Develop Reference

Failed to publish the request over MQTT - Flutter - Parse Server

I have a sample app that uses Parse Server. I've been testing my app on both emulator and physical devices and I noticed that the response time is much slower on the physical device.
This one is from the emulator.
and this is one is from the physical device:
I've been scratching my head regarding this one. I've also posted it on the parse community platform and followed the advice there to manually monitor the server for every change I've made until I reach my prior server configuration. I overhauled the server from scratch. Do some load testing -> Deployed the server on a replica set -> load testing. Now, I'm in the process of doing some basic queries. I used ADB logcat to see what's happening on both device and saw these errors on the physical device and not on the emulator:
E[N rtchannel]_rt_mqtt_publish_callback(356)=>Failed to publish the request over MQTT. token:be925eea-407c-417d-96c9-3af5a7e83e48, category:mcd-sync-data-task-category, requestId:54138, error:Error Domain=mqtt Code=3008
E[S sync]_createResponseError(166)=>Network Response be925eea-407c-417d-96c9-3af5a7e83e48 contains sync error Error Domain=mqtt Code=3008 - Underlying error (null): Error Domain=mqtt Code=3008
This one also shows before pulling the payload.
W[S sync-state-machine]MCDSyncStateMachineScheduleDelayedRetry(173)=>skipping the new retry with longer delay
W[S sync]_scheduleNextCursorRetry(326)=>skipping delayed retry due to state machine state decision
The number of times these errors pop up is related to the number of queries executed. I did not put any configurations on the server which use MQTT. Any help is much appreciated.

Pubnub+Python SDK on an Ubuntu Azure-hosted machine. Connection problems

I am experiencing a bad behavior of Pubnub in the following scenario:
Pubnub SDK for Python as a subscriber
Python 3+Django on Ubuntu 14.04
Ubuntu machine hosted on Azure
Android Pubnub client as a publisher
It seems to be that, at a certain point, the Pubnub connection on the server side becomes stale, that is, any message sent from the client is not received by the subscriber.
I have noticed that there are some errors on the log related to pubnub connection:
WARNING 2015-09-30 17:21:24,778 connectionpool 26551 139638563919616 Retrying (Retry(total=0, connect=None, read=None, redirect=None)) after connection broken by 'ReadTimeoutError("HTTPConnectionPool(host='pubsub.pubnub.com', port=80): Read timed out. (read timeout=320)",)': /subscribe/.../.../0/...?uuid=...&auth=...&pnsdk=PubNub-Python/3.7.3
After about 5 minutes, the message is received and correctly processed.
I guess that the root of the problem lays in the way Azure manages long http connections, as:
The problem does not arise on my local machine, which has the very same OS version and the same stack
There is an obscure 'azure' parameter in the Python SDK. I tried to activate it without any noticeable difference
As a test I added two more subscribers on my pc and they both receive messages instaneously
Thanks.

It seems to be that the root cause is the fact that Azure cuts HTTP connections above 4 minutes (https://azure.microsoft.com/it-it/blog/new-configurable-idle-timeout-for-azure-load-balancer/).
On the other hand, though, Pubnub creates connections with 5 minutes timeout (320 seconds, see https://github.com/pubnub/python/blob/master/pubnub.py#L1881).
Unfortunately, the Pubnub 320 seconds timeout can not be changed, whereas the Azure timeout seems to be modifiable only via Powershell scripts (uncomfortable, especially if you do not have a Microsoft Window machine).
All in all, I changed the Pubnub source code with a 120 seconds timeout and now everything is going pretty well.
It would be advisable to:
Document that on Pubnub side
Modify Pubnub so that the 320 seconds timeout can be changed
Improve the Azure interface in order to change the timeout parameter without using Powershell

If there is anything that can be done from the PubNub SDK, look at this:
Azure flag on init
https://github.com/pubnub/python/blob/master/pubnub.py#L2112
https://github.com/pubnub/python/blob/master/pubnub.py#L2141-L2146
Linux platform
And this should be getting called if Azure is running on linux:
- https://github.com/pubnub/python/blob/master/pubnub.py#L69-L77
Let me know if that helps any.

