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teaching:mfe:is [2014/06/03 11:22] svsummer [Master Thesis in Collaboration with DPI 24/7 Media Publishing] |
teaching:mfe:is [2015/04/13 14:27] svsummer [Compiling SPARQL queries into machine code] |
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| - | ====== MFE 2014-2015 : Web and Information Systems ====== | + | ====== MFE 2015-2016 : Web and Information Systems ====== |
| ===== Introduction ===== | ===== Introduction ===== | ||
| Line 25: | Line 25: | ||
| * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]] | * Contact : [[ezimanyi@ulb.ac.be|Esteban Zimanyi]] | ||
| - | ===== Master Thesis in Collaboration with DPI 24/7 Media Publishing ===== | ||
| - | The goal of the thesis is to set up a Saas / Paas solution for the deployement of the dpi 24/7 media publishing distribution in a Heroku-like style. | + | ===== Compiling SPARQL queries into machine code ===== |
| - | During this master thesis you will not only realize a theoretical and technological analysis of the problem of such a deployment but also implement a concrete solution for the dpi 24/7 distribution. | + | Due to the increasing availability of larger and larger cheap RAM memories, the working set of modern database management systems becomes more and more main memory resident. This implies that, in contrast to traditional database management systems, slow disk accesses are rare, and that hence, the in-memory processing speed of databases becomes an important factor. As recently observed by a number of researchers, (e.g., [[http://sites.computer.org/debull/A14mar/p3.pdf|Neumann and Leis]]), one very attractive approach for fast query processing in this context is the just-in-time compilation of incoming queries into machine code. This compilation avoids the overhead of the traditional interpretation of query plans, and can aid in minimzing memory traffic for boosting performance. |
| - | From a technical point of view you will : | + | A number of recent research prototypes exist that compile SQL queries into machine code in this sense: |
| - | * Develop a service using Docker and Dokku for the on-demand deployment of instances of the DPI 24/7 distribution (full stack architecture) | + | * HyPer – A Hybrid OLTP&OLAP High Performance DBMS http://hyper-db.de/ |
| - | * Realize performance tests of the developed service | + | * Legobase - https://github.com/epfldata/NewLegoBase and http://data.epfl.ch/legobase |
| - | * Study the different options of the Paas mode (full stack or elastic deployment) | + | |
| - | Second, you will analyze the different existing solutions for the orchestration of an elastic virtualization architecture. | + | The objective of this master thesis is to apply the same methodology to engineer a compiler that translates (fragments of) SPARQL (the standard query language for querying RDF data on the semantic web) into machine code. The overall methodology should follow the methodology used by HyPer and Legobase: |
| + | * Use of a high-level language to construct the compiler (Scala, http://scala-lang.org/) | ||
| + | * Use of Latent Modular Staging (LMS for short) for generating low-level portable assembly code at runtime (http://scala-lms.github.io/) | ||
| + | * Use of LLVM (http://llvm.org/) as a portable assembly code and corresponding translator to machine code. | ||
| - | Technology used by the DPI 24/7 distribution : Linux, Varnish, NginX, Php-fpm, Mysql (in background Tomcat, SOLR). | + | Getting aquaintend with these technologies is part of the master thesis objective. |
| + | |||
| + | **Validation of the approach** The thesis should propose a benchmark collection of SPARQL queries that can be used to test the obtained SPARQL-to-machine-code compiler and compare its perforance against a reference, interpreter-based SPARQL compiler. | ||
| + | |||
| + | **Deliverables** of the master thesis project: | ||
| + | * An overview of the state of the art in query-to-machine-code compilation. | ||
| + | * A description of latent modular staging and how it can be used to construct machine-code compilers. | ||
| + | * The SPARQL compiler (software artifact) | ||
| + | * A benchmark set of SPARQL queries and associated data sets for the experimental validation | ||
| + | * An experimental validation of the compiler, comparing efficiency of compiled queries against a reference compiler based on query plan interpretation. | ||
| + | |||
| + | |||
| + | |||
| + | **Interested?** Contact : //Stijn Vansummeren// | ||
| + | |||
| + | **Status**: available | ||
