Silva's Groups functionality comes from a separate product called Groups (surprise). Your Silva may not have Groups installed, in which case you won't see anything about Groups in the Access screen.
It could also happen that the Groups product is installed on the file system, but hasn't been activated in Silva. In that case you see a warning message in the Access screen, with instructions about what steps to take.
Groups can be managed in a subscreen of Access,
reachable via the groups admin button (alt-g) in the
‘existing groups’ box on the right in the Access screen.
Fig. 1 Groups admin.
Silva also offers the ability to group users together and assign a role to a whole group at once. This means whenever a group has a role in a location and a user is a member of that group, the user will also have this role. The group system can be used to manage small groups of Authors and Editors, but is particularly useful when managing the Viewer role, in which case groups could have a large amount of members.
Managing the role assignments of groups is done in much the same way as managing the role assignments of users. The only difference is that groups are not looked up in a separate screen; they are always available in the groups list in the right column of the Access screen.
If Silva has been connected to LDAP, group membership information can be configured to be retrieved from the LDAP server. This allows the reuse of groups defined centrally on such a server, and can scale to many users and large groups.
Silva supports a number of different kinds of groups.
Normal Groups are made out of users. These users are stored in Zope directly by Silva.
Virtual Groups are composed of other groups. Note that a user must be a member of all groups that are included in the Virtual Group, in order to gain the roles assigned to the Virtual Group.
IP Groups specify a range of IP addresses. IP Groups determine membership based on the IP address of the computer the user is using. This way, a user can be given a role only if the user has a particular IP address.
It's thus possible to give all users accessing Silva from your local network, intranet or campus network a particular role. This is particularly useful when using the Viewer role to restrict access; an area of the site could be closed for all users except those on a certain network. Silva can function as an Intranet in this manner.
Using a Virtual Group you could even require that someone is in a particular network as well as being in another group in order to gain access.
Note that protecting access based on IP address is only a minimal security measure. The inherent weaknesses of the underlying IP protocol do not allow strong identification of users.
Using IP groups also may not work in all setups of Silva, as proxy servers could be in play.
In addition to the three built-in groups, it's possible for group membership information to be retrieved from an external source like LDAP. In this case the group cannot be managed from Silva directly, but is available nonetheless to assign roles to.
In the Groups screen new groups can be created and existing groups managed. The interface is much the same as the Contents screen. New groups can be created in the “create a group” box. Type in an id and select a group type, then clicksave (alt-s) or save + edit (alt-e). Groups can be deleted with the delete button (alt-d).
Once created a group will appear in the Access screen “existing groups” clipboard, and will be available throughout the Silva site.
It's important to understand that groups are created in a specific location in Silva, much like content, and while they appear globally they can only be edited by going to the folder where they were initially created. For this reason it's advisable to locate all your groups on an upper level of the Silva site.
Click the name of a group in order to edit it (add or remove users). This takes you to the Group workspace. Existing members are listed in the “group members” box, and can be removed with the remove users button (alt-r). New users can be added via the clipboard. If the clipboard is empty, click the lookup users button (alt-l) to go to the Lookup screen, where you can collect users on the clipboard.
It's possible to combine members of existing groups into the one
you're editing. Select from the “existing user
groups” clipboard and click the copy users from group
button. All users in the selected groups will be copied to the group
being edited.
Further Groups screenshots at Chief Editors - Groups
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