Have you ever seen an Ant error message like this?
BUILD FAILED /Users/elharo/Projects/XOM/build.xml:545: Problem: failed to create task or type scp Cause: Could not load a dependent class com/jcraft/jsch/Logger It is not enough to have Ant's optional JARs you need the JAR files that the optional tasks depend upon. Ant's optional task dependencies are listed in the manual. Action: Determine what extra JAR files are needed, and place them in one of: -/opt/ant/lib -/Users/elharo/.ant/lib -a directory added on the command line with the -lib argument Do not panic, this is a common problem. The commonest cause is a missing JAR. This is not a bug; it is a configuration problem
As usual, the ant error message is completely unhelpful, though for once it’s at least technically correct. (Most of the time when ant says, “This is not a bug; it is a configuration problem”, it is in fact a bug and not a configuration problem.) Here’s what’s really happening.
The jsch jar file distributed from http://www.jcraft.com/jsch/ is corrupt. Either they uploaded it wrong or they misconfigured their web server or both. (Update: it looks like a misconfigured server/poorly designed web page. The so-called download link isn’t that at all. You can follow it but not save it.) The jar file with the relevant classes is there, but it’s no good. You can check your local copy by trying to list its contents with jar tvf:
$ jar tvf /usr/share/ant/lib/jsch*jar java.util.zip.ZipException: error in opening zip file at java.util.zip.ZipFile.open(Native Method) at java.util.zip.ZipFile.
(ZipFile.java:114) at java.util.zip.ZipFile. (ZipFile.java:75) at sun.tools.jar.Main.list(Main.java:979) at sun.tools.jar.Main.run(Main.java:224) at sun.tools.jar.Main.main(Main.java:1149)
If you see anything but a list of classes, the problem is that the JSCH jar is no good. To fix it, use this link to sourceforge instead.
Once again I am reminded of the perils of depending on external libraries, especially ones you don’t build or distribute with your own product. In 2010 ssh and scp are mandatory features of any build and deployment system. Secure communications are too important to be left to random third party web sites.