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:
“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)
“Meek young men grow up in libraries, believing it their duty to accept the views which Cicero, which Locke, which Bacon, have given, forgetful that Cicero, Locke, and Bacon were only young men in libraries, when they wrote these books. Hence, instead of Man Thinking, we have the book-worm.”
—Ralph Waldo Emerson (1803–1882)
“It is surely a matter of common observation that a man who knows no one thing intimately has no views worth hearing on things in general. The farmer philosophizes in terms of crops, soils, markets, and implements, the mechanic generalizes his experiences of wood and iron, the seaman reaches similar conclusions by his own special road; and if the scholar keeps pace with these it must be by an equally virile productivity.”
—Charles Horton Cooley (1864–1929)