Read only and mirror web support

Scope

This topic describes how to set up read-only webs. A read-only web can be mirrored from another site. But how to mirror a web from another site is out of scope.

Motivation

There are cases where read-only webs are useful.

  • %SYSTEMWEB% web being a part of installation rather than a content, it may reside in read-only storage. In that case, It's better for TWiki to recognize as such and not to allow update operations rather than update operations causing errors. Even if you don't see an edit or attach link, users may enter an edit or attach URL manually. In that case, the edit and attach scripts should display "operation not allowed" kind of message.
  • You may want to run a federation of TWiki sites, in which member sites have read-only mirror of other sites' webs. Read-only mirror webs are not so useful for tight collaboration because of the time lag of mirroring, which typically happens once a day. But it's useful for a web viewed by many users geographically distributed.

Master and slave

Let's assume a federated TWiki sites depicted on MetadataRepository#Federation_of_sites. Each web has one master site and the other sites are slave. On such a web, updates happen only on the master site and the slaves get those changes when they mirror the web.

Local webs

Each site in a federation needs to have some webs locally without sharing them with other federation members - definitely with the Trash web. It's not critical but the Sandbox web should not be mirrored hence should be local to each site.

If this feature is not turned on, all webs are regarded local.

Content modes

Given the explanation so far, a web is either of the following content modes.