kapow/spec/README.md

Kapow!

Why is it named Kapow!. You can pronounce it and it is short and meaningless... like every good UNIX command ;-)

TODO: Too hard to jump

Rationale

The web and the shell are two different beasts, both packed with history.

There are some concepts in HTTP and the shell that resemble each other.

                 +------------------------+-------------------------+
                 | HTTP                   | SHELL                   |
  +--------------+------------------------+-------------------------+
  | Input        | POST form-encoding     | Command line parameters |
  | Parameters   | GET parameters         | Environment variables   |
  |              | Headers                |                         |
  |              | Serialized body (JSON) |                         |
  +--------------+------------------------+-------------------------+
  | Data Streams | Response/Request Body  | Stdin/Stdout/Stderr     |
  |              | Websocket              | Input/Output files      |
  |              | Uploaded files         |                         |
  +--------------+------------------------+-------------------------+
  | Control      | Status codes           | Signals                 |
  |              | HTTP Methods           | Exit Codes              |
  +--------------+------------------------+-------------------------+

Any tool designed to give an HTTP interface to an existing shell command must map concepts of boths. For example:

• "GET parameters" to "Command line parameters"
• "Headers" to "Environment variables"
• "Stdout" to "Response body"

Kapow! is not opinionated about the different ways you can map both worlds. Instead it provides a concise language used to express the mapping and a set of common defaults.

Why not tool...?

All the alternatives we found are rigid about how they match between HTTP and shell concepts.

• shell2http: HTTP-server to execute shell commands. Designed for development, prototyping or remote control. Settings through two command line arguments, path and shell command.
• websocketd: Turn any program that uses STDIN/STDOUT into a WebSocket server. Like inetd, but for WebSockets.
• webhook: webhook is a lightweight incoming webhook server to run shell commands.
• gotty: GoTTY is a simple command line tool that turns your CLI tools into web applications. (For interactive commands only)
• shell-microservice-exposer: Expose your own scripts as a cool microservice API dockerizing it.

Tools with a rigid matching can't evade impedance mismatch. Resulting is an easy-to-use software, convenient in some scenarios but incapable in others.

Why not my good-old programming language...?

• Boilerplate
• Custom code = More bugs
• Security issues (Command injection, etc)
• Dependency on developers
• "A programming language is low level when its programs require attention to the irrelevant" Alan Perlis

Kapow! aims to be halfway from one of the mentioned tools and a general programming language. A limited scripting language. Think of awk, 20 years later, for HTTP.

TODO: Definition TODO: Intro to Architecture

API

Spec'ing the endpoints

Usage Example

Test Suite Notes

The test suite is located on [blebleble] directory. You can run it...

Framework

Commands

Any compliant implementation of Kapow! must provide these commands:

kapow

This implements the server, yaddayadda

Example

kroute

TODISCUSS: maybe consider using kapow route instead

Example

request

Example

response

Example

Full-fledged example (TODO: express it more simply)

Test Suite Notes

Server

Test Suite Notes