Skip to content

http-exceptions.md

Latest commit

 

History

History
36 lines (28 loc) · 2.42 KB

http-exceptions.md

File metadata and controls

36 lines (28 loc) · 2.42 KB
Raw

HTTP Exception Handling

WebServer

The request may fail in three locations:

  1. In Helidon server processing code (internal, unexpected error caused by a bug). Such a case will be logged into the server log in Severe/Error log level and the connection will be terminated.
  2. In request processing code, before ServerRequest and ServerResponse are created. Such errors (such as when request cannot be parsed) are handled by DirectHandler, and the server provides as much information as possible to the handler.
  3. Exceptions thrown from user routing code, and most server exceptions thrown after ServerRequest and ServerResponse are created, are handled using error handlers of routing. The exception is BadRequestException which is always handled by DirectHandler (we may discover lazily that a header does not adhere to specification and thrown this exception)

The exception class hierarchy that is used (these exceptions should not be caught by user code, unless you want to handle everything on your own):

  • RequestException - used for case 2 - this is the only exception (final class) used when we need to explicitly throw an exception to be handled by Helidon server code in a DirectHandler.
  • HttpException - used for case 3 - this is the top level exception class for exceptions that provide a status code and message, and that can be handled by error handlers. If Error handles do not handle them, they will create a response with the expected error code, and will send the exception message as entity
  • CloseConnectionException - this exception can be thrown to terminate current connection
  • UncheckedIOException - this exception is NOT handled and will cause the connection to be closed (we expect this to be problems such as socket closed etc.)

WebClient

! we need to discuss this first! Web client will use HttpException and its subclasses (such as NotFoundException) in case the entity is read directly (e.g. the user skips WebClientResponse, and uses as(Class) to read entity) and the status code returned does not provide an expected entity (such as any error)

HttpException reference

The following HTTP status codes have a specific exception class:

  • 403 - ForbiddenException
  • 404 - NotFoundException
  • 400 - BadRequestException - ALWAYS handled by DirectHandler
  • 500 - InternalServerException - the error handler will be first attempted for the cause, then for this exception