[spec] ☿️ — a symbolic protocol

[Petite Abeille]

??://??

The multiaddr bellow is the default location of a Mercury (??) service:

/dns4/??.xyz/tcp/1961

A multiaddr describes how to connect to a ?? service ? for example, ? using DNS, ? resolve hostname ??.xyz, and ? connect over tcp ? to  port 1961.

To find a ?? multiaddr, query the host ?? DNS TXT record:

# dig +short TXT ??._tcp.??.xyz.
multiaddr=/dns/??.xyz/tcp/1958/tls/sni/??.xyz

By default, a ?? service runs over TCP, at port 1961 ?

A ??:// request is one-line ?4,096 bytes long at most, UTF-8 encoded? containing a fully qualified, normalized Internationalized Resource Identifier (IRI):

??://??.xyz/

An IRI is an UTF-8 version of an Uniform Resource Identifier (URI). 
An URI can be either an Uniform Resource Locator (URL), or Uniform Resource Name (URN).

An example of a ?? request, followed by a text/?? response:

# echo -e '??://??.xyz/\r\n' | nc 127.0.0.1 1961
? text/??;charset=utf-8;
Hello ??!

? ??://??.xyz/license CC0-1.0 
<end of connection> 

A successful ?? response is a one-line with status ??optionally followed by a content type, plus associated attributes, such as encoding:  

? text/??;charset=utf-8;

The content type is optional ? defaulting to text/??, UTF-8 encoded.

The content itself follow the  ? status line ? terminated by the service dropping the network connection.

There are 3 status codes:

? [20] SUCCESS ? one-line, with optional content type, plus attributes, 4,096 bytes long at most, UTF-8 encoded
? text/??;charset=utf-8;

? [30] REDIRECT ? one-line IRI, fully qualified, and normalized, 4,096 bytes long at most, UTF-8 encoded
? ??://??.xyz/

? [40] ERROR ? one-line, 4,096 bytes long at most, UTF-8 encoded, with optional description 
? ??

A text/?? consists of two line types: text, and link. 

A link is denoted as one-line, starting with the infinity symbol (?), followed by a space, followed by a fully qualified, and normalized, IRI ? optionally followed by a space and description:

? ??://??.xyz/license CC0-1.0

All other lines are regular text lines.

A ?? URL may anchor a text/?? line number:

??://??.xyz/license#42

A ?? service may optionally respond to the urn:??:capa directive ? listing additional capabilities, specific to the service, as text/?? links:

# echo -e 'urn:??:capa' | nc 127.0.0.1 1961
? text/??;charset=utf-8;
? urn:??:capa
? urn:??:capa:connection:keep-alive
? urn:??:capa:transfer-encoding:chunked
? urn:??:capa:turn
<end of connection> 

Capabilities are optional, and not part of the ?? protocol. They are documented separately.

# while true; do { echo -e '?\r\n? urn:??:capa'; } | nc -l 127.0.0.1 1958; done
# echo -e 'urn:??:capa\r\n' | nc 127.0.0.1 1958
?
? urn:??:capa
<end of connection> 

That's all folks.

?0?

? NASA's Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. The first crewed flight took place in 1961. Therefore the port number.







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