
                  README FILE FOR SENDFILE_SRV, AND GETFILE_CL
                                August 8, 2008

Sendfile_srv and getfile_cl are modifications of sendfileII and getfileII to 
allow for a reversal of their server/client roles. SendfileII and getfileII 
operate with getfileII in the role of server; sendfileII in the role of client. 
Under some circumstances, usually related to firewall issues, it is desireable to
reverse these roles. Sendfile_srv and getfile_cl allow you to do this (at a price).
There are two drawbacks. First, since getfile_cl is now the client and has no 
idea about the availability of files to be sent, it must periodically poll 
sendfile_srv for available files. This can lead to a lot of unproductive connections 
and adds to the mean latency for file transfers. Second, out of laziness on my part,
getfile_cl will only receive files from a single sendfile_srv. There is no reason
it couldn't be modified to poll multiple servers in the future.

                                                             Jim Luetgert

              README FILE FOR SENDFILEII, GETFILEII, AND MAKEHBFILE
                                December 19, 2002


This document contains the following sections:

INTRODUCTION
INSTALLATION AND STARTUP
COMPILING THE PROGRAMS
SENDFILEII NOTES
GETFILEII NOTES
MAKEHBFILE NOTES
PROTOCOL
CHANGES
DISCLAIMER


                                INTRODUCTION

The sendfileII, getfileII, and makehbfile programs are used to transfer files 
between computers running Windows NT and/or Sun Solaris.  The programs run 
continuously, so they are appropriate for real-time applications. These
programs are based on the work of Will Kohler at the Menlo Park USGS
campus. These programs are distributed as part of Earthworm, but they can do
not depend on any other parts of Earthworm. Each of the three programs is
self-contained; no Earthworm library functions are used in them.

SendfileII and getfileII use a slightly different protocol than the original
sendfile and getfile. THEY ARE NOT COMPATIBLE. See the CHANGES section for a
summary of these differences and other recent changes to the programs.

The sendfileII program gets files from a "queue directory", transmits the
files via a socket connection, and deletes the files from the queue directory.
The getfileII program receives data files from sendfileII via a socket
connection and saves them in specified directories.  The makehbfile program
periodically places a "heartbeat file" in the queue directory used by
sendfileII.

If the network connection between computers is down for any reason, files
will accumulate in sendfileII's queue directory until the network comes back
up.  Then all files will be sent immediately.

One getfileII process can accept files from up to 100 sendfileII processes
running on different computers. However, getfileII will handle only a single
file transaction at a time. That is, getfileII is a single-threaded,
non-forking process.

WARNING: The sendfileII and getfileII programs don't do any data
"translation".  If binary files are transferred, the data format and
byte-order of the file may be incompatible with the receiving computer. For
text files, no end-of-line translation is done. Thus it is up to the programs
supplying files to sendfileII and consuming files from getfileII to agree on
file formats.


                          INSTALLATION AND STARTUP

The distribution directory for each program contains executable files for
Windows and Solaris.  Windows executable files are named <progname>.exe, and
Solaris executable files are named <progname>.  To install the programs,
simply copy the executable files to any directory which is in the user's
search path.  The programs can also be run by typing the full path name.  The
name of the program configuration file is specified on the command line, eg:

    sendfileII sendfileII.d     or    getfileII getfileII.d

On Solaris, the programs can be run from the command line, or they can be
started automatically at boot time.

On Windows NT, the executable (or a shortcut to the executable) can be placed
in the users startup directory.  See Windows documentation for details.



                          COMPILING THE PROGRAMS

If it's necessary to recompile a program, change the working directory to the 
program distribution directory.  On a Windows NT system, type:

    nmake /f makefile.nt

On a Solaris system, type:

    make -f makefile.sol

The programs were compiled using Microsoft Visual C++ 6.0 on Windows NT, and
Sun C 4.2 on Solaris 2.7.  All user functions are included in the distribution
directories.


                             SENDFILEII NOTES

The sendfileII program requires a configuration file, typically named
sendfileII.d.  A sample configuration file is included in the distribution
directory and is shown below.  Any line which begins with the # sign is
interpreted as a comment, so feel free to add your own comment lines.

The output (queue) and log directories must exist before running the program.
They should be created manually using the mkdir command (or the equivalent
windows/file manager operation).  In Solaris, the user must have write
permission for these directories.

