Web Application Knowledge 123

1. HTTP protocol

|--Non-stateful communication protocol based on requests (request) and response (Response)

Browsers and Web applications communicate over HTTP. Client requires data at a specific location through a URL to a specified server

The difference between |--post and get

-->get request length limit, request parameters will be stitched to the URL, will expose important information, is idempotent operation (multiple requests will not change the data and state on the server)

The-->post does not have the request length limit, the request parameter is encapsulated, because the parameter is not spliced to the URL, therefore cannot add the bookmark the operation, can effectively avoid the cache;

2. Client programs and service-side programs

|--cannot communicate directly because it executes on a different memory address space; The Eg:web application communicates over HTTP.

-->SERVLET/JSP is a server-side program, JavaScript is a client program

Execution order: Now that the server side executes the servlet/jsp, the JavaScript script is returned to the client and it is not possible to get the values in the HttpServletRequest in all JavaScript.

3, servlet/jsp

|--servlet and CGI

-->CGI is the executable program running on the server, each request will start a program to process the request to the server caused a great burden

-->servlet/jsp is created through a container, the container is started by a JVM running on the server, each request is processed by the same container, a thread is opened, and the Servlet is determined to handle it, multithreading, and mitigating the performance burden.

4. Web container and HTTP server

|--tomcat is a Web container, because a simple HTTP server is built in, so you can open direct access

|--apache is an HTTP server that only handles static content and can be used in conjunction with Tomcat.

Web Application Knowledge 123