HTTP Knowledge Popularization series: HTTP-based feature append protocol

2. Spdy's development goals are designed to address HTTP performance bottlenecks and shorten the load time of Web pages.
4. The bottleneck of HTTP
   1. Only one request can be sent on a connection.
   2. Requests can only be started from the client. The client is not allowed to receive directives other than the response.
   3. The request/response is sent without compression. The more the header information, the greater the delay.
   4. Send a lengthy header. It is wasteful to send the same header each time.
   5. You can choose any data compression format. Non-forced compression is sent.
6. Ajax is an efficient use of JavaScript and DOM operations to achieve partial Web page replacement loading of asynchronous communication means. (Asynchronous loading)
8. Comet, once the server side has content updates, comet will not let the request wait, but directly to the client to return the response. This is a function of simulating server-to-client push through delayed response.
10. The spdy is not completely rewritten as an HTTP protocol, but is operated in the form of a new session layer between the application layer of TCP/IP and transport. At the same time, Spdy specifies that SSL is used in communications, given the security implications.
12. After using Spdy, the HTTP protocol has the following additional features.
    1. Multiplexing streams, which allow unlimited processing of multiple HTTP requests through a single TCP link.
    2. Given the request priority, Spdy not only can handle requests indefinitely, but can also assign priority order to requests individually.
    3. Compresses the HTTP header, compressing the HTTP request and the response header.
    4. Push feature that supports the ability of the server to proactively push data to the client.
    5. Server prompting feature, the server can proactively prompt the client to request the required resources.
14. Websocket,web the full-duplex communication standard between the browser and the Web server.
    1. Push feature that enables push of data pushed by the server to the client.
    2. Reduce traffic, as long as the WebSocket connection is established, you want to keep the connection status
    3. Handshake request, in order to achieve websocket communication, need to use the HTTP Upgrade header field, to inform the server communication protocol changes to achieve the purpose of handshake.
    4. The handshake response, for the previous request, returns the response of the status Code 101 switching protocols.
16. Http/2.0, the goal is to improve the user's speed experience when using the Web.
    1. SPDY
    2. HTTP speed + Mobility
    3. network-friendly HTTP Upgrade
18. WebDAV is a distributed file system that allows you to copy, edit, and more directly on the contents of a Web server.
    1. Concept
       1. Collection, is a unified management of the concept of multiple resources, in a collection of units can do a variety of operations. You can also implement a collection of similar collections such as overlays.
       2. Resources, which refer to files or collections as resources.
       3. Property that defines the properties of the resource. The definition is executed in the format "name = value".
       4. Lock and set the file to a state that cannot be edited. When multiple people are editing at the same time, you can prevent content writing at the same moment.
    2. New method
       1. PROPFIND, getting properties
       2. PROPPATCH, modifying properties
       3. MKCOL, creating a collection
       4. Copy, copying resources and attributes
       5. Move, moving Resources
       6. Lock, Resource plus lock
       7. UNLOCK, Unlocking resources
    3. Status code
       1. 102 Processing: Requests are handled normally but are currently in process state
       2. 207 Multi-Status: There are multiple states
       3. 422 unprocessible Entity: Correct format, incorrect content
       4. 423 Locked: The resource has been locked
       5. 424 Failed Dependency: Processing a request associated with a request failed, so dependency is no longer maintained
       6. 507 Insufficient Storage: Insufficient space to save

HTTP Knowledge Popularization series: HTTP-based feature append protocol