The TimeZone parameter is only used on Windows NT for timestamping entries in
the log file.


#
# sendfileII.d  -  Configuration file for the sendfileII program
#
# ServerIP      = IP address of computer running getfileII
# ServerPort    = Well known port of getfileII program
# TimeOut       = Send/receive will time out after TimeOut seconds.
# AckTimeOut    = Wait AckTimeOut seconds for "ACK" from getfileII.
#                 If ACK is not received, sendfileII assumes that getfileII
#                 did not get the whole file, so sendfileII will try again.
# RetryInterval = If an error occurs, retry after this many seconds
# OutDir        = Path of directory containing files to send to getfileII
# LogFile       = If 0, don't log to screen or disk.
#                 If 1, log to screen only. 
#                 If 2, log to disk only. 
#                 If 3, log to screen and disk.   
# TimeZone      = Timezone of computer system clock (ignored in Solaris)
# LogFileName   = Full path name of log files. The current date will
#                 be appended to log file names.
#
-ServerIP      130.118.43.31
-ServerPort    3456
-TimeOut       15
-AckTimeOut    30
-RetryInterval 60
-LogFile       3   
-TimeZone      GMT

# Solaris
# -------
-OutDir        /home/earthworm/outdir
-LogFileName   /home/earthworm/run/log/sendfileII.log

# Windows
# -------
#-OutDir        c:\earthworm\outdir
#-LogFileName   c:\earthworm\run\log\sendfileII.log

After the sendfileII program is invoked, it patiently waits for files to
appear in output queue directory.  When it detects a file, it opens a socket
connection to getfileII, sends the file, and then deletes the file from the
queue directory.

Under Windows NT, if a file is copied or moved to the queue directory using
the "copy" or "move" command (recommended), sendfileII will wait until the
file is completely transferred to the queue directory before it is sent to
getfileII.  This prevents a partial file from being sent.  The Windows version
also uses the _fsopen() system call which provides file locking.  SendfileII
waits until all other processes are done with a file before accessing it.

The Solaris version of sendfileII works somewhat differently.  If a file is
cp'd to or created in the queue directory, the file may not be complete when
sendfileII starts to send it. Thus it is possible that sendfileII might not
transfer the whole file. The preferred technique is to create a complete file
in another directory in same disk partition (file system) as the queue
directory.  Then create a hard link to the queue directory using the command:

    ln <file> <queue directory)

After the file has been transferred by sendfileII, sendfileII will remove the
link, which leaves the original file intact.

An alternative is to create the file on another directory on the same disk 
partition and move it to the queue directory using the mv command.  After the 
file has been transferred by sendfileII, sendfileII will delete the file from
the queue directory.

This directory for creating files may be located within the queue
directory. That is because sendfileII will never attempt to transfer a
directory; it will only transfer files.


                             GETFILEII NOTES

The getfileII program requires a configuration file, typically named
getfileII.d.  A sample configuration file is included in the distribution
directory and is shown below.  Any line which begins with the # sign is
interpreted as a comment, so feel free to add your own comment lines.

The input, temporary, and log directories must exist before running the
program.  They should be created manually using the mkdir command (or the
equivalent windows/file manager operation). The user must have write
permission for these directories.

The TimeZone parameter is used only for timestamping entries in the log file.

#
#  getfileII.d  -  Configuration file for the getfileII program
#
# ServerIP      = IP address of this computer's host adapter
# ServerPort    = Well-known port used by this program
# TimeOut       = Send/receive will time out after TimeOut seconds.
# LogFile       = If 0, don't log to screen or disk.
#                 If 1, log to screen only.
#                 If 2, log to disk only.
#                 If 3, log to screen and disk.
# TimeZone      = Timezone of computer system clock (ignored in Solaris)
# LogFileName   = Full path name of log files. The current date will
#                 be appended to log file names.
# TempDir       = Full path name of directory to contain temporary files.
#                 This directory must be on the same partition as the
#                 client directories.
# Client        = IP address of trusted client, followed by the path of
#                 directory to contain files sent by this client.
#                 Connections from all other IP addresses are rejected.
#                 From 1 to 100 of these lines are allowed.
#                 The client directories must be on the same disk
#                 partition as is TempDir.
#
-ServerIP    130.118.43.31
-ServerPort  3456
-TimeOut     15
-LogFile     3
-TimeZone    GMT
-LogFileName /home/earthworm/run/log/getfileII.log
-TempDir     /home/earthworm/indir
-Client      130.118.43.36   /home/earthworm/indir/billy
-Client      130.118.43.38   /home/earthworm/indir/campbell


The getfileII program accepts connections from up to 100 sendfileII processes
on remote systems.  Only one socket connection at a time is allowed.  If a
sendfileII process wants to connect while the getfileII connection is busy,
getfileII will queue the connection request.

