[step-manufacturing] Part 29 Specification of the AP Binding
Martin Hardwick
hardwick at steptools.com
Tue Jul 27 16:31:25 EDT 2004
All,
Here is a draft formal specification of the AP binding.
The document is as per the message I sent out just before
the last conference call but with header elements defined
and two corrections made:
a. NVL element deleted and replaced with an unset attribute.
b. Camel case used for entity names.
I had the following goals when defining the header element
1. Make it possible to embed STEP information in other XML
documents including SOAP envelopes and databases. For example,
send the header element to a user in a SOAP message and have
it contain URL's for all of the places to find the data.
2. Enable the reuse of data across Application Protocols including
reuse of geometry defined in P21.
3. Enable the definition of constant entity instances in a reference
data set so that they can be reused by every instance of an
Application Protocol (and be defined by standard names given in the
AP).
4. Enable modularity by defining a new class of conformance checking
that allows the mapping of an Application Object instance to be
checked without checking the rest of an AP.
This should make it possible for us to begin defining re-usable
libraries of Application Objects which is something we need quite
badly in STEP-Manufacturing so that we can start defining libraries
of re-usable processes and features.
5. Give the user freedom to define name spaces for STEP data and name spaces
for other kinds of data and allow the two to be freely mixed within
documents.
I welcome all of your comments and will be happy to make corrections
and add functionality.
I have not done anything to optimize the representation of lists because
I would like to talk to the group working on the representation of large
analysis data sets to discover what will work best for them (simply
allowing lists of primitives to be compressed seems insufficient).
This work is not meant to replace P28 but to supplement it for those
teams that do not anticipate being able to define a simple XML Schema
for their Application Protocol in the short to mid-term.
In this edition the text and table of contents are good (for a draft
rapidly written by one person). The index has not been updated. None
of the Annexes have been updated, but some P21 annexes that do not
apply to P29 have been deleted. I have not yet figured out how to
use the Framemaker spell checker without it complaining about all the
examples so I apologize in advance for all the typos.
Martin Hardwick
At 01:51 PM 7/16/2004 -0400, Martin Hardwick wrote:
>All,
>
>As per the mandate given to T24 at the SC4 meeting here is
>a specification for the AP binding. All and any suggestions
>for improvements are welcomed, particularly when they correct
>errors and ambiguities.
>
>However, when making suggestions please remember that speed
>is an important goal for this project. We want to have a CD
>draft ready for the next SC4 meeting. There are many areas
>where additional flexibility can be added without much cost
>but in most cases it may be best to add these via the ballot
>comment/resolution process.
>
>One of the items for discussion in the teleconference should
>be whether this binding can be completed most efficiently by
>writing a conformance class of P28 or by writing a new document
>using the existing P21 as a model.
>
>Martin Hardwick
>Team Leader T24 STEP-Manufacturing
>
>+++++++++++++++++++++++++++++++++++++++
>AP Binding Requirements
>
>1. The AP binding needs to follow the mainstream conventions for XML data
> (no surprises to the end user).
>2. The AP binding must have sufficient legibility/understandability to
> allow the AP developers to add definitions to the schema that may come from
> the AAM, ARM, mapping tables and AIM rules.
>3. The AP binding specification must be clear, concise and precise to support
> easy conformance checking by vendors and end users.
>4. The AP binding must be implementable by those who have developed
> P21 parsers without requiring them to purchase or otherwise obtain
> additional tooling for any reason including pre-processing or
> post-processing data described by a configuration.
>5. The AP binding must allow AP implementations to inter-operate when
> those AP's contain harmonized AIM definitions.
>
>+++++++++++++++++++++++++++++++++++++++
>Specification of the AP Binding
>
>1. Case conventions
>
> Entity names converted to upper case. Attribute
> names converted to lower case. Type names
> converted to upper case.
>
>2. Handling of entities
>
> Entity is tagged with its name and an id.
>
> Each attribute is tagged with its name.
>
> Each attribute describe by an entity value
> has either an href attribute to the entity
> or the value is described in place using nesting.
>
> AP developers can choose to define only one
> form (href or nesting) in their XML Schema for
> a given attribute and then state that the other
> form may also be used.
>
> Nested instances may be referenced by other instances.
>
> <PRODUCT_DEFINITION id="pd45" >
> <id>PR-3456-Manufacturing</id>
> <formation href="#pdf78" />
> </PRODUCT_DEFINITION>
>
> <PRODUCT_DEFINITION_FORMATION id="pdf78" >
> <id>PR23-67-PDF</id>
> <of_product>
> <PRODUCT id="p078">
> <id>PR2345-76A</id>
> <name>machining project</name>
> </PRODUCT>
> </of_product>
> </PRODUCT_DEFINITION_FORMATION>
>
>3. Handling of selects
>
> Primitive types are always tagged with the most
> specific type name.
>
> Entity types are tagged with the name of the type
> If a path of nested selects is necessary then the
> XML tag contains an attribute called path which contains
> a white space delimited list of type names as per the
> Part 21 specification.
>
> <CIRCLE id="c56" >
> <position href="#a2p-102" /> <!-- this is a select -->
> </CIRCLE>
>
> <AXIS2_PLACEMENT_3D id="a2p-102">
> ...
