Actually, fn:error was added in order to allow a DFDL Expression to create a normal processing error. You need a different mechanism, which is a fatalError type for the dfdl:assert annotation. I have noticed that the use of 'validation' in DFDL is the opposite of the way other people use 'validation'. In the DFDL spec, validation generally just creates warnings and continues parsing. It can't even affect the parse unless you call checkConstrants(....) from an assert. But the CDS community uses validation to indicate an immediate need to stop. I.e., invalid == "dangerous". ...mikeb On Wed, Jul 10, 2013 at 1:37 PM, Garriss Jr., James P. <jgarriss@mitre.org>wrote:

...

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression). ****

** **

Is this intended to address the issue I raised? If so, I think this is not sufficient. I need to have the option to cause a validation error, not a processing error. If not, please ignore this interruption. :-)****

** **

*From:* dfdl-wg-bounces@ogf.org [mailto:dfdl-wg-bounces@ogf.org] *On Behalf Of *Mike Beckerle *Sent:* Tuesday, July 09, 2013 11:29 AM *To:* dfdl-wg@ogf.org *Subject:* Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL****

** **

Proposal revised for dfdl:hex, and clarification added on fn:error when used inside assert.

Revised language below:

Proposed: add fn:error function and add dfdl:hexBinary function.

DFDL only needs one of the several variations of fn:error.

fn:error($error as xs:QName?, $description as xs:string) as none

The behavior of fn:error in DFDL expressions is the same as described in XPath 2.0, an example is given below.

dfdl:hexBinary($arg as xs:anyAtomicType?) as xs:hexBinary?

This function provides an extension to the behavior of the xs:hexBinary constructor. The argument can be a string, in which case the behavior is as the xs:hexBinary constructor. The argument can also be a long, unsignedLong, or any subtype thereof, and in that case a string containing hexadecimal digits is produced. The hexadecimal digits produced that are letters are always uppercase. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The hex digits correspond to a big-endian representation of a twos-complement binary representation of the argument value. So:

dfdl:short(xs:concat('x', dfdl:hexBinary(xs:short(208)))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

If the argument is a numeric literal, then the smallest signed integer type (long, int, short, byte) is selected that can contain the value, and the number of hexadecimal digits produced corresponds to that type. So:

dfdl:hexBinary(208) eq 'D0' dfdl:hexBinary(-2084) eq 'F7FF'

Example of fn:error and dfdl:hexBinary:

This expression allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0x", dfdl:hexBinary(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to 'http://example.com' then the above call might produce:

"Error: {http://example.com}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent.

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression). If the assert or discriminator has a message property, then it is implementation dependent how that message string is combined with the description string argument provided to the fn:error function.

****

On Thu, Jun 20, 2013 at 1:09 PM, Mike Beckerle <mbeckerle.dfdl@gmail.com> wrote:****

Proposed: add fn:error function and add dfdl:hex function.

DFDL only needs one of the several variations of fn:error****

fn:error($error as xs:QName?, $description as xs:string) as none

dfdl:hex($num as xs:integer) as string****

The dfdl:hex function inverts the behavior of the dfdl:byte, and related functions (currently also proposed) which take a string specification of a hex value. The argument to dfdl:hex can be a long, unsignedLong, or any subtype thereof. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The resulting value contains a prefix 'x' character as its first character. So:

dfdl:short(dfdl:hex(xs:short(208))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

Example:

This allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0", dfdl:hex(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to 'http://example.com' then the above call might produce:

"Error: {http://example.com}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent. ****

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com****

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

Ignoring the dfdl:hexBinary thing. I want to suggest a different idea than fn:error function for DFDL: Suppose dfdl:assert (and dfdl:discriminator) message property could be an expression that evaluates to a string. Then instead of writing <dfdl:assert>{ if (...pred...) then ...expr1... else if (...pred2...) then ...expr2... else fn:error(sym, fn:concat("unknown whatever ", ../foobar)) }</dfdl:assert> You could write: <dfdl:assert message="{ fn:concat('unknown whatever ', ../foobar) }"> { if (...pred...) then ...expr1... else if (...pred2...) then ...expr2... else fn:false() }</dfdl:assert> This is almost equivalent. But the message would respect the failureType of the assert. This has advantages. On Wed, Jul 10, 2013 at 3:14 PM, Garriss Jr., James P. <jgarriss@mitre.org>wrote:

...

