Peter J. Zehler

Interoperability testing for the Internet printing protocol

■ Background: What is TES? The Printer Working Group (PWG) is an open consortium of organizations interested in making printing work better. These organizations represent various aspects of the printing industry. There are representatives of operating systems vendors, print services solution providers, and printer manufacturers. The PWG has a number of projects. One of them is the Internet Printing Protocol (IPP) is organized into a number of subgroups to manage various tasks in the development of the IPP specification. Among these groups are those that oversee the IPP Protocol and IPP Object Model. Another group facilitates IPP prototyping and testing. The designation for this IPP group is TES. TES GOALS he objective of TES is to help anyone implementing IPP; it acts as a central resource for implementers. One goal of IPP TES is to get independent implementations of IPP together. TES uses the IPP mailing list to allow implementers to find each other. Private lists of implementers are maintained. A balance must be maintained between the privacy needs of IPP implementers and the need for implementers to find each other. Another goal is to make IPP tools available to the IPP implementers’ community. Various individuals have donated tools useful for implementing and testing IPP implementation. The benefit gained by such donors is having their tools exercised and debugged by a larger population. TES also takes on the organization of interoperability tests for implementers of IPP. These tests, called “bake-offs,” are not competitive events, but gatherings of IPP implementers and their implementations. The primary goal of TES is to help the development of IPP by putting the specification words to the test. One thing has become quite clear: when the same code base is used for an IPP printer and an IPP client, interoperability is high. There is also agreement on the meaning of ambiguity in the IPP specification. When different code bases are used, misunderstandings are revealed.