publish-subscribe

问题 I have a collection with documents like this: { _id: af3F3afafaa, firstName: "John", family: [{name: "David", relation: "brother", alive: true}, {name: "Susan", relation: "mother", alive: false}] } Is there a way to write a publication that hides a field in the family field array? So if I subscribed to the publication I would get: { _id: af3F3afafaa, firstName: "John", family: [{name: "David", alive: true}, {name: "Susan", alive: false"}] } 回答1: According to the Meteor docs, something like

问题 I have a database of users: profiles, products, configurations, and other things that a user could own. I'm trying to figure out a way to successfully chain my redis calls (a "getAll" function) so that I can return an object with all of these things, like: user = { profile: {}, products: {}, config: {}, ... } Here is how I'm accessing them/ what I'm trying to do: User.getAll = function(uid, next){ var user = {}; var multi = client.multi(); var key = 'user' + uid; client.hgetall(key, function

问题 I'm working on an exercise that uses the Turtlesim tool. I have to create a node vel_filter that subscribes to messages published by the pubvel node (from the book A Gentle Introduction to Ros by O'Kane) and immediately republish only those messages who have positive angular velocity. The pubvel code is given below: #include <ros/ros.h> #include <geometry_msgs/Twist.h> #include <stdlib.h> int main(int argc, char**argv){ ros::init(argc, argv, "publish_velocity"); ros::NodeHandle nh; ros:

问题 In my Sails project, I have a User model/controller and a Request model/controller, as well as a Dashboard controller. A user can make a request for data using RequestController.create , and an administrator can approve it using RequestController.grant . What I want to do is to notify a user whenever one of his/her requests is approved (updated). In RequestController.grant , I call Request.publishUpdate(...) , and in my DashboardController.display , I call Request.find(req.session.user.id,

问题 I have a rather complex and large database with about 3000+ objects (tables/triggers/sps combined). I inherited this DB and restructuring it is probably 3-4 years away. meanwhile, I need to implement a pub sub feature for any insert/update/delete on these tables. Given number of tables and existing queries probably query notification (and SQL Dependency) will not work. What I am looking for is a way to push the changes (what changed in table - like records PK and table name) on the service

问题 I want to implement a variety of of a publisher/subscriber pattern using Java and currently running out of ideas. There is 1 publisher and N subscribers, the publisher publish objects then each subscriber need to process the each of the objects once and only once in the correct order. The publisher and each subscriber run in their own thread. In my original implementation, each subscriber has its own blocking queue, and the publisher put objects into each of the subscriber's queue. This works

问题 I'm using Rebus and I want to introduce something like described in CQRS Journey at paragraph " Avoid processing events multiple times ", but I cannot figure it out. I configured Rebus to use SQL Server for Transport and MongoDB for Subscriptions and Sagas . The Routing is configured TypeBased and maps all the commands handlers' types to the queue configured in Transport . var bus = Configure.With(new SimpleInjectorContainerAdapter(container)) .Logging(l => l.Trace()) .Transport(t => { t

问题 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 Method:GET Status Code:101 Switching Protocols Response Headers Connection:Upgrade Sec-WebSocket-Accept:BHzI4XS3kPDZJhNt4BVAaGDvv8I= Sec-Websocket-Protocol:xmpp Upgrade:websocket Request Headers Accept-Encoding:gzip, deflate, sdch Accept-Language

问题 i just wanted to know if I want a collection node act as topic and this collection node has leaf nodes for different questions wouldn't it be highly inefficient to have a dedicated leaf nodes for each question (collection node-leaf1, leaf2, ..., leafN)? This will end up with thousands of different leaf nodes in the database for different questions and not just items (for questions and answers) in one leaf node per topic (collection node)... (collection node-leaf node (where Q&A with big chunk

问题 I'm following this post: http://www.knockmeout.net/2012/05/using-ko-native-pubsub.html to allow one of my vms to communicate with the other. One of my viewModels has an array that I need to expose to another viewModel. If this array is not an observable, the method from the above post works just fine. If the array is an observable array, publishedSelectedFolders is never populated. I'm trying to figure out why; hopefully it's something silly I'm doing. Here's my jsFiddle: http://jsfiddle.net