How to create and understand custom connectors?

[kkacstudent]

I am having a very hard time understanding about how to create connectors. The sample guide for presto-example-http is not very useful. Any guide on creating and testing connectors in detail?

[ZacBlanco]

I'm not aware of any other existing guides for creating a custom connector. I think the best way to understand is by looking at examples - such as the HTTP connector. If you're struggling to understand something in the example connector, feel free to ask a more specific question about it.

At a high level though, all connectors implement portions of Presto's Plugin interface from the SPI:

presto/presto-spi/src/main/java/com/facebook/presto/spi/Plugin.java

Lines 42 to 45 in 1fda136

	default Iterable<ConnectorFactory> getConnectorFactories()
	{
	return emptyList();
	}

You can consider that the main entrypoint. Everything else in the connector revolves around the implementation for the ConnectorFactory specified in the plugin implementation. There are other interfaces within the SPI which are provided by methods within the ConnectorFactory. Those must also created to properly implement each connector. It is a pretty long chain of dependencies which can be confusing. Please let us know which parts specifically are difficult for you to understand and we can try to clarify them in the existing guide.