| + | |||
| + | ===== An implementation of the SCULPT schema language for tabular data on the Web ===== | ||
| + | |||
| + | Despite the availability of numerous standardized formats for semi-structured and semantic web data such as XML, RDF, and JSON, a very large percentage of data and open data published on the web, remains tabular in nature. (Jeni Tennison, one of the two co-chairs of the W3C CSV on the Web working group claims that ``over 90% of the data published on data.gov.uk is tabular data''.) Tabular data is most commonly published in the form of comma separated values (CSV) files because such files are open and therefore processable by numerous tools, and tailored for all sizes of files ranging from a number of KBs to several TBs. Despite these advantages, working with CSV files is often cumbersome because they are typically not accompanied by a //schema// that describes the file's structure (i.e., ``the second column is of integer datatype'', ``columns are delimited by tabs'', etc) and captures its intended meaning. Such a description is nevertheless vital for any user trying to interpret the file and execute queries or make changes to it. | ||
| + | |||
| + | In other data models, the presence of a schema is also important for query optimization (required for scalable query execution if the file is large), as well as other static analysis tasks. Finally, schemas are a prerequisite for unlocking huge amounts of tabular data to the Semantic Web. | ||
| + | |||
| + | In recognition of this problem, the CSV on the Web Working Group of the World Wide Web Consortium argues for the introduction of a schema language for tabular data to ensure higher interoperability when working with datasets using the CSV or similar formats. | ||
| + | |||
| + | The objective of this master thesis is to implement a recent proposal for such a schema language named SCULPT (http://arxiv.org/abs/1411.2351). Concretely, this entails: | ||
| + | |||
| + | * propose an elegant concrete syntax for SCULPT schemas | ||
| + | * implement both the in-memory and streaming validation algorithms of SCULPT proposed in http://arxiv.org/abs/1411.2351 | ||
| + | * extend the SCULPT proposal, by investigating how SCULPT can be combined with complementary features recently proposed by the W3C CSV on the Web Working group (http://www.w3.org/2013/csvw/wiki/Main_Page) | ||
| + | * and in particular, extend sculpt with features that allow tabular files to be converted into RDF | ||
| + | * create associated tooling for SCULPT (i.e., parser and serializer generator, in the spirit of data description tools) | ||
| + | |||
| + | **Deliverables** of this master thesis project: | ||
| + | * detailed description of the SCULPT proposal (document) | ||
| + | * overview of the state of the art; in particular other proposals for schema languages for tabular data (document) | ||
| + | * concrete syntax for sculpt (design document + formal grammar) | ||
| + | * implementation of SCULPT validation algorithms (software artifact) | ||
| + | * extension of sculpt with features for converting into RDF (document + software) | ||
| + | |||
| + | **Interested?** | ||
| + | * Contact: //Stijn Vansummeren// | ||
| + | |||
| + | **Status**: available | ||
| + | |||
| + | ===== Engineering a runtime system and compiler for AQL ===== | ||
| + | |||
| + | Automatically extracting structured information from text is a task that has been pursued for decades. As a discipline, ///Information Extraction/// (IE) had its start with the [[http://acl.ldc.upenn.edu/C/C96/C96-1079.pdf|DARPA Message Understanding Conference in 1987]]. While early work in the area focused largely on military applications, recent changes have made information extraction increasingly important to an increasingly broad audience. Trends such as the rise of social media have produced huge amounts of text data, while analytics platforms like Hadoop have at the same time made the analysis of this data more accessible to a broad range of users. Since most analytics over text involves information extraction as a first step, IE is a very important part of data analysis in the enterprise today. | ||
| + | |||
| + | Broadly speaking, there are two main schools of thought on the realization of IE: the **statistical** (machine-learning) methodology and the **rule-based approach**. Both categories of systems have their strenght and weaknesses. One of the most notable weaknesses is performance: tranditional rule-based systems, for example were mainly built for academic settings, where extraction throughput is far less important than the accuracy of results. | ||
