publish-subscribe

问题 I've made 3 clients connected to a subscription, and one publisher. In the image 2 of the subscriptions are on the terminal, and one subscription is not seen as it is hosted on a DigitalOcean Droplet. It seems every 5 messages, it switches which subscriber actually receives the message, which should not happen. I've also varied the speed and it's always about 5 messages. Here is the code used on all clients for subscriptions: sub.on("message", (msg) => { console.log(`Message:1 ${msg.data

问题 I've made 3 clients connected to a subscription, and one publisher. In the image 2 of the subscriptions are on the terminal, and one subscription is not seen as it is hosted on a DigitalOcean Droplet. It seems every 5 messages, it switches which subscriber actually receives the message, which should not happen. I've also varied the speed and it's always about 5 messages. Here is the code used on all clients for subscriptions: sub.on("message", (msg) => { console.log(`Message:1 ${msg.data

问题 Given something like: class MyClass def subscribe $redis.subscribe('channel') do |on| on.message do |channel, msg| Something.create(msg) end end end end How can I test that when MyClass executes subscribe , it will run Something.create for each message it receives on the channel? 回答1: This code you have, it's not very testable. First of all, absolutely get rid of this global $redis variable. Instead, accept an instance of redis in the constructor. class MyClass attr_reader :redis def

问题 I have a model named Groupfeed which looks like this module.exports = { schema:true, attributes: { groupid: { model:'groups', required:true }, postid: { model:'post', required:true }, objectid: { model:'objects', required:true }, } }; On the client side I can subscribe to the Groupfeed model using io.socket.get('/groupfeed') which is done automatically by the blueprint api and then io.socket.on('groupfeed',function(obj){console.log(obj)}) would give me updates on the model changes when I

问题 Based on this answer about how to scale Orion Context Broker with load balancing https://stackoverflow.com/a/33068119/3706998 what should be the behavior of subscriptions and also notifications? Witch server should it come from? What is the workflow? Could it cause some disturbe or cloned subscriptions ? 回答1: Let's consider different cases, depending on subscription cache usage. Let's consider two Orion nodes (A and B) without loss of generality, both sharing the same MongoDB instance. Using

问题 I am building a distributed system that consists of potentially millions of clients which all need to keep an open (preferrably HTTP) connection to wait for a command from the server (which is running somewhere else). The load of messages / commmands will not be very high, maybe one message / sec / 1000 clients which means it would be 1000 msg/sec @ 1 million clients. => it's basically about the concurrent connections. The requirements are simple too. One way messaging (server->client), only

问题 This a new version of my old question: So thanks to Tom Coleman's help I finally figured out on how to properly check if a subscription is ready() or not. My current code structure looks like this: /client/app.js: eventsHandle = null; groupsHandle = null; // ... // First Deps.autorun(): // Does not depend on any Session var, should just run every time Deps.autorun(function() { eventsHandle = Meteor.subscribe("events", function() { console.log('Deps.autorun(): Events loaded'); }); }); //

问题 I am currently interested in seeing what channels are subscribed to in a Redis pub/sub application I have. When a client connects to our server, we register them to a channel that looks like: user:user_id The reason for this is I want to be able to see who's "online". I currently blindly fire off messages to a channel without knowing if a client is online since it's not critical that they receive these types of messages. In an effort to make my application smarter, I'd like to be able to

问题 I am currently interested in seeing what channels are subscribed to in a Redis pub/sub application I have. When a client connects to our server, we register them to a channel that looks like: user:user_id The reason for this is I want to be able to see who's "online". I currently blindly fire off messages to a channel without knowing if a client is online since it's not critical that they receive these types of messages. In an effort to make my application smarter, I'd like to be able to

问题 I'm a bit rusty on nuances of the HTTP protocol and I'm wondering if it can support publish/subscribe directly? HTTP is a request reponse protocol. So client sends a request and the server sends back a response. In HTTP 1.0 a new connection was made for each request. Now HTTP 1.1 improved on HTTP 1.0 by allowing the client to keep the connection open and make multiple requests. I realise you can upgrade an HTTP connection to a websocket for fast 2 way communications. What I'm curious about is