Views
A distinguishing feature of ClearCase is a proprietary networked filesystem (MVFS: MultiVersion File System), which can be used to mount VOBs as a virtual file system through a dynamic view, selecting a consistent set of versions and allowing for the production of derived objects. The dynamic view allows this to map to a Software Configuration. This was a departure from the repository/sandbox model, allowing for the early management of artifacts (before they are checked in, and not limited to these first order configuration items).
Alternatively, ClearCase supports snapshot views which are just copies of repository data specified by a config-spec which spans one or several VOBs. As opposed to dynamic views, snapshot views are maintained on a local (OS-specific) filesystem and do not require network access. Instead, a snapshot view stores a copy of the VOB data locally on the user's computer. Snapshot views can be used while disconnected from the network and later resynchronized to the VOB when a connection is reestablished. This mode of operation is similar to how the widely-used CVS (Concurrent Versions System) software works.
From the perspective of software on the client computer, a view appears as just another file system. If new data is created in a ClearCase view then ClearCase will refer to the new data (files, directories, ...) as view-private to indicate it is specific to the view being used and not being version controlled (private) by ClearCase. This allows build systems to operate on the same file system structure as the source code, and ensures that each developer can build independently of each other. A view-private object can be added to source control and become a versioned element at any time, making it visible to other users.
Each developer typically has one or more views at their disposal. It is sometimes practical to share views between developers, but sharing branches is usually used instead. Having a branch hierarchy is often useful, so an entire development project shares a common development branch, while a smaller team shares a sub-branch, and each developer has his or her own private branch. Whenever some change is deemed stable enough for a larger group, it can be merged to the parent branch.
Read more about this topic: IBM Rational ClearCase
Famous quotes containing the word views:
“But of all the views of this law [universal education] none is more important, none more legitimate, than that of rendering the people the safe, as they are the ultimate, guardians of their own liberty.”
—Thomas Jefferson (1743–1826)
“Views of women, on one side, as inwardly directed toward home and family and notions of men, on the other, as outwardly striving toward fame and fortune have resounded throughout literature and in the texts of history, biology, and psychology until they seem uncontestable. Such dichotomous views defy the complexities of individuals and stifle the potential for people to reveal different dimensions of themselves in various settings.”
—Sara Lawrence Lightfoot (20th century)
“Political correctness is the natural continuum from the party line. What we are seeing once again is a self-appointed group of vigilantes imposing their views on others. It is a heritage of communism, but they don’t seem to see this.”
—Doris Lessing (b. 1919)