publish-subscribe

问题 I understand that i need to set the clientId and subscription name when writing the jms topic subscriber for my durable topics. But Whats the purpose of setting the clientID when publishing the TOPIC ? I have seen people setting the client Id even for publisher / consumer, but no one explained that why it is required. ConnectionFactory conFactory = this.getConnectionFactory(); Connection connection = conFactory.createConnection(); connection.setClientID("WHATS_MY_PURPOSE"); // Why do we need

问题 Normally, a publish-subscribe pattern is about fetching content updates. But how do subscribers get initial content that was there before they subscribed for updates? I'm using publish-subscribe examples within autobahn framework for my application. The publisher backend publishes a position of the robotic joint when the joint moves. The client frontend subscribes to the topic sometimes later. Due to the nature of the data, the initial value of the "topic" on the client is just as important

问题 Normally, a publish-subscribe pattern is about fetching content updates. But how do subscribers get initial content that was there before they subscribed for updates? I'm using publish-subscribe examples within autobahn framework for my application. The publisher backend publishes a position of the robotic joint when the joint moves. The client frontend subscribes to the topic sometimes later. Due to the nature of the data, the initial value of the "topic" on the client is just as important

问题 I am following this tutorial and I already have my code publishing messages to /devices/sm1/events topic, in which sm1 is my device id. I would like to know how to subscribe to this topic since the tutorial says to use /devices/sm1/config but I am getting empty messages. I already tried use the same "path" used in publishing ( /devices/sm1/events ), but it also did not work. It is strange that the name I gave to the topic was sm1 and the topic associated to my device is on GoogleIoT console

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I've built this sample: Getting Started With RabbitMQ in .net, but made 2 programs: one-publisher one-subscriber I'm using

问题 I am trying to build a generic publish/subscribe server with nodejs and node_redis that receives requests from a browser with a channel name and responds with any data that has been published too that channel. To do this, I am using long polling requests from the browser and dealing with these requests by sending a response when a message is received on a channel. For each new request, an obect is created for subscribing to the channel (if and only if it does not already exist). clients = {};

问题 I'm new in MQTT there is a simple range of numbers which I want to print I have created 2 files in which the 1st file whose send data to the 2nd file and the script is like that: sender.py import paho.mqtt.client as mqtt client = mqtt.Client() client.connect("192.168.1.169", 1883, 60) for i in range(1,100): client.publish("TestTopic", i) print(i) client.disconnect() receiver.py: import paho.mqtt.client as mqtt def on_connect(client, userdata, flags, rc): print("Connected with result code "

问题 Looking at the Publish-Subscribe API and Configuration page, it would seem that the database schema used by NServiceBus to track subscriptions only tracks the Subscriber Endpoint and Message Type. I had hoped that maybe I could change the name of the table in order to use the same database for multiple publishers, but this thread seems to indicate that you can't. The point is - I fully understand and agree with the notion of having a single publisher endpoint per event type - but that

问题 Can I have pure multicasting in pub/sub protocol of the nanomsg. As there can be N subscribers interested in a particular data for a single publisher, the same subscribed data is flowing in N different streams.If my bandwidth for a single stream is 10MB then the total bandwidth required for N streams is 10*N,thus there is a increase in the bandwidth .Can we reduce this bandwidth as we do in the multicasting?? Can anyone help me regarding this issue?? 回答1: As far as I understand the PUB/SUB

问题 What are the pros and cons of each? Please advice when to use one and not the other. 回答1: Data storage Pub/Sub is a Publisher/Subscriber platform, it's not data storage. Published messages evaporate, regardless if there was any subscriber. In Redis Streams, stream is a data type, a data structure on its own right. Messages or entries are stored in memory and stay there until commanded to be deleted. Sync/Async communication Pub/Sub is synchronous communication. All parties need to be active