Mongoose Lua Server Pages

Pre-built Windows and Mac mongoose binaries have built-in Lua Server Pages support. That means it is possible to write PHP-like scripts with mongoose, using Lua programming language instead of PHP. Lua is known for it's speed and small size. Mongoose uses Lua version 5.2.1, the documentation for it can be found at Lua 5.2 reference manual.

To create a Lua Page, make sure a file has .lp extension. For example, let's say it is going to be my_page.lp. The contents of the file, just like with PHP, is HTML with embedded Lua code. Lua code must be enclosed in <? ?> blocks, and can appear anywhere on the page. For example, to print current weekday name, one can write:

<p>
  <span>Today is:</span>
  <? mg.write(os.date("%A")) ?>
</p>

Note that this example uses function mg.write(), which prints data to the web page. Using function mg.write() is the way to generate web content from inside Lua code. In addition to mg.write(), all standard library functions are accessible from the Lua code (please check reference manual for details), and also information about the request is available in mg.request_info object, like request method, all headers, etcetera. Please refer to struct mg_request_info definition in mongoose.h to see what kind of information is present in mg.request_info object. Also, page.lp and prime_numbers.lp contains some example code that uses request_info and other functions(form submitting for example).

Mongoose exports the following to the Lua server page:

mg.read()         -- reads a chunk from POST data, returns it as a string
mg.write(str)     -- writes string to the client
mg.include(path)  -- sources another Lua file
mg.redirect(uri)  -- internal redirect to a given URI
mg.onerror(msg)   -- error handler, can be overridden
mg.version        -- a string that holds Mongoose version
mg.request_info   -- a table with request information

-- Connect to the remote TCP server. This function is an implementation
-- of simple socket interface. It returns a socket object with three
-- methods: send, recv, close, which are synchronous (blocking).
-- connect() throws an exception on connection error.
connect(host, port, use_ssl)

-- Example of using connect() interface:
local host = 'code.google.com'  -- IP address or domain name
local ok, sock = pcall(connect, host, 80, 1)
if ok then
  sock:send('GET /p/mongoose/ HTTP/1.0\r\n' ..
            'Host: ' .. host .. '\r\n\r\n')
  local reply = sock:recv()
  sock:close()
  -- reply now contains the web page https://code.google.com/p/mongoose
end

IMPORTANT: Mongoose does not send HTTP headers for Lua pages. Therefore, every Lua Page must begin with HTTP reply line and headers, like this:

<? print('HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n') ?>
<html><body>
  ... the rest of the web page ...

To serve Lua Page, mongoose creates Lua context. That context is used for all Lua blocks within the page. That means, all Lua blocks on the same page share the same context. If one block defines a variable, for example, that variable is visible in the block that follows.

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Mongoose Lua Server Pages

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