I get a communication link failure while application tries to establish a connection with DB.
[#|2010-04-08T20:09:57.825+0300|SEVERE|glassfish3.0|javax.enterprise.system.std.com.sun.enterprise.v3.services.impl|_ThreadID=24;_ThreadName=Thread-1;|Cannot connect to database server = com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.|#]
Precisely at this string:
Statement s = conn.createStatement();
where conn is defined as follows:
private static java.sql.Connection conn;
For this app I have set a connection pool with default parameters and currently it (app) uses both JPA and direct JDBC queries. Recreation of connection pool gave nothing, connection pool ping gave next message:
Ping Connection Pool for pool is Failed. Ping failed Exce
ption - Connection could not be allocated because: Communications lin
k failure%%%EOL%%%%%%EOL%%%The last packet sent successfully to the s
erver was 0 milliseconds ago. The driver has not received any packets
from the server. Please check the server.log for more details.%%%EOL
%%%Ping failed Exception - Connection could not be allocated because:
Communications link failure
and flushing the connection pool gave:
com.sun.enterprise.admin.cli.CommandException: remote failure: Failed to flush connection pool ...
However I can connect to the database from a terminal. Besides I have the same app working on my local machine with identical connection pool settings.
Any one has an idea on whats going on or how to solve the trouble?
Such problem could be if you have mysql server & glassfish server on the same host, and in mysql configuration you have option bind to some public address (for example 192.168.0.1 of eth0 interface) that normally successfully working with simple jdbc/jpa using user#localhost, but they don`t in a case of glassfish JTA, instead to bind to some of local address you getting link failure. As rule you could not bind to any local (localhost/127.0.0.1) addresses of such mysql host if public address presented.
Example:
my.cnf
bind-address = 127.0.0.1
bind-address = 192.168.0.1
127.0.0.1 - assign to lo interface
192.168.0.1 - assign to eth0 interface
It is glassfish-mysql bug.
Currently in order to use JTA, you should not bind mysql to such address. (remove "bind-address=192.168.0.1" from my.cnf). Or use user#192.168.0.1 what is less secure.
Besides I have the same app working on my local machine with identical connection pool settings.
Are you connecting to the same database? If yes, maybe check that you're using the same JDBC driver.
In my case I set :
URL : jdbc:mysql://10.81.35.66:3306/testDB
and
url : jdbc:mysql://10.81.31.76:3306/vectordb
both When setting values while creating connection pool in additional property part
on glass fish admin console .
Related
I'm stucked in a problem during connection from my java project (play framework ) to a sql server database in Azure.
In local enviroment the connection works fine.
Below parameter in my application.conf :
db.default {
url="jdbc:sqlserver://server-name.database.windows.net:1433;database=database-name"
encrypt=true
trustServerCertificate=false
hostNameInCertificate="*.database.windows.net"
loginTimeout=30
driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
username="root"
password="RootPwd"
}
This is the error received:
ERROR o.h.e.jdbc.spi.SqlExceptionHelper HikariPool-1 - Connection is
not available, request timed out after 30006ms. ERROR
o.h.e.jdbc.spi.SqlExceptionHelper The TCP/IP connection to the host
par-sql-server.database.windows.net, port 1433 has failed. Error:
"par-sql-server.database.windows.net. Verify the connection
properties. Make sure that an instance of SQL Server is running on the
host and accepting TCP/IP connections at the port. Make sure that TCP
connections to the port are not blocked by a firewall.". ERROR
p.api.http.DefaultHttpErrorHandler
play.api.PlayException: Execution exception[[CompletionException:
org.hibernate.exception.JDBCConnectionException: Unable to acquire
JDBC Connection]]
at play.api.http.HttpErrorHandlerExceptions$.$anonfun$convertToPlayException$3(HttpErrorHandler.scala:388)
at scala.Option.getOrElse(Option.scala:201)
at play.api.http.HttpErrorHandlerExceptions$.convertToPlayException(HttpErrorHandler.scala:388)
at play.api.http.HttpErrorHandlerExceptions$.throwableToUsefulException(HttpErrorHandler.scala:373)
at play.api.http.DefaultHttpErrorHandler.onServerError(HttpErrorHandler.scala:264)
at play.core.server.AkkaHttp
I have already checked that tcp/ip port 1433 is correctly available for database, and my ip is correctly setted to avoid firewall.
Any suggestions?
thanks
Usually this error occurs when the database is not getting the connection within the default connectionTimeout property.
