Agreed on the WG call that the behaviour in the table below will be adopted including the restrictions for OCK 'parsed'. List of spec changes as a result of this action are below. Note that the behaviour for OCK 'stopValue' in the table was not correct for unparsing. SSP 'anyEmpty' has a different behaviour than the others - it causes zero-length occurrences not to be output - which is fine. Please review so we can close on next call. 1) 14.2 - updates to paragraphs that describe positional and non-positional sequences Positional sequence - Each occurrence in the sequence can be identified by its position in the data. Typically the components of such a sequence do not have an initiator. In some such sequences, the separators for optional zero-length occurrences may or must be omitted when at the end of the group. In DFDL, a sequence is considered positional if it contains only required elements and/or optional and array elements that have dfdl:occursCountKind 'implicit', 'fixed' or 'expression', and it has dfdl:separatorSuppressionPolicy 'never', 'trailingEmptyStrict' or 'trailingEmpty'. Non-positional sequence - Occurrences in the sequence cannot be identified by their position in the data alone. Often the components of such a sequence have an initiator. Such sequences sometimes allow the separator to be omitted for optional zero-length occurrences anywhere in the sequence. Speculative parsing might need to be employed by to identify each occurrence. In DFDL, a sequence is non-positional if it contains any optional or array elements that have dfdl:occursCountKind 'parsed' or 'stopValue', and/or it has dfdl:separatorSuppressionPolicy 'anyEmpty'. 2) 14.2.2 - updates to the last sentences of the 'When dfdlk:occursCountKind is ...' paragraphs to match the table and notes below. When an element is required and is not an array then one occurrence is always expected along with its separator. The dfdl:separatorSuppressionPolicy of the sequence has no effect (nothing is eligible for suppression). Otherwise the behaviour is dependent on dfdl:occursCountKind. When dfdl:occursCountKind is 'fixed' then XSDL minOccurs must equal maxOccurs and that many occurrences are always expected along with their separators. The dfdl:separatorSuppressionPolicy of the sequence has no effect (nothing is eligible for suppression). When dfdl:occursCountKind is 'expression' the number of occurrences is given by dfdl:occursCount and exactly that many occurrences are always expected along with their separators. The dfdl:separatorSuppressionPolicy of the sequence has no effect (nothing is eligible for suppression). When dfdl:occursCountKind is 'parsed' any number of occurrences and their separators are expected. The dfdl:separatorSuppressionPolicy of the sequence must be 'anyEmpty' and it is a schema definition error otherwise. When dfdl:occursCountKind is 'stopValue', any number of occurrences and their separators are expected followed by the stop value and its separator. The dfdl:separatorSuppressionPolicy of the sequence has no effect. When dfdl:occursCountKind is 'implicit', between XSDL minOccurs and maxOccurs (inclusive) occurrences and their separators are expected, according to the dfdl:separatorSuppressionPolicy of the sequence. 3) 14.2.3 - updates to the last sentences of the 'When dfdlk:occursCountKind is ...' paragraphs to match the table and notes below. When an element is required and is not an array then one occurrence is always output along with its separator. The dfdl:separatorSuppressionPolicy of the sequence has no effect (nothing is eligible for suppression). Otherwise the behaviour is dependent on dfdl:occursCountKind. When dfdl:occursCountKind is 'fixed' or 'expression' the occurrences in the augmented Infoset are always output along with their separators. The dfdl:separatorSuppressionPolicy of the sequence has no effect (nothing is eligible for suppression). When dfdl:occursCountKind is 'parsed' non zero-length occurrences in the augmented Infoset are output along with their separators. The dfdl:separatorSuppressionPolicy of the sequence must be 'anyEmpty' and it is a schema definition error otherwise. When dfdl:occursCountKind is 'stopValue' the occurrences in the augmented Infoset are output along with their separators followed by the stop value and its separator, according to the dfdl:separatorSuppressionPolicy of the sequence. When dfdl:occursCountKind is 'implicit' the occurrences in the augmented Infoset are output along with their separators, according to the dfdl:separatorSuppressionPolicy of the sequence. 4) 16 - update to occursStopValue property description The property is a list of logical values, so need to add: "The dfdl:stopValue property must not be empty string." Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Steve Hanson/UK/IBM To: Mike Beckerle <mbeckerle.dfdl@gmail.com> Cc: DFDL-WG <dfdl-wg@ogf.org> Date: 18/11/2014 12:23 Subject: Re: [DFDL-WG] Fw: Fw: Action 260 Mike Comments in-line. Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB Cc: "dfdl-wg@ogf.org" <dfdl-wg@ogf.org> Date: 17/11/2014 23:11 Subject: Re: [DFDL-WG] Fw: Fw: Action 260 So I looked into what would be changed in the spec to make the adjustment suggested in this email thread, in intent. Rewriting the section is very undesirable at this stage for DFDL, so I was looking for incremental changes. What I came up with is this. In section 14.2.2 simply drop the sentences that mention this idea of an implied SSP, because they suggest the need to reconcile conflicting behaviors in the mixed case. I.e., drop all "The dfdl:separatorSuppressionPolicy is not applicable and the implied behaviour is '....'." With the omission of these sentences, the notion of an implied separator suppression policy that conflicts with one on the sequence goes away. There is only the SSP property of the sequence, and it is either relevant to the decision of whether to expect an item and its separator, or it isn't. The current descriptions in 14.2.2 of the behavior around suppression for each occursCountKind seem to be correct and match the table in this email thread, except for parsed. I'm not sure I agree with the assertion in this email thread that ock parsed only makes sense with "anyEmpty" behavior. We currently say in the spec that it has anyEmpty behavior, but if we drop that sentence (per suggestion above), then we would be loosening the behavior to allow empty elements in some cases. SMH: The intent of the table is that it is a schema definition error if 'parsed' and not 'anyEmpty' Suppose: <sequence dfdl:separatorSuppressionPolicy="trailingEmpty" dfdl:separator="|" dfdl:separatorPosition="infix" dfdl:terminator="%NL;"> <element name="a" type="xs:string" maxOccurs="unbounded" dfdl:occursCountKind='parsed'/> </sequence> In this case, the array is declared last in its sequence. The occurrences will all be element a, so this is positional. The number of them is determined by OCK parsed, and if enabled, validation will check, in this case, that at least 1 occurrence (the default for minOccurs) appears. In this case, empty string is a legal value, and we're not strict about trailing separators, so data like: 5|6|7|| is fine isn't it? The 'parsed' means you'll get 2 more empty string elements for the array when parsing that will not be re-created when unparsing, as they would be suppressed. I believe that is ok. There are many formats that can have that sort of asymmetry. SMH: To be clear, 'anyEmpty' already allows empty content when parsing, it has a lax semantic Change the above example to SSP trailingEmptyStrict, and now: 5,6,7||9 Now makes sense and you get one empty string in position 4. On unparsing this empty string would even get written out. I agree 'parsed' and SSP 'never' don't make sense together (as they don't for OCK implicit - SMH: only if maxOccurs 'unbounded' - see table 18 in 14.2.2), but the other 3 SSPs seem ok to me for declared-last elements. OCK parsed behaves (w.r.t. suppression, and ignoring defaulting and validation) just like OCK implicit with minOccurs 0 and maxOccurs 'unbounded'. (SMH: To be clear, defaulting and validation are independent of OCK). If we want to preserve the current restriction that parsed behaves like 'anyEmpty', then we can stipulate that when OCK is 'parsed', any number of non-empty occurrences and their separators are expected. (I would not be in favor of this.) SMH: So what you are saying is that 'parsed' is same as 'implicit' (0..unbounded). There are circumstances when this combination gives a schema definition error, as per Table 18 in 14.2.2 - this must therefore be the same for 'parsed'. It turns out that you only end up adding one extra legal behaviour for 'parsed', namely where element is declared last and SSP is 'trailingEmpty/Strict'. That's the example you quote above, but it's the only one. So is it buying much? SMH: When IBM put the table below together and said 'parsed' and SSP <> 'anyEmpty' is an error, it was to prevent a subtle change in behaviour for existing schemas with 'trailingEmpty/Strict'. Today the behaviour is 'anyEmpty', in the future it would be 'trailingEmpty/Strict'. Hence making it an error. As already noted in this thread, we also should add a sentence to stopValue: "The dfdl:stopValue property must not include empty string." The net result of these changes still isn't all that great, but it does remove one source of confusion - the 'implied' SSP conflict. SMH: If your 'parsed' proposal is adopted, you would need to document the 'parsed' behaviour as some combinations are schema definition errors. Arguably you would need the equivalent of Tables 18 and 19. Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy On Mon, Oct 13, 2014 at 10:08 AM, Steve Hanson <smh@uk.ibm.com> wrote: IBM has discussed this issue at some length internally, and come to the conclusion that the optional and array elements in a sequence should follow the separator suppression policy (SSP), and not have an implied SSP which is at odds with the sequence's SSP. In the table below, cells marked with a cross imply a schema definition error, and cells marked ok imply that there is a behaviour of the element for that OCK which is in keeping with the SSP of the sequence. SSP (1) OCK fixed implicit expression parsed stopValue (2) never ok ok ok x (5) ok (6) trailingEmpty trailingEmptyStrict ok (3) ok ok (4) x (5) ok (6) anyEmpty ok (3) ok ok (4) ok ok Notes: (1) SSP property applies only to an ordered sequence. An unordered sequence assumes 'anyEmpty' (as all optional/array elements must be 'parsed') (2) Missing restriction - for 'stopValue' the dfdl:stopValue property must not include empty string. (3) maxOccurs provides count, so nothing is eligible for suppression, so SSP has no practical effect (same as a required element) (4) infoset provides count, so nothing is eligible for suppression, so SSP has no practical effect (same as a required element) (5) 'parsed' only makes sense with 'anyEmpty' (6) Because a stop value must appear, and from (2) empty string is not allowed, SSP has no practical effect. The issue of maxOccurs = '0' is discussed in a separate email. Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 13/10/2014 14:40 ----- From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB, Cc: "dfdl-wg@ogf.org" <dfdl-wg@ogf.org> Date: 29/08/2014 21:21 Subject: Re: [DFDL-WG] Fw: Action 260 I reviewed this. It looks good to me. The note at the bottom that we don't say what happens on a zero-trip I.e., a represented element, but where occursCount evaluates to 0, is a useful clarification also. Do we want to create an erratum for this? Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy On Thu, Aug 28, 2014 at 10:13 AM, Steve Hanson <smh@uk.ibm.com> wrote: Please review for Tuesday's WG call ... Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 28/08/2014 15:02 ----- From: Steve Hanson/UK/IBM To: dfdl-wg@ogf.org, Date: 06/08/2014 13:50 Subject: Fw: [DFDL-WG] Action 260 So my suggestion below, to wrap the array in a sequence, does not work; it just moves the problem down into the new sequence. After much deliberation, we think that the definitions of Positional sequence and Non-positional sequence should not be viewed as driving the behaviour of a sequence, but simply as the resultant characteristics of a sequence that has certain properties. That leaves modellers free to mix occursCountKinds, as in Tim's example. No need for any new SDE scenarios. Positional sequence - Each occurrence in the sequence can be identified by its position in the data. Typically the components of such a sequence do not have an initiator. In some such sequences, the separators for optional zero-length occurrences may or must be omitted when at the end of the group. In DFDL, a sequence is considered positional if it contains only required elements and/or optional and array elements that have dfdl:occursCountKind 'implicit', 'fixed' or 'expression', and it has dfdl:separatorSuppressionPolicy 'never', 'trailingEmptyStrict' or 'trailingEmpty'. Non-positional sequence - Occurrences in the sequence cannot be identified by their position in the data alone. Often the components of such a sequence have an initiator. Such sequences sometimes allow the separator to be omitted for optional zero-length occurrences anywhere in the sequence. Speculative parsing might need to be employed by to identify each occurrence. In DFDL, a sequence is non-positional if it contains any optional or array elements that have dfdl:occursCountKind 'parsed' or 'stopValue', and/or it has dfdl:separatorSuppressionPolicy 'anyEmpty'. See parallel email for action 261 that ensures 'expression' behaves itself. One behaviour that is missing from the spec. For a sequence with separators, what is expected in the data stream if occursCount = 'fixed' / 'implicit' and maxOccurs = '0', or occursCountKind = 'expression' and occursCount evaluates to 0 ? We believe that no separator should be expected when parsing and none output when unparsing (same behaviour as inputValueCalc). Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 06/08/2014 12:42 ----- From: Steve Hanson/UK/IBM To: Tim Kimber/UK/IBM@IBMGB, Cc: dfdl-wg@ogf.org, dfdl-wg-bounces@ogf.org Date: 30/06/2014 10:04 Subject: Re: [DFDL-WG] Action 260 You would wrap the array and it's count in a sequence. Then the 'count+array' is treated as a single entity as far as the parent sequence is concerned. Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org, Date: 26/06/2014 20:06 Subject: Re: [DFDL-WG] Action 260 Sent by: dfdl-wg-bounces@ogf.org Before we settle one way or the other, I would like the following data format to be taken into consideration. chars,5,A,B,C,D,E,integers,1,2,3 chars,3,C,,,integers,2,10,11 I am assuming that the occursCountKind for the arrays is 'expression' and the occursCount refers to the integer field that precedes the array. In order to represent the empty strings on the second line it is essential to specify SSP as 'trailingEmpty' or 'never'. If we disallow the combination of ock='expression' and SSP='trailingEmpty' then how would this format be modelled? regards, Tim Kimber, Technical Lead for IBM Integration Bus Healthcare Pack Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 37246742 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB, Cc: "dfdl-wg@ogf.org" <dfdl-wg@ogf.org> Date: 25/06/2014 16:25 Subject: Re: [DFDL-WG] Action 260 Sent by: dfdl-wg-bounces@ogf.org I prefer choice (a) for two reasons * It is more restrictive and therefore more conservative (preserving freedom to change in future if needed) * If a user has a positional data format, you don't want them to even have to understand the concept of speculation in order to model their data. So choice (a) allows a simpler description that doesn't need to introduce the notion that the parser might be speculation. Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy On Wed, Jun 25, 2014 at 5:20 AM, Steve Hanson <smh@uk.ibm.com> wrote: 260 Positional and non-positional sequences (All) 10/6: Spec defines the above but also allows different occursCountKinds within the same sequence which may have different (implied) separatorSuppressionPolicy, which results in a sequence which is a mixture of both. Should this be allowed? If so what are the rules? Can certain combinations be disallowed? 17/6: IBM have discussed internally and will submit a proposal. In the spec we define Positional Sequence and Non-Positional Sequence: Positional sequence - Each occurrence in the sequence can be identified by its position in the data. Typically the components of such a sequence do not have an initiator. In some such sequences, the separators for optional zero-length occurrences may or must be omitted when at the end of the group. A positional sequence can be modelled by setting dfdl:separatorSuppressionPolicy to 'never', 'trailingEmptyStrict' or 'trailingEmpty'. Non-positional sequence - Occurrences in the sequence cannot be identified by their position in the data alone. Typically the components of such a sequence have an initiator. Such sequences allow the separator to be omitted for optional zero-length occurrences anywhere in the sequence. Speculative parsing is employed by the parser to identify each occurrence. A non-positional sequence can be modelled by setting dfdl:separatorSuppressionPolicy to 'anyEmpty'. The problem is that the setting of dfdl:separatorSuppressionPolicy is only examined for child elements with dfdl:occursCountKind 'implicit'. For other dfdl:occursCountKinds, there is the concept of an 'implied' dfdl:separatorSuppressionPolicy: When dfdl:occursCountKind is 'fixed' then ... the implied behaviour is 'never'. When dfdl:occursCountKind is 'expression' ... the implied behaviour is 'never'. When dfdl:occursCountKind is 'parsed' ... the implied behaviour is 'anyEmpty'. When dfdl:occursCountKind is 'stopValue' ...the implied behaviour is 'anyEmpty'. So if a Positional sequence as defined above contains children with dfdl:occursCountKind 'parsed' or 'stopValue' then surely it is no longer a Positional sequence. A solution to this is to prevent the appearance of certain values of dfdl:occursCountKind within a Positional sequence. However, precisely which values to outlaw is subject to interpretation of the phrase "Each occurrence in the sequence can be identified by its position in the data". Is this intended to mean: a) an observer of the raw data can identify an occurrence of an element in the sequence solely by counting separators => SDE if 'parsed', 'stopValue' or 'expression' ** appeared in a Positional sequence; ** Although 'expression' would appear to be like 'fixed' it actually breaks a) so must be included in the SDE list. or b) a parser does not have to speculate to identify an occurrence of an element in the sequence => SDE only if 'parsed' appeared in a Positional sequence. Note that it is possible to wrap a 'parsed' etc element in a local sequence or another element to avoid an SDE. But this could still be seen as a violation of a) if the separators of both are the same, as the observer can not count the separators. So should the rule be applied recursively, ie, a Positional sequence can not contain a non-Positional sequence unless the separators are different? Regards Steve Hanson Architect, IBM DFDL Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU