IPP Mail Archive: Re: IPP> PRO Section 9.7 vs. MOD section 4.3: need clarifica

IPP Mail Archive: Re: IPP> PRO Section 9.7 vs. MOD section 4.3: need clarifica

Re: IPP> PRO Section 9.7 vs. MOD section 4.3: need clarifica

Carl Kugler (kugler@us.ibm.com)
Mon, 6 Apr 1998 19:24:32 -0400

Tom Hastings wrote:
>At 14:28 04/06/1998 PDT, Carl Kugler wrote:
>>Thanks, Bob, I think I get it now.
>>
>>Maybe your answer also provides a clue to my next question:
>>
>>If attributes-charset and attributes-natural-language Job Description=

>>Attributes are MANDATORY according to MOD/4.3, why aren't they shown =
as
>>MANDATORY in "Group 3: Job Object Attributes" under
>>
>> Print-Job Response:
>> Print-URI Response:
>> Create-Job Response:
>> Send-Document Response:
>> Send-URI Response:
>> Get-Job-Attributes Response:
>> Get-Jobs Response:
>>
>>in MOD/15.3.4.3 "Validate the presence of a single occurrence of requ=
ired
>>Operation attributes"?
>
>Because "attributes-charset" and "attributes-natural-language" MUST
>be returned in Group 1 (not Group 3) as shown.
>
>See sections 3.1.4.2 Response Operation Attributes and
>Sections 3.2 Printer Operations under each Xxx Response Group 1.
>
>As Bob explained, MANDATORY in the document mostly means that a
>Server MUST support the attribute. It is a separate question as to wh=
ether
>the client MUST supply a MANDATORY attribute and whether an IPP object=

>MUST return a MANDATORY attribute. In some cases, the client MUST
>supply a MANDATORY attribute and in other cases the client NEED NOT
>supply the MANDATORY attribute in a request. Similarly, in some cases=
,
>an IPP object MUST supply a MANDATORY attribute and in other cases the=
IPP
>object NEED NOT supply the MANDATORY attribute in a response.
>
>We tried to avoid using the word MANDATORY and OPTIONAL to mean whethe=
r
>a sender had to supply in a request or a response. We tried to only
>use the words MANDATORY and OPTIONAL to mean whether an IPP object
>had to implement or not.
>
>So there are four combinations for attributes in requests, of which on=
ly
>three are possible:
>
> MANDATORY OPTIONAL for an IPP object to support
>
>MUST supply we have we don't have
>
>MAY omit we have we have
>

So, attributes-charset and attributes-natural-language are MANDATORY Jo=
b
Description Attributes (4.3.23 and 4.3.24) only in the sense that a Pri=
nter
must support them. I.e., it must be able return them if a client reque=
sts
them specifically?

>
>Keep those questions coming. We can always improve the spec and fix
>bugs that you find.
>
>>
>>Could it be that the word MANDATORY has different meanings in these t=
wo
>>sections?
>
>See above.
>
>>
>> 4.3: MANDATORY ... attribute[s] MUST be supported by Printer object=
s.
>>If it is not indicated as MANDATORY, then it is OPTIONAL
>>
>> 15.3.4.3: MANDATORY attributes [are those] that an IPP object MUST
>>support and that a client MUST supply
>
>I think I see the confusion. The entire section in 15.3.4.3 is:
>
>The following tables list all the attributes for all the operations by=

>attribute group in each request and each response. The left to right =
order
>of the groups is the order that the client supplies the groups as spec=
ified
>in Section 3.3. The order of the attributes within a group is arbitra=
ry,
>though the tables below lists the attributes in the following order wi=
th
>the following notation:
>
>(M) MANDATORY attributes that an IPP object MUST support and that a
client
>MUST supply
>
>(M*) MANDATORY attributes that an IPP object MUST support, but that a
>client may omit in a request or an IPP object may omit in a response
>
>(O) OPTIONAL attributes that an IPP object NEED NOT support
>
>(O*) OPTIONAL attributes that an IPP object NEED NOT support and a
client
>may omit in a request or an IPP object may omit in a response
>
>The first line is NOT the definition of MANDATORY, but is explaining
>the notation (M) which means MANDATORY and that a client MUST supply.

But the context here is a Response, which surely is supplied by a
Printer, never a client?

Why aren't the attributes-charset and attributes-natural-language (M*) =
for
"Group 3: Job Object Attributes"?

>
>The notation (M*) in the second line is also MANDATORY, but a client M=
AY
>omit. The presence or absence of the "*" indicates whether the MANDAT=
ORY
>attribte (for support) MAY be omitted or not in a request or response.=

>
>Would the following rewording help:
>
>In parenthesis the following notation is used:
>
>M indicates a MANDATORY attirbute that an IPP object MUST support
>O indicated an OPTIONAL attirbute that an IPP object NEED NOT support=

>* indicates that a client MAY omit the attribute in a request and tha=
t
> an IPP object MAY omit the attribute in a response. The absence of=

> an * means that a client MUST supply the attribute in a request and=

> and an IPP object MUST supply the attribute in a response.
>
>Perhaps there is a better notation than *? Perhaps surrounding the
>attribute name itself inside [] would be a more familiar notation to
>indicate what can be omitted in a request or a response?
>
>>
>>It's still not clear to me.
>>
>> -Carl
>>
>>
>>
>>robert.herriot@Eng.Sun.COM on 04/06/98 01:48:31 PM
>>Please respond to robert.herriot@Eng.Sun.COM
>>To: ipp@pwg.org, Carl Kugler/Boulder/IBM@ibmus
>>cc:
>>Subject: Re: IPP> PRO Section 9.7 vs. MOD section 4.3: need clarifica=

>>
>>
>>If I understand your question correctly, I think that you have having=
the
>same
>>confusion
>>that many other people have had about the word "MANDATORY". It means=
that
>>the "Printer" must support the attribute. It does NOT mean that the a=
ttribute
>>must
>>be included in each request/response.
>>
>>In this particular case, attributes-charset is MANDATORY, i.e. the pr=
inter
>>must
>>
>>support the attribute, but in the get-jobs reponse it MUST be in the
>operation
>>attributes
>>group and it is only in each job attribute group if the client reques=
ted the
>>attribute via the
>>requested-attributes attribute in the request. Note, even if it is pr=
esent
>>in a
>>job attributes
>>group it does not affect the charset of those attributes. All attrib=
utes in
>>the entire
>>response are in the charset specified by attributes-charset in the op=
erations
>>attribute
>>group, which I still believe must be first in that group (a change we=
need to
>>make
>>to the model document).
>>
>>Note that in the example attributes-natural-language is in one of the=
job
>>attribute
>>groups in order to override the natural-language in the operation att=
ributes.
>>As I
>>have been implementing IPP, I have come to believe that this was a ba=
d idea.
>>It again
>>requires a special ordering, i.e. attributes-natural-language must pr=
ecede
>all
>>other
>>attributes if processing is to be simple.
>>
>>Bob Herriot
>>
>>
>>At 03:34 PM 4/3/98 , Carl Kugler wrote:
>>>Looking at example 9.7, Get-Jobs Response, I don't see an attributes=
-charset
>>>attribute in any of the three job attributes groups.* But section 4.=
3 of the
>>>Model document, "Job Description Attributes", says that
>attributes-charset is
>>>MANDATORY in the "job-description" attribute group.* This is causing=
me
>>>cognitive dissonance.
>>>
>>
>>
=