How to show documents from multiple remote publication in the template? - meteor

Question

I wish to use Meteor to subscribe a few remote publication via DDP. Then show the documents in one template. Here is what I did:
Posts = {};
var lists = [
{server: "localhost:4000"},
{server: "localhost:5000"}
];
var startup = function () {
_.each(lists, function (list) {
var connection = DDP.connect(`http://${list.server}`);
Posts[`${list.server}`] = new Mongo.Collection('posts', {connection: connection});
connection.subscribe("allPosts");
});
}
startup();
This file is at client folder. Every startup, in this example, at browser I have two client collections Posts["localhost:4000"] and Posts["localhost:5000"], both are same schema. I know this format (Collection[server]) is ugly, please tell me if there is a better way.
Is there a way to show these client collections in the same template with reactive. Like this:
Template.registerHelper("posts", function () {
return Posts.find({}, {sort: {createdAt: -1}});
});
I think Connected Client is a big part of the Meteor. There should be a best practice to solve this problem, right?

Answer 1

Solved.
Connect to multiple servers via DDP, then observe their collections reactive via cursor.observeChanges.
Posts = {};
PostsHandle = {};
// LocalPosts is a local collection lived at browser.
LocalPosts = new Mongo.Collection(null); // null means local
// userId is generated by another Meteor app.
var lists = [
{server: "localhost:4000", userId: [
"hocm8Cd3SjztwtiBr",
"492WZqeqCxrDqfG5u"
]},
{server: "localhost:5000", userId: [
"X3oicwXho45xzmyc6",
"iZY4CdELFN9eQv5sa"
]}
];
var connect = function () {
_.each(lists, function (list) {
console.log("connect:", list.server, list.userId);
var connection = DDP.connect(`http://${list.server}`);
Posts[`${list.server}`] = new Mongo.Collection('posts', {connection: connection}); // 'posts' should be same with remote collection name.
PostsHandle[`${list.server}`] = connection.subscribe("posts", list.userId);
});
};
var observe = function () {
_.each(PostsHandle, function (handle, server) {
Tracker.autorun(function () {
if (handle.ready()) {
console.log(server, handle.ready());
// learn from http://docs.meteor.com/#/full/observe_changes
// thank you cursor.observeChanges
var cursor = Posts[server].find();
var cursorHandle = cursor.observeChanges({
added: function (id, post) {
console.log("added:", id, post);
piece._id = id; // sync post's _id
LocalPosts.insert(post);
},
removed: function (id) {
console.log("removed:", id);
LocalPosts.remove(id);
}
});
}
})
});
}
Template.posts.onCreated(function () {
connect(); // template level subscriptions
});
Template.posts.helpers({
posts: function () {
observe();
return LocalPosts.find({}, {sort: {createdAt: -1}}); // sort reactive
}
});