MetainfoExpl

There is a very common task: find out some basic meta data about some object, e.g., for display in some kind of directory listing. Since that's such a common task, there SHOULD be some standard API.

:Beware: these definitions are not yet stable. Please comment concerning usefuleness etc.!

Creating a request

Very unstable: The request needs to be send from some execution context, hence the somewhat ugly syntax:

(me oid 'metainfo)

There will be some better syntax the other day.

Answering A Request

is-metainfo-request?

This predicate tests whether some request encodes a request for metainfo according to the API. is-metainfo-request? is true for a subset of the messages for which is-meta-form? yields true.

Prepare An Answer

Remember that the place is in total control of all information about itself with the exception of the action-document (which is required before any interaction for sake of legal certainty). The kernel-implemented "plain" read operation (as deployed in "public" and "private" places) will just answer with all know information, whenever a normal read operation would succeed too. Other actions might consider some of this information (like the info which links it has) private property and might want to suppress it. See here for an example, which removes those links.

Source code:

<p>There is a very common task:
find out some basic meta data about some object,
e.g., for display in some kind of directory listing.
Since that's such a common task, there SHOULD be some standard API.
</p>
<p>:*Beware*: these definitions are not yet stable.
Please comment concerning usefuleness etc.!</p>
<h2>Creating a request</h2>
<p>Very *unstable*:
The request needs to be send from some execution context,
hence the somewhat ugly syntax:</p>
<p>
 <code>(me </code>
 <var>oid</var>
 <code> 'metainfo)</code>
</p>
<p>There will be some better syntax the other day.</p>
<h2>Answering A Request</h2>
<h3>is-metainfo-request?</h3>
<p>This predicate tests whether some request encodes a request for metainfo according to the API.
<code>is-metainfo-request?</code> is true for a subset of the messages
for which <code>is-meta-form?</code> yields true.</p>
<h3>Prepare An Answer</h3>
<p>Remember that the place is in total control of all information
about itself with the exception of the <a href="/A849640f672ed0df0958abc0712110f3c/ActionDocument">action-document</a>
(which is required before any interaction for sake of legal certainty).
The kernel-implemented "plain" read operation
(as deployed in "public" and "private" places)
will just answer with all know information,
whenever a normal read operation would succeed too.
Other actions might consider some of this information
(like the info which links it has) private property
and might want to suppress it.
See <a xmlns="nu" href="MetainfoServer">here</a>
for an example, which removes those links.</p>