The Unisys Data Management System II (DMSII) is a database system originally created by the Burroughs Corporation in 1972. It was available on the Burroughs (later Unisys) Small (B1000), Medium (4000, V Series) and Large System (5000, 6000, 7000) product lines. The later, A Series, Clearpath, Libra product lines support it and in recent releases of Unisys Clearpath software it has been renamed as the Enterprise Database Server for ClearPath MCP. The original DMS II used a network model.[1]
The Burroughs Corporation was a major American manufacturer of business equipment. The company was founded in 1886 as the American Arithmometer Company, and after the 1986 merger with Sperry UNIVAC was renamed Unisys. The company's history paralleled many of the major developments in computing. At its start, it produced mechanical adding machines, and later moved into programmable ledgers and then computers. It was one of the largest producers of mainframe computers in the world, also producing related equipment including typewriters and printers.
Unisys Corporation is an American global information technology company based in Blue Bell, Pennsylvania, that provides a portfolio of IT services, software, and technology. It is the legacy proprietor of the Burroughs and UNIVAC line of computers, formed when the former bought the latter.
In the 1970s, Burroughs Corporation was organized into three divisions with very different product line architectures for high-end, mid-range, and entry-level business computer systems. Each division's product line grew from a different concept for how to optimize a computer's instruction set for particular programming languages. The Burroughs Large Systems Group designed large mainframes using stack machine instruction sets with dense syllables and 48-bit data words. The first such design is the B5000 in 1961. It is optimized for running ALGOL 60 extremely well, using simple compilers. It evolved into the B5500. Subsequent major redesigns include the B6500/B6700 line and its successors, and the separate B8500 line. 'Burroughs Large Systems' referred to all of these product lines together, in contrast to the COBOL-optimized Medium Systems or the flexible-architecture Small Systems (B1000).
It originally competed with IBM's IMS and CICS products and predated the popularity of relational databases.
Customer Information Control System (CICS) is a family of mixed language application servers that provide online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE.
History
DMSII provided an ISAM (indexed sequential access method) model for data access, transaction isolation and database-recovery capabilities. The database schema was written in the proprietary Data and Structure Definition Language (DASDL). The DASDL source code was compiled with a system utility into a file containing the metadata for the database (known as the description file). A database-utility program would use the database description file to create the remaining components of the database.
ISAM is a method for creating, maintaining, and manipulating indexes of key-fields extracted from random data file records to achieve fast retrieval of required file records. IBM developed ISAM for mainframe computers. Today the term is used for several related concepts:
The database schema of a database system is its structure described in a formal language supported by the database management system (DBMS). The term "schema" refers to the organization of data as a blueprint of how the database is constructed. The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database. These integrity constraints ensure compatibility between parts of the schema. All constraints are expressible in the same language. A database can be considered a structure in realization of the database language. The states of a created conceptual schema are transformed into an explicit mapping, the database schema. This describes how real-world entities are modeled in the database.
Proprietary language compilers (such as COBOL and ALGOL) would use the database description file to create database-related elements in the object code of the compiled program. These compilers used language extensions to provide a more natural interface to the database by the programmer. A number of intrinsic functions were inserted by the compiler to ensure the program and database used the same definition of database structures.
COBOL is a compiled English-like computer programming language designed for business use. It is imperative, procedural and, since 2002, object-oriented. COBOL is primarily used in business, finance, and administrative systems for companies and governments. COBOL is still widely used in legacy applications deployed on mainframe computers, such as large-scale batch and transaction processing jobs. But due to its declining popularity and the retirement of experienced COBOL programmers, programs are being migrated to new platforms, rewritten in modern languages or replaced with software packages. Most programming in COBOL is now purely to maintain existing applications.
ALGOL is a family of imperative computer programming languages, originally developed in the mid-1950s, which greatly influenced many other languages and was the standard method for algorithm description used by the ACM in textbooks and academic sources for more than thirty years.
Originally, DMSII maintained a data dictionary that the application programmer referenced in its source code. The source for the data structures was maintained in an ordinary CANDE source file. That source was then compiled with the DASDL compiler, which created the dictionary (description file) if none existed prior. If a dictionary did exist, the new design indicated by the source file was incorporated into the dictionary; the programs to copy the data from the old file structure(s) and write to the new file structure(s) were automatically generated (a database reorganization task). The application programmer merely needed to re-compile his application source (typically COBOL) against the new description file and the programmer could take advantage of new data elements in the structures.
CANDE is a command line shell and text editor on the MCP operating system which runs on the Unisys Clearpath series of mainframes. Implemented on Burroughs large systems, it has a range of features for interacting with the operating system execution environment, focused on executing, editing and compiling programs, and creating, copying, moving, renaming, and deleting files in general.
DMSII used the concept of "sets" for data storage. A data set contained rows of data, and could be random or ordered. Since DMSII supported both hierarchical and relational models, a data set could be disjointed or embedded. Table indexes were implemented in index sets, and could be full sets or subsets of the target data set. Subsets could be designated as automatic subsets (with rules to select records from the target data set for inclusion) or manual subsets (which used programmatic interfaces to insert and remove records).
Index sets included ISAM styles (which used field keys to reference records) and bit-vectored sets (which used Boolean representation of set membership if the data set record met conditions defined in the set). Like ISAM, it used sets (indexes where all records were referenced, such as the index in Microsoft Access), subsets (a partial list of records dependent upon a definable condition, e.g. females for a database with a "sex" field) and bitmaps (a set of records meeting a certain condition (true/false) on the data set). Those features achieved considerably faster performance in accessing data, with the small penalty of extra time spent on creating a new record if many subsets were defined.
In mathematics and mathematical logic, Boolean algebra is the branch of algebra in which the values of the variables are the truth values true and false, usually denoted 1 and 0 respectively. Instead of elementary algebra where the values of the variables are numbers, and the prime operations are addition and multiplication, the main operations of Boolean algebra are the conjunction and denoted as ∧, the disjunction or denoted as ∨, and the negation not denoted as ¬. It is thus a formalism for describing logical relations in the same way that elementary algebra describes numeric relations.
Microsoft Access is a database management system (DBMS) from Microsoft that combines the relational Microsoft Jet Database Engine with a graphical user interface and software-development tools. It is a member of the Microsoft Office suite of applications, included in the Professional and higher editions or sold separately.
It was claimed that a network-type database could be built using manual-subset capability. This was risky, since it depended upon user programs to add and remove records in a manual subset. There is a substantial difference between DMSII and relational databases: in DMSII, a record can only be retrieved via an index if the index was designed initially (or after a reorganization which generates a new subset from all the data in the set). In the relational model, this is a runtime operation.
In 1988 Burroughs attempted to make an object-oriented model database known as Infoexec, which was an extra layer atop DMSII. That layer was programmed in Pascal and followed the runtime-selection approach, as the relational model does. Designed by Mike Hammer and Dennis McLeod at the Massachusetts Institute of Technology, it performed poorly.
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Distributed Data Management Architecture (DDM) is IBM's open, published software architecture for creating, managing and accessing data on a remote computer. DDM was initially designed to support record-oriented files; it was extended to support hierarchical directories, stream-oriented files, queues, and system command processing; it was further extended to be the base of IBM's Distributed Relational Database Architecture (DRDA); and finally, it was extended to support data description and conversion. Defined in the period from 1980 to 1993, DDM specifies necessary components, messages, and protocols, all based on the principles of object-orientation. DDM is not, in itself, a piece of software; the implementation of DDM takes the form of client and server products. As an open architecture, products can implement subsets of DDM architecture and products can extend DDM to meet additional requirements. Taken together, DDM products implement a distributed file system.
