Elements of the Internet Graphics Service (IGS) architecture that communicate with a multiplexer on the one hand and interpreters/components on the other.


Portwatchers are used for the following:

  • Instantiating interpreters/components
  • Registering with a multiplexer
  • Telling the multiplexer which components are available
  • Sending data packages to the interpreters/components
  • Returning their status to the multiplexer, if requested


The multiplexer sends a data package to the portwatcher which sends it on to the appropriate interpreter on the basis of the package type. The interpreter/component pair carry out the request they have been given (for example, to generate an image or calculate geo-coordinates) and send the result back to the multiplexer.