Develop Reference

error resolving localhost while running java servlets in eclipse's browser

I am new to java servlets. I have installed apache-tomcat-9.0.0.M21.
When I run the project containing servlet in eclipse browser, sometimes I get the error-
Error resolving 'localhost': Name or service not known.
Other times the error is -
Error resolving 'localhost' : Temporary failure in name resolution.
This project runs fine in my web browser.
Also, after I add <servlet>...</servlet> and <servlet-mapping>...<servlet-mapping> in web.xml, I get the error - Server Tomcat v9.0 Server at localhost failed to start.
One more thing, I use Ubuntu operating system (if it has to do something with the question).
Please help. I googled for the solution but I am not able to resolve the error.

Try adding the below to your /etc/hosts file.
127.0.0.1 localhost

Activiti Explorer - Request resource is not available

I have big problem to run activiti-explorer when i try access: http://localhost:8080/activiti-explorer/ tomcat shows me HTTP Status 404 - The requested resource is not available. I'm really don't have any idea why that dosen't work. Can you help me?
This what have I done on my PC:
I'm using 5.19.0 version of activiti-explorer
7.0.63 tomcat
JDK 1.8.0.77 (i think there is no point to downgrade java to previous versions (<=1.7) becouse my main application using this version)
I'm sure I have correctly configured environment variables (JAVA_HOME,JRE_HOME,PATH,CATALINA_HOME)
I configured data base connection (db.properties, context.xml) in activiti-explorer.war and i moved this file to tomcat/webapps
I don't have any errors about activiti during tomcat start

Check if activiti explorer is deployed to tomcat in manager.
http://{host}:{port}/manager/html
More info in https://tomcat.apache.org/tomcat-7.0-doc/manager-howto.html

Check the catalina.out log. There will be something in there that leads you to the solution.

Check Admin Console (cmd that runs behind) after hitting the link. most recent exception occurred will be displayed there.

Update ear in web sphere from command line

I have developed an java ear that i deploy from my local eclipse to my local websphere 8.5 by using the publish button in eclipse. When I try to deploy my ear from command line I get an error after I try to access the webpage.
I update my ear from common line like this:
${was.dir}/profiles/${was.profile}/bin/wsadmin.sh -lang jython -username ${was.username} -password ${was.password} -c AdminApplication.updateApplicationUsingDefaultMerge('${was.app.name}', '${build.dir}/${ear.name}')
The deployment is successful but when I access my application thru my web browser I get the following message instead of seeing my application:
Error 404: com.ibm.ws.webcontainer.servlet.exception.NoTargetForURIException: No target servlet configured for uri: /wwww/index.html
I have verified that the ear is ok by updating it thru the web admin interface of websphere without any configuration.
What am I doing wrong or what additional steps do I need to do to successfully update my ear?

You are using wrong command. You should use something like this:
AdminApp.update('MyAppEAR', 'app', '[ -operation update -contents
MyApp.ear -nopreCompileJSPs -installed.ear.destination C:\WAS\MyAppEAR
-nodistributeApp -useMetaDataFromBinary -nodeployejb -createMBeansForResources -noreloadEnabled -nodeployws -validateinstall warn -noprocessEmbeddedConfig -filepermission ..dll=755#..so=755#..a=755#..sl=755
-noallowDispatchRemoteInclude -noallowServiceRemoteInclude -asyncRequestDispatchType DISABLED -nouseAutoLink -noenableClientModule -clientMode isolated -novalidateSchema -MapModulesToServers [[ MyApp MyApp.war,WEB-INF/web.xml WebSphere:cell=Node02Cell,node=Node02,server=server1 ]]]' )
Also, in WebSphere Application Server you can log every command you issue through Administrative Console.
Steps
login to admin console with administrative user (e.g. wasadmin)
click "System Administration" -> "Console Preferences"
check "Enable command assistance notifications" and "Log command assistance commands"
click Apply button to save changes
You can see commands in help portlet on the upper-right side of admin console:
If you checked "Log command assistance commands", you can also see jython commands in a log file "<WAS_HOME>\profiles\<PROFILE_NAME>\logs\server1\commandAssistanceJythonCommands.log"

I'm not sure about updateApplicationUsingDefaultMerge vs update (the latter is what I use), but don't forget you also have to AdminConfig.save() after you're finished.

Unable to access the resource from Tomcat server in windows

On machine1, I installed apache tomcat 7 listening on port 9999 and copied a sample.html file in ../webapps/dummy folder of tomcat machine.I was able to access the resource with URL http://localhost:9999/dummy/sample.html
On machine2, Tomcat is already part of some product listening on port 8080 which i thought of utilising it for my sample test. So, I copied a sample.html file in ../webapps/dummy folder of tomcat machine. I was unable to access the resource with URL http://localhost:8080/dummy/sample.html
On machine2, I have existing servlet programming modules running in another folder ../webapps/xyz.
My question:
I am trying to understand, What are the list of things that i need to verify on machine, which let me know, why i have an issue in accessing the URL(above) on machine2? Is this something to do with http access configuration like basic.user/basic.groups file?

It has nothing to do with the port on which tomcat is running.
Did you restart Tomcat after copying file over? It might be that on machine2 it's not configured to run in a dev mode so it doesn't pick up changes at runtime.
or
(if this is linux/unix/mac computer) Tomcat on machine2 is running as tomcat:tomcat user, but file you copied can't be read by this user. Change the permissions of the file.
HTH,
Jan

FileNotFoundException while running SolrCloud on Tomcat

I have a Solr 4.2.0 server which is running under the Tomcat 7.0 container. I'm trying to wire it with my external zookeeper (actually, it doesn't work with the embdedded zookeeper too).
I tried this java opts:
-Dbootstrap_confdir=./solr/collection1/conf
-Dcollection.configName=myconf
-DzkRun
-DnumShards=2
for running the embedded zookeeper.
And also this java opts:
-Dbootstrap_confdir=./solr/collection1/conf
-Dcollection.configName=myconf
-DzkHost=localhost:2181
-DnumShards=2
For connecting to external zookeeper
In both cases I continue to get the same exception:
java.io.FileNotFoundException: File '.\solr\collection1\conf \admin-extra.html' does not exist
But the problem is that file admin-extra.html exists and it's right here. And I can't figure out what the problem is.

From your exception it seems your path has a white space after the config directory.
Try to define your bootstrap_configdir between "", like:
-Dbootstrap_confdir="./solr/collection1/conf"