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yajsync

yajsync is a port of rsync written in Java.

yajsync currently supports a minimal subset of rsync protocol version 30.0, with the additional constraint that the peer must also support rsync safe file lists.

Currently implemented rsync options:

  • Incremental recursion (-r, --recursive)

  • Preserve owner (-o, --owner)

  • Preserve permissions (-p, --perms)

  • Preserve times (-t, --times)

  • Module file listings

yajsync is compliant with at least rsync version 3.0.9.

Features

  • rsync Java API

  • Platform independent rsync server

  • Platform independent rsync client with support for both local and remote file transfers

  • Native SSL/TLS tunneling

Please be aware though that the API currently is unstable, not documented and will most probably change in the near future.

Warning

This software is still unstable and there might be data corruption bugs hiding. So use it only carefully at your own risk.

If you encounter any problems please create an issue with https://github.com/perlundq/yajsync/issues/new

Contact

If you have any questions or want to provide feedback of any type please join the yajsync discussion group

Example

Start a Server listening on localhost port 14415, with one implicitly read-only module called Downloads and one readable and writable module called Uploads:

$ cat yajsyncd.conf

# This line and all text after a `#' is a comment. Text within square
# brackets define the name of a new module. A module definition may be
# followed by any number of predefined parameter value statements on
# the form key = value. The current available module parameters are:
#
#    path          An existing path to the module (mandatory).
#    comment       Text that will be shown to the client in module listings
#                  (optional).
#    is_readable   A boolean (true or false) indicating whether files
#                  may be read below this module (optional, default is
#                  true).
#    is_writable   A boolean (true or false) indicating whether files
#                  may be written below this module (optional, default
#                  is false).

# This is a module definition for a module called Downloads. path is
# the only mandatory module parameter. This one also provides a
# comment. All modules are implicitly readable but not writable:
[Downloads]
path = /path/to/Downloads/
comment = this text will be printed on module listings, it is optional
# is_readable = true
# is_writable = false

# Uploads is both readable and writable; it does not provide a
# comment:
[Uploads]
path = /path/to/Uploads/
is_writable = true

Start the server:

$ java -Dumask=$(umask) -jar build/jar/yajsyncd.jar --port=14415 --config=yajsyncd.conf

Recursively upload the directory called example to Uploads:

java -Dumask=$(umask) -jar build/jar/yajsync.jar --port=14415 -r example localhost::Uploads

The same thing using the alternative syntax:

java -Dumask=$(umask) -jar build/jar/yajsync.jar -r example rsync://localhost:14415/Uploads

And finally the same thing using the original rsync client:

rsync --port=14415 -r example localhost::Uploads

Note

  • Recursive transfers always implies incremental recursion.

  • Use --charset for setting common character set (defaults to UTF-8). Note that --iconv is not supported.

  • Client local file transfers always uses rsync:s delta transfer algorithm, i.e. it does not have an option --whole-file.

  • Checksum block size is not computed in the exact same way as rsync. It is computed dynamically based on the file size and is always an even multiple of 2 and at least 512 bytes long.

  • Wild cards are not supported.

Extra feature

yajsync also adds the client/server local option --defer-write which makes the receiver avoid writing into a temporary file if the target file is unchanged.

Build instructions

Requirements:

Procedure:

git clone https://github.com/perlundq/yajsync.git
cd yajsync
ant

Usage

Show client/server help (-h argument):

(Windows):

java -jar build/jar/yajsync.jar  -h
java -jar build/jar/yajsyncd.jar -h

(Unix/Linux, we must inject necessary umask information as a property, assuming Bourne shell compatible syntax)

java -Dumask=$(umask) -jar build/jar/yajsync.jar  -h
java -Dumask=$(umask) -jar build/jar/yajsyncd.jar -h

Recommended extra options to the jvm (i.e. must be placed before the -jar argument):

Turn on assertions:

-ea

Use a more memory conservative garbage collector:

-XX:+UseConcMarkSweepGC

Turn on aggressive optimisations:

-XX:+AggressiveOpts

SSL/TLS is configured externally (see JSSE documentation), but the following properties are used (options to the JVM):

-Djavax.net.ssl.keyStore=...
-Djavax.net.ssl.keyStoreAlias=...
-Djavax.net.ssl.keyStorePassword=...
-Djavax.net.ssl.trustStore=...
-Djavax.net.ssl.trustStorePassword=...

javax.net.debug is useful for debugging SSL/TLS. To see available values to javax.net.debug:

-Djavax.net.debug=help

Note: client side authorisation is not yet implemented - requires changes to server configuration.

License

Copyright (C) 1996-2011 by Andrew Tridgell, Wayne Davison, and others

Copyright (C) 2013,2014 Per Lundqvist

yajsync is licensed under GNU General Public License version 3 or later. See the file LICENSE or http://www.gnu.org/licenses/gpl.txt for the license details.