Introduction to Web Services

Web Services are the foundation of grid Services and the cornerstone of OGSA and IOGSI (GT3). Understanding the WebService architecture is the basis for compiling grid Services using GT3.
Recently there have been many discussions about "Web Services" and many companies have begun to respond to their enterprise applications. So what is Web Services? Simply put, they are another distributed computing technology (such as CORBA, RMI, and EJB) that allows us to create client/server applications.
For example, let's assume that I have to develop a program for a chain store. This chain store is distributed across the country, but my main product catalog (master catalog of product) is only stored in the database of my central office, and the store's software must be able to access this product catalog. I can publish these directories through a Web Service called ShopService.
It is important that errors do not occur when the website is published. The information on the website (as you are reading) is compiled by people. However, information on Web services can be accessed by software and accessed from time to time directly by people (despite the possibility of using the software ). Although Web services rely heavily on existing Web technologies (such as the HTTP we are seeing), they are not associated with the Web browser and HTML. Let's repeat it again: websites serve people, while Web services serve software :-)
The client (the PC in the store) will connect to (the WebService on the server) at that time and send a service request that requires a directory. The server returns the directory information through a service response. Of course, this is a very sloppy example of how the Web Service works. Wait, we will see a very detailed explanation.

Some of us may think like this: "Hey, wait! I can use RMI, CORBA, EJBs, and many other technologies! ". So. Why do we need Web services? Well, there are many advantages over other technologies in Web Services:
Because the Web Service uses the standard XML language, it is platform-independent and language-independent. This means that our client can run in windows using C ++, web services are written in Java and run in linux
Most Web services use HTTP to transmit messages (such as Service requests and responses ). If you want to establish an Internet-wide program, this is a major advantage, because most of the Internet's proxies and firewalls do not disrupt HTTP transmission (unlike the troubles that CORBA may encounter when it passes through the firewall)