Sending large packages over WAMP



we are using Autobahn CPP to send jpg images (encoded as json with base64) to a Webbrowser that receives them with Autobahn.js.

Everything works fine and fast until we hit a certain size barrier. It seems that the we can not send packages larger than 65535 bytes.

We get a write exception in boost:asio:write that is called from wamp_rawsocket_transport::send_message.

We are using latest Autobahn CPP from Git from today and as message broker (Docker image from docker hub).

Any ideas what we can do about it? Do we have to break our message into chunks ourselves? I assumed that a framework like Autobahn will take care of “low-level” protocol stuff like this?

Or do we have a configuration problem? Crossbar is more or less configured with defaults.

Any help appreciated.

Best regards,




It sounds a bit like “max_message_size” … ??



Yep, that was it. Very embarassing. I was pretty sure that I read that the defaults regarding to message size are 0 meaning unlimited. But indeed for the raw socket it is 128 kB. I increased the value and it works like a charm now.

Thanks for the pointer!


Am Freitag, 16. Dezember 2016 04:03:09 UTC+1 schrieb Gareth Bult:

It sounds a bit like “max_message_size” … ??



Hi, no, I think you read it right, I think maybe the documentation doesn’t always keep up with the code … :slight_smile: