An Installable Version Control File System for Unix

Abstract

SUMMARYWe present a file system named VCFS, a Version Control File System that provides transparent version control of files. VCFS is implemented as an installable file system in the Unix operating system. The facility is transparent to users in the sense that VCFS automatically stores changes between incremental versions of a file without user intervention. Access to the latest version of the file retains traditional Unix semantics, enabling all existing Unix applications to be run modified under VCFS if so desired. VCFS provides system call enhancements and supports application level utilities for version number retrieval, displaying changes between two versions of a file, upgrading to a new release number, and related version control functions. Performance measurements show that VCFS provides a significant increase in version control operations compared to application level change management systems such as SCCS, and that the space utilization is significantly better than of the existing version control systems. The primitives and facilities provided by VCFS can be exploited for use in a wide range of applications, ranging from immutable files, transaction processing and file replication support in a distributed file system, to the development of enhanced change management control systems for software project management. ©1997 by John Wiley & Sons, Ltd.key words: version control; software engineering; installable file system; immutable files THE NEED FOR VERSION CONTROL FILE SYSTEMS Efficient version control mechanisms are increasingly required by a wide range of Unix applications. In distributed systems which support file replication across distinct hosts, versioning support is necessary to identify copies of the same file stored on different hosts and determine the hosts that have the latest version of a file.

Management competences, not tools and techniques: A grounded examination of software project management at WM-data

“…4). [16][17][18] Project data analysis PDA Analysis of existing project data (typically collected for the purposes of managing a project, rather than for research purposes) [19,20] Laboratory experiment LE Investigation of laboratory subjects' interaction with a software management tool, often a simulation [21,22] Computer science conceptual CSC Desk-based development of metrics, algorithms, models and simulations intended to support the software management process [23][24][25] Software development SD Development of a software product intended to support the software management process [26][27][28] Theoretical TD Theoretical discussion or meta-discussion other than computer science [29,30] The analysis confirms that the field is largely prescriptive and tool and technique oriented. Researchers focus their attention on the development of tools and techniques; often intended for use by software project managers.…”

“…There is widespread use of mathematical models and solution algorithms. The tools and techniques include: refinements to techniques for estimation [38,46,47], risk management [20,30,48,49], quality assurance [43,50], knowledge reuse [51], project management audits [52], inspections [53], version control [26], metric use [24,32,35,54,55], testing [56], scheduling [44], and workload management [57]. They aim almost exclusively to support the management of the software process, rather than other elements of management reported below in our analysis of WM-data's practice.…”

“…The approach is largely mathematical and algorithm-based, employing Petri nets [58], genetic algorithms [59], fuzzy logic [44], entropy calculation [41], Kepner-Tregoe program, [60], bi-directional simulation [23], data mining [25], Monte Carlo simulation [61] and graph grammars [62]. There is a concentration on software support for process management: expert simulator [43], Unix file system [26], co-operative work support system [63], decision support system [44], project management support system [27], risk projection [60], Object Database Support for Software Project-Management Environment [64], and knowledge-based tools [54]. A significant strand in project management education is advanced through the development of simulations [21,65,66], and simulation techniques also play a significant role and understanding project management [61] and as a management tool [67].…”

A software product model emphasizing relationships

“…In addition to the models described above, we also surveyed various version control models [17][18][19][20][21], which manage versions inside a single product. All those models do not manage inter-DEP relationships.…”

“…We surveyed quite a few models for configuration management and version control [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] (see section 5 for the discussion of related work), and identified that some of them manage configurations and versions within a single product [6, 8, 10, 13-14, 17-21, 24]. With these models, product management across products such as inter-product change ripple effects management, reference incompleteness management, and identification of correlated products for reuse cannot be achieved.…”