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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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Consumer Id and Group Id in Kafka: what makes two consumers the same

I've been using Kafka for some months now, and I realized that some of the core concepts are not so clear for me yet. My doubt is related to the relation between consumerId, groupId and offsets. In our application we need Kafka to work using the…
joanlofe
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Subscribe to a redis channel in Django project

I have multiple applications written with nodejs or python/django or ... These services are working fine. But need to have pub/sub Async communication with each other. In nodejs there is no problem and easily can pub/sub to any redis channel.…
Reza Torkaman Ahmadi
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How to properly handle subscriptions depending on property

I have a global service widgetService which holds data for a number of widgets, each identified by a widgetID. Each widget's data can change at any time. I want to display a widget with a React component, say WidgetReactComponent. The react…
Felk
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how to get offline pubsub message from stanza using smack

I want to get the offline message, I'm using pubsub and I have added addItemEventListener on a node but when the user gets online then the user gets a message in stanza, not in the event listener's handlePublishedItems method. I want to know that if…
gaurang
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IoT data system design: Google Pub/Sub vs Kafka vs Kinesis vs PubNub for IoT data ingestion?

I'm trying to build an IoT + data analytics system and I'm having trouble deciding on what technology or service to use for ingestion. A high level description of the end goal is: IoT devices push data to an IoT gateway (using Zigbee, Z-wave,…
gunit
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How to get a message from a lettuce RedisPubSubListener in Java?

I'm just getting started with redis, lettuce and asynchronous coding at all. Now sadly I fail to find any examples on how to get the message from the listener into my program. Nor does the javadoc or any other info I find on those functions help a…
Anders Bernard
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Sharing RxBindings Observable events between multiple subscribers

I'm using a Focus Observable from the RxBindings library to react on focus changes. As I want to either validate input and trigger an animation I need the focus events twice. Jake Wharton recommends to use the share() operator for multiple…
user1033552
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How can a Phoenix application tailored only to use channels scale on multiple machines? Using HAProxy? How to broadcast messages to all nodes?

I use the node application purely for socket.io channels with Redis PubSub, and at the moment I have it spread across 3 machines, backed by nginx load balancing on one of the machines. I want to replace this node application with a Phoenix…
Willian Schneider
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Surprisingly slow insertion to mongodb capped collections

I'm using mongodb's capped collections + tailable cursors as a pubsub engine, using pymongo. (This approach is described here). My environment includes several topics, several publishers, and a few dozen subscribers. This works great, except that…
shx2
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Re-queue message on exception

I'm looking for a solid way of re-queuing messages that couldn't be handled properly - at this time. I've been looking at http://dotnetcodr.com/2014/06/16/rabbitmq-in-net-c-basic-error-handling-in-receiver/ and it seems that it's supported to…
Snæbjørn
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Mosquitto not publishing on SYS topics

I am using mosquitto server as mqtt broker. I testing mosquitto for performance and I need to subscribe to $SYS hierarchy for some data like number of currently connected from $SYS/broker/clients/active topic. I have following mosquitto config…
Vinod Kumar
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Meteor.publish is not a function

I have a publications.js file that ONLY includes Meteor.publish('org', function(_id){ return Organizations.findOne(_id); }); When things render I get this in the console: Uncaught TypeError: Meteor.publish is not a function What am I missing…
btbJosh
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ZMQ: No subscription message on XPUB socket for multiple subscribers (Last Value Caching pattern)

I implemented the Last Value Caching (LVC) example of ZMQ (http://zguide.zeromq.org/php:chapter5#Last-Value-Caching), but can't get a 2nd subscriber to register at the backend. The first time a subscriber comes on board, the event[0] == b'\x01'…
orange
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ZeroMQ PUB/XPUB/XSUB/SUB filtering

I am trying to determine the exact behaviour and potential limitations of the so-called 'Extended Pub-Sub architecture' from the ØMQ guide. XPUB and XSUB are described: We need XPUB and XSUB sockets because ZeroMQ does subscription forwarding from…
Drew Noakes
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Send real time data from java to android application

I need to send data from a java app to an android app in real time. The data is not large(integers within 0 and 9) but the number of transmissions is high, around 5 transmissions per second. I wish to have a publisher subscriber model. Java app is…
Soumya
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