Nigis RCS also has a keywords mechanism, and the keywords also take two formats, though one is for files which have not yet been inserted into RCS and the other is for those that have: Tutoriap the branch is one of the very important prospect while using version control tool. This feature is called winking in derived objects and requires that the clearmake or omake tool is used for builds. The merges from my temporary branches were fully automatic; no-one had changed the files I worked on while I had them checked out. Learn to use the merging capabilities of Clearcase or use a tool like Beyond Compare or emacs-diff.
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History[ edit ] ClearCase was developed by Atria Software and first released in  on Unix and later on Windows.
The Apollo Domain file system allowed special handler programs to intervene during file access. DSEE made use of this feature to invisibly substitute a versioned copy when a particular file was opened. DSEE relied heavily on a file that described all the software modules and their dependencies. The file had to be generated manually, which was a major impediment to its use in large systems. However, once generated, it enabled DSEE to calculate the optimum way to perform a build, re-using all modules that had previously been processed and whose version specifications matched the specifications for the build.
DSEE also introduced the "version spec," which was called a "thread. A major innovation was the use of build signatures and software release signatures in the thread. The items in a thread might thus be: Any copies reserved for editing i. A labeled version for developers working on a particular revision level The version used in build XYZ.
The version used in software release x. Threads were processed from top to bottom for each file. A developer thread might have "reserved" at the top, followed by a labeled version. For a fix to an existing release, the thread would be "reserved", then the release signature. In the absence of the invisible file redirection of the Apollo Domain file system, ClearCase uses the virtual file system provided by the MVFS feature that is described below.
The "thread" concept corresponds to the dynamic view. On this layer, maintenance takes place using Raima tooling. Around this layer, a set of interfaces with accompanying tools are used to manage the physical database system, which requires specific Database administrator skills.
Before version 7 there was a web service by which users could access ClearCase via their browsers. Views[ edit ] A distinguishing feature of ClearCase is the MultiVersion File System MVFS , a proprietary networked filesystem which can mount VOBs as a virtual file system through a dynamic view , selecting a consistent set of versions and enabling the production of derived objects.
This was a departure from the repository-and-sandbox model because it enabled the early management of artifacts that is, before they are checked in and was not limited to the management of these first-order configuration items. ClearCase also supports snapshot views, which are copies of repository data. As opposed to dynamic views, snapshot views are maintained on a local OS-specific file system and do not require network access.
Snapshot views can be used while disconnected from the network and later synchronized with the VOB when a connection is reestablished. From the perspective of the client computer, a ClearCase view appears to be just another file system.
New files and directories created in a ClearCase view are referred as "view-private" to indicate that they are specific to the view and not version-controlled.
This feature allows build systems to operate on the same file system structure as the source code and ensures that each developer can build independently of one other. At any time, a view-private object can be added to source control and become a versioned object, rendering it visible to other users. Developers typically have one or more views at their disposal. It is sometimes practical to share views between developers, but sharing branches is the more common practice.
A branch hierarchy is often useful: an entire development project can share a common development branch, while a smaller team can share a sub-branch, with each developer having his or her own private branch.
Whenever a change on a branch is deemed stable enough, it can be merged to the parent branch. The configuration specification[ edit ] Under base ClearCase, each view is controlled by its associated configuration specification, commonly referred to as a config spec. This is a collection of rules stored internally in a text file, but compiled before use that specifies what element versions files or directories are to be displayed in a view. To determine which version, if any, of an element should be visible, ClearCase traverses the configuration specification line-by-line from top to bottom, stopping when a match is found and ignoring any subsequent rules.
In the UCM management model, config specs do not need to be created or maintained manually: they are generated and maintained by ClearCase UCM operations.
This allows ClearCase to produce a bill-of-materials which it calls a Configuration Record CR for all builds and enable traceability for either software configuration management purposes or as part of a larger application lifecycle management process. Build auditing is performed with command-line tools such as a built-in make tools omake , clearmake or by using the clearaudit command, which can invoke another build tool, such as Unix make 1.
The Versioned Object Base VOB that stores versions of file elements and directory elements also stores derived objects and metadata associated with these object types. The bill-of-materials artifact produced as the result of build auditing is known as the Configuration Record.
It contains: The build procedure: The method script, makefile, and so on that invoked the build. Inputs: All files and their specific versions that were used for a particular build. The dependency information is stored in a configuration record that can be shown for each derived object.
The configuration record can be used to create another view that shows all files that have been previously read during the build time. The configuration record can also be used to apply a label to the files and versions that were read during the build.
The MVFS allows derived objects that were built in one dynamic view to be automatically "copied" to another dynamic view that requires "exactly the same" derived object. Two derived objects are deemed to be "exactly same" if they have the same configuration record that is, bill of materials. The shareable derived objects are physically present in the VOB server, not in the views that reference them. This feature is called winking in derived objects and requires that the clearmake or omake tool is used for builds.
ClearCase dynamic views are slower than local filesystems, even with a good network infrastructure. Because MVFS requires server access every time a file is accessed, the performance of the file system depends on server capacity. Client types[ edit ] Originally, ClearCase supported only full "fat" clients running native on Unix and Windows.
It is based on Eclipse software and supplied in both fully packaged Eclipse versions, as a plugin-in for Eclipse, and for other environments such as Visual Studio. Client Connection to repository of source-controlled objects View types.
History[ edit ] ClearCase was developed by Atria Software and first released in  on Unix and later on Windows. The Apollo Domain file system allowed special handler programs to intervene during file access. DSEE made use of this feature to invisibly substitute a versioned copy when a particular file was opened. DSEE relied heavily on a file that described all the software modules and their dependencies. The file had to be generated manually, which was a major impediment to its use in large systems. However, once generated, it enabled DSEE to calculate the optimum way to perform a build, re-using all modules that had previously been processed and whose version specifications matched the specifications for the build.
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