Hi Jeff, I'd still like a concrete scenario.
If you can give me an end-to-end example of:
- someone defines a map document type
for purpose x, including your attributes with values y and z
- the values get used when the map references
topic types y and z, which gives benefits a, b, c
Right now I still don't understand what
slots into those letters :-) A concrete example will help me.
Michael Priestley
Lead IBM DITA Architect
http://dita.xml.org/blog/25
"Ogden, Jeff"
<>
09/11/2007 12:58 PM
To
<>
cc
Subject
RE: [dita] Issue 12055 Map referencing
behaviors
It is true that the specializers would need
to add information for a new architectural attribute to their new DTDs
or schemas if they want to override the default behavior, but are developing
new DTDs or schemas anyway so this does not seem like a bad thing or a
large burden.
If we put the new architectural attribute
on individual elements rather than on the root element (more class-like
rather than domain-like), doesn’t most of the need to manage the attributes
through generalization and conref processing go away? Typically we’d
just use the default value, if any, from the DTD or schema for the current
element (generalized or not). If for some reason the architectural attribute
is stored in the document instance, if you have access to the DTD you’d
just get the new value for the “new” element during generalization and
store that in the instance, or if you don’t have access to the DTD or
schema, you could simply delete the architectural attribute from the instance
and fallback to the default behavior.
I guess my desire to add the additional information
to the DTD or schema comes from my desire to make the map to map referencing
behaviors more of a requirement of the DITA Standard and less of an optional
set of behaviors that is left fairly open and handled by output processing.
Perhaps this is a mistake on my part, but I think of the map to map referencing
behavior as being somewhat more complicated than most styling issues (ph
as bold or not) that are handled by output processing entirely or largely
outside of anything in the DITA Standard. The map to map referencing behavior
seems somewhat similar to the portions of the DITA spec. that talk about
“Metadata elements and common attributes” in that the information in
one document is interacting with and possibly overriding information in
another. For the metadata case at least the behavior isn’t optional,
but something that is required by the DITA Standard (things in maps can
override things in topics). I’ve been thinking about the map to
map referencing behavior in a similar way. And adding a new architectural
attribute allows us to give specializers some flexibility while still saying
exactly what the behavior is in the standard.
Here is an example. Imagine an output processing
pipeline that:
1. reads
and resolves information from various maps,
2. gathers
and “transforms” dita topics referenced from the maps, combining and
splitting topics, adding related-links, metadata and other contextual information
including map to map referencing context to the resulting topics or collections
of topics,
3. processes
the “transformed” topics for styling issues, and
4. produces
the desired final output.
The map to map referencing behaviors would
likely be implemented in steps 1 and 2 (probably mostly step 2). Styling
issues would be dealt with in step 3 or possibly step 3 and 4. Steps 3
and 4 may never see information from a map directly. Any reasonable
output processing system will make it fairly easy for someone to customize/style
their documents in step 3. It may be much more difficult or even
impossible to add specialization specific customizations to step 2. If
we can include information about map referencing behavior in the DTD or
schema in some fashion, we can provide flexibility in step 2 without requiring
specializers to implement their own specialization specific customization
in step 2. And if this flexibility is provided as part of the standard,
there would be less work for specializers to do to actually use it.
The alternative is to leave the map to map
behavior up to output processing with a suggestion in the DITA spec. that
suggests how this should work by default. I could live with this
approach, but for the reasons I stated earlier I’d rather see this be
defined as a requirement. If we do leave the map to map referencing
behavior up to output processing, we should make sure our descriptions
in the DITA spec. make that clear and we should probably work to make the
map to map description shorter as Robert suggested in an earlier message.
So far I’m still thinking that the new architectural
attribute here could be pretty simple (inherit or not), but I look forward
to seeing some more cases from Erik Hennum or others.
-Jeff
From: Michael Priestley [mailto:]
Sent: Tuesday, September 11, 2007 10:36 AM
To: Ogden, Jeff
Cc: ; Grosso, Paul
Subject: RE: [dita] Issue 12055 Map referencing behaviors
The specialized behaviors do not override something that is required by
the DITA standard. In fact, the reverse is true: many of the current DITA
standard specializations require processors to override inherited behavior.
