem of streaming XQuery-based transformations. We start with an elegant transducer model for which many static analysis problems are well-understood: the Macro Forest Transducer (MFT). We show that a large fragment of XQuery can be translated into MFTs --- indeed, a fragment of XQuery, that can express important features that are missing from other XQuery stream engines, such as GCX: our fragment of XQuery supports XPath predicates and let-statements. We then rely on a streaming execution engine for MFTs, one which uses a well-founded set of optimizations from functional programming, such as strictness analysis and deforestation. Our prototype achieves time and memory efficiency comparable to the fastest known engine for XQuery streaming, GCX. This is surprising because our engine relies on the OCaml built in garbage collector and does not use any specialized buffer management, while GCX's efficiency is due to clever and explicit buffer management.Comment: Full version of the paper in the Proceedings of the 30th IEEE International Conference on Data Engineering (ICDE 2014

Boosting XML Filtering with a Scalable FPGA-based Architecture

The growing amount of XML encoded data exchanged over the Internet increases the importance of XML based publish-subscribe (pub-sub) and content based routing systems. The input in such systems typically consists of a stream of XML documents and a set of user subscriptions expressed as XML queries. The pub-sub system then filters the published documents and passes them to the subscribers. Pub-sub systems are characterized by very high input ratios, therefore the processing time is critical. In this paper we propose a "pure hardware" based solution, which utilizes XPath query blocks on FPGA to solve the filtering problem. By utilizing the high throughput that an FPGA provides for parallel processing, our approach achieves drastically better throughput than the existing software or mixed (hardware/software) architectures. The XPath queries (subscriptions) are translated to regular expressions which are then mapped to FPGA devices. By introducing stacks within the FPGA we are able to express and process a wide range of path queries very efficiently, on a scalable environment. Moreover, the fact that the parser and the filter processing are performed on the same FPGA chip, eliminates expensive communication costs (that a multi-core system would need) thus enabling very fast and efficient pipelining. Our experimental evaluation reveals more than one order of magnitude improvement compared to traditional pub/sub systems.Comment: CIDR 200

Energy Efficient XPath Query Processing on Wireless XML Streaming Data

An energy efficient way of disseminating XML data to several mobile clients is broadcast. Information such as alert on emergencies, election results and sporting event results can be of interest to large number of mobile clients. Since eXtensible Markup Language (XML) is widely used for information exchange, wireless information services require an energy efficient XML data dissemination. XML Path (XPath) represents selective data required by mobile clients. XPath query processing involves two performance metrics, namely tune-in time and access time. In this paper, we propose a novel structure for streaming XML data called Path Stream Group Level (PSGL) node by exploiting the tree structure of XML document. It possesses various small indices such as level, child, sibling, attribute, text for selective download of XML data by mobile clients. It organizes data based on the level of XML document tree and groups XML elements with same XML path prefix to conserve battery power at mobile clients. Experimental results show that proposed method has reduced tune-in time when compared with existing approaches. Hence PSGL approach enhances performance with energy conservation for processing various types of XPath queries

Microcontroller for the logic tasks

A new SM16 microcontroller architecture is proposed which is intended for the logic-intensive applications in the field-programmable gate array (FPGA). The microcontroller has the stack architecture which provides the implementation of the most of instructions for a single clock cycle. The short but fast programs are derived due to the 16-bit instructions, which code up to three independent operations, and intensive use of the threaded code style. The framework is developed which compiles the program, simulates it, and translates to the ROM. The developed SM16 core with additional three-stack blocks, hash-table, and instructions that accelerate the execution of parsing operations is used for efficient XML-document processing and can be frequently reconfigured to the given document grammar set. The parsing speed equals to one byte per 24 clock cycles