MathSlinger

A simple Producer/Consumer system.

Also work-in-progress React client (see react-client/ subdirectory)

The MathAsker (Producer) sends a series of random arithmetic expressions to the MathAnswerer (Consumer), which will compute the results.

The MathAsker and MathAnswerer are separate NodeJS services
The MathAsker generating random mathematical expressions of varying difficulty and length, e.g. 2+3=, 37-90*2=, 3^2+64-2/4-80+40=
The MathAnswerer computes and returns the correct mathematical result for the each expression it receives
The MathAnswerer successfully processes requests from two MathAskers concurrently at a rate of at least 1 req/sec from each MathAsker (2 req/sec in aggregate)
The MathAnswerer and MathAsker log all messages they generate and receive

Endpoints

GET /math?expression={encodeURIComponent('1+2=')}

Supported Operations

+ Addition
- Subtraction
* Multiplication
/ Division
^ Exponents
( and ) Parentheses

Installation/Requirements

⚠️ Requires node.js v4.x (for node version management I've found nvm to be 👍)

git clone https://github.com/erikthedeveloper/nodejs-math-slinger.git
cd nodejs-math-slinger
npm install

Start the Server/Simulation

npm start will start the server listening on the default port (3000).

npm run simulation will start the server and spawn two bots (3 separate processes). The bots will procede to request solutions to randomly generated mathematical solutions of varying difficulties.

Next Steps

Run Tests

npm test sets NODE_ENV=test and runs all tests.
npm test -- --watch runs tests and watches files for changes.
npm run lint will lint the project using ESLint and the rules defined in .eslintrc.

  Math Evaluator Service [integration]
    GET /math
      ✓ expects expression in query string
      ✓ should accept and evaluate a basic addition expression
      ✓ should accept and evaluate a lengthy addition expression
      ✓ should reject invalid expressions
      ✓ should only accept GET requests
    POST /evaluate @deprecated
      ✓ should return 404 NOT FOUND

  MathBot - Requester of Mathematical Solutions
    ✓ Accepts options and is humanized via "name"
    ✓ should request a "solution" to an "expression" via HTTP "/evaluate"

  expressionEvaluator
    #validateExpression
      ✓ should pass for a simple addition expression
      ✓ should pass for a simple subtraction expression
      ✓ should pass for an expression containing parentheses
      ✓ should fail for an expression containing unclosed/mismatched parentheses
      ✓ should enforce the ending "="
      ✓ should not allow any whitespace
    #evaluateExpression
      ✓ evaluates simple addition expressions
      ✓ evaluates addition/substraction expressions
      ✓ evaluates multiplication/division expressions
      ✓ evaluates exponent expressions
      ✓ evaluates expressions containing parentheses

  expressionGenerator
    #randomExpression
      ✓ should generate a random, simple addition expression
      ✓ should allow specifying count of numbers involved (length)

  Infix to Postfix Converter
    ✓ Should convert simple addition
    ✓ should convert all sorts of infix goodies to postfix...
    ✓ should convert infix expressions containing parentheses to postfix...
    ✓ should reject expressions containing negative numbers

  Postfix Evaluator
    ✓ Evaluates postfix mathematical expressions

erikthedeveloper/nodejs-math-slinger