ncml_module Namespace Reference

NcML Parser for adding/modifying/removing metadata (attributes) to existing local datasets using NcML. More...

Classes
class	AggregationElement
class	AttributeElement
	Concrete class for NcML <attribute> element. More...
class	AttrTableLazyPtr
class	DimensionElement
class	ExplicitElement
	Concrete class for NcML <explicit> element. More...
struct	ModuleConstants
class	MyBaseTypeFactory
	Wrapper for the BaseTypeFactory that lets us create by type name. More...
class	NCMLArray
	A parameterized subclass of libdap::Array that allows us to apply constraints on NcML-specified data prior to serialization. All the code is in the .h, so no .cc is defined. More...
class	NCMLBaseArray
class	NCMLCacheAggResponseHandler
class	NCMLCacheAggXMLCommand
class	NCMLElement
	Base class for NcML element concrete classes. More...
class	NCMLModule
class	NCMLParser
class	NCMLRequestHandler
class	NCMLUtil
class	NetcdfElement
	Concrete class for NcML <netcdf> element. More...
class	OtherXMLParser
class	ReadMetadataElement
	Concrete class for NcML <readMetadata> element. More...
class	RemoveElement
class	RenamedArrayWrapper
	A Decorator Pattern for wrapping a libdap::Array in order to change its name efficiently in the face of buggy subclasses we cannot change. More...
class	SaxParser
	Interface class for the wrapper between libxml C SAX parser and our NCMLParser. More...
class	SaxParserWrapper
	Wrapper for libxml SAX parser C callbacks into C++. More...
class	ScanElement
class	ScopeStack
class	Shape
	A wrapper class for a vector of Array::dimension structs. More...
class	SimpleLocationParser
	SaxParser implementation that just grabs the netcdf@location attribute and returns it. More...
class	ValuesElement
class	VariableAggElement
	Element for the <variableAgg> element child of an <aggregation>. More...
class	VariableElement
	Concrete class for NcML <variable> element. More...
struct	XMLAttribute
class	XMLAttributeMap
struct	XMLNamespace
class	XMLNamespaceMap
class	XMLNamespaceStack
struct	XMLUtil

Typedefs
typedef vector< Array::dimension >::const_iterator	DimItC
typedef std::map< string, string >	TypeConverter

Detailed Description

NcML Parser for adding/modifying/removing metadata (attributes) to existing local datasets using NcML.

Helper class for NCMLParser to maintain the current scope of the parse.

An abstract superclass for NCMLArray<T> that handles the non-parameterized functionality and allows us to treat subclasses of any type T polymorphically.

Core engine for parsing an NcML structure and modifying the DDS (which includes attribute data) of a single dataset by adding new metadata to it. (http://docs.opendap.org/index.php/AIS_Using_NcML).

The main documentation for the NCML Module is here: http://docs.opendap.org/index.php/BES_-_Modules_-_NcML_Module

For the purposes of this class "scope" will mean the attribute table at some place in the DDX (populated DDS object), be it at the global attribute table, inside a nested attribute container, inside a variable, or inside a nested variable (Structure, e.g.). This is basically the same as a "fully qualified name" in DAP 2 (ESE-RFC-004.1.1)

Design and Control Flow:

o We use the SaxParser interface callbacks to handle calls from a SAX parser which we create on parse() call.

o We maintain a lazy-evaluated pointer to the currently active AttrTable via getCurrentAttrTable(). in other words, we only load the DDS of a dataset if we actually require changes to it. As we enter/exit the lexical scope of attribute containers or Constructor variables we keep track of this on a scope stack which allows us to know the fully qualified name of the current scope as well as the type of the innermost scope for error checking.

o As we process NcML elements we modify the DDS as needed. The elements are all subclasses of NCMLElement and are factoried up in onStartElement for polymorphic dispatch. A stack of these is kept for calling handleContent() and handleEnd() on them as needed.

o When complete, we return the loaded and transformed DDS to the caller.

We throw BESInternalError for logic errors in the code such as failed asserts or null pointers.

We throw BESSyntaxUserError for parse errors in the NcML (non-existent variables or attributes, malformed NcML, etc).

Limitations:

o We only handle local (same BES) datasets with this version (hopefully we can relax this to allow remote dataset augmentation as a bes.conf option or something.

Author

mjohnson m.joh.nosp@m.nson.nosp@m.@open.nosp@m.dap..nosp@m.org

Basically, the full scope stack defines the namespace describing the location of a variable or attribute in a DDS. It can be used to generate the fully qualified name of a variable or attribute within the DDS.

For now, an empty scope stack will implicitly mean GLOBAL scope (DDS level, or what have you). We won't actually push an entry for GLOBAL, it will just be assumed if empty(). We also won't put it in the scope strings since they are meant to refer to fully qualified names, where an empty() name means global scope.

Author

mjohnson m.joh.nosp@m.nson.nosp@m.@open.nosp@m.dap..nosp@m.org

Typedef Documentation

DimItC

typedef vector<Array::dimension>::const_iterator ncml_module::DimItC

Definition at line 35 of file Shape.cc.

TypeConverter

typedef std::map<string, string> ncml_module::TypeConverter

Definition at line 868 of file NCMLParser.cc.