abstract

The concern is documenting scott allen’s take on cookies in the context of the nature of the HTTP protocol.

video

contents

1. stateless protocol

  • http is designed as stateless protocol
  • there are transactions, known as request-response transactions
  • stateless means that each transaction is independent from any previous or future transaction
  • nothing in the protocol requires the server to retain state
  • every message is self-descriptive and requires all the information that is required to process that message

ram_cpu_vanNeumann_bottleneck

2. sidestep: on cache

  • From French cache (as used by French Canadian trappers to mean “hiding place for stores”), from the verb cacher
  • cache is the most popular way around the van neumann bottleneck — cache is a very small amount memory on the CPU itself — getting the data at the same speed it is operating.
    • also every CPU core has its own cache memory → there is no contention on what core is getting the date from the RAM
    • the amount of memory is small due to price
    • cache stores the memory
    • the greater the cache hit the better the performance
    • the greater the cache misses the lower the performance
    • cache is split
      • instruction → easier to fill
      • data cache

3. stateful needs

  • most of the applications built atop of the HTTP are stateful
  • example: banking app needs to know that user has logged in before resources can be accessed
  • app needs to know about the user before-hand
  • there are independent transactions, but the app needs to know where the user is

4. embed state in resources

  • state required can travel back on the
  • usually hidden input field
  • .APS is using this
  • state is in HTTP message
  • it is highly scalable
  • but complicates application programming

5. server-side state-tracking

  • required for the state that is to be around for a long time
  • email-address can be mapped to the username and this binding can be persistent
  • for server-side storage there is access to user-session

6. session storage

  • there is a solution called Session storage
  • request must go to the same server → some load balancers are saving this
  • but how can a user track a user to implement Session State
  • in the early days of the internet - IP addresses were tracked
  • today: you can have IP unstable or behind the same one
  • there are more reliable techniques that rely on cookies

7. cookies

  • defined by rfc6265 called HTTP State Management Mechanism
  • describes how website gives a cookie
  • it uses HTTP HEADER
  • browser then sends the same cookie to every other request sent to the site
  • now, a website can track user when then make a request
  • website can put any information into a cookie, mostly just a unique identifier (GUID)
  • assuming browser is configured to accept cookies, it accepts the set cookie instruction
  • it sends it along with any subsequent request that it makes to the domain
  • server looks for appropriate info
  • used for identification, not authentication purposes