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Systematic Design of Data Management for Real-Time Data-Intensive Applications
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Formal Modelling and Analysis of Embedded Systems)
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Modern real-time data-intensive systems generate large amounts of data that are processed using complex data-related computations such as data aggregation. In order to maintain the consistency of data, such computations must be both logically correct (producing correct and consistent results) and temporally correct (completing before specified deadlines). One solution to ensure logical and temporal correctness is to model these computations as transactions and manage them using a Real-Time Database Management System (RTDBMS). Ideally, depending on the particular system, the transactions are customized with the desired logical and temporal correctness properties, which are achieved by the customized RTDBMS with appropriate run-time mechanisms. However, developing such a data management solution with provided guarantees is not easy, partly due to inadequate support for systematic analysis during the design. Firstly, designers do not have means to identify the characteristics of the computations, especially data aggregation, and to reason about their implications. Design flaws might not be discovered, and thus they may be propagated to the implementation. Secondly, trade-off analysis of conflicting properties, such as conflicts between transaction isolation and temporal correctness, is mainly performed ad-hoc, which increases the risk of unpredictable behavior.

In this thesis, we propose a systematic approach to develop transaction-based data management with data aggregation support for real-time systems. Our approach includes the following contributions: (i) a taxonomy of data aggregation, (ii) a process for customizing transaction models and RTDBMS, and (iii) a pattern-based method of modeling transactions in the timed automata framework, which we show how to verify with respect to transaction isolation and temporal correctness. Our proposed taxonomy of data aggregation processes helps in identifying their common and variable characteristics, based on which their implications can be reasoned about. Our proposed process allows designers to derive transaction models with desired properties for the data-related computations from system requirements, and decide the appropriate run-time mechanisms for the customized RTDBMS to achieve the desired properties. To perform systematic trade-off analysis between transaction isolation and temporal correctness specifically, we propose a method to create formal models of transactions with concurrency control, based on which the isolation and temporal correctness properties can be verified by model checking, using the UPPAAL tool. By applying the proposed approach to the development of an industrial demonstrator, we validate the applicability of our approach.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2017.
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 258
National Category
Computer Systems
Identifiers
URN: urn:nbn:se:mdh:diva-35369ISBN: 978-91-7485-334-6 (print)OAI: oai:DiVA.org:mdh-35369DiVA: diva2:1097790
Presentation
2017-06-12, Kappa, Mälardalens högskola, Västerås, 13:30 (English)
Opponent
Supervisors
Projects
DAGGERS
Funder
Knowledge Foundation
Available from: 2017-05-23 Created: 2017-05-22 Last updated: 2017-07-10Bibliographically approved
List of papers
1. DAGGTAX: A Taxonomy of Data Aggregation Processes
Open this publication in new window or tab >>DAGGTAX: A Taxonomy of Data Aggregation Processes
2017 (English)Report (Other academic)
Abstract [en]

Data aggregation processes are essential constituents in many data management applications. Due to their complexity, designing data aggregation processes often demands considerable efforts. A study on the features of data aggregation processes will provide a comprehensive view for the designers and ease the design process. Existing works either propose application-specific aggregation solutions, or focus on particular aspects of aggregation processes such as aggregate functions, hence they do not offer a high-level, generic description. In this paper, we propose a taxonomy of data aggregation processes called DAGGTAX, which builds on the results of an extensive survey within various application domains. Our work focuses on the features of aggregation processes and their implications, especially on the temporal data consistency and the process timeliness. We present our taxonomy as a feature diagram, which is a visual notation with formal semantics. The taxonomy can then serve as the foundation of a design tool that enables designers to build an aggregation process by selecting and composing desired features. Based on the implications of the features, we formulate three design rules that eliminate infeasible feature combinations. We also provide a set of design heuristics that could help designers to decide the appropriate mechanisms for achieving the selected features. 

