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Windows Vista + Java applet + FTP

Posted on 2009-04-14
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Last Modified: 2013-12-08
I have a website with a (signed) Java applet on it. The applet uploads and downloads files using a commercially available FTP application. My problem is that one of my clients gets an UnknownHostException when the applet tries FTP-ing to our site ftp://www.kenjackson.com. From my computer, I can access the FTP site both through the applet and through Internet Explorer/Windows Explorer. However, I'm using Windows XP and our client is using Windows Vista -- I was wondering if there's any setting in Vista or IE that might prevent the applet from looking up an FTP host address.

Granted, I'm trying to diagnose this client's computer over the phone, he's on a completely different local network than I am, don't know what his computer's/network's/firewall's settings are, and he's not technically proficient enough to help me out. Any ideas would be really great.

I posted the output from the Java console below:
1.6.0_13

Url = https://www.kenjackson.com/Interactive/common/downloadfile.aspx?id=2485&user=2225&owner=2225

init finished

(URL)u = https://www.kenjackson.com/Interactive/common/downloadfile.aspx?id=2485&user=2225&owner=2225

clientId = 2225

temp file name: FTA1779626496030999950.tmp

DEBUG [FTPClient] 14 Apr 2009 11:29:04.732 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

INFO [FTA] 14 Apr 2009 11:29:04.747 : connecting to ftp://www.kenjackson.com

ftp://www.kenjackson.com

java.net.UnknownHostException: ftp://www.kenjackson.com

                at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)

                at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source)

                at java.net.InetAddress.getAddressFromNameService(Unknown Source)

                at java.net.InetAddress.getAllByName0(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getByName(Unknown Source)

                at com.enterprisedt.net.ftp.FTPClient.setRemoteHost(FTPClient.java:1350)

                at com.enterprisedt.net.ftp.FileTransferClient.configureClient(FileTransferClient.java:406)

                at com.enterprisedt.net.ftp.FileTransferClient.connect(FileTransferClient.java:368)

                at FTA.DownloadZipFile(FTA.java:942)

                at FTA.Download(FTA.java:667)

                at FTA$10.run(FTA.java:1566)

                at java.security.AccessController.doPrivileged(Native Method)

                at FTA.run(FTA.java:1562)

                at java.lang.Thread.run(Unknown Source)

downloaded to null

DownloadZipFile returned null, applet exiting

Exception occurred during event dispatching:

java.lang.NullPointerException: null pData

                at sun.awt.windows.WComponentPeer._requestFocus(Native Method)

                at sun.awt.windows.WComponentPeer.requestFocus(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocus(Unknown Source)

                at sun.plugin2.main.client.PluginMain$2.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.Dialog$1.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.run(Unknown Source)

Exception occurred during event dispatching:

java.lang.NullPointerException: null pData

                at sun.awt.windows.WComponentPeer._requestFocus(Native Method)

                at sun.awt.windows.WComponentPeer.requestFocus(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocus(Unknown Source)

                at sun.plugin2.main.client.PluginMain$2.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.Dialog$1.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.run(Unknown Source)

(URL)u = https://www.kenjackson.com/Interactive/common/downloadfile.aspx?id=2485&user=2225&owner=2225

clientId = 2225

temp file name: FTA5122763281524435278.tmp

DEBUG [FTPClient] 14 Apr 2009 11:29:30.909 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

DEBUG [FTPClient] 14 Apr 2009 11:29:30.909 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

INFO [FTA] 14 Apr 2009 11:29:30.909 : connecting to ftp://www.kenjackson.com

INFO [FTA] 14 Apr 2009 11:29:30.909 : connecting to ftp://www.kenjackson.com

ftp://www.kenjackson.com

java.net.UnknownHostException: ftp://www.kenjackson.com

                at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)

                at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source)

                at java.net.InetAddress.getAddressFromNameService(Unknown Source)

                at java.net.InetAddress.getAllByName0(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getByName(Unknown Source)

                at com.enterprisedt.net.ftp.FTPClient.setRemoteHost(FTPClient.java:1350)

                at com.enterprisedt.net.ftp.FileTransferClient.configureClient(FileTransferClient.java:406)

                at com.enterprisedt.net.ftp.FileTransferClient.connect(FileTransferClient.java:368)

                at FTA.DownloadZipFile(FTA.java:942)

                at FTA.Download(FTA.java:667)

