Re: Factor

The Gopher protocol is relatively dated now, but when it was first released in 1991, it had a number of modern features that we would later enjoy in the World Wide Web. In particular, in RFC 1436, it lists these features:

• A file-like hierarchical arrangement that would be familiar to users.
• A simple syntax.
• A system that can be created quickly and inexpensively.
• Extending the file system metaphor, such as searches.

We’re going to build a simple word to let us look through Gopherspace using Factor.

Using the URLs vocabulary, we will build a tool to fetch documents from a Gopher server using a URL that looks like this:

gopher://gopher.floodgap.com/0/gopher/proxy

This specifies a host, an optional port (defaulting to 70 if not specified), and a path which includes an item type and a selector identifying the document to obtain.

Once a network connection is opened, we can retrieve the specified document by sending the selector followed by a CRLF (carriage return and line feed, ASCII bytes 13 and 10 respectively), and then reading the response:

: get-selector ( selector -- document )
   "/" split1 "" or nip write "\r\n" write flush contents ;

: gopher ( url -- document )
    >url {
        [ host>> ]
        [ port>> 70 or <inet> ascii ]
        [ path>> rest ]
    } cleave '[ _ get-selector ] with-client ;

The item type, which we are ignoring in the code above, can be used a bit like a filename extension to handle documents of different types in particular ways. Some common types that you might see:

• 0 - plain text
• 1 - menus
• 9 - binary
• s - sound
• g - GIF images

Right now, our code assumes that all the documents we will fetch are ASCII, and it doesn’t have any special handling for menus, or support for a query string that would allow using Gopher “search servers”. I added some basic support for those items in the new gopher vocabulary that I committed yesterday. In addition, I built a simple Gopher browser complete with history support and ability to view GIF images in the gopher.ui vocabulary.

Here’s how you would use it:

IN: scratchpad USE: gopher.ui

IN: scratchpad "gopher://gopher.floodgap.com/1"
               open-gopher-window

That will pop up a window that looks like this, with clickable links and everything:

It’s neat using some of these early protocols, both because they tend to be simpler, but especially when you see that they have a passionate following. As of December 2014, Veronica-2 has indexed 150 gopher servers with over 3 million unique selectors. You can see current stats by going to:

gopher://gopher.floodgap.com/0/v2/vstat

Check it out!