mongo driver have something like middleware to resolve switch hosts ip

[赵玄]

Hi Christaian

     mongo driver have something like middleware to resolve switch hosts ip?

     i have a question about mongo driver, when i use domain name connect mongo server, i switch hosts file,  find my logic server work well, i am not understand, because i use connect pool in my logic server, i think driver use TCP connect mongo server, why my logic server have nothing affect?  unless , driver use RPC server between mongo server and logic server. but i am not found in mogodb package.

Please guide me on this issue.

[Christian Kvalheim]

I'm not sure what you are asking about, can you outline what you are doing in steps ?

[赵玄]

i am sorry for my poor english,

step1: in hosts

test.mongo     10.21.3.44

step2: chang hosts

test.mongo      10.21.3.45

step3: stop 3.44 mongo server

db.test.insert({name:44})

my logic server:

var MongoClient = require('mongodb').MongoClient;
var url = 'mongodb://test.mongo:27017/larvel';

MongoClient.connect(url, function (err, db) {
    var collection = db.collection('test');

    setInterval(function () {
        collection.findOne({}, function (err, res) {
            console.log('res is ', res.name);
        })
    }, 1000)
})

result :

res is 44.

res is 44.

res is 44.

res is 44.

res is 45.
res is 45.

res is 45.

res is 45.

i want to know ,the driver how deal with it. why my logic server have not affect.

在 2016年1月21日星期四 UTC+8下午4:51:54，Christian Kvalheim写道：

[Christian Kvalheim]

The answer unfortunately it no, you have to restart the node application for it to pick up the new DNS resolution. I'm not aware of any way around this.

[赵玄]

thanks a lot for your explain.  

but i found two way to pick up the new DNS, 

1. as you say ,restart my node application;

2. stop first DNS ip 

i find when i change to second DNS, the result is not change , but when i stop first mongo server, the result return one or two null,and continue return the second mongo server result. i want to know how the driver work, is there have some RPC between mongo server and my node application, why my node application not crash for mongo server confused . 

在 2016年1月21日星期四 UTC+8下午5:57:56，Christian Kvalheim写道：

[Christian Kvalheim]

Stopping and restart the mongod processes would work as you discovered as they force the driver to reconnect.

You can find more information about how our drivers work here

https://github.com/mongodb/specifications/tree/master/source

[赵玄]

thank you very much :) , i will back after read doc done.

在 2016年1月22日星期五 UTC+8下午4:56:44，Christian Kvalheim写道：

[赵玄]

i found the answer.

the driver hold the socket err,  and resending the query. so this not affect my application. that is so comfortable. i will watching the driver and star. 

thank you again.

在 2016年1月25日星期一 UTC+8上午10:16:28，赵玄写道：