Brownfield Legacy Network Interfaces

It is advised that OKE implementors use approved CWM network interfaces. They will provide the best customer experience and minimize OKE development effort.

However, some business cases may require OKE implementors to send OKMs over brownfield legacy network interfaces, essentially any network interface other than a CWM.

The CWL serial network and data link layers used by default are not compatible with these legacy network interfaces. To facilitate implementors ability to interface with these alternative network interfaces implementors will need to handle the network and data link layers as part of their application code. These custom network and data link layers are interfaced to the 'WL's message layer transmit and receive functions.

To route outbound messages to the custom application network layer transmit function implementors will call void CWMsgSetAppNWKTx(AppNWKTxCB_t appNWKTxFn), where AppNWKTxCB_t is defined as typedef void (*AppNWKTxCB_t)(const char* okm, int32_t okmLen). During initialization, implementors will pass a function pointer for handling network layer transmits. After an outbound OKM is constructed it will be sent to this function instead of the default serial network layer.

To route inbound messages to the CWL, implementors will call void CWMsgNWKRxCB(char* payload, uint16_t len, uint16_t size). Where payload is the inbound OKM message, len is the string length of the OKM, and size is the maximum size of the OKM buffer.

The CWL does not by default publicly prototype CWMsgNWKRxCB, CWMsgSetAppNWKTx and AppNWKTxCB_t by default since most implementors will not use them directly. Therefore, implementors must prototype them as necessary in their projects.

It is the responsibility of the OKE implementor to transfer OKMs between itself and the cloud service. The OpenKitchen Message Specification details how to properly interface with the OKC.