Re: [xdi] Updates to the link contract spec

[Dan Blum <dan@respectnetwork.net>]

This is helpful. I'll refer to it as I do some more reading, perhaps do the great symbol shift on the policy expressions document of the wiki next week. As I do that I will try to come up with a real-world access control example covering some parts of a moderately complex application or system, and if you are willing to help me, translate it into XDI. That would become at least a good supporting document for the TC and a good source of examples. 

Best regards,

Dan

On Sat, Mar 15, 2014 at 11:10 AM, Markus Sabadello <markus.sabadello@xdi.org> wrote:

On Fri, Mar 14, 2014 at 6:43 PM, Dan Blum <dan@respectnetwork.net> wrote:

On the call today we decided to do some updates to the link contract patterns, and also to perhaps add a few more examples.

Since the additional examples were my suggestion, I've pulled up my notes from reading through the spec the other day for the corner cases that I then thought could use examples:

We need an example where the TA is not the RA or the AA

Yes it would be interesting to have that.

 

Explains why: Templates provided by neutral third parties make it much easier for link contracts to be standardized, promoting interoperability of XDI vocabulary and permission

We need an example of when a link contract node is an entity collection rather than a singleton

This link contract template pattern examples leave me confused – why is there no operation after the $do$if?

Because what you have here is a statement from the policy part of the link contract (the $if part), which is not the part of the link contract where operations are specified.

 

<--template-authority-->{$from}<--template-authority--><--template-id-->$do$if<--boolean-context-->/<--operator-->/<--condition-->

 

This link contract template pattern examples leave me confused – why is there no operation after the $do$if and why is only one member-id shown?  Is that idea that you would do the operation to multiple <member-id>’s? and what is a member-id?

The member id identifies an (ordered / unordered) member of a collection. In this case, it's a collection of link contracts, but it's the same basic mechanism we would also use for collections of email addresses, messages, etc.

So for example it would be [$do]!:uuid:1234

 

 

<--template-authority-->{$from}<--template-authority--><--template-id-->[$do]<--member-id-->$if<--boolean-context-->/<--operator-->/<--condition-->