Resource Acquirer

Acquire entity resources

Libraries:
SimEvents

Description

The Resource Acquirer block acquires for and assigns them to input entities. You can specify which resource amounts and type the block acquires.

An entity does not depart the Resource Acquirer block until the entity acquires all of the requested resources. For example, if an entity requests 5 resources and there are 2 resources available in a Resource Pool block, then the entity waits until all the requested resources are available before exiting. Similarly, if an entity requests 2 resources from one type and 3 resources from another type, the entity waits until all of the resources from both types are available.

Initialize a Resource Pool block with a specified amount of available resources. Then:

Use one or more Resource Acquirer blocks to reserve those resources.
The priority order of Resource Acquirer blocks is determined at the beginning of a simulation and cannot be customized. The entity in the higher priority Resource Acquirer block always acquires the resource first.
For example, suppose only 1 resource is available in the Resource Pool block and Resource Acquirer1 is higher priority than Resource Acquirer2. If Entity1 and Entity2 want to acquire the resource at the same time, Entity1 always acquires the resource. Even if the resource becomes available again and there are two entities Entity1 and Entity2 waiting in the ResourceAcquirer1 and ResourceAcquirer2, Entity1 again acquires the resource.
Use a Resource Releaser block to return resources to the Resource Pool block for future use.

The visibility of the resources is determined by the Resource visibility parameter of the Resource Pool blocks in the model.

To customize actions when entities enter, exit, or are blocked, enter MATLAB^® code in the Entry action, Exit action, or Blocked action field of the Event actions tab.

Available Resources

Use the Available Resources controls to:

Select the resources from the resources defined in all the Resource Pool blocks in the model.
Add the resources to the Selected Resources table, where you can configure resource acquisition details.

The list displays all the available resources in the model. (If there are no resources, the Available Attributes list is empty.)

If the resource list is long, you can type the resource name in the text box to filter the list.

Use the buttons in the Available Resources section to help build the resources table. The buttons perform these actions.

Button	Action
	Refresh the Available Resources list. The list updates with any upstream model changes you make while the block dialog box is open.
	Add the selected resources to the Selected Resources table.
	Move the selected resource from the Selected Resources table to the Available Resources list. Note If the selected resource is one you added manually, this button appears dimmed.

The message area below the available resources list displays additional messages about the resources, as they apply.

Message	Meaning
`> Resource already selected`	You have already added the resource to the Selected Resources table. You cannot add the resource to the table again.

Selected Resources

Use the controls under Selected Resources to build and manage the list of resources to attach to the entity. Each resource appears as a row in a table.

Using these controls, you can:

Add a resource manually.
Modify a resource that you added to the table from the Available Resources list to attach to the entity.

The buttons under Selected Resources perform these actions:

Button	Action	Notes
	Add a template resource to the table.	Rename the resource and specify its properties.
	Add a copy of the selected resource to the table to use as the basis of a new resource.	Rename the copy. Two resources cannot have the same name.
	Remove the selected resource from the Selected Resources table.	When you delete a resource this way, no confirmation appears and you cannot undo the operation.
	Move up the selected resource in order in the Selected Resources table.	N/A
	Move the selected resource down in order in the Selected Resources table.	N/A

Note

If you delete a row and apply the change, the deletion can affect signal output ports corresponding to other attributes. For example, if the block has a signal output port A2 and you delete the attribute with a port marked A1, the block relabels A2 as A1. Verify that any signal that connects to the relabeled port is still connected as you expect.

Property Specify Use

Property	Specify	Use
Name	The name of the resource. Each resource must have a unique name.	Double-click the existing name, and then type the new name.
Amount Source	Whether the resource amount, that an entity requests, comes from the dialog box or an attribute.	Select `Dialog` or `Attribute`. If you select `Attribute`, the source of the resource amount comes from the attribute of the entity. This option allows each entity to acquire varying amounts of resources. For more information, see Set Resource Amount with Attributes.
Amount	The value to assign to the resource (when the resource comes from the dialog box).	Double-click the value, and then type the value you want to assign. This value is the number of resources acquired per entity. For example, if Amount is `3`, each entity that arrives at the Resource Acquire block must wait to acquire 3 resources before departing the block. Granularity of the resources to be acquired matches the granularity of the resources in the Resource Pool block.

Name

The name of the resource. Each resource must have a unique name.

Double-click the existing name, and then type the new name.

Amount Source

Whether the resource amount, that an entity requests, comes from the dialog box or an attribute.

