Change log

This summarizes the changes between released versions. For a complete change log, see the git history. For details on the changes, see the respective git commits indicated at the start of the entry.

Version next

Breaking changes

  • Client observations that have been requested by sending the Observe option must now be taken up by the client. The warning that was previously shown when an observation was shut down due to garbage collection can not be produced easily in this version, and will result in a useless persisting observation in the background. (See <>)

  • Server resources that expect the library to do handle blockwise by returning true to needs_blockwise_assembly do not allow random initial access any more; this this is especially problematic with clients that use a different source port for every package.

    The old behavior was prone to triggering an action twice on non-safe methods, and generating wrong results in block1+block2 scenarios when a later FETCH block2:2/x/x request would be treated as a new operation and return the result of an empty request body rather than being aligned with an earlier FETCH block1:x/x/x operation.

Version 0.4a1

Security fixes

  • 18ddf8c: Proxy now only creates log files when explicitly requested
  • Support for secured protocols added (see Experimental Features)

Experimental features

  • Support for OSCORE (formerly OSCOAP) and CoAP over DTLS was included

    These features both lack proper key management so far, which will be available in a 0.4 release.

  • Added implementations of Resource Directory (RD) server and endpoint

  • Support for different transports was added. The transport backends to enable are chosen heuristically depending on operating system and installed modules.

    • Transports for platforms not supporting all POSIX operations to run CoAP correctly were added (simple6, simplesocketserver). This should allow running aiocoap on Windows, MacOS and using uvloop, but with some disadvantages (see the the respective transport documentations).

Breaking changes

  • 8641b5c: Blockwise handling is now available as stand-alone responder. Applications that previously created a Request object rather than using Protocol.request now need to create a BlockwiseRequest object.
  • 8641b5c: The .observation property can now always be present in responses, and applications that previously checked for its presence should now check whether it is None.
  • cdfeaeb: The multicast interface using queuewithend was replaced with asynchronous iterators
  • d168f44: Handling of sub-sites changed, subsites’ root resources now need to reside at path ("",)


  • e50e994: Rename UnsupportedMediaType to UnsupportedContentFormat
  • 9add964 and others: The .remote message property is not necessarily a tuple any more, and has its own interface
  • 25cbf54, c67c2c2: Drop support for Python versions < 3.4.4; the required version will be incremented to 3.5 soon.

Assorted changes

  • 750d88d: Errors from predefined exceptions like BadRequest(“…”) are now sent with their text message in the diagnostic payload
  • 3c7635f: Examples modernized
  • 97fc5f7: Multicast handling changed (but is still not fully supported)
  • 933f2b1: Added support for the No-Response option (RFC7967)
  • baa84ee: V4MAPPED addresses are now properly displayed as IPv4 addresses


  • Test suite is now run at Gitlab, and coverage reported
  • b2396bf: Test suite probes for usable hostnames for localhost
  • b4c5b1d: Allow running tests with a limited set of extras installed
  • General improvements on coverage

Version 0.3


  • 4d07615: ICMP errors are handled
  • 1b61a29: Accept ‘fe80::…%eth0’ style addresses
  • 3c0120a: Observations provide modern async for interface
  • 4e4ff7c: New demo: file server
  • ef2e45e, 991098b, 684ccdd: Messages can be constructed with options, modified copies can be created with the .copy method, and default codes are provided
  • 08845f2: Request objects have .response_nonraising and .response_raising interfaces for easier error handling
  • ab5b88a, c49b5c8: Sites can be nested by adding them to an existing site, catch-all resources can be created by subclassing PathCapable

Possibly breaking changes

  • ab5b88a: Site nesting means that server resources do not get their original Uri-Path any more
  • bc76a7c: Location-{Path,Query} were opaque (bytes) objects instead of strings; disctinction between accidental and intentional opaque options is now clarified

Small features

  • 2bb645e: set_request_uri allows URI parsing without sending Uri-Host
  • e6b4839: Take block1.size_exponent as a sizing hint when sending block1 data
  • 9eafd41: Allow passing in a loop into context creation
  • 9ae5bdf: ObservableResource: Add update_observation_count
  • c9f21a6: Stop client-side observations when unused
  • dd46682: Drop dependency on obscure built-in IN module
  • a18c067: Add numbers from draft-ietf-core-etch-04
  • fabcfd5: .well-known/core supports filtering


  • f968d3a: All low-level networking is now done in aiocoap.transports; it’s not really hotpluggable yet and only UDPv6 (with implicit v4 support) is implemented, but an extension point for alternative transports.
  • bde8c42: recvmsg is used instead of recvfrom, requiring some asyncio hacks

Package management

  • 01f7232, 0a9d03c: aiocoap-client and -proxy are entry points
  • 0e4389c: Establish an extra requirement for LinkHeader