So far I’ve been using SVN, and now is in need to pick up ClearCase quickly, from developer’s perspective. Is there any good resource for this? Thanks.
— add on —
Is there a map between SVN’s concepts/terminologies (i.e. repository, working copy, trunk, branch, tag, checkout, commit, update, revert) with CC’s? Base on initial reading I came out with the following.
Repository => VOB?
Working copy => Snapshot view?
Trunk => ??
Branch => Integration stream? development stream?
Tag => Label? Baseline?
Checkout from repo as working copy => Checkout from VOB as snapshot view?
Commit from working copy into repo => Checkin from snapshot view into VOB?
Update => Rebase?
Revert => ??
?? => Deliver
AFAIK CC has its own unique concepts, thus I can’t tell the nearest map.
You can start by reading my SO answers:
The two main differences you need to be aware of is:
ClearCase is file-centric, not repository centric, meaning you get read-only files you need to checkout one-by-one to be able to modify, (and you “commit” (checkin) one by one as well): no global workspace revision here
ClearCase consider branching as true metadata, and not as a “directory” with a cheap copy in it: there is non “directory” with the name of a branch in it.
That being said, quickly:
Repository => VOB:
Yes: VOB is just another term for repo (Versioned Object base). It is not a SQL database, but an old Atria flat files base.
Working copy => Snapshot view?
Snapshot view is the closest access mechanism from a working copy, since it copies files on your hard drive.
Dynamic view achieve the same access to a working copy… without copying anything on your hard drive, which is interesting for quick consultation purpose.
Trunk => ??
“
main“: that is the main branch in ClearCase (every element — file or directory — in ClearCase has at least one version on “main”), but actually there is no trunk except the one branch you choose as trunk.Branch => Integration stream? development stream?
A stream is not a branch. It is a metadata with the list of labels (baselines) you need to work. At that is, only if you chooses to use UCM. Otherwise, a branch is any branch you can create without UCM (
mkbranch myBranch).A stream can serve as a pattern to create a branch named after it: any checkout you make within an UCM view (a view configured automatically after a Stream) will create a branch named after its stream.
Tag => Label? Baseline?
First a tag is not a directory with a cheap copy like UCM.
It is a label applied on any version you need to be referenced by it.
The difference between a label (non-UCM) and a baseline (UCM) is that a Baseline is a label applied on all files of a (UCM) component (group of files), whereas a label can be applied on any element of your choice, like only a subset of a given group of file.
Checkout from repo as working copy => Checkout from VOB as snapshot view?
Almost, but the right term for snapshot view is “update”.
For a dynamic view, you don’t even need an update (or svn checkout), since the view is … dynamic: you just see the right working copy through the network instantly. It is just another access mechanism.
Commit from working copy into repo => Checkin from snapshot view into VOB?
Not quite, since a commit will concern all modified files, while a checkin will be file-by-file (even though ClearCase 7.1.1 has introduced the notion of “atomic checkin”: see checkin man page).
Update => Rebase?
Nope: means update in snapshot view (an nothing in dynamic view since it is dynamic: any changes made in another view with similar selection rule will be visible instantly in your view)
Rebase is an UCM merge being done being a branch from a parent stream to a branch from a child stream. In the end, it is just a merge.
Revert => ??
Not trivial… It is a substractive merge.
?? => Deliver
Deliver and Rebase are just merges between branch “source” and branch “destination”:
The only advantage being you can “see” your merge workflow in advance be defineing a hierarchy of streams (which are nothing but a list of labels), knowing that any merge between: