I am sending a data notification every 2 min for the device in order to collect data (GPS, Signal strength ...).
The FCM trigger service that sends the collected data to an API
However, The device stops receive FCM notification to starts that app in some cases or even till restart it.
Is there any reason for this and how Can I pass it?
Note: I have Add server up to white list in the firebase console
Generally there are two types of FCM messages we can send to registered devices. First one is data message and the other one is notification message. The default priority of data message is NORMAL where as the notification messages have a HIGH priority. Messages with HIGH priority are considered to be delivered first (That means there is a chance of not receiving data messages in some case). But it is possible to change the priority of data message to HIGH while sending them from server.
https://firebase.google.com/docs/cloud-messaging/concept-options#setting-the-priority-of-a-message
But in my case i had some situations when i was not able to receive FCM messages even after setting priority to HIGH. Thus i opted to use FCM wrapper services like Onesignal to send push notification. It is way better in case of message delivery. Inside it is FCM, but they handled the message delivery problem up to an extent. Take a look at
https://onesignal.com/
Related
I have a task to fetch data from server at start if application. For purpose i am calling an api by asynctask for notification codes and parse data. The data can go upto 60000 notification codes.
For each notification code i have to call different apis to get data. After performing operation i need to again call an acknowledge api to tell server notification has been acknowledged. So next time when getting notification code it dont repeat.
So in the case i have to call approximately 60000 asynctask for operation and 60000 for acknowledgement. Do each operation for different api urls and then Acknowledge each operation for different url simultaneously
My app is working when notifications are below 1000 but for more than that notification it stucks.
Please anyone can guide what's the best way to implement this.
I want to implement push notification in java so please help me out
1-Each time a new record(Message) pushed into data base(due to event created by some other user), a push notification should be sent to specific Logged in user automatically.
2-Content of the push notification should be the message present in the db.
3-If there are multiple messages, then the user should receive them one by one in a queue fashion.
4-Most important thing is the logged in user need not have to trigger any event to get notification, user should receive it automatically throughout the session.
You could use Server Sent Events. Java provides SseEmitter to send timely notifications.
You can use EventSource API in JavaScript to trigger the SSE event stream and in the server-side, loop the database query code which is wrapped by an ExecutorService - which can spin of separate thread based on the initialization.
Put SSE timeout to -1 for listening for an infinite amount of time.
Please note this answer is only a hint. Use these to explore more from the internet.
How to prevent duplicated msg from happening in Google Cloud PubSub?
Say, I have a code that handles the msg that it is subscribed for.
Say, I have 2 nodes with the same Service that has this code.
Once one has received the msg but not yet acknowledged it, another node will receive the same message. And this is where there's the problem that we have two duplicated msgs.
void messageReceiver(PubsubMessage pubsubMessage, AckReplyConsumer ackReply) {
submitHandler.handle(toMessage(pubsubMessage))
.doOnSuccess((response) -> {
log.info("Acknowledging the successfully processed message id: {}, response {}", pubsubMessage.getMessageId(), response);
ackReply.ack(); // <---- acknowledged
})
.doOnError((e) -> {
log.error("Not acknowledging due to an exception", e);
ackReply.nack();
})
.doOnTerminate(span::finish)
.subscribe();
}
What is the solution for this? Is it normal behaviour?
Google Cloud Pub/Sub uses "At-Least-Once" delivery. From the docs:
Typically, Cloud Pub/Sub delivers each message once and in the order in which it was published. However, messages may sometimes be delivered out of order or more than once. In general, accommodating more-than-once delivery requires your subscriber to be idempotent when processing messages.
This means it guarantees it will deliver the message 1:N times, so you can potentially get the message multiple times if you don't pipe it through something else that deduplicates it first. There isn't a setting you can define to guarantee exactly once delivery. The docs do reference you can get the behavior you desire using Cloud Dataflow's PubSubIO, but that solution appears to be deprecated:
You can achieve exactly once processing of Cloud Pub/Sub message streams using Cloud Dataflow PubsubIO. PubsubIO de-duplicates messages on custom message identifiers or those assigned by Cloud Pub/Sub.
