Develop Reference

Unable to connect to the database using Hikari connection pool

I wish to use Hikari Connection Pool in my Spring application to connect to the Oracle Database
Below is the connection string
JDBC URL:
jdbc:oracle:thin:#ldaps://abc-def-dmz.demo.com:876/SOM_APP,cn=oraclecontext,dc=demo,dc=com
Getting the following error
Error Message: Failed to initialize pool: IO Error: JNDI Package
failure javax.naming.CommunicationException: localhost:876[Root
exception is java.net.ConnectException: Connection refused: connect]
How do I fix this?

java.net.ConnectException: Connection refused: connect
The error implies that your connection is being blocked, most likely by a firewall. Check with your DBA and system or network administrators to make sure the network path to the server is open, and that you are using the right port numbers.

Azure notification hub java.net.ConnectException: Connection timed out: no further information [duplicate]

This question already has an answer here:
Connection timed out. Why? [duplicate]
(1 answer)
Closed 5 years ago.
am trying to use Azure notification hub, via Java. When trying to do create registration, I get a java.net.ConnectException: Connection timed out: no further information. Can someone help me understand why this issue may come? Pls let me know if you need more information. Thanks.
Am using the code found from https://github.com/Azure/azure-notificationhubs-java-backend/blob/master/NotificationHubs.
Jar file versions are as below:
httpclient - 4.3.1
httpcore - 4.3.1
httpcore-nio - 4.3.1
Error happens in SyncCallback class, method - "failed". Exception trace is as below.
java.lang.RuntimeException: java.net.ConnectException: Connection timed out: no further information
at com.org.utils.notifications.SyncCallback.failed(SyncCallback.java:41)
at org.apache.http.concurrent.BasicFuture.failed(BasicFuture.java:130)
at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.connectionRequestFailed(DefaultClientExchangeHandlerImpl.java:318)
at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.access$100(DefaultClientExchangeHandlerImpl.java:63)
at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl$1.failed(DefaultClientExchangeHandlerImpl.java:364)
at org.apache.http.concurrent.BasicFuture.failed(BasicFuture.java:130)
at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager$InternalPoolEntryCallback.failed(PoolingNHttpClientConnectionManager.java:474)
at org.apache.http.concurrent.BasicFuture.failed(BasicFuture.java:130)
at org.apache.http.nio.pool.RouteSpecificPool.failed(RouteSpecificPool.java:165)
at org.apache.http.nio.pool.AbstractNIOConnPool.requestFailed(AbstractNIOConnPool.java:530)
at org.apache.http.nio.pool.AbstractNIOConnPool$InternalSessionRequestCallback.failed(AbstractNIOConnPool.java:778)
at org.apache.http.impl.nio.reactor.SessionRequestImpl.failed(SessionRequestImpl.java:154)
at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvent(DefaultConnectingIOReactor.java:175)
at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvents(DefaultConnectingIOReactor.java:147)
at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:349)
at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.execute(PoolingNHttpClientConnectionManager.java:189)
at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase.doExecute(CloseableHttpAsyncClientBase.java:67)
at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase.access$000(CloseableHttpAsyncClientBase.java:38)
at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClientBase.java:57)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.ConnectException: Connection timed out: no further information
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(Unknown Source)
at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvent(DefaultConnectingIOReactor.java:173)
... 7 more

you can find the some resone of this java.net.ConnectException: Connection timed out Exception.
firewall of your system port rang which you are using into your project.
check your filewale setting and unblock the port.
IP/domain or port is incorrect.
try to ping or telnet command to check connectivity.
may be due to slow internet or havy process server are not processes the request in time period, or may b connection issue.

nested exception is javax.naming.CommunicationException: abc.com:389 [Root exception is java.net.ConnectException: Connection timed out]

I am looking to authenticate google using CAS. And I am getting error as
org.springframework.ldap.CommunicationException: xyz.com:389; nested exception is javax.naming.CommunicationException: abc.com:389 [Root exception is java.net.ConnectException: Connection timed out]
My LDAP credentials are correct. When I use AD LDAP, I can login successful but if I use Luminis LDAP credentials, we are getting error.
Maven version: Apache Maven 3.3.9
CAS version: 3.5.2
Tomcat version: 7.0.70
Java version: 1.7.0_79, vendor: Oracle Corporation
Any suggestions?
Thank you in Advance.
Bob.

