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Lua HTTP

Updated April 5, 2023

Lua HTTP

 

 

Definition of Lua HTTP

  • It is an application-level protocol used to load and fetches the World Wide Web application link on the browser Lua programming language.
  • It is a hypertext transfer text protocol used for transfer information on the internet using Lua technology.
  • It is a generic protocol to provide high-level communication between server and client of the web browser using Lua source code.
  • It is a stateless protocol for flexible data transportation, retrieving HTTP data, and throwing the Error of the Lua code.
  • It is useful for the webserver for the request to the webserver and response to the web browser.

Syntax:

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  • It has many modules and methods to communicate with clients and servers.
  • Some modules information with explanations is below.
  • The syntaxes are below.
  • The client-side request syntax is below.
require "http.request";
  • Example: local lua_variable_name = require ” http.request “
new_from_uri("uri link")
  • Example: local new_variable_name = variable_name.new_from_uri(“http://lua.org/demo”)
  • The http. the request is a hight level interface for client-side requests.
  • The http. the request is using to client-side request to retrieve the server information.
  • The new_from_uri is fetching the given link immediately and working the procedure.
  • The new_from_uri is connected with the http. request object to evaluate the URI.

The server-side syntax is below.

require "http.server"

Example: local lua_server = require “http.server”

require "http. headers"

Example: local lua_headers = require “http.headers”

  • The http. the server is creating the object and used to encapsulate the server socket.
  • The http. the server is sending the information to the client-side.
  • The http. headers are the index of the field name.
  • The http. the header is sensitive data and retrieves it by calling the key value.

The header syntax is below.

headers:append(name, value, never_index)
headers:each()
: status
  • The headers: append used to create and associate the header name, value, and Boolean authorization.
  • The headers: each() is useful for iteration of the header value.
  • The header “: status” for keep value in string format.

The util syntax is below.

require "http.util"

Example: local lua_http_variable = require “http.util”;

The compact socket syntax is below.

require "http.compat.socket"

Example: local lua_http_variable = require “http.compat.socket”;

This is to supply the compatibility of the request.

How HTTP works in Lua?

Step 1: Lua programming IDE Environmental Setup.

The Lua text editor, Lua compiler, and Lua interpreter installed in your virtual machine as per the version of Lua software.

Step 2: The environmental setup.

Install helping with the package manager of Lua modules (luarocks).

Website name:- https://luarocks.org/
  • This manager is automatically installing dependencies.
  • The following command is just entered in the Lua software.
$ luarocks install http.

Step 3: The following dependencies you should install in the Lua software.

    • The basic dependencies are luaossl, basexx, lpeg, lpeg_pattern, binary heap, fifp, and queues(Microsoft windows does not support).
    • The document compression dependencies are lzlib and Lua-zlib.
    • The cookies dependency is lua-psl.
    • The testing dependencies are luacheck, busted, and luacov.

Step 4: Create a variable with the request.

local lua_http_variable= require('http.request');

Step 5: Create a variable with Lua new_from_uri(” uri name “).

local new_http_variable= lua_http_variable.new_from_uri("http://lua.org/demo")

Step 6: The headers and steam uses in the Lua HTTP.

for lua_field, lua_value in headers:each()
do
print(lua_field, lua_value)
end
local body_http_variable = assert(stream:get_body_as_string())

Step 7: Return the required data.

print(body_http_variable)
  • Combine the working procedure.
local lua_http_variable= require "http.request"
local new_http_variable= lua_http_variable .new_from_uri ("http://lua.org/demo")
local headers, stream= assert ( new_http_variable:go());
for lua_field, lua_value in headers:each()
do
print (lua_field, lua_value)
end
local body_http_variable = assert (stream:get_body_as_string())
print (body_http_variable)

Examples

Let us discuss the examples.

Example #1: Client-side server example.

Code:

local lua_http_variable= require "http.request";
local new_http_variable= lua_http_variable .new_from_uri ("http://lua.org/demo")
local headers, stream= assert ( new_http_variable:go());
for lua_field, lua_value in headers:each()
do
print (lua_field, lua_value)
end
local body_http_variable = assert (stream:get_body_as_string())
print (body_http_variable)

Output 1: Enter the $ cat filename.Lua command in Lua command prompt.

lua http 1

Output 2: Enter the $ lua filename.Lua command in Lua command prompt.

lua http 2

Example #2: Client-side server with “if” loop example.

Code:

local lua_http_variable= require "http.request";
local new_http_variable= lua_http_variable .new_from_uri ("http://lua.org/demo")
local headers, stream= assert( new_http_variable:go());
local body_http_variable = assert (stream:get_body_as_string())
if headers : get ":status" ~= "200"
then
error (body_http_variable)
end
print (body_http_variable)

Output:

Output 1: Enter the $ cat filename.Lua command in Lua command prompt.

lua http 3

Output 2: Enter the $ lua filename.Lua command in Lua command prompt.

lua client

Example #3: Server-side example.

Code:

local lua_server = require "http.server";
local lua_header = require "http.headers";
local lua_http_server = lua_server.listen {
host: "localhost";
port: 8005;
onstream: function(sa, sb)
local reqst_header = sb:get_headers(),
local reqst_method = sb:get(":method")
local lua_path = reqst_header:get(":path") or "",
local recv_path = headers.new()
recv_path:append(":status", "200")
recv_path:append("content-type", "text/plain")
sb:write_headers(recv_path, reqst_method == "HEAD")
if reqst_method ~= "HEAD" then
sb:write_chunk(("Received message \n":format(lua_path), true)
end
end
}
lua_http_server.listen();
lua_http_server.loop();

Output 1: This output shows the port of the server.

lua http 4

Output 2: This output shows the message of the server.

received message

Example #4: Util example.

Part 1: use the query-args(string) with http.util example.

local lua_http_vrblr = require "http.util";
for names, values in lua_http_vrblr.query.args("Lua = language & Lua = http")
do
print("names, values")
end

Output:

output 2

Part 2: use the query-args(string) with http.util example.

local lua_http_util = require "http.util"
print(lua_http_util.split_authority("lua.org", "https"))
print(lua_http_util.split_authority("localhost:8005", "http"))

Output:

output 1

Example #5: Socket example.

Code:

local lua_http_socket = require "http.compat.socket"
local bd, dc = assert(lua_http_socket.request("http://google.com"))
print(dc, #bd);

Output:

output

Conclusion

  • It has many ways to control the server and client-side data or information.
  • It is making the Lua application easy, interactive, and protected on the server or internet.
  • It is helped the client to get the server-side information easily with protection.

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