AG VLSI Design and Architecture

SFB 501 - Project D1: Application System "Buildings"

PSiGene Pattern Catalog

Intent

Often it is desirable to access some Attributes from a simulator with external programs. This way, the simulator can be stimulated (e.g. by external control programs) or simulated values ccan be monitored. Most of the functionality that is required for external acesses is already implemented in the simulator's kernel-library. This library handles socket connections and interprets a simple command languege. Basically, there are 3 commands:

• <Sensuator name> getValue
  Request the actual value of the specified sensor. Answer is in the form:
  <Sensuator name> <value>
• <Sensuator name> setValue: <new value>
  Sets the value of the Sensuator to <new value>. Answer should be <Sensuator name> ACK or <Sensuator name> ERROR.
• <Sensuator name> setEventMode or <Sensuator name> resetEventMode
  Sets or resets the event mode. When a Sensuator is in event mode, it automatically reports any changes of its state over the socket connection.

Commands are terminated by the control-sequence ctrl-a and a carriage-return. Ctrl-b means "quit". The commands may be entered using a normal telnet connection to the host the simulator is running on. The default port is 32418. For details see http://hauspc1.informatik.uni-kl.de/doku.html .

All what is needed to access an attribute externally is a mapping between the sensuator's name and the actual attribute. This can be done using this pattern.

Also Known As

 

Motivation

Assume the following situation: The temperature of a building should be simulated and the temperature of some selected rooms has to be monitored by an external program. The following things are required to install an accessible temperature sensor for a room:

• create a class "TemperatureSensor" and connect it to the class Room via an 1:n relation (one room may have several temperature sensors).
• The TemperatureSensor must have a String attribute to hold the sensors name.
• apply pattern RemoteAttribute to the TemperatureSesnor class so that the room temperature is locally accessible (or use some other patterns to calculate the temperature e.g. by averaging the wall temperatures with te air temperature).
• apply the pattern SensorClient to TemperatureSesnor. The sensor name is an attribute of TemperatureSesnor and attribute is the mirrored (or real) attribute.

• instatiate for every room whichs temperature should be monitored a TemperatureSensor and initialize the required attributes (i.e. connect it to the correct room and set a sensor name e.g. `rts1').
• generate and run the simulator "as usual".
• test the connection:
  telnet localhost 32418
  rts1 getValue ^A
  ^B

Applicability

 

Structure

This pattern should be bound to a sensor object with its name and an attribute to be accessed. In simple cases (e.g. every room has only one temperature) it can be directly bound to the simulation objects.

The attribute of a Sensuator ccan be read and written by external processes. Additionally it can be set into eventMode where every change is automatically propagated. To restrict this flexibility, use one of the patterns SensorServer , ActuatorServer , or BinarySensorServer .

Participants

Collaborations

 

Consequences

 

Implementation

The socet connection is automatically handled in the simulator-kernel library. All this pattern does is to register a sensuator object in the kernel.

Generated init method:

{init}
     |aSet anArray |
    self {name} notNil ifTrue:
    [
        aSet := Set new.
            anArray := Array withSize: 6.
        anArray at: 1 put: self.
        anArray at: 2 put: #{attribute}.
        anArray at: 3 put: #{attribute}:.
        anArray at: 4 put: #setEventMode.
        anArray at: 5 put: #resetEventMode.
        anArray at: 6 put: aSet.
        Scheduler simSched remoteAccessibleObjects at: (self {name} asSymbol) put: anArray.
    ]

Related Patterns

ActuatorServer , SensorServer , and BinarySensorServer are special, restricted versions of this pattern.

PEdit description

Pattern SensuatorServer Category sockets

    ObjectType use target
    Attribute use name 
    Attribute use attribute
    SingleMethod implement preset init 
End