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How to connect to a running bigtable emulator from java

I am trying to use the bigtable emulator from gcloud beta emulators.
I launch the emulator, grab the hostname (localhost) and port (in this instance 8885)
gcloud beta emulators bigtable start
Executing: /usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/platform/bigtable-emulator/cbtemulator --host=localhost --port=8885
I am trying to connect to the emulator from a java test client,
here is what I provide:
Configuration conf = BigtableConfiguration.configure(projectId, instanceId);
if(!Strings.isNullOrEmpty(host)){
conf.set(BigtableOptionsFactory.BIGTABLE_HOST_KEY, host);
conf.set(BigtableOptionsFactory.BIGTABLE_PORT_KEY, Integer.toString(port));
}
connection = BigtableConfiguration.connect(configuration);
try (Table table = connection.getTable("tName")){
table.put(<Put instance>);
}
When I execute the test code I get:
16:36:37.369 [bigtable-batch-pool-1] INFO com.google.cloud.bigtable.grpc.async.AbstractRetryingRpcListener - Retrying failed call. Failure #1, got: Status{code=UNAVAILABLE, description=null, cause=java.net.ConnectException: Connection refused: localhost/0:0:0:0:0:0:0:1:8885}
java.net.ConnectException: Connection refused: localhost/0:0:0:0:0:0:0:1:8885
I am using the library: com.google.cloud.bigtable:bigtable-hbase-1.2:0.9.1
Any idea of what I am doing wrong ?
Thanks !

You need one additional config property to be set:
conf.set(BigtableOptionsFactory.BIGTABLE_USE_PLAINTEXT_NEGOTIATION, true);
Also, from the log message it looks like it's trying to connect to an IPv6 address, which I don't think will work. Double-check that host is a valid IPv4 address.
The java client will make this easier to do in the near future.

Now you can set
configuration.set(BigtableOptionsFactory.BIGTABLE_EMULATOR_HOST_KEY,<HOST:PORT>); to connect to an emulator.
Also "https://github.com/googleapis/java-bigtable/tree/master/google-cloud-bigtable-emulator" can be used to start emulators programmatically for tests etc.

Error connecting to Oracle database using JDBC [duplicate]

I am new to Oracle, and am trying to run a simple example code with Java, but am getting this error when executing the code.. I am able to start up the listener via CMD and am also able to run SQL Plus. Can anyone give me a hand and tell me what I might be doing wrong?
Update:
I am using JDBC.
Database is local, and I actually had it working but it stopped working just today. I'm not really sure why though. Would you mind giving me some procedures to follow by since I don't know much.

Either:
The database isn't running
You got the URL wrong
There is a firewall in the way.
(This strange error message is produced by Oracle's JDBC driver when it can't connect to the database server. 'Network adapter' appears to refer to some component of their code, which isn't very useful. Real network adapters (NICs) don't establish connections at all: TCP protocol stacks do that. It would have been a lot more useful if they had just let the original ConnectException be thrown, or at least used its error message and let it appear in the stack trace.)

I had the same problem, and this is how I fixed it.
I was using the wrong port for my connection.
private final String DB_URL = "jdbc:oracle:thin:#localhost:1521:orcll"; // 1521 my wrong port
go to your localhost
(my localhost address) : https://localhost:1158/em
login
user name
password
connect as --> normal
Below 'General' click on LISTENER_localhost
look at you port number
Net Address (ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1522))
Connect to port 1522
Edit you connection
change port 1521 to 1522.
done

Another thing you might want to check that the listener.ora file matches the way you are trying to connect to the DB. If you were connecting via a localhost reference and your listener.ora file got changed from:
HOST = localhost
to
HOST = 192.168.XX.XX
then this can cause the error that you had unless you update your hosts file to accommodate for this. Someone might have made this change to allow for remote connections to the DB from other machines.

I figured out that in my case, my database was in different subnet than the subnet from where i was trying to access the db.

