On Tuesday 06 September 2005 12:21, Steve Hanson wrote:
The MRM model COBOL importer gives the user an option to create xs:enumeration values from level 88 values, and that is all. This is so the MRM parser can validate a byte stream against the model. This is in keeping with the rule that values supplied with metadata are part of the logical model, not the physical model. What's the motivation for doing anything more than this?
Sorry, I don't know what "the logical model" vs. "the physical model" means. IMO, the goal is to have a way for a producer to generate data (e.g., with 88s as discussed below), which a consumer can interpret as either 88 or symbols, depending on the purpose of the consumer.
Using your example that gives:
<xs:element name="AS-COM-TRAN-ID"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="CP80"/> <xs:enumeration value="IC40"/> ... </xs:restriction> </xs:simpleType> </xs:element>
Regards, Steve
Steve Hanson WebSphere Business Integration Brokers, IBM Hursley, England Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848
Mike Beckerle <beckerle@us.ibm. com> To Sent by: dfdl-wg@gridforum.org owner-dfdl-wg@ggf cc .org Subject Enums - Re: split into multiple 06/09/2005 17:40 topics - Re: [dfdl-wg] Issues: additional data types
About enums. Here's starting thoughts:
Here's a real-world example from COBOL:
01 AS-CPST-REC. 06 AS-CPCOM. 09 AS-COM-STORE-TYPE PIC X. 09 AS-COM-STORE-NO PIC 9(05). 09 AS-COM-TRAN-ID PIC X(04). 88 TRAN-COUPON VALUE 'CP80'. 88 TRAN-REVENUE VALUE 'IC40' 'RA40'. 88 TRAN-SALES VALUE 'IC40'. 88 TRAN-DELIVER VALUE 'IC44'. 88 TRAN-RENTS VALUE 'RA40' 'RA42'. 88 TRAN-RENT-RETURN VALUE 'RA41'. 09 AS-COM-QUANTITY PIC S9(05). 09 AS-COM-PART-NO PIC 9(06). .... more fields elided ....
Those "88" entries in there are enumerated constants. Note that for the TRAN-REVENUE and TRAN-RENTS constants, multiple values are associated with the same name. On reference this means that the constant matches either value. When written, this means the first value is used. Cobol doesn't strongly associate these enumerated values with the field to which they can be assigned, but usually it's obvious. In this case it is the AS-COM-TRAN-ID field which is the 4-character-long string which has the string constants associated with it.
This particular example is a common one. The record has variant structure (not shown above) depending on the tag field which is this AS-COM-TRAN-ID field.
Working out how we want this example to work in XSD is the first step.
I like using a hidden field here. For example: Here's a possible idea for how this is represented in XSD:
<xs:element name="AS-COM-TRAN-ID"> <!-- logical tag element --> <xs:simpleType> <xs:restriction base="xs:NCName"> <xs:enumeration value="TRAN-COUPON"/> <xs:enumeration value="TRAN-REVENUE"/> <xs:enumeration value="TRAN-SALES"/> <xs:enumeration value="TRAN-DELIVER"/> <xs:enumeration value="TRAN-RENTS"/> </xs:restriction> </xs:simpleType> </xs:element> <xs:sequence> <xs:annotation> <xs:appinfo source="http://dataformat.org/"> <xs:layer name="rep" type="AS-COM-TRAN-ID-repType"/> <!-- hidden physical tag rep --> </xs:appinfo> </xs:annotation> </xs:sequence>
<xs:simpleType name="AS-COM-TRAN-ID-repType"> <xs:restriction base="xs:string> <xs:enumeration value="CP80"/> <xs:enumeration value="IC40"/> <!-- rest of the tag values elided here --> .... </xs:restriction> </xs:simpleType>
Now in an annotation (not shown above) on the element AS-COM-TRAN-ID there would be a dfdl:valueCalc property which would compute the value of AS-COM-TRAN-ID based on the value of the hidden field. Symmetrically, the 'rep' hidden field would have a dfdl:repCalc property which would give the inverse formula for output.
One difficulty I have with this is the notion that we're projecting into the string type. I.e., these symbolic constants aren't names for integers, but rather we're expressing operations on strings. In the above example the enumerated constants actually are strings, but in other examples they would be integers. The next tier of interpretation, i.e., where we're decidng the variant based on the value of AS-COM-TRAN-ID would be expressed as string comparisons which is potentially inefficient. This is part of the problem with using XSD as our type system basis. XSD doesn't have a notion of symbolic named constant.
Alternative: There is the DTD named entity stuff. Does anybody want to propose that?
Mike Beckerle Architect, Scalable Computing IBM Software Group Information Integration Solutions Westborough, MA
Mike Beckerle/Worcester/IBM@IBMUS
Sent by: To owner-dfdl-wg@ggf.org "Robert E. McGrath" <mcgrath@ncsa.uiuc.edu> cc 09/02/2005 04:34 PM dfdl-wg@gridforum.org, owner-dfdl-wg@ggf.org Subject split into multiple topics - Re: [dfdl-wg] Issues: additional data types
I'd like to split this topic into several distinct ones:
Arrays - I have a placeholder for this in the doc.
Opaque and "code" types are separate. This is related also to the concept of "open content".
Enums
Bitfields
Pointers
Mike Beckerle Architect, Scalable Computing IBM Software Group Information Integration Solutions Westborough, MA
"Robert E. McGrath" <mcgrath@ncsa.uiuc.edu> Sent by: owner-dfdl-wg@ggf.org To dfdl-wg@gridforum.org 09/02/2005 03:13 PM cc
Subject [dfdl-wg] Issues: additional data types
Greetings,
Here is an "issue" for the DFDL: additional data types that should be considered.
Please see attached.
--- Robert E. McGrath National Center for Supercomputing Applications University of Illinois, Urbana-Champaign Champaign, Illinois 61820 (217)-333-6549
mcgrath@ncsa.uiuc.edu (See attached file: DT.htm)
-- --- Robert E. McGrath National Center for Supercomputing Applications University of Illinois, Urbana-Champaign Champaign, Illinois 61820 (217)-333-6549 mcgrath@ncsa.uiuc.edu