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 Pattern	Description	Input Specifications	Output Specifications	Application
Entities with exponential random inter-generation times	Generates entities with random inter-generation times 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 attribute 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.