I had this error when i renamed the pc in the windows-properties. The pc-name must be updated in the listener.ora-file

Most probably you have listener configured wrongly, the hostname you specify in connection string must be the same as in the listener.
First check the Firewall and network related issues.
Check if Oracle Listener service is available and running. If not you may use Oracle Net Configuration Assistant tool to add and register new listener.
If the above steps are ok then you need to configure Oracle Listener appropriately. You may use Oracle Net Manager tool or edit “%ORACLE_HOME%\network\admin\listener.ora” file manually.
There are 2 options that need to be considered carefully:
Listening Locations associated with the Listener – Hostname(IP) and Port in Listening Location must exactly match the ones used in the connection string.
For example, if you use 192.168.74.139 as target hostname, then there must be Listening Location registered with the same IP address.
Also make sure the you use the same SID as indicated in Database Service associated with the Listener.
https://adhoctuts.com/fix-oracle-io-error-the-network-adapter-could-not-establish-the-connection-error/

IO Error: The Network Adapter could not establish the connection (CONNECTION_ID=iKQM6lBbSLiArrYuDqud8A==)
if you are facing this issue
1- make sure you have downloaded oracle databases like oracle 11g,19c, 21c, or any latest databases.
2- search for services in your computer or type win+r then services.mis then search for oracleservice you will find orcl or xe or any other sid like oracleserviceorcl;
after that you can test your connection using sql developer, sql plus or cmd

To resolve the Network Adapter Error I had to remove the - in the name of the computer name.

In my case, I needed to specify a viahost and viauser. Worth trying if you're in a complex system. :)

For me the basic oracle only was not installed. Please ensure you have oracle installed and then try checking host and port.

I was having issues with this as well. I was using the jdbc connection string to connect to the database. The hostname was incorrectly configured in the string. I am using Mac, and the same string was being used on Windows machines without an issue. On my connection string, I had to make sure that I had the full url with the appending "organizationname.com" to the end of the hostname.
Hope this helps.

Just try to re-create connection. In my situation one of jdbc connection stopped working for no reason. From console sqlplus was working ok.
It took me 2 hours to realize that If i create the same connection - it works.

Connecting to derby via I.P. Address fails

When I print the I.P. address of the system using InetAddress.getLocalHost(), I get user-VAIO/192.168.1.3 . Now, when I connect to derby using jdbc:derby://localhost:1527/mydatabase;create=true, it connects without any errors but when I connect the same using jdbc:derby://192.168.1.3:1527/mydatabase;create=true, it fails giving me the following exception:-
java.net.ConnectException : Error connecting to server 192.168.1.3 on port 1527 with message Connection refused: connect.
Any help will be appreciated.

When you start your Derby Network Server, you provide a value for the '-h' argument. You might not realize you are doing this, if you are using the packaged StartNetworkServer.bat file, but look inside the batch file, and you will see the -h argument there.
The batch file comes provided with the syntax '-h default' when you download Derby from the Apache website.
But you can change that, to say, for example, '-h 192.168.1.3', and then your Derby Network Server will accept connections that specify 'jdbc:derby://192.168.1.3/my/database'.
Note that if you want to accept such connections from other computers on the network, you will also have to adjust your Windows Firewall rules, as by default it will prevent such connections.

SQLException: Communications link failure (Java/mysql)

Can someone explain to me why this line works:
conn = DriverManager.getConnection("jdbc:mysql://myWebsite.com:3306/schemaName?user=userX&password=passwordX");
But this line does not:
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/schemaName?user=userX&password=passwordX");
I get a Communications Link Failure when attempting to access through the localhost (or 127.0.0.1). However, I'm able to access the database via localhost through PHP and the MySQLQuery Browser and MySQL Aministrator.
If needed here's the entire method I'm using:
public Database() throws Exception {
Class.forName("com.mysql.jdbc.Driver").newInstance();
try {
conn = DriverManager.getConnection("jdbc:mysql://myWebsite.com:3306/schemaName?user=userX&password=passwordX");
// Next line does not work.
// conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/schemaName?user=userX&password=passwordX");
} catch (SQLException ex) {
displaySQLException(ex); // Seperate routine to display errors.
}
}
Thanks for any help,
Richard

It's possible your mysqld is binding specifically to the ethernet interface instead of all interfaces (0.0.0.0) or the localhost interface (127.0.0.1).
On a *nix platform you can check which interface the daemon is listening on with the following command:
$ netstat -ln|grep 3306
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN

In second code:
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/schemaName?
user=userX&password=passwordX");
It will try to connect to mysql on machine on localhost (on which the code is running). In your case it might be possible that mysql on your machine or from where you are running the code is not available or stopped or usename/password you are passing are not valid or schemaname does not exist. But on myWebsite.com it is up.
There is nothing wrong in your code. Make sure mySql is installed and running and username/password are valid, a schema with provided schemaname exists on machine on which you run this code with localhost.

