PLT Tools can access computers on a network, thereby markedly increasing the number of processors available for the conduct of NONMEM analyses. This document summarizes the means by which PLT Tools accesses a network. Network access requires the user to have a license; in addition, there is a supplemental fee for NONMEM access.

Terminology:

• SSH: Secure shells is a protocol to access remote computers. SSH is available as open-source software for all platforms. Standard installations of OS X, Linux, and UNIX include SSH. With Windows, SSH requires installation.
• Local machine: The user's desktop or laptop computer (operating system can be Windows, OS X, or Linux).
• Remote machine: A networked computer (operating system can be Windows, OS X, Linux, or UNIX; operating system need not match the local machine)

Client software: A copy of PLT Tools resides on the local machine. That machine must be configured with R or S-Plus. Installation of NONMEM (and Fortran) on that machine is optional. If NONMEM is installed on the local machine, the user can choose "Local Only" or "Remote Only" options; alternatively, PLT Tools can attempt to access the local machine for NONMEM runs either before or after the remote machines.

Network access via SSH (secure shells): Each local machine must be configured with SSH; a file "RemoteMachines.txt" must be installed in the PLTTools folder. When the user executes "Run NONMEM + Graphics" or "NONMEM Only", the following steps occur:

• PLT Tools queries (local and) remote machines in sequence to determine if a computer is "available" for a NONMEM job ("availability" is defined as the number of NONMEM jobs in progress being < the number of core processors available on that computer).
• If a computer is available, the control stream and dataset are copied to a temporary folder on that machine and the job is executed.
• Every several seconds, certain files are copied from the remote machine to the local machine.
• If these files indicate that the NONMEM job is in progress, the Real-Time Parameters and Analysis windows are updated.
• If the job is no longer in progress (either because it aborted prematurely or is complete), all files are copied to the local machine and are processed in the usual manner.
• The remote machine on which the analysis was conducted is recorded in a PDF document.

Network access via grid software: If a network already supports transfer to NONMEM jobs to remote machines, PLT Tools can be linked to existing software. Typically, this would involve the following:

• When "Run NONMEM + Graphics" or "NONMEM Only" is executed, PLT Tools copies the control stream and dataset to a temporary folder on the local machine. In addition, a token is sent to the grid controller indicating that a job is ready.
• The grid controller copies the files to the remote machine and monitors its progress. When the job is complete, the grid controller copies all files to the temporary folder on the local machine. Ability to monitor real-time parameters will differ between operating systems and software setups.
• PLT Tools then performs post-processing in the usual manner.
• The remote machine on which the analysis was conducted is recorded in a PDF document.

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