[SCM] source code management-Overview

I. source code management tools

Source code management (SCM/source code management), also known as the version control system (VCS/version control system ).

 

1) Why do we need SCM/VCs?

1. backup and recovery: source code is the wealth of software companies. backup and recovery are used to prevent unexpected losses;

2. Synchronization: MultipleProgramInter-member implementationCodeSharing and synchronization;

3. Short-term revocation: Generally, if a developer's submission results in a break, the submission that leads to the break can be revoked;

4. Long-term revocation: If a bug is submitted a long time ago, it can be removed to the submitted version for debugging;

5. Tracking changes: every time a change is submitted, there is a comment, and the change history will be saved. We can also see the submission time, author, and other information;

6. Sandbox: before submission, developers generally need to ensure that the build is successful and the function runs normally. The local working copy is equivalent to the sandbox to ensure that the submitted source code works normally;

7. Branch and merge (branch and merge): In the module development of the software, the Branch is used for independent module development. After the module development is complete, it is merged together;

 

2) lock type or merge type, lock/merge, source code management tool, according to whether to allow multiple people to modify a file at the same time, divided into merge and lock; lock type, if there is a developer checkout file, other developers cannot checkout; merge type, allowing multiple people to simultaneously Checkout the same file, and then merge at the time of submission. Compared with lock, merge is more flexible and more helpful for collaboration among multiple developers. Now, basically all source code management tools are of the merge type, and merge and lock are also supported.

 

3) centralized and distributed: SERVER + client (centralized)/distributed (decentralized). Traditional source code management is centralized, and all developers have only one copy locally, it must be submitted to the same server repository in the set before it can be shared with other developers. In the recent emerging Distributed Source Code Management, developers not only have working copies locally, there is also its own repository. Each developer's local repository can be used as a server, so that developers can better share the repository before submission.
 

4) Basic Concepts

Source code repository (repo): the database that stores files;
Server: The computer that stores the repo;
Working Set/working copy: The local copy of the developer. The developer obtains the copy from the server's code repository (server repository), and then modifies and submits the copy;

 

2. centralized source code management

1) common centralized source code management tools

SOFTWARE | free or not | client/sever or distributed | merge or lock | platform | website

CVS | GPL/free | Client/Server | merge | all platform | http://www.nongnu.org/cvs/

SVN | Apache/BSD/free | Client/Server | merge or lock | all platform | http://subversion.tigris.org

Perforce | inclucial | cient/Server | merge or lock | all platform | http://perforce.com

Team Foundation server | Administrative cial | Client/Server | merge or lock | Windows | http://microsoft.com

2) Features

Centralized source code tool (centerlized, server/client), developers only have one working copy (working copying) locally, each commit (COMMIT) all are submitted to the only source code repository (server repository) shared by all developers. The developers share the Code through the unique source code repository (server repository.

 

3) Basic Concepts

Check out: Obtain the latest working copy, and record the current version as the base of the working copy to be modified;

Commit: Submit modifications to the local copy to the code repository on the server;

 

4) Basic Process

 

 

Three distributed source code management tools

1) Common distributed source code management tools
SOFTWARE | free or not | client/sever or distributed | merge or lock | platform | website

Bazaar | GPL/free | distributed | merge | all platform | http://wiki.bazaar.canonical.com/

Git | GPL/free | distributed | merge | all platform | http://git-scm.com

Mercurial | GPL/free | distributed | merge | all platform | http://mercurial.selenic.com/

 

2) Features

Distributed Source code management tools, developers not only have working copies locally, but also their own code repositories. In this way, any two developers can share the code before submitting it to the real server code repository through the pull operation of their local code repository. Developers can have multiple versions before submitting them to the real server code repository. developers can work offline and pull them to the real server code repository when there is a network; the commit operation is faster;

 

3) Basic Concepts

Update: Reflect the latest local code repository to a local working copy;

Commit: At this time, the submission is only submitted to the local development code repository;

Push: Submit the local code repository to another remote code repository;

Pull: Synchronize another remote code repository to the local code repository;

 

4) Basic Process

 

Refer:
A visual guide to Version Control: http://betterexplained.com/articles/a-visual-guide-to-version-control/
Intro to distributed version control (Distributed strated): http://betterexplained.com/articles/intro-to-distributed-version-control-illustrated/

Comparison: http://versioncontrolblog.com/comparison/CVS/Git/Mercurial/Subversion/Visual%20SourceSafe/index.html

 

Complete!