You need a different mechanism, which is a fatalError type for the dfdl:assert annotation.

****

Sounds like we are in agreement. Thanks for clarifying.****

** **

...

But the CDS community uses validation to indicate an immediate need to stop. I.e., invalid == "dangerous".

****

In some cases this is true, though in other cases it is not true. That’s why it seems to me that it would be good if DFDL can handle either mindset. For the work I’ve been doing with DFDL and email, the “invalid=dangerous” mindset was a starting assumption. ****

** **

*From:* Mike Beckerle [mailto:mbeckerle.dfdl@gmail.com] *Sent:* Wednesday, July 10, 2013 1:57 PM *To:* Garriss Jr., James P. *Cc:* dfdl-wg@ogf.org *Subject:* Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL****

** **

Actually, fn:error was added in order to allow a DFDL Expression to create a normal processing error.

You need a different mechanism, which is a fatalError type for the dfdl:assert annotation.

I have noticed that the use of 'validation' in DFDL is the opposite of the way other people use 'validation'. In the DFDL spec, validation generally just creates warnings and continues parsing. It can't even affect the parse unless you call checkConstrants(....) from an assert. But the CDS community uses validation to indicate an immediate need to stop. I.e., invalid == "dangerous".

...mikeb****

On Wed, Jul 10, 2013 at 1:37 PM, Garriss Jr., James P. <jgarriss@mitre.org> wrote:****

...

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression). ****

****

Is this intended to address the issue I raised? If so, I think this is not sufficient. I need to have the option to cause a validation error, not a processing error. If not, please ignore this interruption. :-)****

****

*From:* dfdl-wg-bounces@ogf.org [mailto:dfdl-wg-bounces@ogf.org] *On Behalf Of *Mike Beckerle *Sent:* Tuesday, July 09, 2013 11:29 AM *To:* dfdl-wg@ogf.org *Subject:* Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL****

****

Proposal revised for dfdl:hex, and clarification added on fn:error when used inside assert.

Revised language below:

Proposed: add fn:error function and add dfdl:hexBinary function.

DFDL only needs one of the several variations of fn:error.

fn:error($error as xs:QName?, $description as xs:string) as none

The behavior of fn:error in DFDL expressions is the same as described in XPath 2.0, an example is given below.

dfdl:hexBinary($arg as xs:anyAtomicType?) as xs:hexBinary?

This function provides an extension to the behavior of the xs:hexBinary constructor. The argument can be a string, in which case the behavior is as the xs:hexBinary constructor. The argument can also be a long, unsignedLong, or any subtype thereof, and in that case a string containing hexadecimal digits is produced. The hexadecimal digits produced that are letters are always uppercase. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The hex digits correspond to a big-endian representation of a twos-complement binary representation of the argument value. So:

dfdl:short(xs:concat('x', dfdl:hexBinary(xs:short(208)))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

If the argument is a numeric literal, then the smallest signed integer type (long, int, short, byte) is selected that can contain the value, and the number of hexadecimal digits produced corresponds to that type. So:

dfdl:hexBinary(208) eq 'D0' dfdl:hexBinary(-2084) eq 'F7FF'

Example of fn:error and dfdl:hexBinary:

This expression allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0x", dfdl:hexBinary(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to 'http://example.com' then the above call might produce:

"Error: {http://example.com}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent.

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression). If the assert or discriminator has a message property, then it is implementation dependent how that message string is combined with the description string argument provided to the fn:error function.

****

On Thu, Jun 20, 2013 at 1:09 PM, Mike Beckerle <mbeckerle.dfdl@gmail.com> wrote:****

Proposed: add fn:error function and add dfdl:hex function.