| + | |||
| + | In 2005, researchers at the IBM Almaden Research Center developped a new system specifically geared for practical information extraction in the enterprise. This effort lead to SystemT, a rule-based IE system with an SQL-like declarative language named AQL (Annotation Query Language). The declarative nature of AQL enables new kinds of tools for extractor development, and draws upon known techniques form query processing in relational database management systems to offer a cost-based optimizer that ensures high-througput performance. | ||
| + | |||
| + | Recent research into the foundations of AQL (http://researcher.watson.ibm.com/researcher/files/us-fagin/jacm15.pdf) has shown that, as an alternative, it is also possible to build a runtime system for AQL based on special kinds of finite state automata. A potential benefit of this alternate runtime system is that text files need only be processed once (instead of multiple times in the cost-based optimizer backend) and may hence provide greater throughput. On the other hand, the alternate system can sometimes have larger memory requirements than the cost-based optimizer backend. | ||
| + | |||
| + | The objective of this master thesis is to design and engineer a runtime system and compiler for (a fragment) of AQL based on finite state automata. Ideally, to obtain the best performance, these automata should be compiled into machine-code when executed. For this compilation, the following technologies should be used: | ||
| + | * A a high-level language to construct the compiler (Scala, http://scala-lang.org/) | ||
| + | * Use of Latent Modular Staging (LMS for short) for generating low-level portable assembly from the automata at runtime (http://scala-lms.github.io/) | ||
| + | * Use of LLVM (http://llvm.org/) as a portable assembly code and corresponding translator to machine code. | ||
| + | |||
| + | Getting aquaintend with these technologies is part of the master thesis objective. | ||
| + | |||
| + | **Validation of the approach** The thesis should propose a benchmark collection of AQL queries and associated input text files that can be used to test the obtained automaton-based AQL compiler and compare its performance against the reference, cost-based optimizer of SystemT. | ||
| + | |||
| + | **Deliverables** of the master thesis project: | ||
| + | * An overview of AQL, SystemT, and its cost-based optimizer and evaluation engine. (document) | ||
| + | * A description of how AQL can be evaluated by means of so-called vset finite state automata. (document) | ||
| + | * A detailed desription of the state of the art in evaluating finite state automata. (document) | ||
| + | * Identification of the AQL syntaxt that is to be supported. (specification) | ||
| + | * The AQL compiler (software artifact) | ||
| + | * A benchmark set of AQL queries and associated data sets for the experimental validation | ||
| + | * An experimental validation of the compiler, comparing efficiency of compiled queries against the cost-based reference compiler. | ||
| + | |||
| + | **References about SystemT**: -[[http://almaden.ibm.com/cs/projects/avatar/icde2008.pdf|An Algebraic Approach to Rule-Based Information Extraction]] -[[http://www.sigmod.org/publications/sigmod-record/0812/p007.special.krishnamurthy.pdf|SystemT: A System for Declarative Information Extraction]] | ||
| + | |||
| + | **References about finite state automata evaluation**: | ||
| + | * Regular expression pattern matching can be simple and fast. http://swtch.com/~rsc/regexp/regexp1.html | ||
| + | * Regular Expression Matching: the Virtual Machine Approach http://swtch.com/~rsc/regexp/regexp2.html | ||
| + | * Regular Expression Matching in the Wild http://swtch.com/~rsc/regexp/regexp3.html | ||
| + | * [[http://www.diku.dk/kmc/documents/AiPL-CrashCourse.pdf|A Crash-Course in Regular Expression Parsing and Regular Expressions as Types.]] | ||
| + | |||
| + | **Interested?** | ||
| + | * Contact : //Stijn Vansummeren// | ||
| + | |||
| + | **Status**: available | ||
| + | |||
| + | ===== Structural compression of relational databases ===== | ||
| + | |||
| + | Recent research in database management systems at ULB has shown how to theoretically construct succinct (compressed) representations for relational databases and semantic web databases. The advantage of these succinct representations is that they allow querying directly **on the succinct representation**, without needing to consult the underlying database. | ||
| + | |||
