Pattern Reification as the Basis for Description-Driven Systems

One of the main factors driving object-oriented software development for information systems is the requirement for systems to be tolerant to change. To address this issue in designing systems, this paper proposes a pattern-based, object-oriented, description-driven system (DDS) architecture as an extension to the standard UML four-layer meta-model. A DDS architecture is proposed in which aspects of both static and dynamic systems behavior can be captured via descriptive models and meta-models. The proposed architecture embodies four main elements - firstly, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, secondly the identification of four data modeling relationships that can be made explicit such that they can be modified dynamically, thirdly the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourthly the encoding of the structural properties of the five design patterns by means of one fundamental pattern, the Graph pattern. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of description-driven data objects to handle system evolution.Comment: 20 pages, 10 figure

Improving System Design Through the Integration of Human Systems and Systems Engineering Models

The human is a critical aspect of many systems, but frequently there is a failure to properly account for human capabilities and involvement during system design. This inattention results in systems with higher lifecycle costs, decreased user compatibility, and the potential to produce disastrous consequences. This research presents an approach to integrating the human into system models by using two methods: static and dynamic modeling. The static method uses a user-centered design framework to create system- and human-centered models that deconstruct the system and user into their respective components. These models are integrated to create system models that include relevant information about the human and highlight potentially conflicting tasks. The dynamic method uses a human performance modeling tool to create a discrete event simulation (DES) of the system. This DES model is used to perform an analysis between system trades, by which constraints and assumptions placed on the human are verified. Data gained from the analysis are integrated back into system models in order to reflect true system performance. By applying these two integration methods early in the system’s lifecycle, system models can more effectively account for the human as a critical component of the system, thus improving system design

An approach to modeling database activity

Results in the field of data modeling currently suffer from many of the same ills which plagued data management systems in the late 1960's. Advanced semantic modeling systems such as the Semantic Data Model and the Relational Model/Tasmania are extremely complex to understand as well as somewhat ad hoc in design. Such systems capture only static snapshots of activity in the world being modeled. On the other hand, behavioral models which do attempt to model system dynamics typically provide less overall modeling power than comprehensive semantic models. Further, the specifications of behavior which can be expressed with such models are themselves static snapshots which are not integrated with other database objects.This work describes one approach for capturing dynamic relationships by distilling the concepts found in semantic and behavioral data models into a small number of flexible constructs. The resulting Prototype Activity Modeling System (PAMS) captures the containment, feedback, operational, and state dependency roles of entities in the world being modeled. Further, these definitions of database activity are captured as database objects (rather than as a schema) so as to allow dynamic manipulation of entity roles.The key concept of the approach is the bundle - a purposefully designed extension of time-proven relational database modeling concepts which includes support for presentation ordering and complex Cartesian aggregations. By applying the basic nested bundle principle, it is possible to obtain complex hierarchies of static structural information. The static templates so constructed, when used with a non-procedural query language and the value nomination principle which reduces relations to scalar values when necessary, provide a conventional database modeling system for applications. By extending these templates with the non-procedural thunk principle which embeds query specifications within object definitions, variations caused by dependencies within the application can cause the apparent contents of the database description to change. When further extended by the activity monitoring principle which records the interaction between the application and its environment, these dynamic templates can account for changes outside the scope of the application

Towards a Role-Based Contextual Database

Traditional modeling approaches and information systems assume static entities that represent all information and attributes at once. However, due to the evolution of information systems to increasingly context-aware and self-adaptive systems, this assumption no longer holds. To cope with the required flexibility, the role concept was introduced. Although researchers have proposed several role modeling approaches, they usually neglect the contextual characteristics of roles and their representation in database management systems. Unfortunately, these systems do not rely on a conceptual model of an information system, rather they model this information by their own means leading to transformation and maintenance overhead. So far, the challenges posed by dynamic complex entities, their first class implementation, and their contextual characteristics lack detailed investigations in the area of database management systems. Hence, this paper, presents an approach that ties a conceptual role-based data model and its database implementation together, to directly represent the information modeled conceptually inside a database management system. In particular, we propose a formal database model to describe roles and their contextual information in compartments. Moreover, to provide a context-dependent role-based database interface, we extend RSQL by compartments. Finally, we introduce RSQL Result Net to preserve the contextual role semantics as well as enable users and applications to both iterate and navigate over results produced by RSQL. In sum, these means allow for a coherent design of more dynamic, complex software systems

