I'm working on a project that uses Mongoose, and I need to make a POST request to another server. I don't see an example of how to do this in their examples list, does anyone know how to do this?
EDIT to add more detail:
I'm working within a larger C++ app and need to create a simple server such that a user can query the app for information. Right now, I start the server like this:
Status sampleCmd::startServer()
{
Status stat = MS::kSuccess;
struct mg_server *server;
// Create and configure the server
server = mg_create_server(NULL, ev_handler);
mg_set_option(server, "listening_port", "8080");
stopServer = false;
printf("Starting on port %s\n", mg_get_option(server, "listening_port"));
while (!stopServer) //for (;;)
{
mg_poll_server(server, 1000);
}
// Cleanup, and free server instance
mg_destroy_server(&server);
return stat;
}
In my event handler, I parse the provided URI for a particular one and then run some commands with the application's API. I need to send these results back to a server for the user to see. It's this latter step that is unclear to me. It seems odd that a web server library wouldn't have some client functionality, don't servers need to talk to other servers?
Okay, it turns out I was thinking about this wrong. I needed to respond to the POST request I was getting. So using mg_printf_data(...) with the connection object worked for me.
Related
I've been trying to use the javacscript version of the Eclipse Paho MQTT client to access the Google IOTCore MQTT Bridge, as suggested here:
https://cloud.google.com/iot/docs/how-tos/mqtt-bridge
However, whatever I do, any attempt to connect with known good credentials (working with other clients) results in this connection error:
errorCode: 7, errorMessage: "AMQJS0007E Socket error:undefined."
Not much to go on there, so I'm wondering if anyone has ever been successful connecting to the MQTT Bridge via Javascript with Eclipse Paho, the client implementation suggested by Google in their documentation.
I've gone through their troubleshooting steps, and things seem to be on the up and up, so no help there either.
https://cloud.google.com/iot/docs/troubleshooting
I have noticed that in their docs they have sample code for Java/Python, etc, but not Javascript, so I'm wondering if it's simply not supported and their documentation just fails to mention as such.
I've simplified my code to just use the 'Hello World' example in the Paho documentation, and as far as I can tell I've done things correctly (including using my device path as the ClientID, the JWT token as the password, specifying an 'unused' userName field and explicitly requiring MQTT v3.1.1).
In the meantime I'm falling back to polling via their HTTP bridge, but that has obvious latency and network traffic shortcomings.
// Create a client instance
client = new Paho.MQTT.Client("mqtt.googleapis.com", Number(8883), "projects/[my-project-id]/locations/us-central1/registries/[my registry name]/devices/[my device id]");
// set callback handlers
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;
// connect the client
client.connect({
mqttVersion: 4, // maps to MQTT V3.1.1, required by IOTCore
onSuccess:onConnect,
onFailure: onFailure,
userName: 'unused', // suggested by Google for this field
password: '[My Confirmed Working JWT Token]' // working JWT token
function onFailure(resp) {
console.log(resp);
}
// called when the client connects
function onConnect() {
// Once a connection has been made, make a subscription and send a message.
console.log("onConnect");
client.subscribe("World");
message = new Paho.MQTT.Message("Hello");
message.destinationName = "World";
client.send(message);
}
// called when the client loses its connection
function onConnectionLost(responseObject) {
if (responseObject.errorCode !== 0) {
console.log("onConnectionLost:"+responseObject.errorMessage);
}
}
// called when a message arrives
function onMessageArrived(message) {
console.log("onMessageArrived:"+message.payloadString);
}
I'm a Googler (but I don't work in Cloud IoT).
Your code looks good to me and it should work. I will try it for myself this evening or tomorrow and report back to you.
I've spent the past day working on a Golang version of the samples published on Google's documentation. Like you, I was disappointed to not see all Google's regular languages covered by samples.
Are you running the code from a browser or is it running on Node.JS?
Do you have a package.json (if Node) that you would share too please?
Update
Here's a Node.JS (JavaScript but non-browser) that connects to Cloud IoT, subscribes to /devices/${DEVICE}/config and publishes to /devices/${DEVICE}/events.
https://gist.github.com/DazWilkin/65ad8890d5f58eae9612632d594af2de
Place all the files in the same directory
Replace values in index.js of the location of Google's CA and your key
Replaces [[YOUR-X]] values in config.json
Use "npm install" to pull the packages
Use node index.js
You should be able to pull messages from the Pub/Sub subscription and you should be able to send config messages to the device.
Short answer is no. Google Cloud IoT Core doesn't support WebSockets.
All the JavaScript MQTT libraries use WebSocket because JavaScript is restricted to perform HTTP requests and WebSocket connections only.
I have a grails project which uses Spring websockets. I have implemented the DefaultHandshakeHandler to create random principal name for each new session and use convertAndSendToUser to send messages.
