Daffodil has the capability to read in various parameters via an external XML file. Below are the parameters that can be defined.
External Variables
External variables can be defined using the externalVariablesBindings tag. For example, the following configuration file defines to variables, var1 and var2, in the http://example.com namespace.
| Code Block | ||||
|---|---|---|---|---|
| ||||
<?xml version="1.0" encoding="UTF-8"?>
<dfdlConfig xmlns="http://www.w3.org/2001/XMLSchema" xmlns:ex="http://example.com">
<externalVariableBindings>
<bind name="ex:var1">-9</bind>
<bind name="ex:var2">Foo</bind>
</externalVariableBindings>
</dfdlConfig> |
These would allow the external variables to be set or overridden, if defined in a DFDL schema like so:
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<dfdl:defineVariable name="var1" external="true" type="xsd:int">1</dfdl:defineVariable>
<dfdl:defineVariable name="var2" external="true" type="xsd:string">Bar</dfdl:defineVariable> |
Tunable Parameters
Various tunable parameters can be modified to change various Daffodil schema compilation and data parsing properties. For example, the following sets the maxOccursBounds tunable to 1024:
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|---|---|---|---|---|
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<?xml version="1.0" encoding="UTF-8"?>
<dfdlConfig xmlns="http://www.w3.org/2001/XMLSchema" xmlns:ex="http://example.com">
<tunables>
<maxOccursBounds>1024</maxOccursBounds>
</tunables>
</dfdlConfig> |
Below is the list of tunable parameters and their default values:
...
In certain I/O optimized situations (text-only, encodingErrorPolicy='replace', fixed-width encoding) input files larger than this will be mmapped. Input files smaller than this will be simply read using ordinary I/O (because for small files that is just faster). This exists because mmap is more expensive than ordinary I/O for small files.
...
When unexpected text is found where a delimiter is expected, this is the maximum number of bytes (characters) to display when the expected delimiter is a variable length delimiter.
...
Whether to compile a schema to support parsing ("parseOnly"), unparsing ("unparseOnly"), both parsing and unparsing ("both"), or to use the daf:parseUnparsePolicy property from the root node ("schema").
...
If true, require that the bitOrder property is specified. If false, use a default value for bitOrder if not defined in a schema.
...
If true, require that the encodingErrorPolicy property is specified. If false, use a default value if not defined in a schema.
...
Specified how unqualified path steps are resolved. Value values are:
"noNamespace"
Unqualified path steps remain unqualified and will only match elements in NoNamespace. A prefix must be provided to match namespaced elements.
"defaultNamespace"
Unqualified path steps will always use the default namespace. If a default namespace is defined, it is not possible to match a NoNamespace element with this policy. Because of this, this may not work well with elementFormDefault="unqualified".
"preferDefaultNamespace"
Attempt to use the default namespace to resolve an unqualified path step. If that fails to match an element, then try to resolve using NoNamespace.
Configuration Schema
The schema for the configuration file is defined in dafext.xsd.
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