CallId

The CallId feature allows to identify a request/call and can work along the CallLogging feature.

Generating Call IDs

  1. install(CallId) {
  2.     // Tries to retrieve a callId from an ApplicationCall. You can add several retrievers and all will be executed coalescing until one of them is not null.  
  3.     retrieve { // call: ApplicationCall ->
  4.         call.request.header(HttpHeaders.XRequestId)
  5.     }
  7.     // If can't retrieve a callId from the ApplicationCall, it will try the generate blocks coalescing until one of them is not null.
  8.     val counter = atomic(0)
  9.     generate { "generated-call-id-${counter.getAndIncrement()}" }
  11.     // Once a callId is generated, this optional function is called to verify if the retrieved or generated callId String is valid. 
  12.     verify { callId: String ->
  13.         callId.isNotEmpty()
  14.     }
  16.     // Allows to process the call to modify headers or generate a request from the callId
  17.     reply { call: ApplicationCall, callId: String ->
  19.     }
  21.     // Retrieve the callId from a headerName
  22.     retrieveFromHeader(headerName: String)
  24.     // Automatically updates the response with the callId in the specified headerName
  25.     replyToHeader(headerName: String)
  27.     // Combines both: retrieveFromHeader and replyToHeader in one single call
  28.     header(headerName: String)
  29. }

Extending CallLogging

The CallId feature includes a callIdMdc extension method to be used when configuring the CallLogging.It allows to associate the callId to the specified key to be put in the MDC context.

  1. install(CallLogging) {
  2.     callIdMdc("mdc-call-id")
  3. }