Why is SOS faster than VSS over the Internet?

A collection of information about SourceOffSite, including solutions to common problems.

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Why is SOS faster than VSS over the Internet?

Post by lbauer » Thu May 18, 2006 9:36 am

This information applies to SOS and VSS 6.0x.
SourceOffSite is a client server application that provides remote access to a Visual SourceSafe database. In most cases, SourceOffSite is 10-12 times faster than using Visual SourceSafe remotely (over the Internet or via dialup).

There are a number of reasons SOS is faster than VSS for remote users.

SOS is a client/server application that uses a TCP/IP based protocol for communication between client and server, while VSS is an application that uses Windows File Sharing between the client and the VSS database. Over low-speed, high-latency networks, the difference becomes noticeable.

While VSS was not designed for low speed, high latency networks, SOS was. VSS was designed for high speed LANs and the way VSS interacts with the database to obtain files and metadata is what causes VSS to be difficult to use over the Internet.

SOS is designed so that, to the VSS database, the SOS Server appears as a VSS client. The SOS Server communicates with the VSS database via the SourceSafe Automation Component. It uses Windows Files Sharing and interacts with the database in the same way as a VSS Client. But the SOS Server is sitting on the LAN where there is enough bandwidth for these VSS operations.

The SOS Server communicates with the remote client only when the client request file lists, files, sends files, or executes other commands. The Project Tree is cached on the SOS Client side, and only refreshed at the user's request. A remote VSS client on the other hand, will constantly refresh the project tree. This is a very expensive operation, and a real performance hit.

The client cache allows the SOS Client to determine file status. Files in the working directory which have not changed are not re-fetched during a Get Latest operation, as happens with a Visual SourceSafe client.

In most situations SOS is faster than VSS when used remotely. We recommend that users try our 30 demo in their specific network environment to see how SOS will work for them.
Linda Bauer
Technical Support Manager

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