A sonar-based mapping system for an unmanned undersea vehicle

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 115-118).An unmanned undersea vehicle (UUV) must operate autonomously in a complex, dynamic environment and react intelligently to changing tactical, environmental, and mission variables with no outside intervention. To support these real-time, adaptive mission capabilities, the building and updating of an efficient and accurate map of the tactical scene is critical. The challenges are to obtain useful and comprehensive information about the environment, to represent and fuse this data into an on-board map, to update the map in real-time when new data is discovered, and to save the map for future use while maintaining both efficiency and accuracy. This thesis presents the design and implementation of a sonar-based mapping system for a UUV, and discusses the elements of the mapping system design: representation of static and dynamic obstacles in a mapping system, the need for efficient data structures, the incorporation of sonar measurement uncertainty, and the assimilation of new information into the map. The mapping system consists of a static obstacle map that stores information about stationary objects and a dynamic obstacle map that stores information about moving objects in the underwater environment. The static obstacle map consists of a local map that represents the immediate mission area and a global map that represents the entire mission area. The combination of the separate maps forms an integrated mapping system that represents the UUV's tactical scene, supports a query for the presence or absence of an obstacle at any location, time, and level of certainty, and as such, can be used to support the UUV's mission objectives. This thesis also discusses modeling of noise in the sonar measurements. Since the mapping system must handle noisy sonar measurements, a model of a noisy sonar measurement is an imperative part of the sonar simulation and the validation of the mapping system.by Margaret F. Nervegna.M.Eng

An Agent-Based Approach For Collaborative Schema Design

Data modeling is a crucial step towards incorporating successful databases in an organization. The design, operational behavior, and use of a database are affected by the meaning of the information it manages. The cognitive capability of the human mind is rather complex; it has the capability to visualize a problem domain in a variety of perspectives. It would be interesting to conceive of an application, by which the best thoughts of human minds can be pooled together to create a conceptual schema design for a database. Thus, the database design would be enhanced if capabilities were provided for collaboration between different designers working on different platforms at different locations and even at different times but working on the same database design. This paper describes an agent- based approach, using an agent-based architecture communicating through the Internet, which promotes the collaborative conceptual schema design. The agent communication was to be developed using KQML (Knowledge Query Manipulation Language) in Java. The prototype of the system developed captures only the static properties of a system. The dynamic aspects of the operations are resolved by considering certain additional aspects that are not exactly database objects, but are associated with a database occurrence which changes as a result of an operation. These are implementation issues that must be taken care by a database designer during the implementation

A simplified software architecture for self-updating Building Information Models (BIM)

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 61-63).Building Information Modeling (BIM) is an emerging software technology that is revolutionizing the architecture, engineering, and construction (A/E/C) industry. BIM technology employs "object-based 3D models-containing the physical and functional characteristics of a facility-that serve as a repository for lifecycle information in an open, interoperable format" [1]. The major difference between BIM and Computer-Aided Design/Drafting (CADD) is that the former includes geometry and a plethora of building information while the latter includes only geometry. BIM utilization in the AEC industry has increased due to 1) BIM tools increasing productivity in design tasks; 2) the increasing number of private and government agencies that have instituted BIM requirements; 3) the pervasive use of computer analysis and simulations models; 4) the benefits of BIM as lifecycle management tool. Current literature shows trends of a transition from a "passive"-static model-based-approach to an "active"-dynamic model-based-approach. The active approach requires the integration of BIM with sensors to create "self-updating" building models. Previous research introduces the concept of a self-updating building model ([2], [31, [41). These systems involve complex software architecture and may perpetuate the problem of software interoperability. This thesis explores the following question: May a similar system be created to synthesize dynamic sensor data while improving upon previous research and simplifying the software architecture? The author describes a prototype system, called LiveBuild, which integrates commercial BIM software with other off-the-shelf software components to create a self-updating building model. LiveBuild is the first self-updating building model that operates as an extension to existing commercial BIM software. Therefore, the transition from static to active building models is as simple as installing a plug-in. LiveBuild may serve as the basis for future research in self-updating building by providing simplified system that is well integrated with state-of-the art commercial design software. Likewise, the prototype is applicable for professional practice by allowing firms to use their existing BIM software to perform "pilot projects" with self-updating technology. The current prototype supports an interface with single commercial BIM software (Autodesk Revit 2009) product however future prototypes may extend both the functions and interfaces for other BIM software.by Pierre Fuller.S.M

On Modeling and Analyzing Cost Factors in Information Systems Engineering

Introducing enterprise information systems (EIS) is usually associated with high costs. It is therefore crucial to understand those factors that determine or influence these costs. Though software cost estimation has received considerable attention during the last decades, it is difficult to apply existing approaches to EIS. This difficulty particularly stems from the inability of these methods to deal with the dynamic interactions of the many technological, organizational and projectdriven cost factors which specifically arise in the context of EIS. Picking up this problem, we introduce the EcoPOST framework to investigate the complex cost structures of EIS engineering projects through qualitative cost evaluation models. This paper extends previously described concepts and introduces design rules and guidelines for cost evaluation models in order to enhance the development of meaningful and useful EcoPOST cost evaluation models. A case study illustrates the benefits of our approach. Most important, our EcoPOST framework is an important tool supporting EIS engineers in gaining a better understanding of the critical factors determining the costs of EIS engineering projects