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SimEvents Common Design Patterns

The SimEvents® library provides design patterns that you can refer to while modeling. To access these patterns, open the SimEvents library and double-click the Design Patterns block.

Consider these design patterns while modeling:

Design PatternDescriptionInput SpecificationsOutput SpecificationsApplication

Entities with exponential random arrival times

Generates entities with random interval time in exponential distribution fashion.

Not applicable

Structured entity with specified attributes

Model:
  • Customers entering a store

  • Incoming phone calls of a hotline

Service time from random distribution

Specifies waiting time in the Entity Server as a random number uniformly distributed from 0 through 1.

Any entity type

Inherited from the input

Model:
  • Extension of an event that is random within a range (for example, length of a call

  • Purposeful holding of an entity for a random time

Extract attributes of entities as signals

Extracts one or more attributes of entities as signals.

A structured entity or bus object with specified attribute

getAttribute — Real double scalar signal

Extracted Attribute — Inherited from the input

Inspect or use a specific entity attribute

Timestamp entities upon generation

Generates entities with an attribute TimeStamp that records the simulation time upon generation.

Not applicable

Structured entity with attributes Data and TimeStamp

Use when generation time of entities is needed, for example, when calculating the priority in a combined scheduling algorithm.

Release entity upon signal value change

Releases an incoming entity when there is a jump in the step function.

Any entity type

Inherited from the input

Use to control the passing of entities based on the change of a function.

Open gate on service completion

Upon service completion, the gate opens and releases an entity.

Any entity type

Inherited from the input

Use task completion to trigger entity processing.

Sense an entity passing from A to B and open a gate

Passing an entity from A to B opens the gate and releases an entity.

Any entity type

Inherited from the input

Use to model the passing of an entity in one route to control the passing of another route.

Select an entity with a matching attribute

Select entities to advance whose specified attributes are matching the anonymous entity at the control port

A structured entity or bus object with a specified attribute

Inherited from the input

Select entities with a specified attributes to output

Discrete Event Chart: Single Server with Pause

A Ctrl message triggers pause of service for the incoming entity. A second Ctrl message continues the service. Entity data conveys the service time.

Ctrl — Anonymous entity specifying the pause and resume

Entity — Anonymous entity specifying service time

Inherited from the input

Use external events or signals to pause the service of entities.

Discrete Event Chart: Single Server with Timeout

If the service time (which is random) exceeds the timeout limit specified by the entity data, the entity leaves the server.

Anonymous entity with specified timeout limit

Inherited from the input

Model:
  • A protocol that explicitly calls for timeouts.

  • Implementation of special routing or other handling of entities that exceed a time limit.

  • Entities that represent perishable items.

Discrete Event Chart: Custom Output Switch

Randomly routes entities to one of the three output ports.

Anonymous entity

Inherited from the input

Implement a more complicated routing algorithm for an output switch.

MATLAB Discrete Event System: Custom Generator

The Custom Generator block, defined using the MATLAB Discrete Event System block, is a basic entity generator. The generator block requires specification of generation period.

Not applicable

Anonymous entity

Implement a more complicated entity generator.

MATLAB Discrete Event System: Custom Server

Custom Server block, defined using the MATLAB Discrete Event System block, is a basic entity server. The server block requires specification of server number and service time.

Any entity type

Inherited from the input

Implement a more complicated entity server.

MATLAB Discrete Event System: Selection Queue

The Selection Queue block, defined using the MATLAB Discrete Event System block, stores entities of bus type passenger arriving at the IN port. Keys from the call port select passenger entities with the matching trainNum field and send them to the OUT port.

Key — Anonymous entity carrying the selection key

IN — A structured entity or bus object with specified attribute

Inherit from IN

Select a specific entity to output from a queue.

See Also

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