Opened 12 years ago

Closed 12 years ago

#4 closed protocol enhancement (fixed)

URI Encoding

Reported by: zach@… Owned by: zach@…
Priority: major Milestone:
Component: coap Version:
Severity: - Keywords:


The working group needs to consider the encoding of URIs in order to save overhead. The WG needs to converge on an approach to integrate in coap-01.

The following approaches have been suggested so far:

  • Encode the URI with 7-bit ASCII encoding.
  • Encode the URI with Base64 encoding (requires mapping table).
  • Encode the URI with Ascii85 encoding (works on blocks of 5 characters)
  • Define a custom ASCII encoding only for valid URI characters.

There is an obvious tradeoff of space savings vs. complexity in these approaches. At the minimum 7-bit ASCII encoding is doable.

Furthermore, the Uri-code option was dropped in favor of integrating "short" URIs into the normal URI string option. Here is one proposed approach from Carsten:

  • We could do an ASCII form of at least 4000 or so using /.xy or /!xy style shortcuts (essentially encoding the "codedness" in the first ASCII character).

Change History (1)

comment:1 Changed 12 years ago by zach@…

  • Resolution set to fixed
  • Status changed from new to closed

After discussion and contributions on the mailing list, this ticket can be closed for now like this for coap-01:

  • Servers can already assign static short URIs for their resources. This doesn't require anything new to the coap-00 mechanisms. However the resource description should include a field (sh=) to indicate such an alternative static URI exists.
  • The concept of TeRIs proposed in draft-bormann-coap-misc-01 should be experimented with first before considering integration with the base document.
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