In a standard FTP site, all users share access to an area of storage and, depending upon the permissions in place, they might overwrite each others' work. P4FTP uses a Perforce approach, in which each P4FTP user has a private workspace that is mapped to shared areas of the Perforce depot. When a file is uploaded, it is opened for add or edit as appropriate, and locked. When the file is submitted, it becomes the new head revision. Another user who has the same depot path in their FTP client workspace can then download the updated version of the file.

P4FTP uses its client workspaces as temporary storage. Operations such as directory listings are performed by querying the Perforce server, and are always up-to-date.

Standard FTP transfers files one at a time, and there is no facility for grouping changes. One of the key benefits of Perforce is that related changes are grouped together into changelists. P4FTP groups all changes (adds, edits and deletes) made in a single FTP session into one changelist that is submitted at the end of the session.

The following sections describe how your files are transferred between your client computer and a Perforce depot.

The FTP command pwd (print working directory) normally displays the current directory on the remote computer. When you use P4FTP, the pwd command displays the Perforce depot directory but uses the client operating system convention.

For example, if you are connecting from a Windows computer to a depot on a UNIX computer, when you issue the pwd command, the working directory might be displayed as c:\p4client-test\depot.

The following FTP commands are supported by P4FTP. The names in braces are the commands used by common FTP clients, and the uppercase names represent the actual protocol commands.

P4FTP uses only the default changelist. If a submit fails for any reason, Perforce turns the default changelist into a numbered changelist. To ensure that files opened under numbered changelists do not become abandoned, P4FTP consolidates all files opened on a client into the default changelist. Users can resolve most problems by simply retrying, without the assistance of an administrator.

Due to the design of the FTP protocol, P4FTP cannot prompt the user for a description when a changelist is submitted, so a default description is used. If the ability to describe changelists is important to you, use the p4 command line client or P4V.

To override the default change description, specifying the desired description using the -t command line flag when you start P4FTP.

For new files being uploaded to the server, P4FTP uses the Perforce filetype detection mechanism to determine whether a file is a text file or a binary file. For files that already exist on the server but are being updated, P4FTP uses the filetype of the previous revision so that files marked as ktext or binary+S, for example, retain this type of information.

A standard Perforce client workspace is populated with revisions of files in the depot, and is periodically synced to the head revision to obtain changes made by other users. Because P4FTP uses its client workspace only for temporary storage, users do not need to sync to keep the workspace up to date.

P4FTP stores the following types of files in client workspaces:

The client workspace used by P4FTP provides:

After every successful submission, all files in the submitted changelist are removed from the client workspace using p4 sync filename#none. When a user requests a file from P4FTP using the FTP get command, P4FTP retrieves the head revision of the file from the depot, transfers it to the user and then removes it from its workspace by syncing it to #none. This feature enables large areas of the depot to be mapped without wasting disk space.

The only files that are typically present in the client workspace are files that the user is actively using. To prevent empty directories from cluttering the client workspace, you enable the rmdir option when you create clients specifications.

To diagnose client workspace problems, use the p4 command or P4V.

All files opened for add or edit and delete are locked by P4FTP to prevent other users from submitting their change first and thereby denying P4FTP access to the head revision. If a file is locked when a user tries to upload it using P4FTP, permission is denied until the lock is released.