| + | The goal of this thesis is to study scalable algorithms for constructing the actual succinct representations. Some in-memory algorithms are already known, but given the large size of typical database, distributed and out-of-core alternatives need to be found. | ||
| + | |||
| + | **Validation**: apply the compression algorithm on a number of relational databases; illustrate the achieved compression as well as performance characterstics of the developped algorithm (out-of-core characterstics; scaleup; ...). | ||
| + | |||
| + | **Deliverables**: | ||
| + | * Overview of the state of the art in main-memory, and distributed (bi)simulation-based compression algorithms (document) | ||
| + | * Description of the simulation-based compression algorithm to implement (document) | ||
| + | * Selection of the distribution framework (Actors, Pregel, ...) (document) | ||
| + | * Simulation algorithm (software artifact) | ||
| + | * Experimental analysis of distributed algorithm on a number of datasets. (document) | ||
| + | |||
| + | **Required reading**: | ||
| + | * Computing simulations on finite and infinite graphs. Henzinger, henzinger and Kopke | ||
| + | * Ranzato and Tapparo - An efficient simulation algorithm based on abstract interpretation | ||
| + | * Ranzato - An efficient simulation algorithm on Kripke structures. | ||
| + | * Blom, Orzan - Distributed State Space Minimization | ||
| + | * Blom, Orzan - A distributed algorithm for strong bisimulation reduction of state spaces | ||
| + | * Ma et al - distributed graph pattern matching | ||
| + | * (+ signature-based simulation part of Yongming Luo's thesis). | ||
| + | |||
| + | **Interested?** | ||
| + | * Contact : //Stijn Vansummeren// | ||
| + | |||
| + | **Status**: available | ||
| + | |||
| + | ===== A Scala-based runtime and compiler for Distributed Datalog ===== | ||
| + | |||
| + | Datalog is a fundamental query language in datamanagement based on logic programming. It essentially extends select-from-where SQL queries with recursion. There is a recent trend in data management research to use datalog to specify distributed applications, most notably on the web, as well as do inference on the semantic web. The goal of this thesis is to engineer a basic **distributed datalog system**, i.e., a system that is capable of compiling & running distributed datalog queries. The system should be implemented in the Scala programming language. Learning Scala is part of the master thesis project. | ||
| + | |||
| + | The system should: | ||
| + | * incorporate recently proposed worst-case join algorithms (i.e., the [[http://arxiv.org/abs/1210.0481|leapfrog trie join]]) | ||
| + | * employ known local datalog optimizations (such as magic sets and QSQ) | ||
| + | |||
| + | **Validation of the approach** The thesis should propose a benchmark collection of datalog queries and associated data workloads that be used to test the obtained system, and measure key performance characteristics (elasticity of the system; memory frootprint; overall running time, ...) | ||
| + | |||
| + | **Required reading**: | ||
| + | * Datalog and Recursive Query Processing - Foundations and trends in query processing. | ||
| + | * LogicBlox, Platform and Language: A Tutorial (Todd J. Green, Molham Aref, and Grigoris Karvounarakis) | ||
| + | * Dedalus: Datalog in Time and Space (Peter Alvaro, William R. Marczak, Neil Conway, Joseph M. Hellerstein, David Maier, and Russell Sears) | ||
| + | * Declarative Networking (Loo et al). For the distributed evaluation strategy. | ||
| + | * Parallel processing of recursive queries in distributed architectures (VLDB 1989) | ||
| + | * Evaluating recursive queries in distributed databases (IEEE trans knowledge and data engieneering, 1993) | ||
| + | |||
| + | **Deliverables**: | ||
| + | * Semantics of datalog; overview of known optimization strategies (document) | ||
| + | * Description of the leapfrog trie join | ||
| + | |||
| + | **Interested?** | ||
| + | * Contact : //Stijn Vansummeren// | ||
| + | |||
| + | **Status**: available | ||
| + | |||
| + | ===== Design and Implementation of a Curriculum Revision Tool ===== | ||
| + | |||
| + | Stijn Vansummeren (WIT), Frédéric Robert (BEAMS) | ||
| + | |||
| + | This master thesis project concerns the analysis, design, and implementation of a software system that can assist in the revision of teaching curricula (also known as teaching programs). | ||
| + | |||
| + | The primary targetted functionalities of the software system are as follows: | ||
| + | |||
