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In my application architecture I am having two database servers primary db and secondary db server (Replica server).

In my java code I am making a connection with DB to fetch some data now what I want is I will give the IP addresses of both DB servers in my code and will check which DB server is reachable and will connect with that only. But I am not getting how to implement it, the one way is try to telnet but not a good option because I want to disable the telnet on application server for some reasons.

Is there any other and best way to do this?

Cœur
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pyus13
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2 Answers2

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Personally, I would just attempt the connection (using standard database classes) and handle the exceptions if the connection fails.

Even if you confirm connectivity initially, nothing prevents a network problem occurring between that test and your actual attempt to use the database.

Duncan Jones
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You can try pinging both hosts and use the one which responds. Here is a sample program. 

        InetAddress address = InetAddress.getByName("172.16.2.0");

        // Try to reach the specified address within the timeout
        // periode. If during this periode the address cannot be
        // reach then the method returns false.
        boolean reachable = address.isReachable(10000);

        System.out.println("Is host reachable? " + reachable);

For a more elaborate program, see this Ping program example in Java.

MoveFast
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  • i need for a particular port number because it may possible that the server is reachable but DB is not running on the specified port. – pyus13 Feb 17 '13 at 19:41
  • @pyus13 You cannot ping a specific port using `isReachable`. You need to test a connection to a socket in order to do that. Refer to [this answer](http://stackoverflow.com/a/14906123/1247781). – FThompson Feb 18 '13 at 00:11