Metastructures 1999 TechnoTeacher, Inc.

What are

GROVES?

Peter Newcomb

Metastructures 1999 TechnoTeacher, Inc.

What is a GROVE?

• A “grove” represents a structured collection of information objects.– a document– a database– a graphic– ...

Metastructures 1999 TechnoTeacher, Inc.

What is a GROVE made of?

• A grove consists of a set of nodes.

• Each “node” represents an addressable information object.

Metastructures 1999 TechnoTeacher, Inc.

What’s in a NODE?

• A node consists of a set of named values.

• Each named value is called a “property assignment”.

Metastructures 1999 TechnoTeacher, Inc.

What’s a PROPERTY?

• A “property” is a named characteristic of an information object.

• Each property has a specific datatype.

Metastructures 1999 TechnoTeacher, Inc.

What DATATYPES canproperties have?

• Primitive datatypes:– character, string, integer, …– string list, integer list, …

• Nodal datatypes:– node, node list, named node list

Metastructures 1999 TechnoTeacher, Inc.

What’s a NODAL DATATYPE?

• The value assigned to a “nodal property” is a node or list of nodes.

• Nodal properties represent relationships between information objects.

Metastructures 1999 TechnoTeacher, Inc.

What kinds of NODAL RELATIONSHIPS are there?

• Subordinate (SUBNODE)– forms hierarchies (trees) of nodes– each grove is a single SUBNODE tree

Metastructures 1999 TechnoTeacher, Inc.

What kinds of NODAL RELATIONSHIPS are there?

• Internal reference (IREFNODE)– creates cross-references within a

single grove

Metastructures 1999 TechnoTeacher, Inc.

What kinds of NODAL RELATIONSHIPS are there?

• Unrestricted reference (UREFNODE)– creates cross-references within or

between groves– a set of UREFNODE-connected groves

is called a “hypergrove”.

Metastructures 1999 TechnoTeacher, Inc.

How do I know what PROPERTIES a node will have?

• Each node is an instance of a named class of nodes.

• A “node class” defines a set of properties.

Metastructures 1999 TechnoTeacher, Inc.

How do I know what NODE CLASSES a grove will have?

• The set of node classes that may be found in a grove is defined by the grove’s “property set”.

• A property set is a schema for groves.

Metastructures 1999 TechnoTeacher, Inc.

What does a PROPERTY SET represent?

• A property set represents an abstract data model for a specific type of structured information.

• A property set is expressed as an SGML or XML document.

Metastructures 1999 TechnoTeacher, Inc.

What is the GROVE model not?

• A programming interface (API)

• A data format, binary or otherwise

Metastructures 1999 TechnoTeacher, Inc.

What is the GROVE model?

• An abstract generic data model

• A mechanism for defining specific data models

Metastructures 1999 TechnoTeacher, Inc.

How do I use the GROVE model?

• Define an API to the generic data model– How do I build a grove?

– How do I get the value of a property?

– How do I access list values?

– …

Metastructures 1999 TechnoTeacher, Inc.

How do I use the GROVE model?

• Define an API to a specific grove type– Balise

– XML DOM

Metastructures 1999 TechnoTeacher, Inc.

How do I use the GROVE model?

• Implement the API– generically, for any grove type

• GroveMinder

– specifically, for one grove type• Jade (James Clark’s DSSSL engine)

• Any XML DOM implementation