I am using lualoader and I loaded the following script from webserver example
-- a simple http server
srv = net.createServer(net.TCP)
srv:listen(80, function(conn)
conn:on("receive", function(sck, payload)
print(payload)
sck:send("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1> Hello, NodeMCU.</h1>")
end)
conn:on("sent", function(sck) sck:close() end)
end)
I saved it in a file and loaded it to lualoader and then did dofile. Whenever I load send an HTTP request to the esp8266 it loads the webpage. This is even after running other scripts. From reading the script it looks like it can only handle one HTTP request. Why does it keep handling new http requests?
From reading the script it looks like it can only handle one HTTP request.
Not sure what you mean by that. Do you maybe refer to http://nodemcu.readthedocs.io/en/latest/en/modules/http/? That is about sending out requests, only 1 concurrent requests.
Why does it keep handling new http requests?
The server keeps listening until you close it.
srv:close()
Related
I have a Lua proxy that needs to route requests. Each request destination is established based on the response from another HTTP request with a header from the initial request. My understanding is that HAProxy is an event-driven software, so blocking system calls are absolutely forbidden and my code is blocking because is doing an HTTP request.
I read about yielding after the request but I think it won't help since the HTTP request is already started. The library for doing the request is https://github.com/JakobGreen/lua-requests#simple-requests
local requests = require('requests')
core.register_fetches('http_backend', function(txn)
local dest = txn.sf:req_fhdr('X-dest')
local url = "http://127.0.0.1:8080/service";
local response = requests.get(url.."/"+dest);
local json = response.json()
return json.field
end )
How do I convert my code to be non-blocking?
You should consider using HAProxy's SPOE which was created exactly for these blocking scenarios.
I managed to do it using Lua. The thing I was making wrong was using require('requests') this is blocking. Ideally for HA never use a Lua external library. I have to deal with plain sockets and do an HTTP request and very important to use HA core method core.tcp() instead of Lua sockets.
I am using nodemcu with an esp-32 and recently came across an annoying problem. I refer to this sample from the NodeMCU Github page:
-- a simple HTTP server
srv = net.createServer(net.TCP)
srv:listen(80, function(conn)
conn:on("receive", function(sck, payload)
print(payload)
sck:send("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1> Hello, NodeMCU.</h1>")
end)
conn:on("sent", function(sck) sck:close() end)
end)
This doesn't seem to work in every case.
If I try it with telnet, there is no issue:
$ telnet 172.17.10.59 80
Trying 172.17.10.59...
Connected to 172.17.10.59.
Escape character is '^]'.
GET / HTTP/1.1
HTTP/1.0 200 OK
Content-Type: text/html
<h1> Hello, NodeMCU.</h1>
Connection closed by foreign host.
But when using wget, it hangs most of the time:
$ wget http://172.17.10.59/
--2017-05-12 15:00:09-- http://172.17.10.59/
Connecting to 172.17.10.59:80... connected.
HTTP request sent, awaiting response...
After some research, the root cause seems to be, that the receive callback is registered after the first data was received from the client. This doesn't happen when testing manually with telnet, but with a client like wget or a browser, the delay between connecting and receiving the first data seems to be too small to register the receive handler first.
I have looked into the nodemcu code and there doesn't seem to be an easy way to work around this problem. Or do I miss something here?
In HTTP/1.0, you need the "Content-Length" in the HTTP header when there is a message-body.
For example:
"HTTP/1.0 200 OK\r\nContent-Type: text/html\r\nContent-Length: 25 \r\n\r\n<h1> Hello, NodeMCU.</h1>"
ref: https://www.w3.org/Protocols/HTTP/1.0/spec.html#Content-Length
I have this Telegram bot written in Lua that I am doing as a hobby for a language network. And I have been reading new messages via the getUpdates API call all the time. Now I want to rewrite it to use webhooks, but I have no experience with that whatsoever. I have googled but didn't find anything certain. I kinda feel that WSAPI is the library to use, but I am not sure. Moreover, I am not really sure I need any special library just for reading POST requests (which is all that the Telegram bot API uses). I tried using sockets:
socket = require 'socket'
server = assert(socket.bind("*", 9000))
function read(client, pattern, prefix)
local data, emsg, partial = client:receive(pattern, prefix)
if data then
return data
end
if partial and #partial > 0 then
return partial
end
return nil, emsg
end
while true do
local client = server:accept()
client:settimeout(3)
local msg, err = read(client, '*a')
if not err then
print(msg)
client:close()
end
end
The print(msg) here gives me the full POST request including headers, which I am probably able to parse (the body is supposed to always be a JSON). I am not really that familiar with HTTP requests though and I'm not sure I can just throw away everything that goes before the first {.
My setup is Lua 5.2, Ubuntu x64 16.04 and Nginx. What I need to do is to receive and read POST requests, nothing more.
TL;DR: is it okay to parse the POST request I receive from the code above or am I missing something, like a library that'd make my life easier?
Thanks!
We have a Rails app with an integration with box.com. It happens fairly frequently that a request for a box action to our app results in a Passenger process being tied up for right around 15 minutes, and then we get the following exception:
Errno::ETIMEDOUT: Connection timed out - SSL_connect
Often it's on something that should be fairly quick, such as listing the contents of a small folder, or deleting a single document.
I'm under the impression that these requests never actually got to an open channel, that either at the tcp or ssl levels we got no initial response, or the full handshake/session-setup never completed.
I'd like to get either such condition to timeout quickly, say 15 seconds, but allow for a large file that is successfully transferring to continue.
Is there any way to get TCP or SSL to raise a timeout much sooner when the connection at either of those levels fails to complete setup, but not raise an exception if the session is successfully established and it's just taking a long time to actually transfer the data?
Here is what our current code looks like - we are not tied to doing it this way (and I didn't write this code):
def box_delete(uri)
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
request = Net::HTTP::Delete.new(uri.request_uri)
http.request(request)
end
I have written a web-service using Erlang and Mochiweb. The web service returns a lot of results and takes some time to finish the computation.
I'd like to return results as soon as the program finds it, instead of returning them when it found them all.
edit:
i found that i can use a chunked request to stream result, but seems that i can't find a way to close the connection. so any idea on how to close a mochiweb request?
To stream data of yet unknown size with HTTP 1.1 you can use HTPP chunked transfer encoding. In this encoding each chunk of data prepended by its size in hexadecimal. Last chunk is a zero-length chunk, with the chunk size coded as 0, but without any data.
If client doesn't support HTTP 1.1 server can send data as binary chunks and close connection at the end of the stream.
In MochiWeb it's all works as following:
HTTP response should be started with Response = Request:respond({Code, ResponseHeaders, chunked}) function. (By the way, look at the code comments);
Then chunks can be send to client with Response:write_chunk(Data) function. To indicate client the end of the stream chunk of zero length should be sent: Response:write_chunk(<<>>).
When handling of current request is over MochiWeb decides should connection be closed or can be reused by HTTP persistent connection.