> </AXIS2_PLACEMENT_3D>
>
> In the following EXPRESS (from P21)
>
> TYPE Mass = SELECT(Mass_Spec, Mass_Substitute);
> END_TYPE;
>
> TYPE Mass_Spec = SELECT(Measured_Mass, Computed_Mass, Estimated_Mass);
> END_TYPE;
>
> TYPE Measured_Mass = REAL;
> END_TYPE;
>
> TYPE Computed_Mass = Extended_Real;
> END_TYPE;
>
> TYPE Estimated_Mass = REAL;
> END_TYPE;
>
> TYPE Mass_Substitute = SELECT=(Weight, Estimated_Mass);
> END_TYPE;
>
> TYPE Weight = REAL;
> END_TYPE;
>
> TYPE Extended_Real = SELECT(FloatingNumber, NotaNumber);
> END_TYPE;
>
> TYPE FloatingNUmber = REAL(7);
> END_TYPE;
>
> TYPE NotaNumber = ENUMERATION OF (plus_infinity, minus_infinity,
> indeterminate, invalid);
> END_TYPE;
>
> ENTITY Steel_bar;
> bar_length: Extended_Real;
> bar_mass: Mass;
> END_ENTITY;
>
> #1=SEEL_BAR(FLOATINGNUMBER(77.0), MEASURED_MASS(13.25));
> <STEEL_BAR id="id-1" >
> <bar_length><FLOATINGNUMBER>77.0</FLOATINGNUMBER></bar_length>
> <bar_mass><MEASURED_MASS>13.25</MEASURED_MASS></bar_mass>
> </STEEL_BAR>
>
> #2=SEEL_BAR(NOTANUMBER(.INDETERMINATE.)), ESTIMATED_MASS(10.0));
> <STEEL_BAR id="id-2" >
> <bar_length><NOTANUMBER>indeterminate</NOTANUMBER></bar_length>
> <bar_mass><ESTIMATED_MASS>13.25</ESTIMATED_MASS></bar_mass>
> </STEEL_BAR>
>
> #3=STEEL_BAR(FLOATINGNUMBER(77.0), COMPUTED_MASS(FLOATINGNUMBER(14.77719)));
> <STEEL_BAR id="id-3" >
> <bar_length><FLOATINGNUMBER>77.0</FLOATINGNUMBER></bar_length>
> <bar_mass>
> <FLOATINGNUMBER path="COMPUTED_MASS">13.25</FLOATINGNUMBER>
> </bar_mass>
> </STEEL_BAR>
>
>
>4. Handling of simple aggregates
>
> The EXPRESS attribute serves as the container for the aggregate. Every
> element in the aggregate is represented by an XML element. For those
> data types that are not described by entities, the name of the most specific
> type is used as the element name.
>
> <CARTESIAN_POINT id="cp45" >
> <coordinates>
> <LENGTH_MEASURE>6.78</LENGTH_MEASURE>
> <LENGTH_MEASURE>3.2</LENGTH_MEASURE>
> <LENGTH_MEASURE>10.32</LENGTH_MEASURE>
> </coordinates>
> </CARTESIAN_POINT>
>
> <APPLIED_DATE_AND_TIME_ASSIGNMENT id="adta23">
> <items>
> <DATED_EFFECTIVITY href="#ef-45" />
> <APPROVAL_STATUS>
> <name>approved</name>
> </APPROVAL_STATUS>
> <PERSON_AND_ORGANIZATION href="#pno-24" />
> </items>
> </APPLIED_DATE_AND_TIME_ASSIGNMENT>
>
>5. Handling of nested aggregates
>
> New keyword <AGGREGATE> is used to tag each nest except the
> outermost which is tagged by the attribute. Elements in
> the aggregate are tagged using their most specific type
> name.
>
> <RATIONAL_B_SPLINE_SURFACE id="rbss89" >
> <weights_data>
> <AGGREGATE>
> <REAL>5.6</REAL>
> <REAL>6.7</REAL>
> </AGGREGATE>
> <AGGREGATE>
> <REAL>3.2</REAL>
> <REAL>4.3</REAL>
> </AGGREGATE>
> </weights_data>
> </RATIONAL_B_SPLINE_SURFACE >
>
>6. External mapping
>
> Tagged using the Part 23 name generation algorithm but
> with a "-" replacing the "_and_".
>
> For example, an AND/OR of foo and bar, is foo_and_bar
> in Part 23 and is foo-bar in the AP Binding
>
> There is no requirement to generate the external mapping
> names in advance.
>
> AP developers can use the generated names to make assertions
> about the AND/OR instance in XML Schema at their discretion.
>
> Early bound implementations can choose to generate the names
> in advance, or process the type using late bound External mapping
> software by recognizing the hyphen.
>
> #28=(LENGTH_UNIT()
> NAMED_UNIT(*)
> SI_UNIT(.MILLI.,.METRE.)
> );
>
> <NAMED_UNIT-SI_UNIT id="id-28" >
> <prefix>milli</prefix>
> <name>metre</name>
> </NAMED_UNIT-SI_UNIT >
>
>7. Null ($ sign equivalent).
>
> The keyword NVL shall be used to indicate a NULL element.
>
> <position><NVL/></position>
> <items><REAL>1.5</REAL><NVL/><REAL>2.6</REAL></items>
>
> When an AP developer wants to allow NULL values, the <NVL>
> element should be included in the XMLSchema definition.
>
>8. Attribute order.
>
> The attribute order does not matter. If an entity inherits two
> attributes with the same name then qualify each name with the
> name of the entity that defined that attribute.
>
> Attributes with unrecognized names shall be ignored.
> Missing attributes shall be unset.
>
>9. Entity instance order.
>
> The order is unspecified. Unrecognized instances shall be
> ignored.
>
>10. href
>
> The form of an href is "document#id"
>
> Document shall be the URL of a file. Id shall be the id of
> an entity instance in that file. Document may be omitted
> if the instance is in the current file.
>
> The id must be a valid XML NMTOKEN (must begin with a
> a letter)
>
>_______________________________________________
>wg11 mailing list
>wg11 at steptools.com
>http://lists.steptools.com/mailman/listinfo/wg11
>
>
>!DSPAM:40f815d4183261392010872!
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