| + | * It should allow to make different versions of the teaching programs, much in the same way as version control systems like GIT and subversion offer the possibility to make different "development branches" of a program's source code. | ||
| + | * It should allow an extensible means to check the modified program for inconsistentcies. (For example, if course X has course Y as prerequisite, then course Y should not be scheduled in 2nd semester and X in 1st semester. Moreover, the total number of ECTS of all courses should be at most 60 ECTS. ) | ||
| + | * It should allow to analyze the modifications proposed in the teaching programs, and summarize the impact that these changes could have on other programs. (For example, if a course is removed from the computer science curriculum, it should be flagged that it should also be removed from all curricula that included the course.) | ||
| + | * It should load data from (and preferably, save data to) the ULB central administration database. | ||
| + | * It should give suggestions concerning the impact of the modifications on the course schedules. | ||
| + | |||
| + | A proof-of-concept implementation of a revision tool that supports the first two requirements above is currently being developped in the context of a PROJH402 project. The MFE student that selects this topic is expected to: | ||
| + | |||
| + | * Develop this prototype to a production-ready implementation. | ||
| + | * Implement the communication with the central ULB database. | ||
| + | * Implement the impact analysis concerning the course schedules. | ||
| + | * Interact with the administration of the Ecole Polytechnique to fine-tune the above requirements; test the implementation; and integrate remarks after testing | ||
| + | |||
| + | **Interested?** | ||
| + | * Contact : Stijn Vansummeren (stijn.vansummeren@ulb.ac.be), Frédéric Robert <frrobert@ulb.ac.be> | ||
| - | Virtualization technology : Container virtualization and deployment with Dokku | ||
| - | Interested? DIP 27/7 Contact [[ddu@audaxis.com|Dimitri Dujardin]]. Academic Supervisor [[svsummer@ulb.ac.be|Stijn Vansummeren]] | ||
| ===== Automatic detection of name variations ===== | ===== Automatic detection of name variations ===== | ||
| Line 154: | Line 317: | ||
| Contact : Stijn Vansummeren <stijn.vansummeren@ulb.ac.be>, Frédéric Robert <frrobert@ulb.ac.be> | Contact : Stijn Vansummeren <stijn.vansummeren@ulb.ac.be>, Frédéric Robert <frrobert@ulb.ac.be> | ||
| - | |||
| - | ===== Design and Development of a Comprehensive DICOM validation application===== | ||
| - | |||
| - | Using the new XML machine-readable format of the DICOM standard (in the form of docbook documents), the architecture of software tools and services for the automatic extraction and utilization of the full content of the DICOM standard will be defined and the corresponding software solutions will be developed. A comprehensive DICOM validation application will also be developed as a pilot project using the previously created DICOM standard digital services. | ||
| - | |||
| - | References: <http://dicom.nema.org/; http://www.oasis-open.org/docbook/> | ||
| - | Requirements: XML, XSL, database, Java or Python or C++. | ||
| - | |||
| - | Contacts : Arnaud Schenkel <arnaud.schenkel@ulb.ac.be>, David Wikler <david.wikler@ulb.ac.be>, Stijn Vansummeren <stijn.vansummeren@ulb.ac.be> | ||
| - | ===== Structural compression of relational and semantic web databases ===== | ||
| - | |||
| - | Stijn Vansummeren (WIT) | ||
| - | |||
| - | Recent research in database management systems at ULB has shown how to | ||
| - | theoretically construct succinct (compressed) representations for | ||
| - | relational databases and semantic web databases. The advantage of | ||
| - | these succinct representations is that they allow querying directly | ||
| - | *on the succinct representation*, without needing to consult the | ||
| - | underlying database. | ||
| - | |||
| - | The goal of this thesis is to study scalable algorithms for | ||
| - | constructing the actual succinct representations. Some in-memory | ||
| - | algorithms are already known, but given the large size of typical | ||
| - | database, distributed and out-of-memory alternatives need to be found. | ||
| - | |||
| - | |||
| - | * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]] | ||
| - | |||
| - | |||
| - | ===== A contribution to Apache DRILL ===== | ||
| - | |||
| - | Google's research lab has produced a remarkable number of software | ||
| - | systems for the analytics of Big Data: | ||