This might happen for many reasons, like
MySQL server might be stopped on the target machine
MySQL might be configured not to accept remote connections
The firewall might be blocking remote connections on port 3306

In my case, I faced this error when trying to connect to mysql-server running inside a container on a Ubuntu host VM from the same host.
Example:
If my VM name is abc.company.com, the following jdbc URL would not work:
jdbc:mysql://abc.company.com:3306/dbname
Above jdbc url would work fine from other machines like xyz.company.com but just not abc.company.com.
where as the following jdbc URL would work just fine on abc.company.com machine:
jdbc:mysql://localhost:3306/dbname
which led me to check the /etc/hosts file.
Adding the following line to /etc/hosts fixed this issue:
127.0.1.1 abc.company.com abc
This seems to be an OS bug that requires us to add these on some Ubuntu versions.
Reference: https://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_the_hostname_resolution
Before trying this, I had tried all other solutions like GRANT ALL.., changing the bind-address line in mysql.cnf.. None of them helped me in this case.

Hbase client can't connect to remote Hbase server

i have written a following hbase client class for remote server:
System.out.println("Hbase Demo Application ");
// CONFIGURATION
// ENSURE RUNNING
try {
HBaseConfiguration config = new HBaseConfiguration();
config.clear();
config.set("hbase.zookeeper.quorum", "192.168.15.20");
config.set("hbase.zookeeper.property.clientPort","2181");
config.set("hbase.master", "192.168.15.20:60000");
//HBaseConfiguration config = HBaseConfiguration.create();
//config.set("hbase.zookeeper.quorum", "localhost"); // Here we are running zookeeper locally
HBaseAdmin.checkHBaseAvailable(config);
System.out.println("HBase is running!");
// createTable(config);
//creating a new table
HTable table = new HTable(config, "mytable");
System.out.println("Table mytable obtained ");
addData(table);
} catch (MasterNotRunningException e) {
System.out.println("HBase is not running!");
System.exit(1);
}catch (Exception ce){ ce.printStackTrace();
it is throwing some exception:
Oct 17, 2011 1:43:54 PM org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation getMaster
INFO: getMaster attempt 0 of 1 failed; no more retrying.
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:567)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:404)
at org.apache.hadoop.hbase.ipc.HBaseClient$Connection.setupIOstreams(HBaseClient.java:328)
at org.apache.hadoop.hbase.ipc.HBaseClient.getConnection(HBaseClient.java:883)
at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:750)
at org.apache.hadoop.hbase.ipc.HBaseRPC$Invoker.invoke(HBaseRPC.java:257)
at $Proxy4.getProtocolVersion(Unknown Source)
at org.apache.hadoop.hbase.ipc.HBaseRPC.getProxy(HBaseRPC.java:419)
at org.apache.hadoop.hbase.ipc.HBaseRPC.getProxy(HBaseRPC.java:393)
at org.apache.hadoop.hbase.ipc.HBaseRPC.getProxy(HBaseRPC.java:444)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getMaster(HConnectionManager.java:359)
at org.apache.hadoop.hbase.client.HBaseAdmin.<init>(HBaseAdmin.java:89)
at org.apache.hadoop.hbase.client.HBaseAdmin.checkHBaseAvailable(HBaseAdmin.java:1215)
at com.ifkaar.hbase.HBaseDemo.main(HBaseDemo.java:31)
HBase is not running!
can you tell me why is it throwing an exception, what is wrong with code and how to solve it.

