mo-delay-agent is a component in the MO eco system. MO sends messages to an AMQP broker every time an object is created, changed or deleted with a timestamp of when said event is scheduled. This agent saves all those messages and sends them to a new queue when they are due. This makes it possible to write integrations for MO, that react to changes when they are scheduled to occur. Please refer to the MO docs for more information about the messages.
mo-delay-agent consists of the consumer and the producer. consumer is responsible for receiving the messages from MO and writing them to PostgreSQL. producer is responsible for reading the due messages from PostgreSQL and writing them to the delayed queue.
mo-delay-agent depends on PostgreSQL and rabbitmq. The easiest way to run these locally is with docker and docker-compose:
$ docker-compose up --build -dIt has proven very hard to test the application, because it is undeterministic. There are unit tests for the consumer, but not the producer. If you aspire to write integration tests, try digging through the git history for inspiration. Lessons learned: it is hard to test undeterministic and time sensitive applications.
These are the environment variables used to configure mo-delay-agent listed with their default values.
| Environment variable | Default value |
|---|---|
| AMQP_HOST | localhost |
| AMQP_PORT | 5672 |
| AMQP_MO_EXCHANGE | moq |
| AMQP_DELAYED_QUEUE | delayed_moq |
| POSTGRES_HOST | localhost |
| POSTGRES_PORT | 5432 |
| POSTGRES_DB | delay_agent |
| POSTGRES_USER | delay_agent |
| POSTGRES_PASSWORD | delay_agent |
mo-delay-agent is free software. You are entitled to use, study, modify and share it under the provisions of Version 2.0 of the Mozilla Public License as specified in the LICENSE file.
This software was developed by Magenta ApS.