2.8 KiB
Mongoose Lua Server Pages
Pre-built Windows and Mac mongoose binaries support Lua Server Pages functionality. 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 a file that is called <something>.lp. For example,
let's say it is going to be my_page.lp. It is important to have a file
name that ends up with .lp, cause this is the way mongoose recognises
Lua Page file. The contents of the file, just like
with PHP, is HTML with embedded Lua code. Lua code must be enclosed within
<? ?> blocks, and can appear anywhere on the page.
Mongoose does not send HTTP headers for Lua pages. Therefore, every Lua Page must begin with HTTP status line and headers, like this:
<? mg.write('HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n') ?>
<html><body>
<span>Today is:</span> <? mg.write(os.date("%A")) ?>
</body></html>
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).
Information about the request is available in mg.request_info object.
I contains request method, all headers, etcetera. Please refer to
struct mg_request_info definition in
mongoose.h
to see what is available in mg.request_info. Also,
page.lp and
prime_numbers.lp
contain some example code that uses request_info and other functions,
like form submission.
Mongoose exports the following to the Lua server page:
mg.write(str) -- writes string to the client
mg.onerror(msg) -- error handler, can be overridden
mg.request_info -- a table with request information
sqlite3 -- Sqlite3 interface
slite3 functions are documented at lua.sqlite.org, and usage example is at page.lp.
Using Lua scripting it is easy to emulate SSI functionality. For example, to include the content of another file, one can write:
<? mg.write(io.open('MY_FILE.TXT'):read('*all')) ?>
To serve a 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.