Select Dialog or Attribute. If you select Attribute, the source of the resource amount comes from the attribute of the entity. This option allows each entity to acquire varying amounts of resources. For more information, see Set Resource Amount with Attributes.

Amount

The value to assign to the resource (when the resource comes from the dialog box).

Double-click the value, and then type the value you want to assign.

This value is the number of resources acquired per entity. For example, if Amount is 3, each entity that arrives at the Resource Acquire block must wait to acquire 3 resources before departing the block.

Granularity of the resources to be acquired matches the granularity of the resources in the Resource Pool block.

Examples

Using Custom Visualization for Entities

These examples show how you can create MATLAB®-based custom visualization for entities. The example illustrates the visualization of a restaurant layout with customer entities entering, dining, and leaving.

Open Script

Resource Allocation from Multiple Pools

A technique for allocating resources from multiple resource pools. It shows how to choose a pool from which to draw a resource, based on given criteria.

Open Model

Optimization of Shared Resources in a Batch Production Process

Identify resource deficiencies and improve capacity planning in a system that shares resources.

Open Script

Ports

Input

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Port_1 — Input entity
scalar | vector | matrix

Input entity port for entities entering the block.

Output

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Port_1 — Output entity
scalar | vector | matrix

Output entity port for entities exiting the block.

Port_d — Number of entities that have departed the block
scalar

Number of entities that have departed the block.

Dependencies

To enable this port, click the Statistics tab and select the box labeled Number of entities departed, d.

Data Types: double

Port_n — Number of entities that have not yet departed the block
scalar

Number of entities that have not yet departed the block.

Dependencies

To enable this port, click the Statistics tab and select the box labeled Number of entities in block, n.

Data Types: double

Port_w — Average wait time for entities in the block
scalar

Average wait time for entities in the block.

Dependencies

To enable this port, click the Statistics tab and select the box labeled Average wait, w.

Data Types: double

Port_ex — Number of entities extracted
scalar

Number of entities that are pulled out of this block.

Dependencies

To enable this port, click the Statistics tab and select the box labeled Number of entities extracted, ex.

Data Types: double

Parameters

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Maximum number of waiting entities — Maximum number of entities that can wait for a resource
`1` (default) | `scalar`

Enter the maximum number of entities that can wait for a resource.

Programmatic Use

Block Parameter: NumberWaitingEntities

Type: character vector

Values: '1' | scalar

Default: '1'

Event actions — Specify the behavior of the entity on certain events
`Entry` (default) | `Exit` | `Blocked`

Define the behavior in the Event actions. For example, the Entry action is called when an entity enters the block.

Note

If an event action changes an entity, related block behavior such as resorting a priority queue, and rescheduling of any events, will occur after the event action has fully finished and returned.

Programmatic Use

Block Parameter:

EntryAction, ExitAction,
                                BlockedAction

Type: character vector

Values: MATLAB code

Default: ''

Number of entities departed, d — Outputs the number of entities that have departed the block
`off` (default) | `on`

Selecting this check box outputs the number of entities that have exited the block.

Programmatic Use

Block Parameter: NumberEntitiesDeparted

Type: character vector

Values: 'on' | 'off'

Default: 'off'

Number of entities in block, n — Outputs the number of entities present in the block, which have yet to depart
`off` (default) | `on`

Selecting this check box outputs the number of entities present in the block, which have yet to depart.

Programmatic Use

Block Parameter: NumberEntitiesInBlock

Type: character vector

Values: 'on' | 'off'

Default: 'off'

Average wait, w — Outputs the average wait time
`off` (default) | `on`

Sum of the wait times for entities departing the block divided by their total number. Wait time is the duration between the entity's entry into and exit from the Resource Acquirer block. For more information, see Interpret SimEvents Models Using Statistical Analysis.

Programmatic Use

Block Parameter: AverageWait

Type: character vector

Values: 'on' | 'off'

Default: 'off'

Number of entities extracted, ex — Number of entities extracted from this block
`off` (default) | `on`

Outputs the number of extracted entities which are pulled out from this block by the Entity Find block. When an entity is extracted, its resource acquisition from the Resource Pool block is canceled and Number of entities departed, d, Number of entities in block, n, and Average wait, w statistics are updated accordingly. For more information about finding and extracting entities, see Find and Extract Entities in SimEvents Models.

Programmatic Use

Block Parameter: NumEntitiesExtracted

Type: character vector

Values: 'on' | 'off'

Default: 'off'

Version History

Introduced in R2016a

Resource Acquirer