Encyclopedia of Computer Science and Technology

434 smart buildings and homesThis means “send the message + 1 to the object thatis referenced by the variable called Total.” This messagereferences the + method, one of the methods that numericobjects “understand.” The object therefore adds 1 to itsvalue, and returns that value as a new object, which in turnis now referenced by the variable Total.A “program” in Smalltalk is simply a collection of objectswith the capabilities to carry out whatever processes arerequired. The objects and their associated variables makeup the “workspace,” which can be saved to disk periodically.For the Smalltalk programmer there is no distinctionbetween Smalltalk and the host computer’s operatingsystem. The operating system’s capabilities (such asfile handling) are provided within the Smalltalk system aspredefined objects. Kay envisaged Smalltalk as a completeenvironment that could be extended by users who were notnecessarily experienced programmers, and he designed itspioneering graphical user interface as a way to make it easyfor users to work with the system.Smalltalk includes a “virtual machine,” whose instructionsare then implemented in specific code for each majortype of computer system. Because of Smalltalk’s consistentstructure and ability to build everything up from objects,almost all of the Smalltalk system is written in Smalltalkitself, making it easy to transplant to a new computer oncethe machine-specific details are provided.Because of its elegance and consistency and its availabilityon personal computers, by the 1980s Smalltalk hadaroused considerable interest. The language has not beenwidely used for mainstream applications, in part becausethe mechanisms needed to kept track of classes and inheritanceof methods are hard to implement as efficiently asthe simpler mechanisms used in traditional languages. Theapproach of building object-oriented features onto existinglanguages (as with developing C++ from C) had greaterappeal to many because of efficiency and a less steep learningcurve.Nevertheless, the conceptual power of Smalltalk hasmade it attractive for certain AI and complex simulationprojects, and it appeals to those who want a pure objectorientedapproach where an application can cleanly mirrora real-world situation. Smalltalk also remains a good choicefor teaching programming to children (and others). A versioncalled Squeak provides a rich environment of graphicsand other functions. Squeak and a number of other Smalltalkimplementations are available for free download for anumber of different computer systems.Further ReadingDucasse, Stéphane. Squeak: Learn Programming with Robots. Berkeley,Calif.: Apress, 2005.Klimas, Edward J., Suzanne Skublics, and David A. Thomas. Smalltalkwith Style. Englewood Cliffs, N.J.: Prentice Hall, 1996.Lewis, Simon. The Art and Science of Smalltalk. Englewood Cliffs,N.J.: Prentice Hall, 1995.Smalltalk. Available online. URL: http://smalltalk.org. AccessedAugust 21, 2007.Squeak. Available online. URL: http://www.squeak.org/. AccessedAugust 21, 2007.smart buildings and homesA smart building, whether commercial space or a home, isone in which components ranging from HVAC (heating,ventilation, and air conditioning) to appliances, computers,communications, security, and entertainment systems areintegrated into a network for easy control.Some typical features of a smart building include thefollowing:• lighting that is controlled by time of day, scheduling,and occupancy sensors• temperature and air-flow sensors to determine theamount of cooling, heating, or fresh air needed• controls for central heating, hot water, and air conditioningsystems, optimizing efficiency and minimizingenergy use• alarms for intrusion, fire, carbon monoxide/dioxide,and other hazards• alarms indicating failure or unsafe operating conditionsfor various devices• integration of alarm and status messages withcommunications systems, enabling users to receivethem by e-mail, text message, phone, or othermeansUsing a secure link, the user can connect to the buildingvia mobile phone or perhaps Internet connection andgive it commands, such as to turn the heating or porch lighton, close the drapes, and so on. The system can also let theremote user know who is at the door and allow for communication,or let them in.Smart office or other buildings use many of the sametechnologies as smart homes, but the priorities and emphasesmay be different. Smart buildings are more likely tobe centrally controlled and fully automated rather thanallowing individuals to interact with them. (Regulatory andsafety requirements are also likely to be different and morecomplex.)Applications and QuestionsThe integrated controls in a smart house are potentiallyvery useful for disabled persons or seniors who have limitedmobility. Lighting could automatically be turned onas a person gets up from bed and goes to the bathroom, forexample. Appliances could be controlled remotely, and evencupboards or tables could be designed to raise or lower atthe touch of a button. (See disabled persons and computingand seniors and computing.) If such systems areeffective, their cost may be well worth the psychologicalbenefits of allowing people to remain in their homes, and incomparison to the cost of assisted living or residence facilities.Smart homes could also help parents monitor toddlersor small children as well as restrict them from enteringpotentially hazardous parts of the house.Critics of the smart-house concept point out that installingand integrating all the required equipment for a full