Distributed SCM Repositories

Justin R. Erenkrantz

ICS 280

December 4th, 2002

Subversion

• “Compelling replacement for CVS”

• Still has a centralized server model

• WebDAV is the core transport protocol

• How can we distribute the repositories?– Geographical dispersion– Offline access

Internal or External Replication

• Subversion internally uses Berkeley DB– Has primitive notion of replication– Can we use its replication?

• Another strategy is leverage WebDAV– Intercept calls to the original server– Proxies are well-defined by HTTP– Virtually ignored by WebDAV

Proposed Solution

• Combination of two approaches

• Master pushes out database changes– Requires registration of slave servers

• Slaves handle all operations– Read-only slaves– Handles read on its own– Transparently divert write to master