XDI Glossary - Terms (1 of 3)

["Drummond Reed" <drummond.reed@cordance.net>]

XDI TC Members:

I had an action item coming out of the last telecon to do an update to the
proposed XDI glossary to incorporate the key functional concepts that have
appeared in use cases. This updated glossary is appended to this message and
also appears in the XRI/XDI wikiweb at
http://xrixdi.idcommons.net/moin.cgi/XdiGlossary). 

As always at this stage in the development of a new specification, creating
this glossary was a highly enlightening exercise. My key conclusions:

1) It's quite short, which I hope reflects the "simplicity on the other side
of complexity" we are seeking in the XDI specs.

2) It's also short because it builds on top of the XRI glossary. Not
surprisingly, a number of the key terms there are also key terms here.

3) It generalizes to just four primary actors/roles - Data Authorities (DAs)
and Identifier Authorities (IAs), XDI Service Providers (XSPs), and XDI
Service Consumers (XSCs) (note than any particular entity may be all four at
different times or in different capacities). These generalizations seem to
fit all the use cases I've tested against so far (see action items, below).

4) The terms "XDI link" and "XDI link contract" have proved so useful that I
have included them here. I would argue that at this stage in our work they
can be treated purely as functional constructs, not architectural
constructs. An XDI link is just a data sharing relationship of some kind
between two XDI resources an XDI link contract the control data that
describes that relationship, regardless of the form it takes in the final
specs.

I've also composed some scenarios just to illustrate this glossary. To
prevent this message from getting too long, I'm sending that as a follow-on
message.

=Drummond 


***INITIAL XDI GLOSSARY***

IMPORTANT: This glossary is an EXTENSION of the glossary in the XRI 1.0
specification
(http://www.oasis-open.org/committees/download.php/5109/xri-syntax-resolutio
n-1.0-cd.pdf). It inherits all terms from that specification. Several of the
most important terms('identifier', 'community', 'resource', and 'resource
representation') have been copied here for clarity.

 Authority: A resource that controls other resources.

 Community (or Identifier Community): The set of resources that share a
common identifier authority, often (but not always) a common root authority.
Technically, the set of resources whose identifiers form a directed graph or
tree. 

 Control Data: A type of data that is used to control the sharing of other
types of data. Control data may be recursive and control the sharing of
itself.

 Data: Any information that when associated with an identifier becomes a
resource. See a list of different /DataCategories.

 Data Authority (DA): A resource that asserts authority over data and can
delegate control over data to another resource. People and organizations are
the most obvious types of data authorities, but people and organizations can
delegate authority to software agents and applications, which then become
Delegated Authorites.

 Delegated Authority: An Authority that has been granted control over a set
of resources by another Authority.

 Identifier (from XRI 1.0 Spec): Per [RFC2396bis], anything that "embodies
the information required to distinguish what is being identified from all
other things within its scope of identification." In UML terms, an
identifier is an attribute of a resource (the identifier context) that forms
an association with another resource (the identifier target). The general
term "identifier" does not specify whether the identifier is abstract or
concrete, absolute or relative, persistent or reassignable, human-friendly
or machine-friendly, delegated or local, or resolvable or self-referential.

 Identifier Authority (IA): A type of Data Authority that has authority over
the assignment of identifiers, including the assignment of identifiers to
other Identifier Authorities (delegation). Because XRI syntax supports
unlimited delegation, the term "Identifier Authority" can be used to refer
to an identifier authority at any level.

 Policy: The set of rules or conditions used by an Authority to control
interactions with a resource. All policies are either human-readable or
machine-readable Control Data.

 Resource (from XRI 1.0 Spec): Per [RFC2396bis], "anything that can be named
or described." Resources are of two types: network resources (those that are
network addressable) and non-network resources (those that exist entirely
independent of a network). Network resources are themselves of two types:
direct resources (resources which are their entire embodiment) or resource
representations (see Resource Representation).

 Resource Representation (from XRI 1.0 Spec): A network resource that
represents the attributes of another resource. A resource representation may
represent either another network resource (such as a machine or an
application) or a non-network resource (such as a person, organization, or
concept).

 XDI Account: An XDI resource representing a Data Authority hosted by an XDI
Service Provider (XSP) acting as a Delegated Authority.

 XDI Community: The set of Authorities that share a common XDI link contract
governing their XDI data sharing relationships.

 XDI Link: A data sharing relationship between two XDI resources. XDI links
may exist between XDI resources under the control of a single Data
Authority, or between different Data Authorities. XDI links within a single
Data Authority may not require an XDI link contract, but XDI links between
different data authorities will generally require an XDI link contract.

 XDI Link Contract: An XDI resource that controls the sharing of data across
an XDI link. XDI link contracts may control any aspect of an XDI data
sharing relationship. See /DataCategories.

 XDI Resource: A network resource (see Resource) that is addressable by at
least one XRI and has at least one XDI interface offered by an XDI Service
Provider.
 
 XDI Service Consumer (XSC): An Authority that requests interactions with an
XDI resource via an XDI interface.

 XDI Service Provider (XSP): An Authority that controls the interactions
with an XDI resource via an XDI interface.

 XRI: An Extensible Resource Identifier, a URI-compatible abstract
identifier as defined by the XRI 1.0 specification
(http://www.oasis-open.org/committees/download.php/5109/xri-syntax-resolutio
n-1.0-cd.pdf) developed by the OASIS XRI TC
(http://www.oasis-open.org/committees/xri).