Actually I’d be happy with no flexibility
and no new architectural attribute. With that approach the referencing map
would always override the referenced map. But this makes it hard for me
to come up with concrete scenario’s that require flexibility.
I think Robert has cases where specializers
don’t want the referencing map context to override the referenced map
context. And he thinks Erik has some more complicated cases where simple
inherit or not options aren’t enough. This leads to the desire to allow
exceptions and to give specializers some flexibility.
So what we might do is have Robert or Erik
provide the concrete case(s). I’d be happy to plug those cases into the output
processing pipeline implementation and architectural attributes that I
described in my previous note.
-Jeff
From: Michael
Priestley [mailto:]
Sent: Tuesday, September 11, 2007
1:29 PM
To: Ogden, Jeff
Cc:
Subject: RE: [dita] Issue 12055
Map referencing behaviors
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
>