Everything works fine in local run. I am also able to deploy the WAR file on an AWS EC2 Linux Instance running latest tomcat. The file deploys fine and the Connect and Disconnect events on websockets can be detected correctly.*
The only problem is, My CustomHandshakeHandler's determineUser does not get called on production. Due to this my StompHeaderAccessor's principal is always null and the code starts spitting NPEs.
This is how i have declared the CustomHandshakeHandler :
class CustomHandshakeHandler extends DefaultHandshakeHandler {
#Override
protected Principal determineUser(ServerHttpRequest request,
WebSocketHandler wsHandler,
Map<String, Object> attributes) {
// Generate principal with UUID as name
return new StompPrincipal(UUID.randomUUID().toString())
}
}
This is how i set the handshake handler configuration :
#Override
void registerStompEndpoints(StompEndpointRegistry stompEndpointRegistry) {
stompEndpointRegistry.addEndpoint("/ws-ep") // Set websocket endpoint to connect to
.setHandshakeHandler(new CustomHandshakeHandler()) // Set custom handshake handler
.withSockJS() // Add Sock JS support for frontend
}
I tried deploying the same WAR file on local Tomcat 8 and it again works fine. It seems problem happens due to AWS. I also searched for some other AWS and websocket related issues. I came across some ELB compatibility related things but i Don't think that's my case since my websockets are working fine (Events are being received)
Can someone please help out or point me in right directions
Problem was with Nginx settings which upgrade the Http Request to WS request. This question helped a lot : Spring WebSocket: Handshake failed due to invalid Upgrade header: null
Our new phone system is making use of Asterisk manager API which allows to read events and issue commands over a TCP/IP stream. My question is.. Is there any way at all to use ColdFusion to read (and in-turn process) the stream of events? As of now I'm able to view the phone events (incoming calls, transfers, hang-ups etc) via telnet and I'm wondering if it's possible to use a ColdFusion event gateway to process these events as they come over?
Once the initial connection is made (via telnet), I have to submit the following key:values in order to authenticate the connection before the stream begins.
Action: login<CRLF>
Username: usr<CRLF>
Secret: abc123<CRLF>
<CRLF>
Just wanted to specify that as I'm not sure if that's a deal-breaker with possibly using a web service in this manner. Also note we are using ColdFusion 10 Enterprise.
I realize this is an old thread, but I am posting this in case it helps the next guy ....
AFAIK, it cannot be done with a standard CF Event Gateway. However, one possibility is using Asterisk-Java. It is a java library that allows communication with an Asterisk Server. More specifically it Manager interface:
... is capable of sending [actions] and receiving [responses] and
[events]. It does not add any further functionality but rather
provides a Java view to Asterisk's Manager API (freeing you from
TCP/IP connection and parsing stuff).
So it can be used to issue commands to the server, and receive events, just like telnet.
Starter example:
Download the Asterisk-Java jar and load it via this.javaSettings in your Application.cfc
Create a ManagerConnection with the settings for your Asterisk server
factory = createObject("java", "org.asteriskjava.manager.ManagerConnectionFactory");
connection = factory.init( "hostNameOrIP"
, portNum
, "userName"
, "theSecret" ).createManagerConnection();
Create a CFC to act as a listener. It will receive and handle events from Asterisk:
component {
public void function onManagerEvent(any managerEvent)
{
// For demo purposes, just output a summary of the event
WriteLog( text=arguments.managerEvent.toString(), file="AsteriskLog" );
}
}
Using a bit of dynamic proxy magic, register the CFC with the connection:
proxyListener = createDynamicProxy("path.YourCFCListener"
, ["org.asteriskjava.manager.ManagerEventListener"]);
connection.addEventListener( proxyListener );
Login to the server to begin receiving events. Setting the appropriate event level: "off", "on" or csv list of available events - "system", "call" and/or "log".
connection.login("on");
Run a simple "Ping" test to verify everything is working. Then sleep for a few seconds to allow some events to flow. Then close the connection.
action = createObject("java", "org.asteriskjava.manager.action.PingAction").init();
response = application.connection.sendAction(action);
writeDump(response.getResponse());
// disconnect and stop events
sleep(4000);
connection.logoff();
Check the demo log file. It should contain one or more events.
"Information","http-bio-8500-exec-4","10/14/16","15:17:19","XXXXX","org.asteriskjava.manager.event.ConnectEvent[dateReceived=Fri Oct 14 15:17:19 CDT 2016,....]"
NB: In a real application, the connection would probably be opened once, in OnApplicationStart, and stored in a persistent scope.
Events would continue to stream as long as the connection remained open. The connection should only be closed when the application
ends, to halt event streaming.
