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Programming Microsoft .NET Authors: Prosise J. Published year: 2002 Pages: 13-14/101 |
Part 1
Essential Concepts
Chapter 1
Hello, .NET
A journey of a thousand miles must begin with a single step. |
Software development today is an industry beset by incompatibilities. Modules written in different languages dont easily integrate. Programs run on separate machines must jump through hoops to talk to each other. Applications developed for different operating systems are built on incompatible APIs, making porting difficult. And as the industrys focus shifts from stand-alone applications and client/server programs to applications that live and run on the Web, new kinds of incompatibilities appearincompatibilities between programming models that have stood the test of time and models that have evolved without planning or forethought to fill a void that needed filling. Instead of compiled languages, we have scripting languages. Instead of rich graphical user interfaces, we have HTML. And instead of object-oriented programming, we have enterprise-class applications built with mixtures of procedural code, HTML, DHTML, XML, COM, and other unrelated technologies.
Microsoft has a vision of the future that addresses these issues and many more. That vision is embodied in an initiative called Microsoft .NET. Microsoft .NET, or simply .NET as it is more commonly called, is a new way of building and deploying software that leverages standards such as HTTP and XML to make interoperability a reality rather than a dream, and that relies on the Internet to make software services available on an unprecedented scale. An important part of the initiative is the .NET Framework, which is a platform for building and running .NET applications. The framework isnt required for building .NET applications, but it makes the development process eminently easier and less time-consuming . Among its many benefits: it brings object-oriented programming to the Web; it eliminates many of the most common and debilitating kinds of software bugs ; and it provides a common API for all languages, meaning the language that you choose at the beginning of a project wont paint you into a corner at the end.
This chapter is your first step on the road to becoming a .NET Framework programmer. In it, youll become acquainted with the frameworks two core components : the common language runtime and the .NET Framework class library. Youll learn about metadata, common intermediate language, managed modules, and assemblies. At the end of the chapter, youll write your first framework application. The information you come away with will enrich your understanding of the .NET Framework and help you understand what goes on under the hood when you build and run the applications presented in subsequent chapters.
The Microsoft .NET Initiative
The term Microsoft .NET refers to a massive effort on Microsoft s part to get away from traditional software development and to build ”with help from partners all over the industry ”the Internet into a service-oriented software platform. Read the documents that provide an overview of .NET on Microsoft s Web site, and you ll encounter the term XML Web services repeatedly. An XML Web service is an application that runs on a Web server and exposes callable API functions, or Web methods , to clients on the Internet. XML is part of the name because Web services and Web service clients use XML to exchange data. As XML Web services proliferate, the Internet will become a software platform with an API far richer than any operating system. Today s applications rely primarily on operating system services. Tomorrow s applications will use Web services to validate credit card purchases, check the status of airline flights , and perform other everyday tasks . With luck, your favorite restaurants will make their menus available via a Web service so that you can check the daily specials from the comfort of your computer desk.
Web services aren t something that Microsoft invented, nor are they proprietary to Microsoft .NET. Web services rely on open standards such as HTTP, XML, and SOAP. (SOAP, in case you don t know, is an acronym for Simple Object Access Protocol; it s an Internet standard that describes how applications can interoperate ”that is, call methods on each other ”using HTTP and other protocols.) Because they re an industry standard and not a Microsoft standard, Web services are already proliferating on the Internet. Significantly, most of the Web services that are available today do not use the .NET Framework and do not run on Windows. Web services are about interoperability. It s relatively simple to write a Web service client that runs on Windows and invokes methods on a Web service running on Linux. In the future, online directories that are themselves Web services will enable companies to advertise their Web services. Need a Web service that exposes real-time stock quotes or shipment tracking information? Microsoft and others are building UDDI (Universal Description, Discovery, and Integration) registries that make such information available on a global scale.
If XML Web services can be written without Microsoft s help, then what does Microsoft .NET bring to the party? Plenty. First, .NET validates the Web service concept by throwing the weight of an industry giant behind it. Second, Microsoft is busy writing Web services of its own, promoting Web service initiatives such as .NET My Services, upgrading its enterprise server products to fit seamlessly into a service-oriented world, and upgrading Visual Studio and other development tools to speak the language of Web services. Third, and perhaps most important, is that Microsoft .NET includes the .NET Framework. You can write Web services using x 86 assembly language if you want to, but the .NET Framework makes writing Web services so easy that just about anyone can write one. You ll learn all about Web services and the framework s support for them in Chapter 11.
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Programming Microsoft .NET Authors: Prosise J. Published year: 2002 Pages: 13-14/101 |