Xml WebService full instance resolution (1)

I have nothing to worry about recently. I think that my blog has not written any new articles for a long time. I just want to write a special topic. I 'd like to write a sample article about webservice.
First, we must understand what is webservice. in terms of concept, it may be complicated, but we can have a macro understanding that webservice is an external interface with functions that can be called by external customers (note: there are also functions that cannot be called by the customer ). if we are a server, we have written a webservice and then gave it to the customer (and we also gave them the call rules ), the customer can be in a relatively transparent State when obtaining information from the server. that is, the customer does not understand (or need to) the process, and they only obtain data.
The data transmitted by webservice can only be serialized data, typically xml data. Here we only discuss the transmission of xml data.
With some preliminary understanding of xml webservice, we will discuss the specific webservice usage in the form of a specific webservice example, it is easier to understand a concept with specific examples.
Here, we will take a simple distributed courseware search system as an example. use VS2003 as the compiling environment, C # As the language, and SqlServcer2000 as the database. (This example is inspired by an online friend's article. I think it is very representative of the characteristics of webservice. I just used this system as an example)
First, clarify what we want to do. we need an interface to the customer, that is, a site. We call it ServiceGatherSite. It doesn't matter in what form, even it doesn't need a database, it only provides a query interface for users, real services, and common users are not exposed to it. then, we also need several sites that provide services. We can call them resource sites. For simplicity, we suppose there are two resource sites, WebSiteA, WebSiteB, they may not be made public, but exist to enrich the query data. finally, we need to pay attention to the service that the resource station provides to ServiceGatherSite. the two resource sites have two services, namely SiteAService and SiteBService. there is no relationship between the two services, and the internal methods provided are completely unrelated. They just need to tell ServiceGatherSite how to use the methods. This means that the service only provides the query interface and how to process the returned data, services are not managed by themselves, and are all allocated by the site using the services.
After writing so much, I briefly introduced the concept of xml webservice and the structure of our example. In the next article, we will start to enter the code design stage.