                at FTA$10.run(FTA.java:1566)

                at java.security.AccessController.doPrivileged(Native Method)

                at FTA.run(FTA.java:1562)

                at java.lang.Thread.run(Unknown Source)

downloaded to null

DownloadZipFile returned null, applet exiting

Exception occurred during event dispatching:

java.lang.NullPointerException: null pData

                at sun.awt.windows.WComponentPeer._requestFocus(Native Method)

                at sun.awt.windows.WComponentPeer.requestFocus(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocusHelper(Unknown Source)

                at java.awt.Component.requestFocus(Unknown Source)

                at sun.plugin2.main.client.PluginMain$2.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.Dialog$1.run(Unknown Source)

                at java.awt.event.InvocationEvent.dispatch(Unknown Source)

                at java.awt.EventQueue.dispatchEvent(Unknown Source)

                at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

                at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

                at java.awt.EventDispatchThread.run(Unknown Source)

(URL)u = https://www.kenjackson.com/Interactive/common/downloadfile.aspx?id=2485&user=2225&owner=2225

clientId = 2225

temp file name: FTA3536697804974830263.tmp

DEBUG [FTPClient] 14 Apr 2009 11:29:53.968 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

DEBUG [FTPClient] 14 Apr 2009 11:29:53.968 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

DEBUG [FTPClient] 14 Apr 2009 11:29:53.968 : Class: com.enterprisedt.net.ftp.FTPClient

Location: https://www.kenjackson.com/Interactive/common/FTAS.jar

Version: 2.0.4

Build timestamp: 13-Feb-2009 15:09:20 EST

Java version: 1.6.0_13

CLASSPATH: C:\\PROGRA~1\\Java\\jre6\\classes

OS name: Windows Vista

OS arch: x86

OS version: 6.0

 

INFO [FTA] 14 Apr 2009 11:29:53.968 : connecting to ftp://www.kenjackson.com

INFO [FTA] 14 Apr 2009 11:29:53.968 : connecting to ftp://www.kenjackson.com

INFO [FTA] 14 Apr 2009 11:29:53.968 : connecting to ftp://www.kenjackson.com

ftp://www.kenjackson.com

java.net.UnknownHostException: ftp://www.kenjackson.com

                at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)

                at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source)

                at java.net.InetAddress.getAddressFromNameService(Unknown Source)

                at java.net.InetAddress.getAllByName0(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getAllByName(Unknown Source)

                at java.net.InetAddress.getByName(Unknown Source)

                at com.enterprisedt.net.ftp.FTPClient.setRemoteHost(FTPClient.java:1350)

                at com.enterprisedt.net.ftp.FileTransferClient.configureClient(FileTransferClient.java:406)

                at com.enterprisedt.net.ftp.FileTransferClient.connect(FileTransferClient.java:368)

                at FTA.DownloadZipFile(FTA.java:942)

                at FTA.Download(FTA.java:667)

                at FTA$10.run(FTA.java:1566)

                at java.security.AccessController.doPrivileged(Native Method)

                at FTA.run(FTA.java:1562)

                at java.lang.Thread.run(Unknown Source)

downloaded to null

DownloadZipFile returned null, applet exiting

Thanks.
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Question by:tjgquicken
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6 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 24139676
See below (and i don't even run Windows ;-))
goose@seegobin:/tmp$ ftp ftp://www.kenjackson.com
ftp: ftp://www.kenjackson.com: Unknown host
ftp> 

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Accepted Solution

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CEHJ earned 500 total points
ID: 24139722
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Author Comment

by:tjgquicken
ID: 24139759
It looks like it's working okay on my Mac...

And like I said, I can log into the site from my Windows machine, too.
ftp ftp://[username]:[password]@www.kenjackson.com
Connected to www.kenjackson.com.
220 Serv-U FTP Server v6.4 for WinSock ready...
331 User name okay, need password.
230 User logged in, proceed.
Remote system type is UNIX.
Using binary mode to transfer files.
200 Type set to I.
250 Directory changed to /
ftp> 

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LVL 86

Expert Comment

by:CEHJ
ID: 24139898
It might differ between different software. I would try the hostname i mentioned in the non-working situations
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LVL 86

Expert Comment

by:CEHJ
ID: 24139941
Could be a nameserver problem. Just tried it again and it worked that time. Nonetheless, try the other host name
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Expert Comment

by:CEHJ
ID: 24141289
:-)
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