Code Management System

The Code Management System (CMS) is a library system for software development and maintenance, part of DECset. Its features include:

• storing code and other related files in libraries
• controlling versions of code (generations)
• manipulating groups of objects as a unit
• manipulating versions of the entire system (classes)
• managing code reviews
• keeping track of history and storing comments
• merging changes made to different generations of the software
• additional security mechanisms
• providing notifications when an event occurs

Concepts

• A CMS library is a repository for CMS objects. It resides in a directory that has been initialized for use solely by CMS; your default directory cannot be a CMS library. The CREATE LIBRARY command creates CMS control files in the specified directory. A working library is chosen with the SET LIBRARY command; CMS$LIBRARY logical is defined to point to your current library. Once the library is created, it should only be accessed through CMS commands.
• A CMS element represents all versions of a particular file in a CMS library. An element cannot be a directory file.
• A CMS generation represents a specific version of an element. When an element is first created, CMS creates generation 1 of that element. When the element is later modified (reserved and replaced), CMS creates a new generation of that element.
• A CMS group is a set of elements that can be manipulated as a unit.
• A CMS class is a set of particular generations of elements. Typically generations of elements are combined into classes to represent progressive stages, or base levels, in the development of an entire system.
• A reservation is when an element is taken out for modification and then replaced with a new version.
• A reference copy directory is a directory that stores the copies of the latest main-line generation of selected library elements.

Working with Libraries

A CMS library is a bit like a Git repository: it is a directory where the code files are stored and where CMS stores its files. All CMS work happens within a library. To start working with CMS, you need to create a library first.

If there is already a CMS library in a directory, you can just do a CMS SET LIBRARY followed by that directory:

$ CMS SET LIBRARY [JDOE.TEST]

Files that are already in the directory can be added to the library with the following command:

$ CMS CREATE ELEMENT/KEEP full-path-to-file "Commit message"

To create a CMS library, make sure your default directory is NOT the directory that you want your CMS library to be in. Then execute CMS CREATE LIBRARY directory-specification "Commit message":

$ CMS CREATE LIBRARY [.TEST] "First library"

To display elements in the library, issue the CMS SHOW ELEMENT command:

$ CMS SHOW ELEMENT

Working with Elements

Elements in a library are files that you want to track, e.g. code files. Add them to the library with the CREATE ELEMENT command; if the file already exists, use the /KEEP qualifier:

CMS CREATE ELEMENT/KEEP TEST.C "First version"

To change an element:

• RESERVE it
• edit it
• REPLACE it

For example, here is how to change TEST.C:

First, set the library where the file is:

CMS> set library [.test]
 %CMS-I-LIBIS, library is WORK7:[JDOE.TEST]
 %CMS-S-LIBSET, library set
 -CMS-I-SUPERSEDE, library list superseded

View the latest generation for TEST.C:

CMS> show generation test.c

Element generations in CMS Library WORK7:[JDOE.TEST]

TEST.C        3      16-DEC-2022 07:26:30 JDOE"Changed the message"

Reserve the file. By default, the latest generation is reserved; you can specify the generation using /GENERATION:

CMS> reserve test.c
_Remark: "Add another message"
%CMS-S-RESERVED, generation 3 of element WORK7:[JDOE.TEST]TEST.C reserved

Exit CMS and edit the file using EVE:

CMS> exit
$ edit test.c
#include<stdio.h>
void main()
{
printf("Hello Everyone!");
printf("Goodbye!");
getch ();
}
[End of file]
Buffer: TEST.C
7 lines written to file WORK7:[JDOE]TEST.C;2

Enter CMS and see that the file is still reserved:

$ cms
CMS> sh reservation

Reservations in CMS Library WORK7:[JDOE.TEST]

TEST.C
   (1)   JDOE   3      16-DEC-2022 08:56:18 "Add another message"

Replace the file:

CMS> replace test.c "Added a message"
%CMS-S-GENCREATED, generation 4 of element WORK7:[JDOE.TEST]TEST.C created

See that the new generation has been added:

CMS> sh generation

Element generations in CMS Library WORK7:[JDOE.TEST]

TEST.C        4      16-DEC-2022 08:57:11 JDOE "Added a message"

Variant Generations

To create an alternative development path for an element (similar to a branch in Git, but for a particular file), you need to create a variant generation. When you replace the file, use /VARIANT to specify a letter that will be used to refer to that variant generation:

$ CMS RESERVE TEST.C
$ EDIT TEST.C                    !some edits happen here
$ CMS REPLACE TEST.C /VARIANT=C

Before, there were 4 generations of TEST.C: 1, 2, 3 and 4. After the REPLACE command is executed, generation 4C1 appears. If then CMS RESERVE TEST.C is executed without /GENERATION, generation 4 is reserved and when the file is replaced, generation 5 is created. To reserve generation 4C1, execute RESERVE TEST.C /GENERATION=4C1; when the file is replaced, generation 4C2 is created.

Merging

You can merge two variant generations into one with RESERVE/MERGE:

CMS> reserve test.c /merge=4c2
_Remark: Merging the Christmas version with master
 %CMS-W-MERGECONFLICT, 0 changes successfully merged with 1 conflict
 %CMS-W-RESERVED, generation 5 of element WORK7:[JDOE.TEST]TEST.C reserved and merged with 4C2
CMS> sh generation test.c

Element generations in CMS Library WORK7:[JDOE.TEST]

TEST.C        5      16-DEC-2022 08:57:11 JDOE "Added a message"
CMS> exit

Because the same lines were changed in versions 5 and 4C2, there was a merge conflict. When we EDIT the reserved file, it looks like this:

$ edit test.c
#include<stdio.h>
void main()
{
**************** Conflict 1     ************************************************
printf("Goodbye!");
printf("Hello Everyone!");
********************************************************************************
printf("Merry Christmas Everyone!");
printf("And happy New Year!");
************** End of Conflict 1     *******************************************
getch ();
}
[End of file]

When the conflict is resolved, generation 6 of TEST.C is created.