[Moims-dai] RE: DEDSL for review

[Boucon Daniele]

Hi Mike,

Please find  in this email the answers to your 3 points below (prepared with Beatrice): 


1.	The DEDSL abstract syntax is already a data description language and a data entity dictionary specification language.
According to the CCSDS recommendation, "the representational attributes describe interpretational aspects of data or dictionary entities".
Therefore, it possible (but not mandatory) to describe data structure with DEDSL.
DEDSL abstract syntax is nevertheless not as rich as most data description languages : arrays can only have one dimension (if you want to describe a two dimension array, you have to define the array as the repetition of lines, each line being the repetition of elementary items).

2.	"A_" or "_TYPE" is just a naming convention used in the XML schema. It has no effect on data dictionaries. At CNES, we use the "A_" convention to define types. But we can change the proposed DEDSL implementation if another convention is largely preferred.

3.	We already had a look at the ISO11179. It is a good idea to merge the two standards in the future. For now, we focus on defining a backward compatible standard.

Regards,

Daniele

-----Message d'origine-----
De : Mike Martin [mailto:tahoe_mike at sbcglobal.net] 
Envoyé : mercredi 21 octobre 2015 16:33
À : Boucon Daniele
Cc : moims-dai at mailman.ccsds.org; D or C Sawyer; John Garrett; Bob Downs; Larzul Beatrice
Objet : Re: DEDSL for review

Hi Daniele

1.  In Annex C.3 there is an example (shown below) that seems to cross the line between a data description language and a data entity dictionary.  Do you really want to be describing data structures with DEDSL?  For this information to be useful the number of axes and size of each axis would also need to be specified as additional constants.

2.  This specification uses the convention "A_" or "AN_" prefixed to the name for defining TYPES.  I have seen other XML specifications that use the suffix "_TYPE" to indicate a type definition.  I think I like that convention better than what is used in this document.

3.  Do you know if anyone ever done a comparison of DEDSL vs ISO11179 Part 3, Metadata Registries?  Might there be a way to bring these two standards together in the future?  PDS adopted ISO11179, Part 3 for its
PDS4 data dictionary.

Thanks, Mike

Extract from Annex C.3.

<DATA_ENTITY_DEFINITION CLASS="CONSTANT" NAME="W_IMAGE_SIZE"> <DEFINITIONAL_PART>
	<DEFINITION>It represents the number of pixels for an image take from spacecraft W.
</DEFINITION>
	<SHORT_DEFINITION>Spacecraft W Image pixel</SHORT_DEFINITION> </DEFINITIONAL_PART> <RELATIONAL_PART>
	<RELATION WITH="DATA_1">Number of pixels of a spacecraft W image</RELATION> </RELATIONAL_PART> <REPRESENTATIONAL_PART>
	<INTEGER_TYPE CONSTANT_VALUE="1440000"/> </REPRESENTATIONAL_PART> </DATA_ENTITY_DEFINITION>

<DATA_ENTITY_DEFINITION CLASS="DATA_FIELD" NAME="DATA_2"> <DEFINITIONAL_PART>
	<DEFINITION>It represents an image taken from spacecraft W.</DEFINITION>
	<SHORT_DEFINITION>Spacecraft W Image</SHORT_DEFINITION>
	<COMMENT>The image is an array of W_IMAGE_SIZE items called DATA_2_PIXEL.
</COMMENT>
</DEFINITIONAL_PART>
<RELATIONAL_PART>
	<KEYWORD>IMAGE</KEYWORD>
</RELATIONAL_PART>
<REPRESENTATIONAL_PART>
	<COMPOSITE_TYPE>
		<COMPONENT MAX="W_IMAGE_SIZE" MIN="1"> DATA_2_PIXEL </COMPONENT>
	</COMPOSITE_TYPE></REPRESENTATIONAL_PART>
<USER_DEFINED_ATTRIBUTES_PART>
	<FIELD_LOCATION>DATA_2</FIELD_LOCATION>
</USER_DEFINED_ATTRIBUTES_PART>
</DATA_ENTITY_DEFINITION>

<DATA_ENTITY_DEFINITION CLASS="DATA_FIELD" NAME="DATA_2_PIXEL"> <DEFINITIONAL_PART>
	<DEFINITION>It represents a pixel belonging to the image taken from spacecraft W.
</DEFINITION>
	<SHORT_DEFINITION>Spacecraft W Image pixel</SHORT_DEFINITION> </DEFINITIONAL_PART> <REPRESENTATIONAL_PART>
	<INTEGER_TYPE><INTEGER_RANGE MAX="255" MIN="0"/></INTEGER_TYPE> </REPRESENTATIONAL_PART> <USER_DEFINED_ATTRIBUTES_PART>
	<FIELD_LOCATION>DATA_2.DATA_2_PIXEL</FIELD_LOCATION>
</USER_DEFINED_ATTRIBUTES_PART>
</DATA_ENTITY_DEFINITION>

On 10/9/2015 3:02 AM, Boucon Daniele wrote:> Hi all,  > Please find enclosed the DEDSL document, for internal review.
 > Thank you in advance to send comments by the 23^rd October.
 > By the way, do you know what the process is for an orange book?
 > Regards,
 > Daniele


On 10/9/2015 3:02 AM, Boucon Daniele wrote:
> Hi all,
> Please find enclosed the DEDSL document, for internal review.
> Thank you in advance to send comments by the 23^rd October.
> By the way, do you know what the process is for an orange book?
> Regards,
> Daniele