node. JS IO processing input and echo, and the history of today's Web applications

1. About node. JS IO processing input and Echo

Enter Echo ' I must learn about node. js ' in Windows terminal or CD

Result will just input echo ' I must learn about node. js ' content echoing output to CD

The terminal is also the input relative to the echo ' I must learn about node. js ' Display results as follows:

　　

Move the angle of the data, this is a simple echo Text tool

1. The text string is passed to the Echo program (input)
2. Text string flow through Echo's logic
3. The Echo program displays its result output to the terminal

Personal understanding (big boys do not like, do not spray):

TV according to the remote control button back, the remote control can be understood as the TV input switch channel request, the results echo to the TV display screen, the final switch channel.

Talk about the history of Web applications today

(1) Web development was originally designed to read HTML documents, storing HTML files on a server that can be accessed through a Web server whenever an Internet connection is available

(2) with the development of the web, evolved into a database and scripting language

　　　　　　

(3) Today's Web application design is much more complex, third-party Interface Application Interface (API) heavy interaction, the user simultaneously connected and real-time interaction

　　

Personal Understanding Web server (big guys do not like, do not spray):

When the browser sends a request to the server, the server accesses the database server according to the request, and the response completes the request to the browser.

The browser displays the relative data based on the requested status code.

Response of the Web server:

1. Time to resolve DNS requests
2. Busy programs for servers
3. How big is the data to be answered?
4. Available bandwidth for servers and customers
5. Software efficiency that is served in response
6. How busy you are using

About the status code for http:

1. 1XX: Information class, indicating receipt of Web server request, processing further
2. 2XX: Successful, indicates that the user request is received correctly, understood and processed for example: 200| | ok| | 4
3. 3XX: Redirect to indicate that the request was unsuccessful and the customer must take further action
4. 4XX: Client error, indicating that the client submitted a request with an error, for example: 404
5. 5XX: Server error, indicating that the server could not complete the processing of the request, for example: 500
6. Found: means that the document referenced in the request does not exist

node. JS IO processing input and echo, and the history of today's Web applications