| - | * [[|Map/Reduce]] for offline, batch-oriented data analysis over arbitrary datasets | ||
| - | * [[http://googleresearch.blogspot.be/2009/06/large-scale-graph-computing-at-google.html|Pregel]] for offline analysis over graph-structured datasets | ||
| - | * [[http://research.google.com/pubs/pub36632.html|Dremel]] for on-line analysis over structured datasets | ||
| - | |||
| - | For Map/Reduce and Pregel, the Apache Software foundation has | ||
| - | previously constructed open source implementations ([[http://hadoop.apache.org/|Hadoop]], | ||
| - | [[https://giraph.apache.org/|Giraph]]). For Dremel, a project is | ||
| - | currently underway to provide an Open Source implementation (known as | ||
| - | [[http://incubator.apache.org/drill/index.html|Apache Drill]]). | ||
| - | |||
| - | The goal of this thesis is to (1) study the current architecture of Apache | ||
| - | Drill, (2) compare this with the state of the art in query processing | ||
| - | for structured datasets; (3) contribute to the development of the | ||
| - | Drill implementation. | ||
| - | |||
| - | Students interested in this MFE are highly advised to follow the | ||
| - | course {{http://cs.ulb.ac.be/public/teaching/infoh417|INFOH417 | ||
| - | Database Systems Architecture}} for a background on query processing | ||
| - | in traditional database management systems. | ||
| - | |||
| - | * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]] | ||
| - | ===== Aspects of Text Analytics and Information Extraction ===== | ||
| - | |||
| - | Automatically extracting structured information from text is a task that has been pursued for decades. As a discipline, //Information Extraction// (IE) had its start with the [[http://acl.ldc.upenn.edu/C/C96/C96-1079.pdf|DARPA Message Understanding Conference in 1987]]. While early work in the area focused largely on military applications, recent changes have made information extraction increasingly important to an increasingly broad audience. Trends such as the rise of social media have produced huge amounts of text data, while analytics platforms like Hadoop have at the same time made the analysis of this data more accessible to a broad range of users. Since most analytics over text involves information extraction as a first step, IE is a very important part of | ||
| - | data analysis in the enterprise today. | ||
| - | |||
| - | Broadly speaking, there are two main schools of thought on the realization of IE: the //statistical// (machine-learning) methodology and the //rule-based// approach. The first started with simple models, then progressed to approaches based onprobabilistic graph models. Within the rule-based approach, most of the solutions build upon [[https://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CEEQFjAB&url=http%3A%2F%2Fwww.dfki.de%2F~neumann%2Fesslli04%2Freader%2Foverview%2FIJCAI99.pdf&ei=1yZIUdSZPMWHPa2rgagP&usg=AFQjCNFA6QYIt4yNR0oZRL4yjd--kev37A&sig2=nEILF_cNDk4JWiVDS5BXvg&bvm=bv.43828540,d.ZWU|cascaded finite-state transducers]]. Most systems in both categories were built for academic settings, where most users are highly-trained computational linguists, where workloads cover only a small number of very well-defined tasks and data sets, and where extraction throughput is far less important than the accuracy of results. | ||
| - | |||
| - | In practice, these existing tools suffer from a number of practical problems. For example, users need to have an intuitive understanding of machine learning or the ability to build and understand complex and highly interdependent rules. Determining why an extractor produced a given incorrect result | ||
| - | is hence often deemed extremely difficult, which makes reuse of extractors across different data sets and applications impractical. And extremely | ||
| - | high CPU and memory requirements made extractors cost-prohibitive to deploy over large-scale data sets. | ||
| - | |||
| - | In 2005, researchers at the IBM Almaden Research Center started work on a new system specifically geared for practical information extraction in the enterprise. This effort lead to [[https://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CEYQFjAB&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.179.356%26rep%3Drep1%26type%3Dpdf&ei=gyhIUe-XPIexPJ-fgLAG&usg=AFQjCNHgkbcREbd6bCA26BVf0FuIZ9n7Sg&sig2=LVQkus_67uSVlwK34BXZ8w&bvm=bv.43828540,d.ZWU|SystemT]] , a rule-based IE system with an SQL-like declarative language named [[http://pic.dhe.ibm.com/infocenter/bigins/v2r0/topic/com.ibm.swg.im.infosphere.biginsights.analyze.doc/doc/aql_overview.html|AQL (Annotation Query Language)]]. | ||
