SimpleServer

A simple java multi-server that allows clients to connect and request the square of a number.

Protocol

The server binds port 2000, which is hardcoded in SimpleServer.server.ServerApp. Each connection carries one newline-terminated message per line in both directions.

Message format

A message is a sequence of key=value pairs, each one terminated by a comma:

process=square,number=10,

The format is implemented by SimpleServer.Message, and three of its properties are worth knowing before it is used:

• The comma is what terminates a pair, so a final pair written without one is dropped by the parser rather than being read as the end of the message.
• Neither = nor , is escaped when a message is written, and both are read as delimiters, so no key and no value can carry either character.
• A key is appended to the message once per write, so a key written twice is emitted twice.

Requests

Key	Value
process	The operation being requested. square is the only value the server recognises.
number	The integer to be squared. Read only by the square process.

Responses

Every response carries success. On success it is followed by answer, and on failure by reason.

Key	Value
success	true or false.
answer	Sent only when success is true. Worded as the English sentence The square of that number is <result> rather than as a bare number.
reason	Sent only when success is false. One of the three strings below.

reason	Sent when
process not recognized	process held a value other than square.
Wrong type of input!	number could not be parsed as an integer.
Something went wrong when processing input.	Processing threw, which includes a message that carried no process key at all.