Topic: event time

topics > computer science > Group: distributed systems

asynchronous processing
discrete vs. continuous
local vs. global
Newtonian physics
Petri net transitions and events
reliable communication
special relativity
synchronized processing
temporal relationships
version control
version identification


Every sequence of events, every activity, makes time, and every interaction takes time. Time is then a local relation between states and between events, with post-states of an interaction happening after its pre-states.

Event time is seen as a understanding of reality where phenomena, once they happen, can not unhappen. A world without events is a world without time; so is a world with only one event. But a world with many events, richly interrelated, is a world inseparable from time. (cbb 6/83)

Subtopic: time as abstraction up

Quote: time does not exist in its own right; it is part of things at motion and at rest; what happens to things in the past, present, and future [»lucr_55]
Quote: there is no absolute space, no absolute time, no simultaneity across distance, not even geometry; these concepts are no more than a language [»poinH_1902, OK]
Quote: to say A happens before B is equivalent to a new thing U whose first tick is A and second tick is B [»cbb_1980, OK]

Subtopic: time as simultaneous events up

Quote: all judgments of time concern simultaneous events [»einsA9_1905]
Quote: choice uncertainty principle -- can not chose between near-simultaneous events within a deadline [»dennPJ11_2007]

Subtopic: time as responsibility up

Quote: every time you take on anything, it requires action within a finite interval of time; like spinning plates in a circus act [»holtAW_1997]

Subtopic: clocks up

Quote: the propagation of light assigns equal tracts to equal time intervals [»einsA_1923]
Quote: clocks at rest relative to each other are synchronized if, by definition, the time for light to travel from A to B is the time for it to travel from B to A [»einsA9_1905]
Quote: if ideal clocks go at the same rate, they always go at the same rate; e.g., sharp spectral lines from atoms of the same chemical element; a foundation of 4-d space-time
Quote: objective time requires a local time (clock) that is extended to events in the whole space [»einsA3_1936]
Quote: without physical time, there is no way to distinguish a failed process from one that is just pausing between events [»lampL7_1978]
Quote: use heartbeat messages for communication between master and chunkservers

Subtopic: time as state transitions up

Quote: programming is not interested in the state of the machine at every moment; only at prepulses
Quote: can judge incidence between states or transitions but not the coincidence of either; e.g., a clock dial is between 1 and 2 vs. exactly 1; i.e., continuous motion [»petrCA_1996]
Quote: time is a strictly, local relation between states [»petrCA1_1966]
Quote: logical execution time (LET) separates the observable real-time behavior from its physical execution; execute between logical release and terminate events; outputs have the value of the previous execution [»farcE6_2005]
Quote: a system's transitions and interactions impose a temporal ordering on events [»holtAW3_1979]
Quote: a switching element only defines the temporal successor of a state [»petrCA1_1966]
Quote: a hiker going between valleys is like a clock whose ticks are the hiker's transitions from valley to ridge [»holtAW11_1980]
Quote: time is activity; the ticking of a clock is the simplest activity; or is time a single tick [»cbb_1980, OK]

Subtopic: time is succession of local events up

Quote: time in a process is only identifiable by a succession of events; two processes in a temporal relationship but no absolute time [»mantMJ2_1983]
Quote: a temporal relationship defines a partial ordering; events are concurrent if they are unordered [»holtAW_1970]
Quote: a temporal relationship defines a directed acyclic graph [»holtAW_1970]
Quote: every actor has a local time axis defined by messages arrival from other actors
Quote: time is a (single?) ordered sequence of event times [»nygaK10_1983, OK]
Quote: the local time axis defines acquaintances (other actors) known at an event [»hewiC8_1977]
Quote: in DELTA time is defined by a global variable; next version of DELTA will use a petri net definition of time [»handP_1981]

Subtopic: time in petri nets up

Quote: Petri assumed that metrics do not exist for space, time, or any physical magnitude [»petrCA1_1966]
Quote: a Petri net treats time as a partial order on event occurrence; no inherent measure of time [»peteJL9_1977]
Quote: Petri nets feature proper concurrency; i.e., the priority of causality over temporal order, and partial independence [»petrCA_1996]

Subtopic: derived time up

Quote: flows can follow slower clocks; e.g., 'x when c' is x's values when c is true; most flow operators use the same clock [»benvA1_2003]
Quote: flow operators deactivated if an operand clock is false [»benvA1_2003]
Quote: CATOCS message ordering delays unrelated messages; happens-before does not imply dependency
Quote: user-defined time, e.g., the date when the promotion committee approved the promotion [»snodR9_1986]

Subtopic: time local to each process up

Quote: implement time by a timestamp on each message; receiver advances its process time to be later than the timestamp [»lampL7_1978]
Quote: a queued model of communication allows local time for each process and avoids issues of simultaneity [»stroRE5_1985]
Quote: in process paradigm there is no global state or global time due to concurrent activity [»stroR10_1986]
Quote: a message system defines a partial order of events; send event is before its receive event [»lampL7_1978]
Quote: when a receiver receives a message its local time is after the local time of the sender when sending the message [»stroRE5_1985]
Quote: order all system events by the process times at which they occur; break ties with a process id [»lampL7_1978]

Subtopic: time as a sequence of versions up

Quote: use object versions to implement logical clocks; i.e., changes to state; slower than message clock ticks [»cherDR12_1993]

Subtopic: time as a counter up

Quote: time in occam represented by a counter; different parts of a program may use different timers; easier than global time [»mayD_1987]
Quote: a clock is an unbounded number of ticks, i.e., CLOCK = (tick -> CLOCK) [»hoarCA_1985]
Quote: a clock is a body or system that counts a series of events which can be regarded as equal
Quote: signal the occurrence of an event by incrementing its event count [»reedDP2_1979]

Related Topics up

Topic: asynchronous processing (30 items)
Topic: discrete vs. continuous (47 items)
Topic: events (44 items)
Topic: local vs. global (29 items)
Topic: Newtonian physics (79 items)
Topic: Petri net transitions and events (21 items)
Topic: reliable communication (29 items)
Topic: special relativity (73 items)
Topic: synchronized processing (35 items)
Topic: temporal relationships (40 items)
Topic: time (49 items)
Topic: timestamps (19 items)
Topic: topology (29 items)
Topic: version control (34 items)
Topic: version identification
(12 items)

Updated barberCB 2/06
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Thesa is a trademark of C. Bradford Barber.