| - | The declarative nature of AQL enables new kinds of tools for extractor | ||
| - | development, and a cost-based optimizer for | ||
| - | performance. | ||
| - | |||
| - | The goal of this thesis is to study and compare both the | ||
| - | traditional methods towards information extraction and the new | ||
| - | AQL-based method proposed by SystemT, based on experimental | ||
| - | evaluation of information extraction problems on the | ||
| - | Web. Additional possible topics of study include the (1) | ||
| - | implementation and optimization aspects of AQL, (2) the extension | ||
| - | of AQL with probablistic methods, or (3) the inference of AQL | ||
| - | rules from examples. | ||
| - | |||
| - | |||
| - | Interested? Contact [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]] | ||
| - | |||
| - | ===== Models for programming Data Management in the Cloud ===== | ||
| - | |||
| - | Many say that "The Cloud" is the next computing platform on the | ||
| - | Web. Unfortunately, "the cloud" has become a marketing buzzword with | ||
| - | many different services offered, from the rental of virtual machines, | ||
| - | to the rental of storage space, to specific compute platforms | ||
| - | (e.g. MapReduce) that offer transparent parallelization. | ||
| - | |||
| - | In this thesis, we are interested in the cloud from the point of view | ||
| - | of data management. There is a recent trend in data management | ||
| - | research to use logic programming rule-based languages to specify | ||
| - | distributed applications, most notably on the web, as well as | ||
| - | inference in the semantic web (see below for a list of | ||
| - | references). The goal of this thesis is to study, compare, and where | ||
| - | possible extend the current (logic-programming based) proposals for | ||
| - | managing data in the cloud. | ||
| - | |||
| - | * References: | ||
| - | * http://boom.cs.berkeley.edu/ | ||
| - | * http://p2.cs.berkeley.edu/index.php | ||
| - | * http://www.comlab.ox.ac.uk/files/3608/RR-10-21.pdf | ||
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| - | \\ | ||
| - | * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]] | ||
| - | * Status: **already taken** | ||
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| - | ===== Distributed Structural Indexes for RDF Data ===== | ||
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| - | In an effort to enable people to share information in a | ||
| - | structured form on the Web as easily as they can share unstructured | ||
| - | HTML documents today, the World Wide Web Consortium (W3C for short) is | ||
| - | calling for the creation of a Web of Linked Data. In the same way as | ||
| - | one uses HTML and hyperlinks to publish and connect information on the | ||
| - | Web of Documents, one uses the RDF data model and RDF links to publish | ||
| - | and connect structured information on the Web of Linked Data. The | ||
| - | advantage of RDF over HTML lies in its simplicity: all information is | ||
| - | represented uniformly as triples of the form (subject, predicate, | ||
| - | object). This allows one to represent both facts about entities (e.g., | ||
| - | (Tim Berners-Lee, age, 54)) and links between entities (e.g. (Tim | ||
| - | Berners-Lee, author of, http://...)) in an easily | ||
| - | machine-interpretable manner. This is much more difficult with HTML | ||
| - | where there is little or no constraint on the way information is | ||
| - | represented. | ||
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| - | Linked Data has the potential to turn the Web into one huge database | ||
| - | with structured querying capabilities that vastly exceed the limited | ||
| - | keyword search queries so common on the Web of Documents today. | ||
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| - | As a key component of efficient query answering in Linked Data Management systems, much research is focused on devising high-performance native RDF indexing data structures. One class of such indexes, called structural indexes, seem very promising in this respect. Currently however, structural indexes for RDF are difficult to distribute accross the web. Given the importance of distribution in web-scale data, the goal of this thesis is to investigate how structural RDF indexes can be used in a distributed query answering platform. | ||
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| - | * Contact : [[stijn.vansummeren@ulb.ac.be|Stijn Vansummeren]] | ||
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