The most performant way to handle intermittent network issues with vendor applications and ensure successful transaction reprocessing is to use a combination of the Scatter-Gather scope and the Until-Successful scope. Here’s how it works:

Scatter-Gather Scope: This scope allows you to send requests to multiple endpoints (in this case, the two vendor applications) simultaneously. This ensures that both vendors are queried at the same time, reducing overall processing time.

Until-Successful Scope: This scope is used to implement a retry mechanism. By wrapping each route to the vendor applications with an Until-Successful scope, the flow can automatically retry the request if a timeout error occurs. This scope retries the request until it succeeds or until a specified number of retries is reached.

Implementation Steps:

Configure a Scatter-Gather scope in your Mule application.

Inside each route of the Scatter-Gather scope, place an Until-Successful scope.

Configure the Until-Successful scope with appropriate retry policies, such as retry count and delay between retries.

Inside the Until-Successful scope, configure the HTTP request to the vendor application.

This approach ensures that:

Both vendor applications are queried in parallel.

Each request is retried upon timeout errors, ensuring eventual success without manual intervention.