Crate coap_handler_implementations

The coap-handler-implementations crate provides a few convenience, example or reference implementations of the coap-handler interface.

They range from the generic “4.04 Not Found” responder up to a handler that creates a write formatter for GET-only resources, and even provides block-wise transfer that. The TypeHandler enables the easy creation of serde_cbor based resource implementations with GET, PUT and POST support in CBOR format. The HandlerBuilder implements crude static path based routing that may suffice for some applications, and is also useful to get started quickly.

History

This code used to be part of coap-handler, but while the interface needs to stabilize fast (as incompatible changes there propagate to implementations), the implementations still need to develop fast (but it doesn’t hurt too much if one code part is using the old SimpleRenderable while another uses a newer NeverFound).

Version 0.1 is what was available in coap-handler (if Cargo allowed cyclic dependencies, coap-handler would pub use this crate); users are encouraged to just use coap-handler-implementations directly.

Options Hiding

A common mechanism in handlers is that handlers “consume” options. For example, the ForkingHandler built through HandlerBuilder::at “eats” the Uri-Path; likewise, an Accept-based dispatcher would consume the Accept option.

This allows the handlers themselves to check for any left-over critical options and fail if they can’t handle them – without the need to mask them out there assuming (without an actual check) that prior wrappers took care of them.

Feature flags

• leaky_names — Make a few items pub available that do not have stability guarantees. While this is useful in the context of building handlers into statics, apply the same caution as with any other crate feature that’s disabling stability guarantees: Don’t use this from libraries, for your dependents will run the risk of accidentally using unstable names.
• serde-std — This crate has nothing in terms of std to activate, but due to serde’s non-additive std feature that extends down to serde_cbor, a user may need to declare that serde’s std feature is used just so that all serde implementers are instructed to properly switch on their std as well.

Modules

• helpers
• wkc
  Tools to implement a .well-known/core resource easily

Structs

• Empty
  A type that (for minicbor typed handlers) represents an empty payload.
• ForkingHandler
• ForkingTreeHandler
• NeverFound
  A resource that unconditionally responds 4.04 Not Found.
• SimpleRenderableData
  Information a SimpleRenderable needs to carry from request to response.
• SimpleRendered
  A container that turns any SimpleRenderable (including &str) into a CoAP resource Handler.
• TypeHandler
  Wrapper for resource handlers that are implemented in terms of GETting, POSTing or PUTting objects in CBOR format.
• TypeRequestData
  Data carried around between a request and its response for TypeHandlers
• TypedStaticRenderable

Enums

• ForkingRequestData
  Tagged-union container for ForkingHandler

Traits

• HandlerBuilder
  Trait implemented by default on all handlers that lets the user stack them using a builder-like syntax.
• ReportingHandlerBuilder
  Extension trait for handlers that also implement Reporting.
• SimpleRenderable
  A simplified Handler trait that can react to GET requests and will render to a fmt::Write object with blockwise backing.
• TypeRenderable
  A simple Handler trait that supports GET, POST and/or PUT on a data structure that supports serde.

Functions

• new_dispatcher
  Start building a tree of sub-resources