This problem is occuring due to your HBase server's hosts file.
You just need to edit you HBase server's /etc/hosts file.
Remove the localhost entry from that file and put the localhost entry in front of HBase server IP.
For example, your HBase server's /etc/hosts files seems like this:
127.0.0.1 localhost
192.166.66.66 xyz.hbase.com hbase
You have to change it like this by removing localhost:
# 127.0.0.1 localhost # line commented out
192.166.66.66 xyz.hbase.com hbase localhost # note: localhost added here
This is because when remote machine asks hbase server machine where HMaster is running, it tells that it is running on localhost.
So if the entry is 127.0.0.1 then HBase server returns this address and remote machine start to find HMaster on its own machine (locally).
When we change that with the HBase Server IP then everything works fine :)

I agree.. The HBase is very sensitive to /etc/hosts configurations.. I had to set the zeekeeper bindings property in the hbase-site.xml correctly in order for the above mentioned Java code to work...For example: I had to set it as follows:
{property}
{name}hbase.zookeeper.quorum{/name}
{value}www.remoterg12.net{/value} {!-- this is the externally accessible domain --}
{/property}
{property}
{name}hbase.zookeeper.property.clientPort{/name}
{value}2181{/value} {!-- everything needs to be externally accessible --}
{/property}
{property}
{name}hbase.master.info.port{/name} {!-- http://www.remoterg12.net:60010/ --}
{value}60010{/value}
{/property}
{property}
{name}hbase.master.info.bindAddress{/name}
{value}www.remoterg12.net{/value} {!-- Use this to access the GUI console, --}
{/property}
The Remote GUI will give you a clear picture of the Binding Domains.. For example, the [HBase Master] property in the "GUI Web console" should be something like this: www.remoterg12.net:60010 (It should NOT be localhost:60010 )... AND YES!!, I did have to play around with the /etc/hosts just right as I didn't want to mess up the existing Apache configs :-)

The same problem can be solve by editing the conf/regionservers file in hbase directory to add the Hbase server (Remote) in it . Then no need to change the etc/hosts file
After editing conf/regionservers will look like:
localhost
ip address of the remote hbase server
eg
localhost
10.132.258.366

Exact same problem here with HBase 1.1.3.
2 virtuals machines (Ubuntu) on the same network. The logs show that the client can reach Zookeeper but not the HBase server.
TL;DR: remove the following line in /etc/hosts on the server (server_hostame):
127.0.1.1 server_hostname server_hostname
And add this one with 127.x.y.z the ip of your server on the (local) network:
192.x.y.z server_hostname
I tried a lot of combinations on the client and server sides. In standalone mode I don't think there is a better approach.
Not really proud of that. It is a shame to have to mess with the network configuration and to not even provide a HBase shell client able to connect remotely to a server (welcome to the Java world of illusions...)
On the server side, leave the files conf/hbase-site.xml empty. You don't need to put a Zookeeper configuration in here, defaults are fine.
Same for etc/regionservers. Leave it with the default entry (localhost) because I don't think in standalone mode it really cares (and I tried to put server_hostname in it and of course this does not works).
On the client side, It must know the server by hostname if you want to resolve with it so again add an entry in your /etc/hosts client file for the server.
As a bonus I give you my sbt configuration and some complete working code for the client since the HBase team seems to have spent the documentation budget at Vegas for the last 4 years (again, welcome the «Business ready» world of Java/Scala).
build.sbt:
libraryDependencies ++= Seq(
...
"org.apache.hadoop" % "hadoop-core" % "1.2.1",
"org.apache.hbase" % "hbase" % "1.1.2",
"org.apache.hbase" % "hbase-client" % "1.1.2",
)
some_client_code.scala:
import org.apache.hadoop.hbase.HBaseConfiguration
import org.apache.hadoop.hbase.client.{HTable, Put, HBaseAdmin}
import org.apache.hadoop.hbase.util.Bytes
val hbaseConf = HBaseConfiguration.create()
hbaseConf.set("hbase.zookeeper.quorum", "server_hostname")
HBaseAdmin.checkHBaseAvailable(hbaseConf)
val table = new HTable(hbaseConf, "my_hbase_table")
val put = new Put(Bytes.toBytes("row_key"))
put.add(Bytes.toBytes("cf"), Bytes.toBytes("colId1"), Bytes.toBytes("foo"))

I know it is too late to answer this question but I want to share my way of resolving a similar issue.
I had the same issue and I tried to set the zookeeper quorum from the java program and also tried via the CLI but none of them worked.
I am using CDH 5.7.7 with HBase version 1.1.0
Finally I had to export few configs to the Hadoop classpath to fix the issue. Here is config that I have exported.
export HADOOP_CLASSPATH=/etc/hadoop/conf:/usr/share/cmf/lib/cdh5/hbase-protocol-0.98.1-cdh5.5.0.jar:/etc/hbase/conf:/driven/conf
Hope this helps.