Creating A Subscription
Subscriptions are defined in node configuration where they define what data moves where. Subscriptions are exclusively table level and operate independently. In order for data to fully move across a large Cluster, a grouping of subscriptions across nodes will need to be created. Channels, Publish, and Subscribe are all settings within a Subscription. See below definitions for more information about each. Subscriptions can also be referred to as pub/sub functionality.
Publish
A single directionality data flow that will push table transactions from one HarperDB node to another across a clustering connection. Transactions are published only after a transaction has completed on the local node.
{ "operation": "add_node", "name": "node_2", "host": "192.168.0.12", "port": 12345, "subscriptions": [ { "channel": "dev:dog", "subscribe": false, "publish": true } ] }
Subscribe
A single directionality data flow that listens for table transactions on another HarperDB node. When a transaction completes on the other node that transaction is then sent to the subscriber node where it will be executed upon receipt.
{ "operation": "add_node", "name": "node_2", "host": "192.168.0.12", "port": 12345, "subscriptions": [ { "channel": "dev:dog", "subscribe": true, "publish": false } ] }