https://github.com/datenhahn/simple-postgres-queue

This is a simple message queue implementation based on the postgresql database and the `SELECT FOR UPDATE` table locking.
https://github.com/datenhahn/simple-postgres-queue

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This is a simple message queue implementation based on the postgresql database and the `SELECT FOR UPDATE` table locking.

• Host: GitHub
• URL: https://github.com/datenhahn/simple-postgres-queue
• Owner: datenhahn
• License: apache-2.0
• Created: 2020-03-17T21:40:09.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2022-09-08T01:10:05.000Z (almost 4 years ago)
• Last Synced: 2025-02-23T22:28:14.673Z (over 1 year ago)
• Language: Java
• Size: 22.5 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Simple Postgres Queue

This is a simple message queue implementation based on the postgresql database and the `SELECT FOR UPDATE`

table locking.

Why another message queue implementation?

* You have a postgresql database and want to make use of the existing scaling and backup features

* The application has only moderate performance requirements, but high requirements regarding data consistency

* Debugging and admin friendlyness are keyfeatures

* Simple code which you can understand (both the queue implemenation, as well as client code)

## Usage

see `src/main/java/de/ecodia/simplequeue/examples/ExampleApp.java` for the full example.

```java

    // dataSource is some standard jdbc datasource

    var queue = new SimpleQueue(dataSource);

    queue.publish("myqueue", "well that was easy");

    queue.subscribe("myqueue", x -> {

        System.out.println(x.getMessage());

    });

```

## Subscriber Callback

The subscriber callback has access to the message properties:

    id

    queue

    traceId

    created

    updated

    publisherId

    subscriberId

    status

    statusText

    message

The subscriber and publisher ID can be set as `hostId`in the constructor.

    public SimpleQueue(DataSource ds, String hostId, boolean notifyProcessing, String tableName)

    

If parameter `notifyProcessing` is set to true it will update the table to state "PROCESSING" when starting

to process the callback. If set to false it will only update after finishing the callback.