Websocket Ping Interval

[arnehaber]

Hi,

is it possible to configure websocket pings for the current JSONClient?

I found some related code here but it seems to be removed for the most current version,

Best, Arne

[TVolden]

Hi Arne,

Thanks for your question. I'm curious, are you Scandinavian?

Sorry I didn't reply earlier, just saw your issue now. The ping (which they call hearthbeat) function is obsolete with the websocket, since a socket has linkstate functionality build in. If I remember correctly, OCA made Heartbeat optional in OCPP 1.6-j and I guess it's gone in 2.0.

Wait are you asking if the websocket component ai use can be reconfigured? I would have to investigate that.

Sincerely, Thomas

[arnehaber]

Hi Thomas,

no, I'm not Scandinavian, just my name is ;)

I do not mean the OCPP heartbeat message, I was writing about the websocket ping. Please see "Open Charge Point Protocol JSON 1.6, OCPP-J 1.6 Specification" chapter "5.3. WebSocket Ping in relation to OCPP Heartbeat". According to the 1.6 JSON Spec, the OCPP heartbeat SHALL still be used for time synchronization (once a day). The "is alive" function is given by the built in Ping and Pong frames from the WebSocket specification. This (client) library does not seem to send pings to a connected (via ws) ocpp server. So my question is, how to enable web socket pings and how can I configure the interval.

Best, Arne

[TVolden]

Hi Arne,

Well it sure looks like the lib I use can send ping messages. The websocket client appears to have a SendPing method, but I'll have to think about how to work it in. What do you think? Should the client send a ping message at a configurable interval with it's own internal timer? Or should the implementer (you) be able to write their own ping rutine?

[arnehaber]

Hi Thomas,

I would suggest a "setPingInterval" in the JSONClient which controls the internal behavior.

• A value of 0 disables client side websocket Ping / Pong. In this case there is either no ping /pong or the server initiates the ping and client responds with Pong.
• Positive values are interpreted as number of seconds between pings.
• Negative values are not allowed and will cause a checked exception
• Default value is "0" --> inactive ping/pong

According to "Open Charge Point Protocol JSON 1.6, OCPP-J 1.6 Specification" chapter "7. Configuration", the configuration key "WebSocketPingInterval" can be used by the implementer to control the timer by using the "setPingInterval" method.

Best, Arne

[robert-s-ubi]

@arnehaber: That's already implemented. See https://github.com/ChargeTimeEU/Java-OCA-OCPP/blob/master/OCPP-J/src/main/java/eu/chargetime/ocpp/JSONConfiguration.java

JSONConfiguration.get().setParameter(PING_INTERVAL_PARAMETER, pingInterval) builds a configuration with the given pingInterval, which you then pass into the JSONClient constructor. Voilá!

[AaronVanStappen]

@robert-s-ubi well voila ... a simple reconnect is not possible. One has to reboot the system to adjust the WebSocketPingInterval. Not only that, the WebSocketPingInterval has to be persisted in order to "survive" a reboot.

[robert-s-ubi]

@robert-s-ubi well voila ... a simple reconnect is not possible. One has to reboot the system to adjust the WebSocketPingInterval. Not only that, the WebSocketPingInterval has to be persisted in order to "survive" a reboot.

How do you get to these conclusions? This is just a library, it has no concept of "rebooting". The maximum "reset" within its scope would be stopping the JAVA VM and starting a new one. If you have this library running on a system which indeed requires a reboot to change the WebSocket ping interval, then you have some weird issue with the system, but not with the library itself.