GetfileII writes data from the socket connection to a directory of temporary
files.  After the data transfer from the socket is complete, getfileII moves
the file from the temporary directory to the client directories.  This ensures
that all files in the client directories are complete.


                              MAKEHBFILE NOTES

The makehbfile program makes heartbeat files and places them in a specified 
directory.  The output directory should be the same as the sendfileII queue 
directory, and it must exist before running makehbfile. Makehbfile uses a
directory named "temp.dir" for creating its heartbeat files before moving them
to the output directory. It will create this directory within the
output directory if it does not exist at startup.

The makehbfile program requires a configuration file, typically named 
makehbfile.d.  A sample configuration file is included in the distribution 
directory and is shown below.  Any line which begins with the # sign is 
interpreted as a comment, so feel free to add your own comment lines.

#
# makehbfile.d  -  Configuration file for the makehbfile program
#
# Path     = Name of directory to contain heartbeat files.
# HbName   = Name of the heartbeat file (without path)
# Interval = Create a heartbeat file every "Interval" seconds
#
-HbName   hb.hollyhock
-Interval 60

# Solaris
-Path     /home/earthworm/outdir

# Windows
#-Path     c:\earthworm\outdir

All heartbeat files will be created with the same name, as specified in the
makehbfile configuration file.  If a heartbeat file already exists in the
output directory, it will be overwritten by the most recent heartbeat file.

All heartbeat files contain a sequence of ASCII characters representing the 
computer system time, in seconds since midnight, Jan 1, 1970.


PROTOCOL

SendfileII and getfileII use the following protocol for transferring files.

GetfileII opens its socket to listen on the TCP "ServerPort". When sendfileII
has a file to send, it will make a connection to the getfileII socket.

Each "block" of data that sendfileII sends is preceded by a six-digit integer
indicating the block size.

SendfileII first sends the name of the file it is about to transmit (preceded
by the name length as described above). It then sends blocks of 4096
characters of file contents (or the remaining file contents if less than
4096) to getfileII. Again, each block is preceded by its size.

After sendfileII has completed sending the file, it sends one more six-digit
integer of zeros, to indicate that the file transmission is complete.

When getfileII accepts the connection from sendfileII and receives the file
name, it will create a new file by this name in TempDir. GetfileII will then
write the data it receives from sendfileII into this file. When getfileII
receives the file block size of zero, it will close the file in TempDir and
move it to the directory for the client from which it received the
file. GetfileII will also send the three characters "ACK" back to sendfileII
when getfileII has successfully written the file to disk in TempDir.

If getfileII has errors receiving the file data, sending the "ACK", or times
out receiving or sending, it will close its active socket, delete the file
from TempDir, and go back to listening for client connections.

If sendfileII has errors connecting to getfileII, has errors sending the file,
or cannot send a packet within "TimeOut" seconds, it will close its socket,
wait for "RetryInterval" seconds, and make another attempt to send the
file. It will keep trying to send the file until it has received and
acknowledgment from getfileII.



CHANGES

2002/12/09
Changed names from getfile to getfileII and from sendfile to sendfileII, due
to changes in the protocol used by these two programs.

GetfileII now sends the three characters "ACK" to sendfileII after getfileII
has received the entire file.

SendfileII now waits "AckTimeOut" seconds for the "ACK" from getfileII after
sendfileII has completed sending the file. If sendfileII does not receive
"ACK" within the timeout interval, it assumes that getfileII did not receive
the entire file. So sendfileII will make additional attempts to send this same
file after waiting "RetryInterval" seconds.

A bug was fixed in getfileII whereby incomplete files were moved from TempDir
to the output directory. Now if getfileII failed to receive the complete file,
it will delete the incomplete files from TempDir and it will not send the
"ACK" to sendfileII.


CONTACT INFORMATION
Please direct questions and bug reports to:

The earthworm mail list:
earthw@lyris.nmt.edu 

or Earthworm Central:
bogaert@usgs.gov
