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There are four main renowned simulation approaches: Event-Scheduling method, Activity Scanning, Process- Interaction, and Three-Phase approach, in comparison, the following can be noted:
The Event-Scheduling method is simpler and only has two phases so there is no Cs and Bs, this allow the program to run faster since there are no scanning for the condition nalconditional events. All these advantages also tells us something about the disadvantages of the method since there are only two phase then all events are mixed (no Bs and Cs) then the method is not parsimony, which means it is very hard to enhance (Pidd,1998). The Activity Scanning approach is also simpler than the Three-Phase method since it has no calendar, and it support the parsimonious modeling. However this approach is much slower than Three-Phase since it treats all activities are treated as conditional. On the other hand, the executive has two phases. Usually this approach is confused with the Three-Phase method (Pidd, 1998). The Process- Interaction “share two common advantages first; they avoid programs that are slow to run. Second, they avoid the need to think through all possible logical consequences of an event” (Pidd, 1998). Yet, as (Pidd, 1998) claims this approach suffers from DEADLOCK problem, but this approach is very attractive for novice modelers. Although, (Schriber et al, 2003). Says “process interaction was understood only by an elite group of individuals and was beyond the reach of ordinary programmers”. In fact (Schriber et al, 2003).adds “.Multi- threaded applications were talked about in computer science classes, but rarely used in the broader community”. Which indicates that the implementation of Process-Interaction was very difficult to implement. The obvious contradiction, in the previous quote is due to the mix up between the Process Interaction approach and the Transaction-flow approach. To see the complete idea of the origins of Transaction-Flow best stated by (Schriber et al, 2003): This was the primordial soup out of which the Gordon Simulator arose. Gordon’s transaction flow world-view was a cleverly disguised form of process interaction that put the process interaction approach within the grasp of ordinary users. . Gordon did one of the great packaging jobs of all time. He devised a set of building blocks that could be put together to build a flowchart that graphically depicted the operation of a system. Under this modeling paradigm, the flow of elements through a system was readily visible, because that was the focus of the whole approach. The Three-Phase approach allows to “simulate parallelism, whilst avoiding deadlock” (Pidd and Cassel, 1998). Yet, Three-Phase has to scan through the schedule for bound activities, and then scans through all conditional activities which slow it down. Yet many forgo the time spent in return for solving the deadlock problem. In fact, Three-Phase is used in distributed systems whether talking about operating systems, databases, etc, under different names among them Three-Phase commit see (Tanenbaum and Steen, 2002).<ref name=":0">{{Cite journal|last=Abu-Taieh|first=Evon|date=2007|title=COMMERCIAL SIMULATION PACKAGES: A COMPARATIVE STUDY|url=http://ijssst.info/Vol-08/No-2/paper7.pdf|journal=International Journal of Simulation|volume=8|pages=8|via=}}</ref>
==Electronics==
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