.NET框架程序设计

Over the years, our computing lifestyles have changed. Today, everyone sees the value of
the Internet, and our computing lifestyle is becoming more and more dependent on Webbased
services. Personally, I love to shop, get traffic conditions, compare products, buy
tickets, and read product reviews all via the Internet.
However, I’m finding that there are still many things I’d like to do using the Internet that aren’t
possible today. For example, I’d like to find restaurants in my area that serve a particular
cuisine. Furthermore, I’d like to be able to ask if the restaurant has any seating for, say, 7:00
p.m. that night. Or if I had my own business, I might like to know which vendor has a
particular item in stock. If multiple vendors can supply me with the item, I’d like to be able to
find out which vendor offers the least expensive price for the item or maybe which vendor
can deliver the item to me the fastest.
Services like these don’t exist today for two main reasons. The first reason is that no
standards are in place for integrating all this information. After all, vendors today each have
their own way of describing what they sell. The emerging standard for describing all types of
information is Extensible Markup Language (XML). The second reason these services don’t
exist today is the complexity of developing the code necessary to integrate such services.
Microsoft has a vision in which selling services is the way of the future—that is, companies
will offer services and interested users can consume these services. Many services will be
free; others will be available through a subscription plan, and still others will be charged per
use. You can think of these services as the execution of some business logic. Here are
some examples of services:
§ Validating a credit card purchase
§ Getting directions from point A to point B
§ Viewing a restaurant’s menu
§ Booking a flight on an airline, a hotel room, or a rental car
§ Updating photos in an online photo album
§ Merging your calendar and your children’s calendars to plan a family vacation
§ Paying a bill from a checking account
§ Tracking a package being shipped to you
I could go on and on with ideas for services that any company could implement. Without a
doubt, Microsoft will build some of these services and offer them in the near future. Other
companies (like yours) will also produce services, some of which might compete with
Microsoft in a free market.
So how do we get from where we are today to a world in which all these services are easily
available? And how do we produce applications—HTML-based or otherwise—that use and
combine these services to produce rich features for the user? For example, if restaurants
offered the service of retrieving their menu, an application could be written to query every
restaurant’s menu, search for a specific cuisine or dish, and then present only those
restaurants in the user’s own neighborhood in the application.