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2021.1.1560.3 Active MQ

Owned by Bob Ebergen
Jun 08, 2022
3 min read

Overview

This feature is used to make an ActiveMQ connection between Prespective(acts as a client) and an external ActiveMQ server to transport messages.

Architectural view of MQTT.

Ref: - A Survey of Distributed Message Broker Queues - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/ActiveMQ-Architecture_fig5_315764651 [accessed 28 Jul, 2021]

Where to find

The feature can be found under Prespective Menu > Logic > Add Logic Simulator > Adapter Settings > Adapter Target > ActiveMQ

Feature Layout

Gateway settings

 

Gateway settings

 

Adapter Target

Select a different adapter, please see respective documentation for more information

Adapter Setting (ActiveMQServerSettings)

 

IP Address

The address of the ActiveMQ server. This can be a be in IPv4 address or a hostname like localhost

Port

The port on which the ActiveMQ broker is running, the default port is 61616.

CorrelationID

The identifier on which a message responds. Different Correlation IDs can communicate over the same queue, but is not recommended. Make sure other clients use the same Correlation ID

DeliveryMode

Int that defines whether the message is persistent(0) or non_persistent(1).

Persistent is default and makes sure the message survives a broker reset. It can be a slower than non_persistent

Lifecycle settings

Not implemented for Active MQ

How to use

Tutorial on how to set us an ActiveMQ client

Prerequisites for ActiveMQ

ActiveMQ can work with an online broker on the internet, but is more commonly used with a local broker. A local broker can be downloaded from the Apache Website: https://activemq.apache.org/components/classic/download/

Java Runtime Environment is required. Download the Latest Java LTS Free

The README.txt in the zip file will help you setup the broker.

Once the broker is running you will find the broker admin page on http://localhost:8161/admin/

In the admin panel you will find an overview of the current queues and its connected consumers and producers when you click on ‘Queues’.

Used Protocol

To communicate with the ActiveMQ adapter in prespective you need to have to apply the following protocol:

  • Message is not supported, only MapMessage.

  • The structure for the MapMessage is:

<MAPMESSAGEINSTANCE>.Properties.Set<TYPE>("<TYPE>",<VALUE>);

<MAPMESSAGEINSTANCE>.Properties.Get<TYPE>("<TYPE>");

Each type has a specific Set and Get command. This differs a little bit per language. Please visit the ActiveMQ supported language page to check yours https://activemq.apache.org/cross-language-clients

c#:

_mapMsg.Properties.SetBool("BOOL", true); _mapMsg.Properties.GetBool(”BOOL”);

  • Destination = queue as defined in plc address

  • CorrelationID = same as defined in ActiveMQ adapter settings

Supported Types

  • BOOL

  • BYTE

  • SBYTE

  • WORD

  • DWORD

  • SHORT

  • USHORT

  • INT16

  • UINT16

  • INT32

  • UINT32

  • INT64

  • UINT64

  • REAL32

  • REAL64

  • BYTEARRAY

  • STRING

  • STRUCT

 

Naming Rules

Setting up the component works as like any other prelogic component. The thing you have to take into account is how the PLC Address Path Format (or implicit naming rule) is configured. The output of this Address is the path to the queue.

ie. Simulator1.DrivenStepper.iPosition

Simulator1 is the instance name of the simulator

DrivenStepper the instance of a motor object

iPosition is the variable name as defined in the signal definition

This structure is based on MQTT and can be adapted to any personal preference, because this adapter implementation uses queues instead of topics.

 

Prespective Documentation