Finally I got the solution:
The cas server does not have access to LDAP server. so I had to add cas server's ip to firewall of LDAP server on port 389.
And it works just fine.

RMI Server on Unix machine

I have an RMI server and RMI client programs, when I execute RMI server on unix machine, and RMI client on Windows machine, I am getting
java.rmi.ConnectException: Connection
refused to host: ; nested exception is: java.net.ConnectException:
Connection refused: connect at
sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619) at
sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216)
at the client side. I am able to execute on server and client on windows system but the server on linux is not working.
I searched using google, but I am unable to find the reason and fix.
I would appreciate your help.
Thank you in advance!

Referring the url
java.rmi.ConnectException: Connection refused to host: 127.0.1.1;
I added a line to /etc/hosts file and it works, but I am accessing the host using the IP address in my client program.
I did not understand why do we need to add a line to the /etc/hosts file.
Any comments. Thank You!.

Can't connect to cassandra : NodeContext killing all pooled connections for session

When I try to connect to cassandra within my java application I receive the exception at the end of this message. I am using pelops library to access database. Database is working on linux and my development environment is on windos 7. Intresting line is
WARNING: 10.0.0.7 NodeContext killing all pooled connections for session 44
10.0.0.7 is the IP of the cassandra node. And I can connect this node with cassandra-cli. After a few hours of googling I decided to ask, what i am doing wrong?
Complete stack trace is below.
SEVERE: org.apache.thrift.transport.TTransportException: java.net.ConnectException: Connection refused: connect
at org.apache.thrift.transport.TSocket.open(TSocket.java:185)
at org.wyki.cassandra.pelops.ThriftPool$Connection.open(ThriftPool.java:329)
at org.wyki.cassandra.pelops.ThriftPool$NodeContext.createConnection(ThriftPool.java:438)
at org.wyki.cassandra.pelops.ThriftPool$NodeContext.access$5(ThriftPool.java:429)
at org.wyki.cassandra.pelops.ThriftPool$NodeContext$1.run(ThriftPool.java:494)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at org.apache.thrift.transport.TSocket.open(TSocket.java:180)
... 7 more
WARNING: 10.0.0.7 NodeContext killing all pooled connections for session 44

"Connection refused" means that Cassandra isn't listening on the interface you're connecting to. By default Cassandra listens on port 9160 on localhost. You will need to change that if you want to connect externally; read the comments for ThriftAddress in the configuration file.

Pelops isn't doing anything remotely tricky when it comes to making connections to Cassandra so it seems very unlikely it's Pelops specific.
I've just had a quick look at the Hector connection code and it looks pretty much the same:
https://github.com/rantav/hector/blob/master/core/src/main/java/me/prettyprint/cassandra/connection/HThriftClient.java
The cassandra-cli code looks pretty much the same as well:
https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/cli/CliMain.java#L57
p.s. Cassandra should not be configured to listen on 0.0.0.0. See the "Why can't I make Cassandra listen on 0.0.0.0 (all my addresses)?" on the Cassandra FAQ.

It seems that this is a problem with pelops, which is a library on top of cassandra's thrift client. It has some problems for connection to Cassandra working on linux and client on a windows machine.

I've got the same exception connecting with "any" client to cassandra remotely:
ConnectException: Connection refused
Looking through SO I couldn't find a quick solution for that, just reading carefully through cassandra docs and comments within cassandra.yaml - they are very handy!
So for me worked following:
change rpc_address value to the hostname or ipaddress you are using to connect to the cassandra instance with the client