jlowfuse provides APIs to use FUSE (Filesystem in Userspace) from Java. It provides two kinds of APIs. The classic and the async API.
The classic API resembles closely the FUSE lowlevel C API. You basically subclass a special class that receives calls from FUSE. This is probably the one easier to use, as little additional code is needed. Every method in this class corresponds to a FUSE callback function like open, readdir, etc.
The async API is based on java asynchronous tasks. Every FUSE callback is converted to a Task object and scheduled on an ExecutorService.
This way every FUSE Operation is a separate class. The API is intended for multi threaded environments as it is easy to schedule the incoming tasks on multiple CPUs.
- SWIG >= 2.0.1
- FUSE/libfuse >= 2.8.1
- Apache Ant with cpptasks
- Oracle JDK >= 1.6
- Python
- ant
- ant-contrib-cpptasks
- sun-java6-jdk
- swig2.0
- build-essential
- libfuse-dev
- GNU/Linux x86
jlowfuse can be build using apache ant:
ant dist
This leaves you with the compiled jlowfuse.jar and libjlowfuse.so in the dist/
directory.
It seams that debian’s ant library path lacks the cpptasks.jar. Use the following instead:
ant -lib /usr/share/java/ant-contrib-cpptasks.jar dist
For an example how to use jlowfuse see the example filesystem objectfs
included. You can run it with objectfs.sh MOUNTPOINT. It is not very
feature rich and stores every byte into memory. But as a starting
point it should be quite useful.
Place the compiled library libjlowfuse.so somewhere and add
-Djava.library.path=somewhere to your java call
Development using jlowfuse is similar to other FUSE wrapper libraries. In C you would implement a set of function callbacks and add pointers to them to a lowlevel_ops struct. In jlowfuse this is done by sub-classing AbstractLowlevelOps.
Almost all setup and helper functions in FUSE are available in jlowfuse, too.
The basic setup code for a filesystem looks like this:
String[] fuseArgs = {"-o foo,subtype=objfs", "-d"};
String mountpoint = strArgs[0];
JLowFuseArgs args = JLowFuseArgs.parseCommandline(fuseArgs);
:
SWIGTYPE_p_fuse_chan chan = Fuse.mount(mountpoint, args); SWIGTYPE_p_fuse_session sess = JLowFuse.lowlevelNew(args, new ObjectFsOps());
:
Session.addChan(sess, chan); Session.loopSingle(sess);
:
Session.removeChan(chan);
:
Session.destroy(sess); Session.exit(sess);
:
Fuse.unmount(mountpoint, chan);