Merge pull request #66 from donmendelson/issue64

Support for easy constant value setting in fields #64

Author: donmendelson

v2-0-RC1/doc/02FieldEncoding.md

@@ -135,7 +135,7 @@ Attributes are optional unless specified otherwise.
 | Schema attribute  | Description                                                                                                                                                                        |
 |-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | presence=required | The field must always be set. This is the default presence. Mutually exclusive with nullValue.                                                                                     |
-| presence=constant | The field has a constant value that need not be transmitted on the wire. Mutually exclusive with value attributes.                                                                 |
+| presence=constant | The field has a constant value that need not be transmitted on the wire. Mutually exclusive with nullValue, minValue, and maxValue attributes.                                                                 |
 | presence=optional | The field need not be populated. A special null value indicates that a field is not set. The presence attribute may be specified on either on a field or its encoding.             |
 | nullValue         | A special value that indicates that an optional value is not set. See encodings below for default nullValue for each type. Mutually exclusive with presence=required and constant. |
 | minValue          | The lowest valid value of a range. Applies to scalar data types, but not to String or data types.                                                                                  |
@@ -567,10 +567,9 @@ M S F T
 A character array constant specification
 
 ```xml
-<type name="EurexMarketID" primitiveType="char" length="4" description="MIC code"
- presence="constant">XEUR</type>
+<type name="MarketID" primitiveType="char" length="4" description="MIC code"/>
 
-<field type="EurexMarketID" name="MarketID" id="1301" semanticType="Exchange"/>
+<field name="EurexMarketID" type="MarketID" id="1301" semanticType="Exchange" presence="constant">XEUR</field>
 ```
 
 ### Variable-length string encoding

v2-0-RC1/resources/Examples.xml

@@ -9,6 +9,7 @@ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 		<type name="enumEncoding" primitiveType="char"/>
 		<type name="idString" length="8" primitiveType="char"/>
 		<type name="intEnumEncoding" primitiveType="uint8"/>
+		<type name="currency" length="3" primitiveType="char" description="ISO 4217"/>
 		<composite name="DATA">
 			<type name="length" primitiveType="uint16"/>
 			<type name="varData" length="0" primitiveType="uint8"/>
@@ -122,4 +123,14 @@ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 		<field name="Price" id="44" type="decimalEncoding" offset="38" presence="optional" semanticType="Price"/>
 		<field name="StopPx" id="99" type="decimalEncoding" offset="46" presence="optional" semanticType="Price"/>
 	</sbe:message>
+	<sbe:message name="MarketOrder" id="100" blockLength="54" semanticType="D" description="Demonstration of constants">
+		<field name="ClOrdId" id="11" type="idString" offset="0" semanticType="String"/>
+		<field name="Account" id="1" type="idString" offset="8" semanticType="String"/>
+		<field name="Symbol" id="55" type="idString" offset="16" semanticType="String"/>
+		<field name="Side" id="54" type="sideEnum" offset="24"/>
+		<field name="TransactTime" id="60" type="timestampEncoding" offset="25" semanticType="UTCTimestamp"/>
+		<field name="OrderQty" id="38" type="qtyEncoding" offset="33" semanticType="Qty"/>
+		<field name="OrdType" id="40" type="ordTypeEnum" presence="constant" valueRef="ordTypeEnum.Market"/>
+		<field name="Currency" id="15" type="currency" presence="constant">USD</field>
+	</sbe:message>
 </sbe:messageSchema>

v2-0-RC1/resources/sbe.xsd

@@ -292,7 +292,7 @@
 			</xs:extension>
 		</xs:simpleContent>
 	</xs:complexType>
-	<xs:complexType name="fieldType">
+	<xs:complexType name="fieldType" mixed="true">
 		<xs:annotation>
 			<xs:documentation>
 				A field of a message of a specified dataType