Yes-- you'd want to use a Socket Gateway. Ben Nadel has a great writeup about how to do this: Using Socket Gateways To Communicate Between ColdFusion And Node.js
Although he uses Node.js in his example, you should be able to use his guide to set up the Socket Gateway, then handle the data passed to it as you see fit.
What you want is a server-side TCP client. I suggest easySocket, a simple UDF that allows you to send TCP messages via Coldfusion by utilizing Java sockets.
I am using Microsoft Synch Service Framework 4.0 for synching Sql server Database tables with SqlLite Database on the Ipad side.
I want to customize the C# code. The client will be sending me some parameters e.g. SessionId with the synch services. Depending on the parameters, the code will decide whether to continue with the synching or not. Now, the below code is for initializing the synch service. Where can I put the custom code for processing the parameters. Basically,
If ( Session Id already exists)
// Continue with synching
else
{
Do not continue with synching
}
I believe this is possible using Interceptors: Request, Response OR Conflict Interceptors.
Could anyone provide an example so that I can write business logic before synching
i think you should be writing a Request Interceptor.
here's a quick/basic intro on how to write one.
Well, I faced some problem while using Interceptors when downloading changes from server.
Client is sending me "Server_Code" through header.
if (serverCode == "DEV")
{
foreach (IOfflineEntity entity in context.IncomingChanges)
{
context.RejectChange(entity, "Invalid Server");
}
}
When client is downloading changes from server, I get IncomingChanges value = 0. Thus I cannot reject changes.
How about using filters for sync. i.e. Sync will happen based on the parameters sent by the client.
If client sends SessionId, then sync will happen only for that particular SessionId.
Any ideas?
I'm trying to figure out how to shut down an instance of Express. Basically, I want the inverse of the .listen(port) call - how do I get an Express server to STOP listening, release the port, and shutdown cleanly?
I know this seems like it might be a strange query, so here's the context; maybe there's another way to approach this and I'm thinking about it the wrong way. I'm trying to setup a testing framework for my socket.io/nodejs app. It's a single-page app, so in my testing scripts (I'm using Mocha, but that doesn't really matter) I want to be able to start up the server, run tests against it, and then shut the server down. I can get around this by assuming that either the server is turned on before the test starts or by having one of the tests start the server and having every subsequent test assume it's up, but that's really messy. I would much prefer to have each test file start a server instance with the appropriate settings and then shut that instance down when the tests are over. That means there's no weird dependencies to running the test and everything is clean. It also means I can do startup/shutdown testing.
So, any advice about how to do this? I've thought about manually triggering exceptions to bring it down, but that seems messy. I've dug through Express docs and source, but can't seem to find any method that will shut down the server. There might also be something in socket.io for this, but since the socket server is just attached to the Express server, I think this needs to happen at the express layer.
Things have changed because the express server no longer inherits from the node http server. Fortunately, app.listen returns the server instance.
var server = app.listen(3000);
// listen for an event
var handler = function() {
server.close();
};
Use app.close(). Full example:
var app = require('express').createServer();
app.get('/', function(req, res){
res.send('hello world');
});
app.get('/quit', function(req,res) {
res.send('closing..');
app.close();
});
app.listen(3000);
Call app.close() inside the callback when tests have ended. But remember that the process is still running(though it is not listening anymore).
If after this, you need to end the process, then call process.exit(0).
Links:
app.close: http://nodejs.org/docs/latest/api/http.html#server.close (same applies for)
process.exit:
http://nodejs.org/docs/latest/api/process.html#process.exit
//... some stuff
var server = app.listen(3000);
server.close();
I have answered a variation of "how to terminate a HTTP server" many times on different node.js support channels. Unfortunately, I couldn't recommend any of the existing libraries because they are lacking in one or another way. I have since put together a package that (I believe) is handling all the cases expected of graceful HTTP server termination.
https://github.com/gajus/http-terminator
The main benefit of http-terminator is that:
it does not monkey-patch Node.js API
it immediately destroys all sockets without an attached HTTP request
it allows graceful timeout to sockets with ongoing HTTP requests
it properly handles HTTPS connections
it informs connections using keep-alive that server is shutting down by setting a connection: close header
it does not terminate the Node.js process
Usage with Express.js:
import express from 'express';
import {
createHttpTerminator,
} from 'http-terminator';
const app = express();
const server = app.listen();
const httpTerminator = createHttpTerminator({
server,
});
await httpTerminator.terminate();
More recent version of express support this solution:
const server = app.listen(port);
const shutdown = () => {
server.close();
}
You can easily do this by writing a bash script to start the server, run the tests, and stop the server. This has the advantage of allowing you to alias to that script to run all your tests quickly and easily.
I use such scripts for my entire continuous deployment process. You should look at Jon Rohan's Dead Simple Git Workflow for some insight on this.