CODEWITHSUNDEEP
node.jsredis
chacha_nehru
chacha_nehru

Reputation: 43

Storing and retrieving Sockets in Redis

I am new to Node and Redis, so forgive me if I'm missing something crucial here. I am trying to store a Node.js net.Socket object in Redis, using the node_redis client, so I could reuse a connection made previously on this Socket. I am storing the socket as a Value as a part of a "users" set:

client.sadd("users", username); //username is a string
client.hmset(username, "ip", socket.remoteAddress, "connection", net.Socket(socket));

At a different point, I am retrieving this socket as:

    client.smembers("users", function(err, replies) {

            replies.forEach(function(reply,i){
            if(recipient == reply) {       //recipient is the username i've got

                    client.hget(reply, "connection", function(err, obj) {
                    console.log("socket's remoteaddress = " +  net.Socket(obj).remoteAddress);
        net.Socket(obj).write("asdasdasd");
            });

            }
    });
    });

But, the: net.Socket(obj).remoteAddress); is logged as 'undefined'. Also, net.Socket(obj).write("asdasdasd"); gives me and error saying:

Error: This socket is closed.

So I guess my question is - can you store Sockets this way in Redis and expect them to work upon retrieval? Is there a correct / better way to do this?

P.S. I tried retrieving the Socket without the cast to net.Socket and it still didn't do any good.

Upvotes: 4

Views: 5464

Answers (3)

Parth
Parth

Reputation: 215

as @maerics said , redis store only string. so your socket data will be destroyed and will give undefined as answer.

you can store your socket like this.

var OBJECT = Object.prototype;
OBJECT.rhash = {};
OBJECT.rset = function(id, object) {
  OBJECT.rhash[id] = object;
  return id;
};
OBJECT.rget = function(id) {
  return OBJECT.rhash[id];
};

this will store reference to that object and reuse it again.. 

var id = OBJECT.rset("a123",socket);
var ref = OBJECT.rget("a123");
console.log(ref.remoteAddress);

Upvotes: 3

Niloct
Niloct

Reputation: 10015

Regarding the IP address, it's on a different hash key (not connection, but ip). So to get the value you just read from that key: 

client.hget(reply, "ip", function(err, obj) {
   console.log("socket's remoteaddress = " +  obj);
});

Upvotes: 0

maerics
maerics

Reputation: 156662

Sockets and socket APIs (such as Berkeley Sockets) intrinsically handle special system-specific resources for which it just wouldn't make any sense to store or reference on a remote system, or even serialize for that matter.

Although, in reality, sockets are often uniquely identified by file descriptors so you could easily store that small, unique integer in a database for later access; however, that integer would only be meaningful during the active lifetime of that socket within that process instance. A strategy such as this one will be fraught with challenges, mainly having to do with the transient nature of the socket file descriptor number.

Upvotes: 3

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