DEPL — Alternative Locations

It should be possible to supply alternative URI locations for
artifacts.

Here's another issue that I'd like to put on record before it
gets forgotten. It goes back to the discussion on HTTP. At the
moment, NodeManagers are essentially forced to use HTTP for
downloading artifacts from the Repository, since (a) that is
the "least common denominator" as defined by the specification
and (b) the Repository can offer only a single location.

The proposed solution enables the RepositoryManger to supply
multiple alternative locations for an artifact, one of which
must be a HTTP URI. Other locations could use more optimal
(including non-standard) transports that a NodeManager could
use if supported. (Otherwise, the NodeManager would fall back
to HTTP.)

Proposed resolution:

In section 6.3, "Model Diagram Conventions," change the text
for the standard "location" attribute from

location: references an entity outside of the model. The
location attribute is of type String, its value must comply
to the URI syntax.

to

location: references an entity outside of the model. The
location attribute is of type String, its value(s) must
comply to the URI syntax. Multiple alternative locations
to the same entity may be supplied (multiplicity 1..*);
applications can then choose any of these locations to
access the entity (e.g. choosing a local file URI over
a http reference).

In section 6.4.15.2 (ImplementationArtifactDescription
attributes), change the location attribute to

location: String [1..*] Alternative locations to the
ImplementationArtifact.

In section 6.8.2.2 (ArtifactDeploymentDescription attributes),
change the location attribute to

location: String [1..*] Alternative locations where the
artifact can be loaded from. Copied from Implementation-
ArtifactDescription.

In section 9.3.1 (ComponentInterfaceDescription), change the
idlFile attribute from

idlFile: String

to

idlFile: String [*]

and change the second sentence from

If it is not the empty string, it contains a URL that
references an IDL file that contains the definition for
this component or home.

to

The idlFile attribute, if present, contains alternative URIs
that reference an IDL file containing the component's (or
home's) interface definition.

In section 9.7.5, change the fourth (last) paragraph from

If a RepositoryManager supports URL schemes in addition to
http, it shall offer a configuration parameter that allows
user selection of the scheme(s) that will be used in
ImplementationArtifactDescription elements.

to

The RepositoryManager must supply a "http" URI as part of
the location attribute in the ImplementationArtifactDescription
element. A RepositoryManager may optionally include other
alternative locations to provide NodeManger implementations
with a choice of transports to use for downloading artifacts.