What is a Web service?

I think that the next generation of Internet software will be based on Web service (i.e. "cloud").

I put the study notes and learning experience, put on the blog, Welcome to correct.

Write a basic question today, what exactly is a Web service?

First, the concept of WEB service

To understand a Web service, you must first understand what a service is.

Traditionally, we have provided the function of the computer daemon (Daemon), called the service. For example, let an anti-virus software run in the background, it will automatically monitor the system, then this automatic monitoring is a "service." In Layman's words, "service" is a function that a computer can provide.

Depending on the source, the service can be divided into two types: Local Service(using the same machine service, no network), and " Network Service"(a service provided by another computer, which must be done over the network).

For example, I now have a bunch of pictures that need to be scaled down by half. So, we can think of "scaling pictures" as a service. You can use the "Local Service", the software on your own computer to reduce the image, you can also use the "Network Service" to upload pictures to a website, let the server for you to reduce the image, complete and then send back to you via the network. It's like, one thing you can do it yourself, or you can give it to another person to do it. Hungry, you can cook your own meals, you can also call to order a pizza, let the store for you to do a good job.

The essence of the Web service is to invoke the resources of other sites over the network.

For example, last year I wrote a "Sichuan earthquake picture Wall", which can dynamically display the latest pictures of the Sichuan earthquake. However, all the pictures are not stored on my server, but from flickr.com. I just made a dynamic request to ask Flickr.com to provide me with a picture. In this case, Flickr.com provides a Web service. If I keep the pictures on the local server and do not call flickr.com, then I am using "Local Service".

So, Web service allows your site to use resources from other sites, such as displaying weather, maps, updates on Twitter, and more on a Web page.

Second, the WEB service architecture and the cloud

If the main part of a software uses "network Services", that is, it "outsourced" storage or computing links to other sites, then we say that this software belongs to the Web service architecture.

The basic idea of WEB service architecture is to give the non-core function to others to do it, and develop the core function. For example, if you want to develop a photo album software, you can fully use Flickr Web services, the photos are stored on it, you just do your best to do the album itself. On the whole, the function that does not belong to your core competence should be "outsourced".

The recent "Cloud computing" or "cloud service", which is a very red one, is actually synonymous with Web service, but more visually. They do not say you give things to other computers to do, and that you give things to the "cloud" to do.

Iii. Deficiencies in local services

"Network Services" is the future trend of software development and use, local services will be used less and more, mainly because of the following three reasons:

* Insufficient local resources. A lot of data and information are not available locally, only to other websites.

* Cost factor. Local services are often not economical, and services using professional websites are cheaper. This involves two parts of hardware and personnel, even if you can afford to buy hardware, to find a person to manage the system, it is also very troublesome.

* Portability is poor. If you want to transfer the services of this machine to other machines, it is often difficult, especially in the case of cross-platform.

Iv. Advantages of WEB Service

In addition to the disadvantages of local services, WEB service has the following advantages:

* Platform Independent. No matter what platform you use, you can use Web service.

* Programming language Independent. You can use any programming language to request a Web service from other Web sites as long as the relevant agreements are adhered to. This greatly increases the usability of the Web service and reduces the requirements for programmers.

* For Web service providers, deploying, upgrading, and maintaining Web service is simple and does not need to account for client compatibility issues and can be done at once.

* For Web service users, multiple data and aggregation (mashups) of multiple services can be easily implemented, so you can do things that you never imagined before.

Five, the development trend of WEB service

According to my observation, there are several development trends of Web service at present.

* In terms of usage, RPC and SOAP usage is decreasing, and restful architectures dominate.

* In the data format, the use of XML format is reduced, and the use of lightweight formats such as JSON is increasing.

* In the design architecture, more and more third-party software allows users to speak directly to the cloud on the client (ie, browser) and no longer use third-party servers for staging or processing data.

Finish