SWE Common Data Model OGC 08-094r1
Requirement
http:www.opengis.netspecSWE2.0reqxml-encoding-rulesarray-wrapper-elt-valid
Req 100. All elements of each nested “DataArray” and “Matrix” shall be
encapsulated in a parent element as specified in Req 94 and this element shall also
have an “elementCount” attribute that specifies the array size.
The following example builds on the sample profile series dataset introduced in clause 9.2.6 and shows how the same values could be encoded with the “XMLEncoding”
method:
swe:encoding swe:XMLEncoding
swe:encoding swe:values
xmlns:ns =
urn:myorg:dataset:PS3658 ns:profileData
ns:time 2005-05-16T21:47:12Z
ns:time ns:profilePoints
elementCount =
5 ns:point
ns:depth ns:depth
ns:salinity 45
ns:salinity ns:point
ns:point ns:depth
10 ns:depth
ns:salinity 20
ns:salinity ns:point
ns:point ns:depth
20 ns:depth
ns:salinity 30
ns:salinity ns:point
ns:profilePoint ns:depth
30 ns:depth
ns:salinity 35
ns:salinity ns:point
ns:profilePoint ns:depth
40 ns:depth
ns:salinity 40
ns:salinity ns:point
ns:profilePoints ns:profileData
ns:profileData ns:time
2005-05-16T22:43:05Z ns:time
ns:profilePoints elementCount
= 4
ns:point ns:depth
ns:depth ns:salinity
45 ns:salinity
ns:point ns:point
ns:depth 10
ns:depth ns:salinity
20 ns:salinity
ns:point ns:point
ns:depth 20
ns:depth ns:salinity
30 ns:salinity
ns:point ns:point
ns:depth 30
ns:depth ns:salinity
35 ns:salinity
ns:point ns:profilePoints
ns:profileData swe:values
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OGC 08-094r1 SWE Common Data Model
This example shows how the array size is specified on the ‘profilePoints’ element corresponding to each nested array, and how element local names correspond to the
“name” attributes of each component’s parent property.
9.3.6 MIME Media Types
When array or stream values are encoded with the XML encoding method and provided standalone i.e. outside of any wrapper format, the
textxml
or
applicationxml
identifiers shall be used whenever media type information is needed by the application. Note however that the
textxml
media type is not always appropriate when some of the characters in the data stream are encoded with a different character set than US-ASCII.
Please read the relevant IETF standards for details.
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SWE Common Data Model OGC 08-094r1
9.4 Requirements Class: Binary Encoding Rules Requirements Class
http:www.opengis.netspecSWE2.0reqbinary-encoding-rules
Target Type Encoded Values Instance
Dependency
http:www.opengis.netspecSWE2.0requml-advanced-encodings
Dependency
http:www.opengis.netspecSWE2.0reqgeneral-encoding-rules
The “BinaryEncoding” method encodes field values by their binary representation. The ABNF syntax defined in IETF RFC 5234 is used to formalize the encoding rules, and
thus all ABNF snippets provided in this section are normative.
Requirement
http:www.opengis.netspecSWE2.0reqbinary-encoding-rulesabnf-syntax-valid
Req 101. The encoded values block shall be formatted as defined by the ABNF
grammar defined in this clause.
The encoding rules are similar to those of the “TextEncoding” method except that numerical values are encoded directly as their binary representation and that no
separators are used. Separators are not needed because data types have either a fixed size or contain length information See String encoding.
9.4.1 Rules for Scalar Components
The value for a scalar component is encoded as its binary representation. This especially applies to numerical values that are encoded directly in binary form in accordance to the
selected data type and the value of the “byteOrder” attribute.
scalar-value = binary value encoded according to data type, byte encoding and byte order specifications
The last column of Table 8.1 in clause 8.6.1 indicates how each data type shall be binary encoded into a low level byte sequence. The actual order of bytes composing a multi-
bytes data type depends on the value of the “byteOrder” attribute. The ‘bigEndian’ option indicates that muti-bytes data types are encoded with the most significant byte MSB
first, while selecting ‘littleEndian’ signifies that encoding is done with the less significant byte LSB first. A UTF-8 string is not considered as a multi-byte data type and is always
encoded in the same order, as specified by the Unicode Standard.
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