GeoblacklightMessaging

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GeoblacklightMessaging is a plugin that enables Geoblacklight applications to synchronize with external services using a RabbitMQ exchange. The plugin subscribes to events on the exchange and updates Geoblacklight records when they're created, updated, or deleted.

Dependencies

• RabbitMQ

Installation

Add this line to your Geoblacklight application's Gemfile:

gem 'geoblacklight_messaging'

And then execute:

$ bundle

Run generator:

$ rails generate geoblacklight_messaging:install

Configure the events settings in config/messaging.yml:

defaults: &defaults
  events:
    server: <%= ENV['RABBIT_SERVER'] || 'amqp://localhost:5672' %>
    exchange:
      geoblacklight: 'gbl_events'

Usage

1. Start RabbitMQ:

   $ rabbitmq-server

1. Run your geoblacklight application:

   $ rake geoblacklight:server
   

2. In a separate console, run:

   $ WORKERS=GeoblacklightMessaging::GeoblacklightEventHandler rake sneakers:run

1. If the RabbitMQ Management Plugin is installed, you can inspect the exchange and publish messages manually using the web interface at http://localhost:15672/.

Message Format

Create

1. The event workers expect a json create message in the following format:

   {
     "id": "princeton-abc123",
     "event": "CREATED",
     "doc": { "layer_slug_s": "princeton-abc123", "dc_title_s": "Cool Map", ... }
   }
   

2. id is the record's unique key. layer_slug_s in this case.

3. doc is the unescaped geoblacklight json document.

Update

1. Update is similar to create.

   {
     "id": "princeton-abc123",
     "event": "UPDATED",
     "doc": { "layer_slug_s": "princeton-abc123", "dc_title_s": "New Map Name", ... }
   }
   

Delete

1. No doc value is needed for delete:

   {
     "id": "princeton-abc123",
     "event": "DELETED"
   }
   

Thanks

This gem was based on work done by @tpendragon for Plum and Pomegranate.