Performance Implications for Internet Connected Brew Devices

QA Consultants Performance Engineering Group

Advisory to RFC- 7168,?The Hyper Text Coffee Pot Control Protocol for Tea Efflux Appliances (HTCPCP-TEA)??

Let’s talk about the performance implications for internet-connected brewing devices, focusing on a protocol known as RFC-7168, which extends the Hyper Text Coffee Pot Control Protocol (HTCPCP) to include tea brewing devices.

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1. Background: RFC-7168, established in April 2014, extends the protocol for controlling coffee pots to also manage internet-connected teapots. It recommends storing certain TEA-client elements such as JavaScript framework components, style sheets, and static images be cached on the client side to prevent unnecessary re-requests, similar to how web browsers store elements for faster loading.
2. BREW Method: This method replaces the standard POST method for connecting internet-connected brewing devices. It's crucial for managing the brewing process effectively.
3. Response Codes: From a performance perspective, we should be concerned with several key response codes when connecting to the URI. Different HTTP response codes signify various stages of the brewing process:

• HTTP 200: A Response to a brew_start request indicates that brewing has started, and the user is designated as the "kettle master" responsible for monitoring and stopping the process at the right time. Failure to issue a stop request can result in a tea of negative strength as the water-to-leaf ratio becomes too small. This status also indicates a successful brew_stop request from the kettle master.
• HTTP 300: Shows that brewing has not yet begun, and additional selections are needed from the user.
• HTTP 377: In response to brew_status, if the brew is not yet complete, 377 is returned.
• HTTP 403: When a TEA client not designated at kettle master attempts to issue a brew_stop, this status will be generated
• HTTP 418: Occurs when a coffee pot is asked to brew tea, which is not its intended purpose.
• HTTP 503: Indicates that a teapot is asked to brew coffee, which it cannot do (Service not Available).

For brew_start, brew_stop, and brew_status, the following example message bodies are returned where an HTTP 200 or 377 BREW status code is present:

{"/{tea type[dejarling!earl grey|english breakfast|oolong|...]" {type message/teapot}},

The problem: A watched pot never boils??

Watching the Pot: Monitoring the brewing process too closely can overwhelm the teapot with requests, potentially causing service disruptions and prolonging the brewing time.

Recommendations

RFC-7168 is silent on cache status on the individual TEA client requests. To optimize performance and prevent overloading the teapot, the performance engineering group, QA Consultants, recommends a brew cache status of 15 seconds to be maintained by a caching proxy or CDN in front of the brewing cluster. ?This allows for efficient brewing without the need for constant monitoring.

Optimal Options for this task are:?

• Nginx.?
• Any versions of the varnish caching server.?
• Any blade-based caching solutions from the client networking vendor.

Cache Timing: The recommended cache window of 15 seconds strikes a balance between efficient brewing and user experience. It's essential not to cache certain response codes to ensure accurate status updates.

?Fifteen seconds is also within the significant perception window for caffeinated individuals. As such, a brew status with a fifteen-second or less cache age is unlikely to cause abandonment of a TEA client session or a DBT (Denial of Brewed Tea) hostile response. If experimenting, this window should never be shorter than five seconds, or the watch process will lengthen the time required to boil the kettle, leading to a hostile DBT response.??

BREW Status response codes 200, 300, 403, 418, & 503 should never be cached.?

Overall, we want to emphasize the importance of managing the internet-connected brewing process efficiently, considering both technical performance and user experience factors.

Does it work? Does it Scale? Is it Secure? Is it accessible? Is the tea done yet? How can we help you today?

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