15-499 Advanced Software Engineering - Spring 1997

Carnegie Mellon University

School of Computer Science

http://cascade1.se.cs.cmu.edu/15-499

Handout 2

14 January 1997

Problem Statement

OWL II: Object-Oriented Workplace Laboratory

1. Introduction

40% of the nations energy is used for heating, cooling, ventilating, and lighting buildings. Lighting and heating/cooling requirements are directly interrelated. In commercial buildings all lighting energy eventually becomes heat energy and must therefore be cooled away, adding additional energy requirements. The deefficacy of lighting systems is about two to six percent when measured from the powerplant (powerplant efficiency 25%; transmission loss to buildings 15%; conversion of electricity into light efficiency 25%; light provided for unoccupied areas and regardless of daylight availability adds further penalties). About 35% of all electric energy is used in office buildings and the majority of the electricity is used for lighting. Health, well-being, motivation and productivity of office workers (over half of the U.S. workforce of 120 Million people) depend significantly on the appropriate quantity and quality of lighting, including daylighting systems. Glare (reflected or indirect), illuminance and contrast values are critical.

The OWL (Object-Oriented Workplace Laboratory) system developed in the Fall 96 is an attempt to deal with these problems. OWL users have a high degree of control over their work space at the Intelligent Workplace. From their user interface, they may request changes in the temperature, light level, and other aspects of the environment. These changes are then effected through adjustments in exterior louvres, internal lighting systems, and the HVAC system. Through a network of environmental sensors located in each work area, an energy-efficient adjustment of building climate systems can be formulated and executed.To schedule workplace resources, a reservation system (aware of the day-to-day geometry of the Intelligent Workplace) assists users in requesting conference rooms and other shared resources.

The OWL system offers major advantages over standard lighting systems currently employed in commercial office buildings. The benefits are substantial energy savings, improved functionality and user satisfaction through the use of internet and componentware technologies.

Buildings offer major challenges because the human/machine interface is very complex (many users with different tastes and preferences, many parts/components/systems, many functional changes ). Therefore systems that allow for individual control, combined with embedded intelligence to guard against energy and environmental waste must be develeoped. The OWL system directly addresses these issues.

OWL System Architecture

The OWL software architecture is designed as a framework that can be reused for other application domains that be modeled as a space of sensor objects, where we define a sensor as an object with several attributes whose values are read, visualized and controlled by remote method invocation. We believe the framework can be applied to other application domains with sensor spaces such as airplanes, cars, trucks, ships...not just buildings.

Based on a software architecture that combines Web (Java) and Object technology (CORBA), OWL offers opportunities for remote diagnostics, remote facility management, remote control and remote visualization of lighting systems in the workplace. OWL's software architecture provides flexibility as well: As the operational needs of building occupants change, the interior modular walls may be rearranged to provide suitable work environments. These changes may be simulated in a CAD package for analysis of thermal efficiency implications, then visualized in 3D using the Liquid Reality toolkit.

CORBA allows a unique degree of collaboration amongst the OWL subsystems and hardware resources running on a variety of architectures and operating systems.

The first demonstration of OWL held on December 5, 1996 employed a speech recognition system written in tcl/tk and a graphical User Interface written in Java running under Solaris on a Sun SPARCstation. This interface obtained building geometry and environmental information via the object request broker from an object-oriented database running on a remote HP workstation. The Database Subsystem was accessed by several other OWL subsystems each of them accessing existing software products running on different plaforms and often written in a different language: the Facility Management subsystem providing access to Reservation and Site Editors written in Java running on a Windows NT Pentium PC; the thermal Simulation subsystem written in tcl/tk, employing a CAD tool - Microstation - running on an NT system, but whose computation is performed by a remote Unix server; the Control subsystem written in Java and interacting directly with the building sensors, louvres, and other Intelligent Workplace hardware through an NT workstation; and the Visualization subsystem building VRML representations of CAD models stored in the database running on a Solaris SPARCstation.Communication between the OWL subsystems is provided by a powerful event service called Notification. The event service is based on a push architecture, helping to coordinate computation, data storage and physical manipulation of the Intelligent Workplace hardware.

2. Functional Requirements

The OWL II System

3. Nonfunctional Requirements

The OWL System provides concurrent access to the light sensors and the blinds for multiple users, accessing the system locally and remotely. Each of the applications can be run independently from each other as a separate process, while still allowing the applications to communicate with each other.

The software architecture must be extensible.

The delivered OWL I prototype is not model-based, that is, the code and the design are not consistent with each other. The documentation, in particular the System Design Document, do also not reflect the code of the delivered system. To make the system model, code and documentation consistent with each other, you are asked to do the following tasks:

4. Constraints

4. Project Management of the OWL System

The second iteration will continue with the communication scheme introduced in the first iteration. The development of OWL I was based on face-to-face group meetings, project-wide reviews and distributed communication via NetNews. We have replaced the NetNews bboard by Lotus Notes 4.5. Because the Lotus Notes Server is HTTP compliant, any Web browser - in addition to the Lotus Notes client - can be used to access the Lotus Notes dabases. The machines in the software engineering lab will be equipped with Lotus Notes 4.5 clients. Access rights will be set during the first week of the project.

 



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