Discovering and calling services at runtime

Overview

Vyne lets you look up & invoke services at runtime. In this walkthrough, we'll continue with our compliance engine from our previous, and deploy a new rule, observing how Vyne automatically adjusts to include it our calls.

Vyne.gather() - Invoking services by Type

Vyne allows us to invoke services based on their return type, and works out the parameters to pass. The type we use for discovery can be anywhere in the type hierarchy.

We've already used this approach in our previous example, but let's take a deeper look.

First, we defined an interface called RuleEvaluationResult. Here's the definition in both Kotlin and Taxi:

type RuleEvaluationResult {
    message : String
    ruleId : String
    status : RagStatus
}

We then defined some services that return implementations of this interface:

type JurisdictionRuleResponse inherits RuleEvaluationResult {}
type NotionalLimitRuleResponse inherits RuleEvaluationResult {}
type TradeValueRuleResponse inherits RuleEvaluationResult P{

operation evaluate(JurisdictionRuleRequest):JurisdictionRuleResponse {}
operation evaluate(NotionalLimitRuleRequest):NotionalLimitRuleResponse {}
operation evaluate(TradeValueRuleRequest):TradeValueRuleResponse {}

To invoke these services, we simply asked Vyne to find us all the implementations RuleEvaluationResult:

fun evaluate(@RequestBody tradeRequest: TradeRequest): TradeComplianceResult {
   val ruleEvaluations = vyne
      .given(tradeRequest)
      .gather<RuleEvaluationResult>()

   return TradeComplianceResult(ruleEvaluations)
}

Here's the resulting call graph:

You can see that Vyne has called all three of our services, constructing their request objects, and collating their responses.

Summary

By using Vyne.gather(T), Vyne is able to discover services to invoke that return either:

• An instance of type T.
• A subclass (or implementation) of type T.

Vyne will construct the parameter objects necessary to invoke the services, and collate the results back.