Saying all of this, I've never actually seen Google Cloud Pub/Sub send a message twice. Are you sure that's really the problem you're having, or is the message being reissued because you are not acknowledging the message within the Acknowledgement Deadline (as you stated above, this defaults to 10 seconds). If you don't acknowledge it, it will get reissued. From the docs (emphasis mine):
A subscription is created for a single topic. It has several properties that can be set at creation time or updated later, including:
An acknowledgment deadline: If your code doesn't acknowledge the message before the deadline, the message is sent again. The default is 10 seconds. The maximum custom deadline you can specify is 600 seconds (10 minutes).
If that's the situation, just acknowledge your messages within the deadline and you won't see these duplicates as often.
You can use Redis from Memorystore in order to deduplicate messages. Your publisher should add trace iD to the message body just before publishing it to PubSub. On the other side client (subscriber) should check if the trace ID is in the cache - skip the message. If there is no such message - process the message and add trace ID to cache with 7-8 days expiry time (PubSub deadline is 7 days). In such a simple way You can grant the correct messages received.
All messages in a given topic have a unique messageID field:
ID of this message, assigned by the server when the message is published. Guaranteed to be unique within the topic. This value may be read by a subscriber that receives a PubsubMessage via a subscriptions.pull call or a push delivery. It must not be populated by the publisher in a topics.publish call.
You can use it to deduplicate incoming messages. No need to manually assigning ID.
It is a bit harder in distributed systems (e.g. multiple instances of consumers for a given subscription). You would need a global synchronization mechanism, the simplest would be to setup database (e.g. Redis) and use it to keep processed messages IDs.
You should take a look at Replaying and discarding messages which describes how to configure message retention.
There are two properties of subscription:
retain_acked_messages - keep acknowledge messages,
message_retention_duration - how long to keep messages.
If you do not plan to rewind your subscription to a past point in time, e.g. if you do not plan to reprocess messages or have bugs forcing you to reset your subscription you can set retain_acked_messages=false and message_retention_duration='3600s'. This will allow you to keep only last hour message IDs.
Bear in mind that PubSub message also have publish_time so you don't need to add it in your message's data. It can be used with message_id. Both of these are set by a PubSub server when it receives a message.
I'm developing a websocket application by using Netty. I'd like to know if a message is really delivered from a source to a destination. In particular, let's assume that a client and a server have an open channel and exchange some messages for a while. At a certain point, the client goes down, but the channel is still active in Netty. I tried to use isReachable() before sending the message, but this method seems to be buggy in some scenarios (e.g. a machine with Win7 is up, but isReachable() returns false). Now, my idea is to implement a mechanism using ACKs, namely the server sends the message and the client sends back an ack. To do that, I need a timeout to see if, after a certain interval, the corresponding ack does not arrive. Is there something similar in Netty?
Regarding isReachable() - it's only a best effort API. The documentation points out that it tries to send an ICMP echo request or create a TCP connection to port 7 on the destination host, both of which are highly likely to be blocked by a firewall. Is this happening in your case?
As for the acknowledgement, there's nothing in Netty that provides this as standard, but it shouldn't be too difficult to implement. Firstly each message needs to be uniquely identifible by some sort of identifier, possibly a sequence number but a globally unique identifier means you can potentially recover across disconnections. Then you want to create a combined handler that implements both ChannelInboundHandler and ChannelOutboundHandler (assuming Netty 4). When a message is sent
add the message to a map indexed by its id
create a timer associated with the message id. Add it to another map indexed by message id
forward the message
When the ACK is received cancel the timer and remove the timer and message from their respective maps. If the timer fires use the associated id to decide what to do with the timer and message (possibly retransmit and reset the timer).
Netty provides a HashedWheelTimer for efficiently managing lots of timers with a resolution suitable for this kind of activity.
You may also want to consider putting a limit on the number of retries so you can stop and raise an error rather than continually indefinitely.
Is it possible to auto respond to incoming call with an SMS?
For example if a user is on a metting and want to set is phone state to busy, and automaticlly send reponse SMS saying "I am busy, call you later".
I saw that blocking incoming phones is impossible, but here i want the call to come and simply send reply SMS automaticlly.
Thanks.
Yes it is possible,it can be done by creating a broadcast listener and sms Manager,that is whenever the app is turned to do not disturb mode,you can register any incoming phone number in the app and can send an automated sms reply to the number as soon as possible. and as the matter of fact there's already an app present in the app store