I have the following javascript node.js code:
var options = {
host: "x.y.z"
,path: "/api/abc/"
,method: "GET"
};
var req = http.request(options);
req.on('response' , function(data) {
console.log("response: ",data.statusCode);
done();
});
req.on('error' , function() {
console.log("error");
done();
});
req.end();
I can't get the error event when an actual HTTP request error occurs. What am I missing ?
Preliminary findings: It would appear that the failure case "no response from server" (e.g. due to network issue) does not fire any event. So, the workaround is to create a 'timer' and trap this condition by yourself.
Try using an if / else statement instead of two independent functions.
if(response you want && response.statusCode = 200){
//logic
} else {
//console.log("error")
}
You should create your own Timeout function inside the request. In fact, I believe that after a lot of time (maybe a minute?) the request would fail. But, if you require something more earlier, you can check this thread that asks for the same thing:
How to set a timeout on a http.request() in Node?
Related
An error is being passed by the callback in my request function. I am trying to determine under what conditions an error is passed to the callback.
var request = require('request');
request('http://www.google.com', function (error, response, body) {
if(error){
//why or when would an error be created?
}
else if (response.statusCode == 200) {
console.log(body) // Show the HTML for the Google homepage.
}
else{
// when would this happen ?
}
})
the documentation doesn't seem to cover what conditions will cause an error object to be created and passed. Right now I just assume anything but a 200 or 300 will cause an error to be created, but I am just guessing.
request library uses the node.js http module internally for making GET request. From it's doc:
If any error is encountered during the request (be that with DNS
resolution, TCP level errors, or actual HTTP parse errors) an 'error'
event is emitted on the returned request object.
I guess you have to go though the http module source to exactly find out what are the errors.
In a Parse custom webhook, which is of the form:
app.post('/receiveSMS', function(req, res) {
Where receiveSMS is hooked up to the Twilio api and this method is properly called (I have logs to prove it), but I'm trying to query on my tables within this method and it doesn't seem to be working.
Is this allowed, or is there anything special I need to do to make this work?
var contactObj = Parse.Object.extend("Contact");
var contactQuery = new Parse.Query(contactObj);
console.log(req.body.From);
contactQuery.each(function(contact) {
and the body of the each call never gets called.
Is this allowed, and if so, what am I doing wrong here?
Update -- The entirety of the webhook code block is:
app.post('/receiveSMS', function(req, res) {
console.log('receive SMS');
console.log(req.body.Body);
res.send('Success');
if(req.body.Body.toLowerCase() == "in" || req.body.Body.toLowerCase() == "out") {
twilio.sendSMS({
From: "(xxx) xxx-xxxx",
To: req.body.From,
Body: "It's been noted, and notifications have been sent. Check us out!"
}, {
success: function(httpResponse) {
console.log(httpResponse);
response.success("SMS Sent!");
},
error: function(httpResponse) {
console.error(httpResponse);
response.error("Uh OH, something went wrong");
}
});
if(req.body.Body.toLowerCase() == "in") {
console.log("in was received");
// eventQuery
var contactObj = Parse.Object.extend("Contact");
var contactQuery = new Parse.Query(contactObj);
console.log(req.body.From);
// contactQuery.equalTo("phone", req.body.From);
contactQuery.first({
success: function(contact) {
console.log("found contact");
console.log(contact);
}, error: function(error) {
alert("Error: " + error.code + " " + error.message);
}
});
}
}
});
This code is called and the logs "console.log('receive SMS')" and the like are all called, except for what is inside the query's first call.
Queries on tables is fine, but you can't use the each() function, as that is restricted to only work in background jobs.
You'll have to use find() or first() or get() depending on your needs.
UPDATE
OK, after seeing your full code I have some ideas as to why it isn't working. First off you're sending res.send("Success"); before you're finished, I'm not positive but I think this causes it to stop running the rest of your code (haven't checked, could be wrong).
Also you're doing multiple async operations without chaining them so the contactQuery.first() will run before the twilio.sendSMS() is finished.
Inside twilio.sendSMS() you're calling response.success() / response.error(). These are for cloud methods, not web hooks, so I expect these would be throwing errors server-side (check the logs on the Dashboard).
Inside contactQuery.first() you are using alert() which isn't supported in cloud code.