Volley + OkHttp on Android gives error on status 200 response

When I make my request with only Volley everything goes well and my StringRequest goes to onResponse.
But when I switch to Volley + Okhttp combination, my request goes through, I receive the same response as before but then I get the following error message:
E/Volley﹕ [122319] BasicNetwork.performRequest: Unexpected response code 200 for <my request url>
java.io.IOException: closed
com.android.volley.NetworkError: java.io.IOException: closed
at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:182)
at com.android.volley.NetworkDispatcher.run(NetworkDispatcher.java:114)
Caused by: java.io.IOException: closed
at okio.RealBufferedSource$1.read(RealBufferedSource.java:345)
at java.io.InputStream.read(InputStream.java:162)
at com.android.volley.toolbox.BasicNetwork.entityToBytes(BasicNetwork.java:254)
at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:130)
            at com.android.volley.NetworkDispatcher.run(NetworkDispatcher.java:114)
Im using this https://gist.github.com/bryanstern/4e8f1cb5a8e14c202750 for my OkHttpStack for Volley.

I haven't had too much time to investigate but I was running into the same issue when using the emulator connected through a proxy (Charles). For me the problem goes away when I test without a proxy or on device.

This exact same problem happened to me when using the start and stop methods of the RequestQueue. It was pointed out in many popular blogs that the RequestQueue should be stopped when user is flinging to ensure there's no jerking. However when you call stop, all RequestQueue's requests are stopped, even the ones which were already doing network call. The above exception happened when these requests are stopped preliminarily. Not calling the stop function solved the problem for me.

For those people using a Proxy (in my case Charles) besides configuring your proxy in Settings it is necessary to configure also your proxy in the Android Emulator.
So, here is my configuration in Settings Emulator
And this are the steps to configure the proxy using wifi in Android Emulator
Settings
Network & Internet
Wi-Fi
Android Wifi
Click on Setting icon
Click Edit icon
Configure your proxy

SMTPTransport sendMessage stuck on connection loss

i am using javamail's SMTPTransport.sendMessage method to send emails in my android app and everything works fine... but when i start sending a message and in the middle, i disable my wifi, it gets stuck. I have waited for more than 1hour now and it is still stuck; no exception is thrown... any idea how to handle this situation?
edit:
i have added a timeout
props.put("mail.smtp.connectiontimeout", "3000");
props.put("mail.smtp.timeout", "3000");
does not seem to work ... i have simulated a connection loss and it's already 5mins now and it is still in sending state and has not timed out
edit2:
timeout/error(not even sure if it is a timeout) occurred after 16mins
06-30 18:47:27.722: I/System.out(15906): javax.net.ssl.SSLException: Write error: ssl=0xdf8268: I/O error during system call, Invalid argument
edit 3:
it does not always throw an exception... i have simulated a connection loss and after 1hr, still no exception... it is in sending state..... and have not return yet :(

The current version of JavaMail only handles timeouts for reads, because that's all the JDK supports. For the next JavaMail release I've added support for write timeouts. You can experiment with it using the 1.5.1-SNAPSHOT release of JavaMail available in the maven.java.net repository. You'll need to set the "mail.smtp.writetimeout" property. Don't know if this will help you on Android since it's not really Java...

Confirm MediaPlayer automatic retry on streaming HTTP error

I originally posted this question to the Android developers Google group a few days ago, but have yet to hear a response. Maybe someone on Stack Overflow can help?
I have an app which streams mp3s from the web, proxied through a local HTTP server. At times, this local proxy server returns an HTTP error. It seems that upon receiving this error during the prepare state, the MediaPlayer makes one more attempt to stream, sending another request to the URL specified in setDataSource().
From a thread, I'm calling MediaPlayer.prepare() once. But from the proxy thread, I can see that after sending an HTTP error response, another request for the same URL is made. Can someone confirm this behavior? I'm seeing this from the emulator running a 1.6 AVD.
Can I disable this automatic retry? Is there a specific HTTP error code that I can send that will prevent this retry?
Thanks!