DFDL only needs one of the several variations of fn:error****

fn:error($error as xs:QName?, $description as xs:string) as none

dfdl:hex($num as xs:integer) as string****

The dfdl:hex function inverts the behavior of the dfdl:byte, and related functions (currently also proposed) which take a string specification of a hex value. The argument to dfdl:hex can be a long, unsignedLong, or any subtype thereof. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The resulting value contains a prefix 'x' character as its first character. So:

dfdl:short(dfdl:hex(xs:short(208))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

Example:

This allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0", dfdl:hex(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to 'http://example.com' then the above call might produce:

"Error: {http://example.com}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent. ****

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com****

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com****

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

On Fri, Jul 12, 2013 at 4:25 AM, Steve Hanson <smh@uk.ibm.com> wrote:

I agree that is simpler and making the message string an expression is an easy change to make.

But in the your example if expr1 or expr2 evaluated to false, then in form #1 no message would be issued, but in form #2 it would be issued. Is that what you intended?

I think this is an artifact of my contrived example. More realistically each of expr1 and expr2 would be fn:true(), because really, the decision is in the corresponding pred1 and pred2, or they would be another tree of complex conditional branch each leaf ending in fn:error or fn:true(). So in the version that calls fn:error false/fail is always a call to fn:error instead. In the version where message is an expression, false/fail is fn:false(), then the message prints. A large complicated decision tree with many different fn:error calls at the leaves (in the fn:error formulation) will convert into several distinct assert statements in the other formulation. One assert per distinct message.

From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: dfdl-wg@ogf.org, Date: 11/07/2013 18:47 Subject: Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL Sent by: dfdl-wg-bounces@ogf.org ------------------------------

Ignoring the dfdl:hexBinary thing.

I want to suggest a different idea than fn:error function for DFDL:

Suppose dfdl:assert (and dfdl:discriminator) message property could be an expression that evaluates to a string.

Then instead of writing

<dfdl:assert>{ if (...pred...) then ...expr1... else if (...pred2...) then ...expr2... else fn:error(sym, fn:concat("unknown whatever ", ../foobar)) }</dfdl:assert>

You could write:

<dfdl:assert message="{ fn:concat('unknown whatever ', ../foobar) }"> { if (...pred...) then ...expr1... else if (...pred2...) then ...expr2... else fn:false() }</dfdl:assert>

This is almost equivalent. But the message would respect the failureType of the assert.

This has advantages.

On Wed, Jul 10, 2013 at 3:14 PM, Garriss Jr., James P. <* jgarriss@mitre.org* <jgarriss@mitre.org>> wrote:

...

You need a different mechanism, which is a fatalError type for the dfdl:assert annotation.

Sounds like we are in agreement. Thanks for clarifying.

...

But the CDS community uses validation to indicate an immediate need to stop. I.e., invalid == "dangerous".

In some cases this is true, though in other cases it is not true. That’s why it seems to me that it would be good if DFDL can handle either mindset. For the work I’ve been doing with DFDL and email, the “invalid=dangerous” mindset was a starting assumption.

*From:* Mike Beckerle [mailto:*mbeckerle.dfdl@gmail.com*<mbeckerle.dfdl@gmail.com>] * Sent:* Wednesday, July 10, 2013 1:57 PM* To:* Garriss Jr., James P.* Cc:* *dfdl-wg@ogf.org* <dfdl-wg@ogf.org>* Subject:* Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL

Actually, fn:error was added in order to allow a DFDL Expression to create a normal processing error.

You need a different mechanism, which is a fatalError type for the dfdl:assert annotation.

I have noticed that the use of 'validation' in DFDL is the opposite of the way other people use 'validation'. In the DFDL spec, validation generally just creates warnings and continues parsing. It can't even affect the parse unless you call checkConstrants(....) from an assert. But the CDS community uses validation to indicate an immediate need to stop. I.e., invalid == "dangerous".

...mikeb

On Wed, Jul 10, 2013 at 1:37 PM, Garriss Jr., James P. <* jgarriss@mitre.org* <jgarriss@mitre.org>> wrote:

...

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression).

