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Questions tagged [publish-subscribe]

Publish/subscribe is a messaging pattern where senders (publishers) of messages do not program the messages to be sent directly to specific receivers (subscribers). Rather, published messages are characterized into channels, without knowledge of what, if any, subscribers there may be.

Publish/subscribe is a messaging pattern where senders (publishers) of messages do not program the messages to be sent directly to specific receivers (subscribers). Rather, published messages are characterized into channels, without knowledge of what, if any, subscribers there may be. Subscribers express interest in one or more channels, and only receive messages that are of interest, without knowledge of what, if any, publishers there are.

Among technologies known to implement the Publish/Subscribe pattern you can find :
( in a purely alphabetical order )

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ejabberd: Why is Websocket connection not opening

I am trying to make a websocket connection from Strophe.js to Ejabberd but ejabberd is not able to make a websocket connection. Here is the detail: ejabberd version: 16.02 Web socket headers General Request URL:ws://localhost:5280/websocket Request…
Tanu Gupta
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What are the scenarios which can cause message backlogs in SYSTEM.INTER.QMGR.PUBS queue?

We have a queue manager in Production system which is having around 10 cluster topics and 50 subscriptions. All the queue managers are in IBM MQ cluster topology and the data in NAS ( shared storage ) so that all queue managers are MI (…
sijo0703
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Strange ghost object behavior in rails/redis app

I'm trying to create a simple settings object for a RoR application. I want just a single instance of the object class and I want it to be able to read/write to a redis database. Most importantly, it should always be up-to-date with the database.…
randall
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How to get offline message from Tigase pubsub in smack library in android

I have integrated Tigase server and I want to store pubsub offline message and retrive all of it when user get online. For Ex: User_A and User_B is connected, if User_A sends message to User_B and at that time User_B is offline. then in which…
Jalpesh Khakhi
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How to emit events in Knockout between separate view models

I come from Angular (which has/had event emitting) and I see that Knockout has 'observables'/pubsub, though I could not fully grasp the concept of this with using separate view models. Here is an example of what I'm trying to do: I have an array of…
HImynameis
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Data Returning undefined with Meteor Router, Publish/Subscription

Meteor.publish('oneStory', function (postId) { return Stories.find({ _id: new Meteor.Collection.ObjectID(postId) }); }); FlowRouter.route('/:postId', { subscriptions: function (params, queryParams) { post =…
G.L.3
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Real Time Communication With PHP Server and Android Application

In my project I have to send user's location periodically (E.g. 30Sec) to server using Android application and the PHP server returns nearest users and app displays them on the map. I am looking for a publish subscribe protocol for the real time…
MobDev
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Topic errors when publishing an event to MQTT

I'm using the pubsub library from an ESP8266 NodeMCU and the Arduino IDE. https://github.com/knolleary/pubsubclient/tree/master/examples/mqtt_esp8266 My device is registered with the IBM Bluemix IoT Foundation (IoTF). The client name I'm using is…
Henryw4
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"Topic name format is invalid" when trying to subscribe to GCM topic

I am trying to subscribe my app instance for a topic as described here. Creating a relation mapping for one app instance works ok. Problem appears when I am trying to create relation mapping for multiple app instances. GCM returns HTTP status 400…
Oliver Pentek
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How can I receive the missing messages in STOMP?

I have a python script which has to run 24/7 on a linux server and receive ActiveMQ push notification from another server via STOMP. It can happen that the script fails for any reason and will be down for some time, apparently for 30 minutes at most…
Alan Coromano
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Akka Distributed Publish Subscribe Guarantees

I've been unable to find the answer to this question in the Akka documentation. I know that two messages published to the same topic in sequence are guaranteed to arrive in the same/correct order. If I publish two messages to two different topics -…
joebuild
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Transactional Replication: Distributor to Subscriber failure

I just set up transactional replication following the instructions here I am getting the following error: The process could not connect to Subscriber 'SUBSCRIBERSERVER'. (Source: MSSQL_REPL, Error number: MSSQL_REPL20084) Login failed for user 'NT…
amindomeniko
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PyQT equivalent of wx CallAfter?

I recently switched from wxPython to PyQT and can't find an equivalent of CallAfter. I need to use pubsub due to some imports and with wx I just sent messages with CallAfter -- is there a way to do something similar in PyQT? Basically, I want to…
linus72982
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MQTT Java puts all subscription messages in the same queue

I tried the below app where two clients continously send a message and another one receives them. But in here, it seems that the messageArrived method is been called in a single thread. Because as soon as a message from one client gets stuck, the…
AnOldSoul
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OpenDDS Error in Running Messenger Example

EDIT: I have switched from DCPSInfoRepo to RTPS, and everything is working fine. I don't know if this question should stay open to answer the problem for anyone working with DCPSInfoRepo I am looking into using OpenDDS, and I am currently following…
Abdulrahman Alhadhrami
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