Topic: a single system image

topics > computer science > Group: distributed systems


hypertext as a global database
identifying the user interface with the system
heterogeneous database
managing shared memory
open systems
replicated data
specification and design of distributed systems
system integration
unique names


Users want to interact with distributed systems as if it was one system. This unification can be done at file level (Vice), name level (Clearinghouse), information level, or function level. (cbb 12/88)
Subtopic: single system image up

Quote: a single system image insulates users from distributed systems [»giffDK12_1985]
Quote: there should be a single UserInterface for all computing tasks [»mccrDL10_1984]
Quote: extraordinary ability to unify things; e.g., clutch, gear, accelerator, brake [»nelsTH_1974]
Quote: ZOG is a UserInterface to all computing resources [»robeG5_1981]
Quote: even when distributed, all services should be as if from a centralized data bank [»nelsTH_1987]
Quote: emphasize integration of tools and users [»akscRM5_1984]

Subtopic: shared state up

Quote: the primary challenge of distributed systems is shared state; shared memory is the most natural model [»cherDR3_1988]
Quote: make communication look like memory via ports (a queue of buffers), message screening or filtering, and logical addressing [»cherDR5_1986]

Subtopic: system-wide names up

Quote: a unique, system-wide name for an object provides world-wide, transparent access and simple directories

Subtopic: one religion up

Quote: should there be multiple religions (i.e., views of a system) or only one?
Quote: reality is closer to one true religion because there exists a global reality that subsumes all local views [»wegnP10_1986]

Subtopic: examples of unified, distributed systems up

Quote: Vice removes worries about replication of data; just store it in Vice [»boreN2_1988]
Quote: in Vice, mail recipients can be on any machine [»boreN2_1988]
Quote: Grapevine treated as one, large computer; propagation delays can surprise [»schrMD2_1984]
Quote: all Grapevine servers can accept and send mail from/to anyone; but delays differ [»schrMD2_1984]
Quote: Clearinghouse assumes one global database that is decentralized [»oppeDC7_1983]
Quote: clients may use any name known anywhere in Clearinghouse [»oppeDC7_1983]
Quote: uniform access to Clearinghouse by a stub on each client that knows a server [»oppeDC7_1983]
Quote: Clearinghouse easily adds new networks, adds servers, or merges networks [»oppeDC10_1981]
Quote: Telesophy provides location transparency; remote data same as local [»schaBR11_1987]
Quote: Telesophy transparently stores and retrieves knowledge [»schaBR11_1987]
Quote: with V, users can run interactive editors on any node without performance problems [»cherDR3_1988]
Quote: Amoeba gives users illusion of a single timesharing system even though it is implemented on hundreds of processors [»taneAS12_1990]
Quote: using wide-area network gateways, Amoeba forms a single, uniform system across possibly different countries
Quote: Amoeba implements remote procedure calls on each processor and in UNIX; allows transparent use of Amoeba [»vanrR10_1988]
Quote: a name service client sees a single hierarchy even though the database is distributed and replicated

Subtopic: heterogeneous database up

Quote: a heterogeneous database may need a common view despite different definitions, algorithms, and units; users can specify the mappings [»ahmeR12_1991]
Quote: a Pegasus schema makes a local data source appear as Pegasus database; maps between data models and query languages [»ahmeR12_1991]
Quote: Pegasus is a heterogeneous, multidatabase management system developed by Hewlett-Packard; object-oriented and relational [»ahmeR12_1991]

Subtopic: problems up

Quote: Amoeba creates a file and its directory entry in separate operations; garbage collects if inaccessible (may be impractical for a huge system)

Related Topics up

Group: communication   (27 topics, 819 quotes)
Group: systems   (17 topics, 530 quotes)

Topic: hypertext as a global database (30 items)
Topic: identifying the user interface with the system (16 items)
Topic: heterogeneous database (6 items)
Topic: managing shared memory (74 items)
Topic: open systems (33 items)
Topic: replicated data (51 items)
Topic: specification and design of distributed systems (14 items)
Topic: system integration (5 items)
Topic: unique names
(58 items)

Updated barberCB 3/04
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