As a simple example, look at the highlighting domain. Bold is not the default
output from a <ph> element.
If we're doing it within the spec when we specialize, we can certainly
expect others to do it when they add their own specializations outside
the spec.
Re your option 3 below: Can you give me a scenario that would actually
make use of this proposal? I'm having a hard time understanding the need
in the abstract. My initial reaction is not positive, just because it adds
a new architectural attribute that needs to be set by specializers and
managed/preserved/adjusted through generalization and conref processes
- so it will turn this relatively modest proposal into a major proposal
on the same order of magnitude as constraints (or larger, given the recent
reduction of that proposal).
Michael Priestley
Lead IBM DITA Architect
http://dita.xml.org/blog/25
"Ogden, Jeff"
<>
09/10/2007 03:57 PM
To
Michael Priestley/Toronto/IBM@IBMCA
cc
<>, "Grosso,
Paul" <>
Subject
RE: [dita] Issue 12055 Map referencing
behaviors
OK, but for those cases where “the DITA Open Toolkit provides specialized
behaviors for about a third of the specialized elements in the DITA spec”
do the specialized behaviors provided override something that is required
in the DITA standard or do they override the processing for the base element
as implemented by the DITA Open Toolkit?
I see the “Specialization in processing” section of the DITA specification
as a collection of good practices for writing XSLT or CSS stylesheets for
use with DITA. I don’t think it defines a standard method of sharing
processing behaviors unless the sharing is being done using the same processing
system such as the DITA Open Toolkit.
The DITA Open Toolkit, like all output processing systems, implements portions
of the DITA standard as well as other things that have not been standardized
and very often we do not want to standardize. I guess a question
we may need to answer is, Are the behaviors being defined in Issue 12055
ones that we want to include in the DITA Standard or are they ones that
we want left open for customization? And if we include them in the
DITA Standard, how much force do we want to give them? Are they requirements?
Are they recommendations? Are they examples?
Michael, do you see any harm in providing additional information in the
DTD or schema as I have been suggesting (my option #3)?
-Jeff
From: Michael Priestley [mailto:]
Sent: Monday, September 10, 2007 3:17 PM
To: Ogden, Jeff
Cc: ; Grosso, Paul
Subject: RE: [dita] Issue 12055 Map referencing behaviors
Re:
>The reason I am uncomfortable with this is that it requires that someone
who wants to define a new specialization that requires exceptions provide
both the specialized elements and behavior. We have a standard way
to provide the specialized elements. We do not have a standard way to provide
the specialized behavior.
Actually we do - see the architectural spec section "Specialization
in processing".
>Without a standard way to provide the specialized behavior, someone
will need to reimplement the specialized behavior for different output
processing implementations. That will be extra work and seems likely to
result in different results as documents are moved from site to site and
implementation to implementation. We should avoid that if we can.
It's within the scope of normal DITA specialization to create a new specialized
element that has specialized processing. Some of the critics of specialization
have claimed that's the norm, which it's not, but it's not the exception
either. As one example, I believe the DITA Open Toolkit provides specialized
behaviors for about a third of the specialized elements in the DITA spec.
I believe most DITA users that are specializing DITA are also providing
specialized processing for at least some of their new elements.
Michael Priestley
Lead IBM DITA Architect
http://dita.xml.org/blog/25
"Ogden, Jeff"
<>
09/10/2007 03:05 PM
To
Michael Priestley/Toronto/IBM@IBMCA,
"Grosso, Paul" <>
cc
<>
Subject
RE: [dita] Issue 12055 Map referencing
behaviors
My own thought here is that we have three options:
1. Define standard
behavior that applies to all cases, no exceptions.
2. Say that
the behavior is implementation dependent, possibly giving an example of
a desired behavior that may be implemented.
3. Provide
a standard behavior and a way to designate exceptions to that standard
behavior.
