This is a microgateway action which supports the conditional evaluation of activities. The microgateway has one setting: 'uri' which is the URI of the microgateway JSON resource.
The JSON Schema for the Microgateway resource can be found here.
A service defines a function or activity of some sort that will be utilized in a step within an execution flow. Services have names, refs, and settings. Any Flogo activity works as a service. Services that are specific to a microgateway can be found here. Services may call external endpoints like HTTP servers or may stay within the context of the gateway, like the js activity. Once a service is defined it can be used as many times as needed within your routes and steps.
Each microgateway is composed of a number of steps. Each step is evaluated in the order in which it is defined via an optional if condition. If the condition is true, that step is executed. If that condition is false the execution context moves onto the next step in the process and evaluates that one. A blank or omitted if condition always evaluates to true.
A simple step looks like:
{
"if": "$.payload.pathParams.petId == 9",
"service": "PetStorePets",
"input": {
"method": "GET",
"pathParams.id": "=$payload.pathParams.petId"
}
}As you can see above, a step consists of a simple condition, a service reference, input parameters, and (not shown) output parameters. The service must map to a service defined in the services array that is defined in the microgateway resource. Input key and value pairs are translated and handed off to the service execution. Output key value pairs are translated and retained after the service has executed. Values starting with = are evaluated as variables within the context of the execution. An optional halt condition is supported for steps. When the halt condition is true the execution of the steps is halted.
Each microgateway has an optional set of responses that can be evaluated and returned to the invoking trigger. Much like routes, the first response with an if condition evaluating to true is the response that gets executed and returned. A response contains an if condition, an error boolean, a code value, and a data object. The error boolean dictates whether or not an error should be returned to the engine. The code is the status code returned to the trigger. The data object is evaluated within the context of the execution and then sent back to the trigger as well.
A simple response looks like:
{
"if": "$.PetStorePets.outputs.data.status == 'available'",
"error": false,
"code": 200,
"data": {
"body.pet": "=$.PetStorePets.outputs.data",
"body.inventory": "=$.PetStoreInventory.outputs.data"
}
}An example of a basic gateway can be found here.
An API example can be found here.