ocpp

As I mentioned in #93, we downcast to check. This creates direct dependencies from higher level entities to lower level entities.

Here is an example where we downcast to check if it's an instance of a 3rd part library, thereby creating a hard dependency to that 3rd part library. In this case an XML component, and since XML is being replaced by json in the OCPP standard, this dependency is unfor

Follow-up to #40

Errors sent over the errC channels in WsServer and WsClient are currently basic errors.

In some cases errors should be structs, containing some additional info, such as:

• client ID
• operation? (ping, write, close, ...)

Any struct will still be sent as an error, therefore not breaking the API. Channel consumers, however, may optionally perform type assertion and