Masoud R.

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7 years, 2 months ago.

mbed connector and mbed client limitations

Hi, I'm using mbed device connector and mbed client with mbed os device. I have a question, what is the bandwidth limitation of mbed connector? for example, I can create a resource and define it as a string. what is the maximum size of it? I want to put a large string into a resource that can be accessed from a web application. If this solution doesn't work. do you know a similar way to putting a simple text file to a resource? thanks.

As far as I know there shouldn't be any real limitation on this, as it could be used for updates over CoAP over LWM2M as well. However, when trying on a 2000 byte value I get an error from Connector. I've asked the Connector / mbed Client team for a clarification.

posted by Jan Jongboom 08 Feb 2017

1 Answer

Jan Jongboom
7 years, 2 months ago.

The default limit is 1152 bytes, but can be expanded to 65K. From the docs:

Quote:

The maximum single UDP message size that mbed Client can receive is 1152 bytes. The actual payload size is 1137 bytes, the header information using the remaining 15 bytes.

For transferring larger amounts of data, the Blockwise feature must be deployed. When using this feature, mbed Client can handle messages up to 65KB by default. This feature is disabled by default. To receive more than 65KB, see Setting an external handler for block-wise messages.

That page also contains instructions on how to up the limit.

Accepted Answer

thanks, so with this Can I send files (with splitting)? what is the minimum of wait time for putting data into mbed connector? I mean splitting a file into many strings and send them one by one, is it possible?

posted by Masoud R. 08 Feb 2017