For this particular case I don’t think #3 would be too hard and so that
would seem to be a good way to go.
I am uncomfortable with the option that is being proposed which I take
as defining standard behavior, but allowing exceptions. The reason
I am uncomfortable with this is that it requires that someone who wants
to define a new specialization that requires exceptions provide both the
specialized elements and behavior. We have a standard way to provide
the specialized elements. We do not have a standard way to provide the
specialized behavior. Without a standard way to provide the specialized
behavior, someone will need to reimplement the specialized behavior for
different output processing implementations. That will be extra work and
seems likely to result in different results as documents are moved from
site to site and implementation to implementation. We should avoid that
if we can.
I could live with option #1 (no exceptions). That puts the burden
on the author to use the “right” map elements when the behavior they
want isn’t the standard behavior.
I could live with option #2 (no standard). That is what we do for
most output processing today.
And as I said, I think option #3 is the best approach. I think all
we need is either:
a) a
new attribute similar to domain on the root element of a map that accepts
a space separated list of topicref specializations whose behavior
should not be overridden when they are referenced using a different element
from a higher level map, or
b) a
new attribute similar to class on topicref and topicref specializations
that indicates that this element’s behavior should not be overridden when
referenced from a higher level map.
In either case, like domain or class, the new attribute would usually appear
with its default value in a DTD or schema and not in the instance.
And, if we want to, rather than using a simple list or a single attribute
value, we might define a keyword or grouping syntax for the values so that
we could use the same attributes for other similar purposes in the future
should the need arise. Some possible approaches:
Simple list on the root element: norefoverride=”element1
element2 … elementn”
Single valued attribute on the topicref
element or specialization: refoverride=”no”
Grouping syntax on the root element:
processing_exceptions=”norefoverride(element1
element2 … elementn) somenewoption(somenewvalues)”
Keyword list on any element: processing_exceptions=”norefoverride
somenewoption someothernewoption”
-Jeff
From: Michael Priestley [mailto:]
Sent: Monday, September 10, 2007 12:06 PM
To: Grosso, Paul
Cc:
Subject: RE: [dita] Issue 12055 Map referencing behaviors
I think the wording needs some clarification - I don't think what you're
reacting to is actually Robert's intent.
Robert, I'm going to try to paraphrase here:
If someone specializes a map to create a new map-referencing element, they
can define specialized processing for that element if they want. Applications
that are not customized or extended to provide special handling for the
specialized element should instead treat the specialized element according
to its ancestry (ie, according to whatever behavior is provided in the
spec for that element).
I don't think Robert is saying more than the above, and that's true of
all specializations. He's just pointing out that the behavior defined in
the spec can be overridden by someone providing specialized elements and
behavior.
Why is it worth calling out at all then? I think because there are some
behaviors that we consider architectural (eg conref, the class attribute...)
that need to be consistent across specializations because they are designed
to provide interoperability across specializations; there are other behaviors
that are implementation-specific, in which the behaviors we provide are
defaults that can be overridden, rather than normative for the class of
all possible DITA document types. I think map-referencing behaviors fall
in the latter class, and that's what Robert is trying to say.
Robert, correct me if I'm wrong. Paul, does that re-interpretation address
your concerns?
Michael Priestley
Lead IBM DITA Architect
http://dita.xml.org/blog/25
"Grosso, Paul"
<>
09/10/2007 11:27 AM
To
<>
cc
Subject
RE: [dita] Issue 12055 Map referencing
behaviors
Robert,
If I understand correctly, you are suggesting that different
specializations can do different things based only on some
writeup in the standard.
Jeff and I have said that is the one choice we find unacceptable.
Either there needs to be some machine-readable way to determine
behavior (e.g., encode it in the DTD/XSDs), or all behavior must
be consistent. Having to hardwire potentially conflictly behavior
into an implementation for each specialization is not a good option.
Jeff and I will try to discuss this some more before tomorrow's
meeting, but I wanted to respond as soon as possible.
paul
>
