Develop Reference

Embedded Database project

So I received this error message:
java.sql.SQLNonTransientConnectionException: java.net.ConnectException
: Error connecting to server localhost on port
What does this even mean? I searched it up and what I found was that I never created an embedded database but rather a server? Regardless, the steps I followed were exact in order to create an embedded database.

Tomcat closes websocket conection with an error

For a customer we build a HTML5 websocket application with Tomcat 8.0.29.
If we start the application from our network or from our home network all works fine. But if the customer starts the application from his network, after a certain time the websocket stops with a error. This can happen after 5 or 20 Minutes.
We have tested it with and without SSL and on two different servers. Only in the customer network the connection breaks with a error.
We also make a test with an websocket echo example which is included in Tomcat. the same as with our websocket. After a certain time the websocket stops with a error. But only if we start the application from the customer network.
When the echo example stops with an error the following message will written in server.log
08-Dec-2015 10:20:37.757 SEVERE [http-apr-8081-exec-2] org.apache.tomcat.websocket.pojo.PojoEndpointBase.onError No error handling configured for [websocket.echo.EchoAnnotation] and the following error occurred
java.io.IOException: Unexpected error [730,054] reading data from the APR/native socket [1,639,490,672] with wrapper [org.apache.tomcat.util.net.AprEndpoint$AprSocketWrapper#231e01e4:1639490672].<br/>
at org.apache.coyote.http11.upgrade.AprServletInputStream.doRead(AprServletInputStream.java:133)<br/>
at org.apache.coyote.http11.upgrade.AbstractServletInputStream.read(AbstractServletInputStream.java:124)<br/>
at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:51)<br/>
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler$WsReadListener.onDataAvailable(WsHttpUpgradeHandler.java:183)<br/>
at org.apache.coyote.http11.upgrade.AbstractServletInputStream.onDataAvailable(AbstractServletInputStream.java:198)<br/>
at org.apache.coyote.http11.upgrade.AbstractProcessor.upgradeDispatch(AbstractProcessor.java:96)<br/>
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:669)<br/>
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2500)<br/>
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2489)<br/>
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)<br/>
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)<br/>
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)<br/>
at java.lang.Thread.run(Unknown Source)
If we starts the test on http://www.websocket.org/echo.html the connection will not closed with an error.
For me it looks like a problem with Tomcat. But what can I do to make it run properly?
Tomcat: 8.0.29 (also with earlier versions)
Windows 7: 64 Bit
Protocol: HTTP/1.1

I apologize to the readers who came here specifically because of websockets, but we had a similar error in our application while serving files over REST API from Spring. While searching for answers, one of the places I found first was this question. Here's what I was able to find out about the error:
The numbers in Unexpected error [730,054] are somehow significant and are some sort of error codes. In our case, the error looked like this:
java.io.IOException: Unexpected error [120,001] writing data to the APR/native socket [140,041,540,128,928] with wrapper [org.apache.tomcat.util.net.AprEndpoint$AprSocketWrapper#4f1861c:140041540128928].
I found that this supposedly means that the connection was interrupted by the client.
We were able to solve the issue by reimplementing the controller method to always return the generic ResponseEntity<Resource> object with ByteArrayResource body and content type application/octet-stream:
responseEntity = ResponseEntity.ok()
.headers(createHttpHeaders())
.contentLength(file.length())
.contentType(MediaType.APPLICATION_OCTET_STREAM)
.body(new FileSystemResource(file));
It appears that the errors in our case were caused by non-standard headers we were using, such as Content-Type: application/force-download. It's possible that it caused browsers to terminate the connection in a non-standard way.