Is this intended to address the issue I raised? If so, I think this is not sufficient. I need to have the option to cause a validation error, not a processing error. If not, please ignore this interruption. :-)

*From:* *dfdl-wg-bounces@ogf.org* <dfdl-wg-bounces@ogf.org> [mailto:* dfdl-wg-bounces@ogf.org* <dfdl-wg-bounces@ogf.org>] *On Behalf Of *Mike Beckerle* Sent:* Tuesday, July 09, 2013 11:29 AM* To:* *dfdl-wg@ogf.org* <dfdl-wg@ogf.org>* Subject:* Re: [DFDL-WG] proposal: add fn:error function and dfdl:hex function to DFDL

Proposal revised for dfdl:hex, and clarification added on fn:error when used inside assert.

Revised language below:

Proposed: add fn:error function and add dfdl:hexBinary function.

DFDL only needs one of the several variations of fn:error.

fn:error($error as xs:QName?, $description as xs:string) as none

The behavior of fn:error in DFDL expressions is the same as described in XPath 2.0, an example is given below.

dfdl:hexBinary($arg as xs:anyAtomicType?) as xs:hexBinary?

This function provides an extension to the behavior of the xs:hexBinary constructor. The argument can be a string, in which case the behavior is as the xs:hexBinary constructor. The argument can also be a long, unsignedLong, or any subtype thereof, and in that case a string containing hexadecimal digits is produced. The hexadecimal digits produced that are letters are always uppercase. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The hex digits correspond to a big-endian representation of a twos-complement binary representation of the argument value. So:

dfdl:short(xs:concat('x', dfdl:hexBinary(xs:short(208)))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

If the argument is a numeric literal, then the smallest signed integer type (long, int, short, byte) is selected that can contain the value, and the number of hexadecimal digits produced corresponds to that type. So:

dfdl:hexBinary(208) eq 'D0' dfdl:hexBinary(-2084) eq 'F7FF'

Example of fn:error and dfdl:hexBinary:

This expression allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0x", dfdl:hexBinary(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to '*http://example.com* <http://example.com/>' then the above call might produce:

"Error: {*http://example.com* <http://example.com/>}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent.

fn:error, if called from inside an assert or discriminator, causes the assert or discriminator to fail (as with any processing error that occurs during evaluation of the assert or discriminator expression). If the assert or discriminator has a message property, then it is implementation dependent how that message string is combined with the description string argument provided to the fn:error function.

On Thu, Jun 20, 2013 at 1:09 PM, Mike Beckerle <*mbeckerle.dfdl@gmail.com*<mbeckerle.dfdl@gmail.com>> wrote:

Proposed: add fn:error function and add dfdl:hex function.

DFDL only needs one of the several variations of fn:error

fn:error($error as xs:QName?, $description as xs:string) as none

dfdl:hex($num as xs:integer) as string

The dfdl:hex function inverts the behavior of the dfdl:byte, and related functions (currently also proposed) which take a string specification of a hex value. The argument to dfdl:hex can be a long, unsignedLong, or any subtype thereof. The number of hex digits in the resulting string is a function of the input type. If byte or unsigned byte, exactly 2 hex digits are produced, for short and unsignedShort, 4 hex digits, and so on. The resulting value contains a prefix 'x' character as its first character. So:

dfdl:short(dfdl:hex(xs:short(208))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL functions that construct integers from hexadecimal, if you replace the 208 above with a value in range for the corresponding numeric type.

Example:

This allows a meaningful error message that includes the offending parts of data.

fn:error(ex:magic_number, fn:concat("The magic number: 0", dfdl:hex(.), " was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."))

The $error argument (of type QName) is used in an implementation-dependent manner to provide the context of the error. So for example, if namespace prefix 'ex' is bound to '*http://example.com* <http://example.com/>' then the above call might produce:

"Error: {*http://example.com* <http://example.com/>}magic_number - The magic number: 0xFEFF0000 was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian)."

Only the part of the above string after the hyphen is standardized. The hyphen and part before the hyphen is implementation dependent.

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | * www.tresys.com* <http://www.tresys.com/>

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | * www.tresys.com* <http://www.tresys.com/>

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | * www.tresys.com* <http://www.tresys.com/> -- 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

-- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com