In the February Cloud Imaging face-to-face, we asked Glen to find out if he could spend time making a proper subset of PWG PJT for GCP/CDD. He did and he could and he provided his suggestions in a nice draft. But on discussing this, it was unclear that we had a consistent notion of what we wanted to do with what turned out to be two subsets. I think we all see some value in Glen’s contribution; buy we need agree on what this is. I offer the following thoughts and questions. Corrections and contradictions are welcomed.
1. The motivation to define the proper subset was the belief that the size of the full PJT set and the perceived lack of need for some of the elements in the typical cloud application would make the set appear unduly complex and inappropriate to Google and other Cloud Print Service suppliers.
2. As Mike indicated that “Supported elements are the intersection of the client, cloud, and printer capabilities”. ⁃He also wrote “Defining levels are nice, but clients still need to discover what elements are supported by the printer” and that limiting to elements in support level “ prevents adoption of useful higher-level elements.”
3. It is my , perhaps incorrect, understanding that the print job ticket elements in a job request did not need to specify values for all of the elements in the reported printer capabilities. Indeed, a job request could be sent without the client even querying printer capabilities. Therefore, although it may be desirable for a Client to support (which is to say, provide values for) a set of elements commensurate with the anticipated needs of the User, it is unnecessary to require clients to support some defined subset of elements or values. I therefore would moderate the contention that clients need to discover what elements are supported by the printer, to say that client would need to determine whether the printer support those elements and value that are of interest to the User. Therefore, element subsets may be at most useful suggestions to what different clients should support.
4. The Printer (and Cloud Print Manager) will support those few elements that are required and whatever additional elements are necessary to expose the service capabilities. There appears no reason that they should support elements for capabilities that do not exist. So the subsets are not applicable to them beyond perhaps being suggestions as to what features might be provided.
5. If these contentions are valid, the Cloud Server must communicate subset of printer capabilities determined by the printer and a subset of desired job elements determined by the Client. If Cloud servers have essentially infinite capacity, they should handle the full set of elements and values. But practically, if the Cloud Print Service is intended for an identifiable User base, it is probably justified to support both for capabilities and job requests, a subset of the full PJT elements and values. That is, a Cloud Print Service need support just an element subset which is the intersection of the client job requests and printer capabilities. I think that our proper subset was to be our suggestion of what might be in that intersection.
Bill Wagner
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