I'm not sure if those mistakes will be caught early and throw errors or if they'll raise run-time exceptions, but they should be fixed, your code re-deployed and try again. Then report any errors in the server logs.
Yes, it's allowed, I'm using the same web hooks.
My guess is that you probably have defined security restriction on your Contact class that prevent the query to fetch anything. What's the security setting on this class ?
You can either try to relax the constrains, or login as a dummy user, and execute the query (approach that I chose).
cheers
-A
How to handle etimedout error on this call ?
var remotePath = "myremoteurltocopy"
var localStream = fs.createWriteStream("myfil");;
var out = request({ uri: remotePath });
out.on('response', function (resp) {
if (resp.statusCode === 200) {
out.pipe(localStream);
localStream.on('close', function () {
copyconcurenceacces--;
console.log('aftercopy');
callback(null, localFile);
});
}
else
callback(new Error("No file found at given url."), null);
})
There are a way to wait for longer? or to request the remote file again?
What exactly can cause this error? Timeout only?
This is caused when your request response is not received in given time(by timeout request module option).
Basically to catch that error first, you need to register a handler on error, so the unhandled error won't be thrown anymore: out.on('error', function (err) { /* handle errors here */ }). Some more explanation here.
In the handler you can check if the error is ETIMEDOUT and apply your own logic: if (err.message.code === 'ETIMEDOUT') { /* apply logic */ }.
If you want to request for the file again, I suggest using node-retry or node-backoff modules. It makes things much simpler.
If you want to wait longer, you can set timeout option of request yourself. You can set it to 0 for no timeout.
We could look at error object for a property code that mentions the possible system error and in cases of ETIMEDOUT where a network call fails, act accordingly.
if (err.code === 'ETIMEDOUT') {
console.log('My dish error: ', util.inspect(err, { showHidden: true, depth: 2 }));
}
In case if you are using node js, then this could be the possible solution
const express = require("express");
const app = express();
const server = app.listen(8080);
server.keepAliveTimeout = 61 * 1000;
https://medium.com/hk01-tech/running-eks-in-production-for-2-years-the-kubernetes-journey-at-hk01-68130e603d76
Try switching internet networks and test again your code. I got this error and the only solution was switching to another internet.
Edit: I now know people besides me that have had this error and the solution was communicating with the ISP and ask them to chek the dns configuration because the http request were failing. So switching networks definitely could help with this.
That is why I will not delete the post. I could save people a few days of headaches (especially noobs like me).
Simply use a different network. Using a different network solved this issue for me within seconds.
I'm writing a mobile app with Appcelerator Titanium that makes a lot of different xhr requests. This is not really an Appcelerator Titanium specific question. But if you do write some code, I hope it's javascript.
The app needs to authenticate itself, the user must be logged for some interactions, etc.
I've come to a point where any request might get any kind of response such as:
not authenticated
not logged
bad params
successful
...
The requests are wrapped in different model methods or helpers.
The thing is, I'm not familiar with this kind of app. I was wondering what are the best practices.
Some real questions for example would be:
If the app is not authenticated (token expired, first launch), should the app try to authenticate itself and then send again the request that was denied ? (transparent to user)
Should I send an authentication request each time the app launches and then "forget" about it?
The problem I'm facing is that the code becomes quickly big if I try to handle this for each request. Full of nested callbacks, retry conditions, various events listeners to manage, etc. It just does not feel very "nice". And it's not DRY at all, when what I really need is for any request, check what was wrong, try to fix it (authenticate if not, automatic login if possible or show the login UI, etc..) then if that works retry the original request a couple of times, abort if needed.
I've been looking at the promise pattern but only know theory and don't know if it could be what I need.
So I welcome any advice regarding this particular problem. I wonder how apps like "Facebook" handle this.
Thank you for your help
This question is not easily answered, but let me try to give you some Ideas:
The most important thing, before coding anything in your app, is the API itself. It has to be reliable and adhere to standards. I will not go into too much detail here, but a well written RESTful API can reduce the complexity of your httpClient significantly. It has to respond with standard http status codes and to methods like POST, GET, PUT, DELETE...
A pretty good read is The REST API Design Handbook by George Reese.
My approach to httpClients with Titanium is a single module, which is loaded via require() wherever needed. I stick to one single client at a time, as I had massive problems with multiple parallel calls. Whenever a call is made, the client checks if there is already a call in progress and sends it to a queue if necessary.