You can try to increase the value of connectionTimeout in Java config as below:
config.setConnectionTimeout(300000);
below is one of the sample config:
HikariConfig config = new HikariConfig();
config.setMaximumPoolSize(20);
config.setConnectionTimeout(300000);
config.setConnectionTimeout(120000);
config.setLeakDetectionThreshold(300000);
If possible let me know the steps to reproduce this issue so that I can fix it accordingly, also based on the information you've provided these blogs (Blog1, Blog2) will help you in establishing the connection
I had a problem here, is it possible that JDBC connecting to the amazon MySQL server remotely? I searching on the Internet for solution but ended up receiving the error
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
I am using jsch.jar to connect the remote server, then call up JDBC connector trying to connect MySQL DB, I had successfully connected to the remote server yet I cannot connect MySQL DB on amazon, here is my code
testPutty t = new testPutty();
t.connect("admin", "", "xx:xx:xx:xx", "openSSHPrivateKey", 22);
t.connect();
System.out.println("connected");
Class.forName("com.mysql.jdbc.Driver");
DriverManager.getConnection("jdbc:mysql://staging.ppyhcsxnlkji.ap-southwest-1.rds.amazonaws.com:3306/staging","superuser","password");
System.out.println("hello world");
t.close();
First set up the tunnel with SSH. You haven't shown what testPutty is so I'll assume it's a thin Java wrapper around a command line invocation of Putty. The command line option for setting up a tunnel is
-L[localport]:[host]:[remoteport]
For your example this would be
-L3306:staging.ppyhcsxnlkji.ap-southwest-1.rds.amazonaws.com:3306
This sets up a tunnel that forwards connections to local port 3306 to port 3306 on the given host (staging...amazonaws.com) on port 3306, routed through the host that is the target of the SSH command (in your sample xx:xx:xx:xx).
Then, your connection string needs to use localhost instead of the actual remote:
jdbc:mysql://localhost:3306/staging
If 3306 on your local host is not available because you are also running a local copy of MySQL, just choose a different unused port.
I'm trying to make a connection to an already existing database in SQL Server 2012n with Netbeans 8.
Using the connection wizard I select Sql Server 2012 and enter the credentials and fields.
However I get the message that a connection cannot be established.
You can see screenshots of the entered fields:
I also tried using "localhost" instead of "STIJN" this didn't work. I also tried with the default port "1433". Also didn't worked, however what port should this be? Where can I see what port I'm using? Maybe the error lies in the port, otherwise I wouldn't know where I made a mistake.
Go to your SQL Server configuration manager -> SQL server network configuration -> protocols for SQLEXPRESS -> TCP/IP (double click on it for properties).
On protocol page set enabled to Yes.
On IP Addresses page, scroll to bottom.
TCP Dynamic Ports: 54629
TCP Port: 1433
Apply and ok.
Make a connection with:
Host: localhost
Port: 1433
Your credentials
Instance field = blank.
This should work.
This question already has answers here:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
(51 answers)
Closed 6 years ago.
I Have developed an application to capture data, retrieve information,delete and also update info. The application is developed in java swing and hibernate and uses MySQL version 5.5 as a database. I tested it on my local server or local host and its working fine. So now i took it a step further trying to access the database on the remote server. Please note that also the MySQL version i use on my local server is the same as the MySQL in the remote server.
I get the following error:
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
Error Code: 0
The problem is that your MySqlConnector/Driver can't establish a Connection to the remote server.
Check your jdbc URL and also the check if the wrong ports are used.
Maybe the Mysql DB is not reachable from outside, than you can use a port forwarding with ssh, for example :
port forwarding:
ssh -L3306:127.0.0.1:3306 user#remoteServer
than change your jdbc url to:
jdbc:mysql://localhost:3306/database
Explanation:
-L port:host:hostport
Specifies that the given port on the local (client) host is to be
forwarded to the given host and port on the remote side.
...
Whenever a
connection is made to this port, the connection is forwarded over
the secure channel, and a connection is made to host port
hostport from the remote machine.
Source: http://www.openbsd.org/cgi-bin/man.cgi?query=ssh&sektion=1
That means you request with your MySQL JDBC Driver(jdbc url) on the local 3306 port
will be forwarded to the remote server on his local 3306 port,
where the Mysql Database is listing.
I used the same connection string for obtaining direct connection. But it is not getting connected when used from java code. What could be the problem?
jdbc:sqlserver://DEVSQL\mssql2008:1433
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection to the host DEVSQL, named instance \mssql2008 has failed.
There are two instances of SQL Server (2005 and 2008) running on the same port 1433. So what would be the connection string.
\mssql2008 is not an instance.
DEVSQL connects to the 2005 instance, while DEVSQL\mssql2008 connects to the 2008 instance
You have to escape the backslash
jdbc:sqlserver://DEVSQL\\mssql2008:1433
Based in the information provided in your example, I cannot differentiate:
Database server (maybe DEVSQL)
SQL Server instance name (maybe mssql2008)
Database name (for this, I'll just assume dbName)
With this info, you can construct your Connection String based in MSDN help
jdbc:sqlserver://DEVSQL:1433;databaseName=dbName;instance=mssql2008.
Also, check that your MSSQL server has the TCP/IP connection enabled. Check here for more info:
How to: Enable the TCP/IP Protocol for a Database Instance
Protocols for MSSQL 2008 (image)
You are missing part of the connection string (microsoft: before sqlserver:. This should work:
jdbc:microsoft:sqlserver://DEVSQL\\mssql2008:1433