Tokens
    [A-Z]+ - command name or status
    .*     - byte stream (the '.' here means any byte value 0-255)
    [SP]   - space separating character/byte (this is a sequence of space and/or space characters of an arbitrary length greater than zero.)
    [0-9]+ - numeric value/length in our case



Valid Messages

    MESSAGE := (REQUEST | RESPONSE)



Request Protocol Definition

    REQUEST := <COMMAND>[SP]<LENGTH>[SP]<NAME> |
               <COMMAND>[SP]<LENGTH>[SP]<NAME>[SP]<LENGTH>[SP]<RELATIVE PATH>

        <COMMAND>   := [A-Z]+
        <LENGTH>    := [0-9]+
        <NAME>      := .*
        <PATH>      := .* 

    Note: 0 length objects are allowed.  However, we would like to treat those
          as an error case in this project.


    (1) Get Object Command
            
            GETRD[SP]<LENGTH>[SP]<NAME>
 
        The response should either be: OK or NOTFOUND.

        If OK, then the RESPONSE <DATA> should be a valid URL, with
        <LENGTH> = len(<DATA>).

        If NOTFOUND, then the RESPONSE <LENGTH> should be zero, and a trailing
        [SP] with no bytes following for the remainder.

    (2) Add Object Command

            ADDFILE[SP]<LENGTH>[SP]<NAME>[SP]<LENGTH>[SP]<RELATIVE PATH>

        The response should either be: OK or ERROR.

        If OK, then RESPONSE <LENGTH> should be zero, and a trailing [SP] with
        no bytes following for the remainder.

        If ERROR, then RESPONSE <LENGTH> may optionally be a value greater than
        0 and RESPONSE <DATA> should contain an ASCII-encoded error message
        (not nul-terminated).



Response Protocol Definition

    RESPONSE := <STATUS>[SP]<LENGTH>[SP]<DATA>

        <STATUS>    := [A-Z]+
        <LENGTH>    := [0-9]+
        <DATA>      := .*

    (1) OK Response to a GET Object Command

            OK[SP]<LENGTH>[SP]<URL>

        <LENGTH> can not be 0, <URL> must be a valid URL.

    (2) OK Response to a Add Object Command

            OK[SP]0[SP]

    (3) ERROR Response to a Get Object Command

            NOTFOUND[SP]0[SP]

    (4) ERROR Response to an Add Object Command

            ERROR[SP]<LENGTH>[SP]<ASCII ERROR MESSAGE>

        <LENGTH> is allowed to be 0, which means no error message follows.