applicationAn Application is a collection of microservices that run in a single process and share the same lifecycle. The ability to run multiple microservices in a single executable is one of the big benefits of the Microbus approach. It is much easier to develop, debug and test a system when all its microservices can be run in a single debuggable process with minimal memory requirements.
Here’s a simple example of an Application hosting two microservices: a “Hello, World!” microservice and the HTTP ingress microservice.
package main
import (
"net/http"
"os"
"github.com/microbus-io/fabric/application"
"github.com/microbus-io/fabric/connector"
"github.com/microbus-io/fabric/coreservices/httpingress"
)
func main() {
hello := connector.New("helloworld")
hello.Subscribe("GET", "/", func(w http.ResponseWriter, r *http.Request) error {
w.Write([]byte("Hello, World!"))
return nil
})
app := application.New(
httpingress.NewService(),
hello,
)
err := app.Run()
if err != nil {
os.Exit(1)
}
}
Microservices are added to an Application either during creation in application.New or later via the Include method. In either case, the microservices are not automatically started. A call to Startup starts up all included microservices that are not already started. Conversely, a call to Shutdown shuts down all included microservices that are not already shut down.
The Run method starts up all microservices, waits for an interrupt and then shuts down all microservices. Interrupt allows to programmatically interrupt a running Application.
The methods Services, ServicesByHost (plural) and ServiceByHost (singular) allow searching for microservices included in the app.
Microservices can be Joined to the Application without being included in it. The lifecycle of a joined microservice is not managed by the Application and it must be explicitly started up and shutdown. Joined microservices can fully communicate with other microservices included with or joined to the app.