Implementations #

Basically, Implementation is a wrapper around a popular library with the equal interface and semantics, which makes the library suitable to use in the protocol-agnostic code, generated from the AsyncAPI document.

go-asyncapi supports many protocols, and has at least one default out-of-the-box Implementation for each one.

The sections below describe how to select the built-in Implementation or make your own.

Built-in Implementations #

How to use #

By default, go-asyncapi generates the default implementations for every protocol met in the provided AsyncAPI document. Implementations list and what of them are default are available by list-implementations subcommand.

You can select a built-in Implementations in configuration file:

implementations:
  - protocol: kafka
    name: sarama

How to disable #

Built-in Implementation for a particular protocol can be disabled in the configuration file:

implementations:
  - protocol: kafka
    disable: true

To disable all built-in Implementations, use the --disable-implementations CLI flag or set this in the configuration file:

code:
    disableImplementations: true

Custom Implementation #

How to make #

You can make your own Implementation. To send/receive messages or open/close connection/channel, the generated code uses the interfaces, described in abstract.go in “runtime” package for every protocol. See github.com/bdragon300/go-asyncapi/run

Basically, you need the Producer/Consumer, that opens a connection to the server (if needed) and able to create Publisher/Subscriber. Also, you need the envelope type, that represents a protocol-specific outgoing (EnvelopeWriter) and incoming (EnvelopeReader) message.

See the “implementations” directory in go-asyncapi repository for examples. Also, see code structure for the details.

Customizing the generated code #

It’s possible to additionally customize the generated code, that uses the implementation. Use the templating for that. See templates code/proto/<protocol> in template tree.

For example, let’s add our code to Seal* methods in generated channels for “kafka” protocol:

{{define "code/proto/kafka/channel/publishMethods/block1"}}
    {{goQual "fmt.Printf"}}("Seal{{. | goIDUpper}} for envelope: %v", envelope)
{{end}}