HTTP transport error: java.net.SocketException: Connection reset

A client application has been built using Jdeveloper 10.1.3.2 and it is running on OC4J server. This application is sending data to external server application. It is working for quite long time without any issue. Lately a connection issue occurred and the following stack trace is generated:
com.sun.xml.ws.client.ClientTransportException: HTTP transport error: java.net.SocketException: Connection reset
at com.sun.xml.ws.transport.http.client.HttpClientTransport.getOutput(HttpClientTransport.java:133)
at com.sun.xml.ws.transport.http.client.HttpTransportPipe.process(HttpTransportPipe.java:153)
at com.sun.xml.ws.transport.http.client.HttpTransportPipe.processRequest(HttpTransportPipe.java:93)
at com.sun.xml.ws.transport.DeferredTransportPipe.processRequest(DeferredTransportPipe.java:105)
at com.sun.xml.ws.api.pipe.Fiber.__doRun(Fiber.java:629)
at com.sun.xml.ws.api.pipe.Fiber._doRun(Fiber.java:588)
at com.sun.xml.ws.api.pipe.Fiber.doRun(Fiber.java:573)
at com.sun.xml.ws.api.pipe.Fiber.runSync(Fiber.java:470)
at com.sun.xml.ws.client.Stub.process(Stub.java:319)
at com.sun.xml.ws.client.sei.SEIStub.doProcess(SEIStub.java:157)
at com.sun.xml.ws.client.sei.SyncMethodHandler.invoke(SyncMethodHandler.java:109)
at com.sun.xml.ws.client.sei.SyncMethodHandler.invoke(SyncMethodHandler.java:89)
at com.sun.xml.ws.client.sei.SEIStub.invoke(SEIStub.java:140)
at $Proxy44.sendRem(Unknown Source)
After goggling I found out a good discussion about the error sockets - What's causing my java.net.SocketException: Connection reset? .One answer in this link says that the issue mostly from the client side because if it is from the server side the exception will be (SocketException reset by peer).
What I did:
I tried out to increase the socket time out for the OC4J with the help of this form How to change OC4J HTTP Timeout. What I did is I changed the propriety oracle.j2ee.http.socket.timeout to be 5000 instead of 500 (10 times longer)
But the error still there. So, any suggestion to over come this issue?
Note: I able to use telnet command for external server IP and Port and it is working fine.
-------------------------------------------------------- Update 1 --------------------------------------------------------
I increase the server clock skew where the client application is running using the following command on server start up:
-Dweblogic.wsee.security.clock.skew=72000000
-Dweblogic.wsee.security.delay.max=72000000
But no luck, problem is not resolved.
-------------------------------------------------------- Update 2 --------------------------------------------------------
I realized that the problem is not from application at all; I test the external URL using SoapUI and I got the same error Connection rest. I think this new update clreay shows that there is nothing wrong with program code. But I need to know where to go or check now. Where is the starting point now to overcome the issue. Any clue will be helpful.

As you can see from Update 2 in the question, the problem was not from the client application because same error occurred from SoapUI.
The problem was that the machine where the client application was running have low bandwidth which was not enough for APIs communication. Using simple speed test , I found out that the upload bandwidth was low comparing to minimum requirements given by server application team.
I concluded this fact by monitoring the network resource using Resource Monitor in Windows while the client application was running and by using online speed check
To solve the issue, the machine bandwidth has to be increased where the client application is running.

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet success fully received from the server was 176,705,355 milliseconds ago. The last packet sent successfully to the server was 176,705,366 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
I am getting above exception when ever insert query in log4j.xml gets executed??

Proxy Error 502 : The proxy server received an invalid response from an upstream server

We are building a mass mailing sending application in Java. Mail is being send by third party SMTP. After sending 400-500 mails tomcat6 service get stopped. Below is the error.
Proxy Error
The proxy server received an invalid response from an upstream server. The proxy server could not handle the request GET
/lin/Campaignn.jsp.
Reason: Error reading from remote server
Additionally, a 502 Bad Gateway error was encountered while trying to use an ErrorDocument to handle the request.
Apache Server at msizzler.com Port 80
But when we are sending from localhost I did not received any error. It send all the mails.
Please help me to sort it out this problem.

The HTTP 502 "Bad Gateway" response is generated when Apache web server does not receive a valid HTTP response from the upstream server, which in this case is your Tomcat web application.
Some reasons why this might happen:
Tomcat may have crashed
The web application did not respond in time and the request from Apache timed out
The Tomcat threads are timing out
A network device is blocking the request, perhaps as some sort of connection timeout or DoS attack prevention system
If the problem is related to timeout settings, you may be able to resolve it by investigating the following:
ProxyTimeout directive of Apache's mod_proxy
Connector config of Apache Tomcat
Your network device's manual

Add this into your httpd.conf file
Timeout 2400
ProxyTimeout 2400
ProxyBadHeader Ignore

The java application takes too long to respond(maybe due start-up/jvm being cold) thus you get the proxy error.
Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /lin/Campaignn.jsp.
As Albert Maclang said amending the http timeout configuration may fix the issue.
I suspect the java application throws a 500+ error thus the apache gateway error too. You should look in the logs.

I had this issue once. It turned out to be database query issue. After re-create tables and index it has been fixed.
Although it says proxy error, when you look at server log, it shows execute query timeout. This is what I had before and how I solved it.

I had this problem too.
I was using apache as a reverse proxy for tomcat, my problem was associated with the return time of the response for "apache" proxy
I solved it like this:
open the "etc/apache/apache2.conf" and the ssl mod conf file "etc/apache/sites-available/000-default-le-ssl.conf" and add the following lines:
Timeout 28800
KeepAlive On
maybe this will help you