Place, publisher, year, edition, pages
Västerås: , 2017
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-35366 (URN)MDH-MRTC-319/2017-1-SE (ISRN)
Projects
DAGGERS
Funder
Knowledge Foundation
Available from: 2017-05-22 Created: 2017-05-22 Last updated: 2017-05-29Bibliographically approved
2. A Formal Approach for Flexible Modeling and Analysis of Transaction Timeliness and Isolation
Open this publication in new window or tab >>A Formal Approach for Flexible Modeling and Analysis of Transaction Timeliness and Isolation
2016 (English)In: Proceedings of the 24th International Conference on Real-Time Networks and Systems, Brest, France, 2016Conference paper, Published paper (Refereed)
Abstract [en]

Traditional Concurrency Control (CC) mechanisms ensure absence of undesired interference in transaction-based systems and enforce isolation. However, CC may introduce unpredictable delays that could lead to breached timeliness, which is unwanted for real-time transactions. To avoid deadline misses, some CC algorithms relax isolation in favor of timeliness, whereas others limit possible interleavings by leveraging real-time constraints and preserve isolation. Selecting an appropriate CC algorithm that can guarantee timeliness at an acceptable level of isolation thus becomes an essential concern for system designers. However, trading-off isolation for timeliness is not easy with existing analysis techniques in database and real-time communities. In this paper, we propose to use model checking of a timed automata model of the transaction system, in order to check the traded-off timeliness and isolation. Our solution provides modularization for the basic transactional constituents, which enables flexible modeling and composition of various candidate CC algorithms, and thus reduces the effort of selecting the appropriate CC algorithm.

Place, publisher, year, edition, pages
Brest, France: , 2016
Keyword
Transaction management, concurrency control, timeliness, isolation, model checking
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:mdh:diva-33826 (URN)10.1145/2997465.2997495 (DOI)000391255400001 ()2-s2.0-84997170469 (Scopus ID)
Conference
24th International Conference on Real-Time Networks and Systems RTNS'16, 19 Oct 2016, Brest, France
Projects
DAGGERS - Data aggregation for embedded real-time database systems
Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2017-05-22Bibliographically approved
3. Towards the verification of temporal data consistency in Real-Time Data Management
Open this publication in new window or tab >>Towards the verification of temporal data consistency in Real-Time Data Management
2016 (English)In: 2016 2nd International Workshop on Modelling, Analysis, and Control of Complex CPS, CPS Data 2016, 2016, Article number 7496422Conference paper, Published paper (Refereed)
Abstract [en]

Many Cyber-Physical Systems (CPSs) require both timeliness of computation and temporal consistency of their data. Therefore, when using real-time databases in a real-time CPS application, the Real-Time Database Management Systems (RTDBMSs) must ensure both transaction timeliness and temporal data consistency. RTDBMSs prevent unwanted interferences of concurrent transactions via concurrency control, which in turn has a significant impact on the timeliness and temporal consistency of data. Therefore it is important to verify, already at early design stages that these properties are not breached by the concurrency control. However, most often such early on guarantees of properties under concurrency control are missing. In this paper we show how to verify transaction timeliness and temporal data consistency using model checking. We model the transaction work units, the data and the concurrency control mechanism as a network of timed automata, and specify the properties in TCTL. The properties are then checked exhaustively and automatically using the UPPAAL model checker. 

Keyword
Complex networks, Embedded systems, Information management, Model checking, Real time systems, Concurrent transactions, Cyber physical systems (CPSs), Early design stages, Real time data management, Real-time database, Real-time database management systems, Temporal consistency, Uppaal model checkers, Concurrency control
National Category
Embedded Systems
Identifiers
urn:nbn:se:mdh:diva-32523 (URN)10.1109/CPSData.2016.7496422 (DOI)000390778200005 ()2-s2.0-84980619578 (Scopus ID)9781509011544 (ISBN)
Conference
2nd International Workshop on Modelling, Analysis, and Control of Complex CPS, CPS Data 2016, 11 April 2016
Available from: 2016-08-18 Created: 2016-08-18 Last updated: 2017-05-22Bibliographically approved

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