Let me show you an example. I have left out lots of stuff for sake of brevity:
// lib/customClient.js
var xhrRequest; // This will be our HTTPClient
var callQueue = []; // This will be our queue
// Register the request
// params are:
// method (e.g. 'GET')
// url (e.g. 'http://test.com/api/v1/user/1')
// done (callback function)
function registerRequest(params) {
if(!xhrRequest) {
sendRequest(params);
} else {
queueRequest(params);
}
}
// This simply sends the request
// to the callQueue
function queueRequest(params) {
callQueue.push(params);
}
// Send the request with the params from register
// Please note that I do not hardcode error messages,
// I just do it here so it is easier to read
function sendRequest(params) {
// Set callback if available and valid
var callback = params.done && typeof(params.done) === "function" ? params.callback : null;
// Set method
var method = params.method || 'GET';
// Create the HTTP Client
xhrRequest = Ti.Network.createHTTPClient({
// Success
onload: function() {
// You can check for status codes in detail here
// For brevity, I will just check if it is valid
if (this.status >= 200 && this.status < 300) {
if(this.responseText) {
// You might want to check if it can be parsed as JSON here
try {
var jsonData = JSON.parse(this.responseText);
if(callback) callback({ success: true, response: jsonData });
} catch(e) {
if(callback) callback({ success: false, errormessage: 'Could not parse JSON data' });
}
processQueue();
} else {
if(callback) callback({ success: false, errormessage: 'No valid response received' });
processQueue();
}
} else {
if(callback) callback({ success: false, errormessage: 'Call response is success but status is ' + this.status });
processQueue();
}
},
// Error
onerror: function(e) {
if(this.responseText) {
try {
var jsonData = JSON.parse(this.responseText);
if(callback) callback({ success: false, reponse: jsonData });
} catch(e) {};
}
processQueue();
},
});
// Prepare and send request
// A lot more can (and should) be configured here, check documentation!
xhrRequest.setTimeout(10000);
xhrRequest.open(method, params.url);
xhrRequest.send();
}
// Checks if there is anything else in the queue
// and sends it
function processQueue() {
xhrRequest = null;
var nextInQueue = callQueue.shift();
if(nextInQueue) sendRequest(nextInQueue);
}
// Our public API
var publicAPI = {
sendRequest: function(params) {
registerRequest(params);
}
};
module.exports = publicAPI;
I can then send a call from any other controller/view
var customClient = require('lib/customClient'); // omit 'lib' if you use alloy
// Send the request
customClient.sendRequest({
method : 'GET',
url : 'http://test.com/api/v1/user/1',
done : function(response) {
Ti.API.debug(JSON.stringify(response));
}
});
Note that this is not complete and does not check for connectivity, has no real error handling etc., but it might help you to get an idea.
I think there is loads of stuff to talk about here, but I will stop here for now...
Hey fellow Chrome Devs, how would one go about detecting when a chrome.extension.sendRequest has failed? I tried this, and no dice:
chrome.extension.sendRequest({ /* message stuff here */ }, function(req){
if(req == null || chrome.extension.lastError == null){
alert("No response. :(");
}
});
But what happens is that the callback never even fires, which is what I half expected. Is there any way to detect when a sendRequest fails?
Thanks!
You could surround it with a try{}catch(err){} to catch any errors thrown, but an error is not thrown if there is no response, and there is also no null response.
This would have been done by design, to allow a message receiver to do it's thing. For instance, it might involve a couple of web service requests, or ajax requests that could take a while.
If you know how long it should take to respond, you should implement a timeout (it would have been nice if the sendRequest function included one)
So, you could do something like this:
var noResponse = setTimeout(100, function() {
alert('No response received within 100ms!');
});
chrome.extension.sendRequest({ /* message stuff here */ }, function(req){
clearTimeout(noResponse);
alert('I have a response!');
});
You need to change....
if(req == null || chrome.extension.lastError == null){
alert("No response. :(");
}
...to....
if(req == null){
alert("No response. :( and the error was "+chrome.extension.lastError.message);
}
As the docs say for sendRequest If an error occurs while connecting to the extension, the callback will be called with no arguments and chrome.extension.lastError will be set to the error message.
http://code.google.com/chrome/extensions/extension.html#method-sendRequest
http://code.google.com/chrome/extensions/extension.html#property-lastError