The checks whether a request body is present are now done at a higher
level. This removes the need to do the checks at the resource handler
callback, removing duplicated code.
The checks are done by adding constraints to resources that must be
fulfilled by each request.
Added debug assertions to make sure that the core logic of the REST API
resource system works.
The module command self links now point to an endpoint that executes the
module command. Depending on the type of the module command, either a GET
or a POST request must be made.
The resource system now tracks both the time when a resource was last
modified and the revision number of the resource. This allows working
Last-Modified and ETag headers to be generated by the REST API.
The If-Modified-Since and If-None-Match request headers are not yet
processed and using them will always return the resource instead of a 304
Not Modified response.
Cleaned up various parts of the resource, request and response class
headers.
Moved `using` declarations into .cc files.
Made the Resource class non-copyable as it isn't really meant to be
copied.
The resources are now declared by simply typing the path that they match
and providing a callback for that path. This makes it easier to add new
resources without having to create a new class for each added resource
endpoint. It also removes some of the pathname processing that was done
inside the child class handler functions.
The HTTP side of the REST API is better handled with an actual
library. The libmicrohttpd library provides a convenient way of handling
the HTTP traffic between the clients and MaxScale.
The Resource class is intended to be an abstraction of a resource
tree. Each node in the tree can perform actions. The tree is traversed
depth first so that deeper command paths resolve to the correct nodes.
Currently all the base resources defined in the REST API documents are
implemented in a way that they return a 200 OK response to all
requests. When the internal data can be represented as JSON, the resources
can be hooked up to functions that generate JSON.
