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Microsoft Visual Basic .NET Tutorials
Web Services / How Do They Work?
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Subtitles of the Movie (Microsoft Visual Basic .NET / Web Services / How Do They Work?)
Now let's talk about how web services work and there is two different ways. First of all I'm just going to talk about just how generically web services work and then before I close the video we are going to talk about how they get put into place in visual studio. The first thing we want to do with web service is simply build the methods that we want to provide, just like we did in DCOM, we just simply build the methods that have the functionalities either subs or functions and then when we turn these things into web services a WSDL document gets created. This is a XML formatted document that describes how this data is used what is expected, exactly how to implement this functionality and so forth. This is a contract that both people have to agree on, and it's describing what's happening. And again this is in XML format, I'll show you one of these a little later. The data is then serialized as XML passed across port 80 to the requesting machine via http. And then execution occurs; now every bit of this happens with no DCOM, DCOM is not involved. There is no smoke and mirrors for remoting here. So now the question arises, wait a minute, without DCOM how do I know which machine to contact to get this particular service. And the answer is we do this through URL. Now let's go back just a second and talk about how this works in visual studio; we build our methods and we mark our methods with an attribute called web method. And then when we compile this it builds the WSDL for us, it serializes the data as XML and gets it ready and then when a request is made; now it also builds a proxy object that when a request comes in to our XML application, or if we request something out, it goes through of proxy, gets the information and returns it, it takes the returned information which is in format and drops that into an object much like the ASP objects were - response and requests. Very similar to a record set I guess you could say, and so then the beauty of this is that we can use web services in visual studio and never even realize we are using web services. The bottom line is that we are simply calling methods across disparate systems, across the Internet, simply because we are now speaking a common language in the middle. And that's XML. And the next video I'm going to actually create a web service and show you how to do this and show you how really simple this can be.
Tutorial Information
| Course: | Microsoft Visual Basic .NET |
| Author: | Mark Long |
| SKU: | 33433 |
| ISBN: | 1932072349 |
| Release Date: | 2003-05-27 |
| Duration: | 6 hrs / 87 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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