Encyclopedia of Computer Science and Technology

Microsoft Windows 309Here the various parameters passed to the CreateWindowfunction specify the type of window, window title,characteristics, and location. The function returns a “windowhandle,” which is a pointer that holds the window’saddress and allows it to be accessed later.Most Windows programming environments, includingC++ and particularly, Visual Basic, now let program designersavoid having to specify code such as the above to createwindows and other objects. Instead, the programmer canclick and drag various objects onto a design screen to establishthe interface that will be seen by the program’s user.The programmer can then use Properties settings to specifymany characteristics of the screen objects without havingto explicitly program them.Microsoft and third-party developers also provide readymadeprogramming code in dynamic link libraries (DLLs).These resources (see library, program) can be called byany application, which can then use any object or functiondefined in the library. Windows also provides a facilitycalled OLE (Object Linking and Embedding). This lets anapplication such as a word processor “host” another applicationsuch as a spreadsheet. Thus, the Microsoft Word, forexample, can embed a Microsoft Excel spreadsheet into adocument, and the spreadsheet can be worked with usingall the usual Excel commands. In other words, OLE letsapplications make their features, controls, and functionalityaccessible to other applications. Indeed, collections ofcontrols are often packaged as OCX (OLE controls) andsold to developers.Despite all this available help, Windows presents a steeplearning curve for many programmers. There are hundredsof functions for handling interface objects, drawing graphics,managing files, controlling devices, and other tasks.With the growing use of object-oriented programming languages(see object-oriented programming and C++) inthe late 1980s and 1990s, Microsoft devised the MicrosoftFoundation Classes (MFC). This framework defines all ofthe interface objects and other entities (such as data structures)as C++ classes.Using MFC, a programmer, instead of calling a functionto create a window, creates an object of a particularWindow class. To customize a window, the programmercan use inheritance to derive a new window class.The various functions for controlling windows are thendefined as member functions of the window class. Thisuse of object-oriented, class-based design organizes muchof the great hodgepodge of Windows functions into alogical hierarchy of objects and makes it easier to masterand to use.For example, using the traditional Windows API (seeapplications programming interface) one puts a textstring into a list box using this code:LRESULT LRes;LRes = SendMessage(hMyListBox,LB_ADDSTRING,0,“Network Services”);(LRes is a number that will hold a code that says whetherthe item was successfully added)Using MFC, this code can be rewritten as:CListBox * pListBox;int nRes;nRes = pListBox->AddString (“Network Services”);Here a pointer is declared to an object of the ListBoxclass, and a member function of that class, AddString, isthen called. While this code may not look simpler, it uses aconsistent object-oriented approach.The new common framework for Windows programmingis called .NET. Closely integrated with the latestversions of Windows (XP SP2 and Vista), the class frameworkhas been revamped and expanded. .NET provides acommon language runtime (CLR) for access from differentlanguages such as C++, C#, and Visual Basic .NET. (SeeMicrosoft .NET.)TrendsBy just about any standard Microsoft Windows has achievedremarkable success, capturing and largely holding thelion’s share of the PC operating system market. However,Windows has been persistently criticized on grounds ofreliability and security. Perhaps feeling the pressure fromusers and potential regulators, Microsoft has placed greateremphasis on security in recent years; Windows Vista integratessecurity much more tightly into the structure of thesystem. However, as long as Windows is the most widelyused operating system, it will continue to be the biggest targetfor creators of viruses and other malware.Microsoft has included powerful facilities that allowWindows applications to be controlled by other applicationsor remotely (see scripting languages). Unfortunately,these facilities have proven to be quite vulnerable to computerviruses that can use them to damage systems connectedto the Internet. There seems to be a never-ending racebetween developers of program “patches” designed to plugsecurity holes and inventive, albeit malicious virus writers.Windows continues to face a variety of challenges. Theability to deliver applications directly through Web browserson any platform may make it less compelling for a user withsimple computing needs to pay the premium for a WindowsbasedPC. (For example, Google now delivers basic wordprocessing, spreadsheet, email, and other applications—seeapplication service provider.) Linux, too, may be graduallygaining a greater share on the desktop. Versions suchas the popular and frequently updated Ubuntu now installabout as easily as Windows, provide a similar user interface,and include a variety of software, including Open Office (seeLinux and open-source movement).While Windows still remains the dominant PC operatingsystem with tens of thousands of applications and atleast several hundred million users around the world, it islikely that the PC operating systems of 2020 will be as differentfrom today’s Windows as the latter is from the MS-DOS of the early 1980s.Further ReadingBellis, Mary. “The Unusual History of Microsoft Windows.” About.com. Available online. URL: http://inventors.about.com/od/mstartinventions/a/Windows.htm. Accessed August 15, 2007.