HTTP



What is HTTP?



• HTTP stands for Hyper Text Transfer Protocol
• Communication between web servers and clients
• HTTP Requests / Responses
• Loading pages, from submit, Ajax calls

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HTTP is Stateless



• Every request is completely independent
• Similar to transactions
• Programming, Local Storage, Cookies, Sessions are used to create enhanced user experience

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What is HTTPS?



• HTTPS stands for Hyper Text Transfer Protocol Secure
• Data sent is encrypted
• SSL / TLS
• Install certificate on web host

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HTTP Methods



HTTP MethodsMeaning
GETRetrieve data from the server
POSTSubmit data to the server
PUTUpdate data already on the server
DELETERemove data from the server


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HTTP Headers Fields



images/205-1.png

General HeaderResponse HeaderRequest Header
Request URIServerCookies
Request MethodSet-CookieAccept-xxx
Status CodeContent-TypeContent-Type
Remote AddressContent-LengthContent-Length
Referrer PolicyDateAuthorization
User-Agent
Referrer


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HTTP Status Codes



CategoryMeaningCommon Status Codes
1xx: InformationalReqeuest received / processing
2xx: SuccessSuccessfully received, understood and accepted200 - OK 201 - OK created
3xx: RedirectFurther action must be taken / redirect301 - Moved to new URL 304 - Not modified (Cached version)
4xx: Client ErrorRequest does not have what it needs400 - Bad request 401 - Unauthorized 404 - Not found
5xx: Server ErrorServer failed to fullfill an apparent valid request500 - Internal server error


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HTTP/2



• Major revision of HTTP (current HTTP 1.1_
• Under the hood changes
• Respond with more data
• Reduce latency by enabling full request and response multiplexing
◇ May get html, css, js, image files at the same time within 1 request
• Fast, efficient and secure

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How to View HTTP Related Info



• Browser: Dev Tools > Network
• Postman
• Express Server







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