Reading a subset of data on a BLE server

[Jim]

I am definitely missing something here, but I can't figure out how to specify a subset of data to read from my peripheral.

Here's the setup: my nrf51822 device is a server, publishing a custom service with custom characteristics.

I have in memory is the nrf51822 a long (2048 bytes) list of historical data.

I want to allow a client to be able to read a specific portion of this data rather than having to transfer all 2048 bytes (which I can't anyway).

The SoftDevice handles characteristic reads automatically, but even if I could intercept them I don't see how I can pass parameters to a characteristic read operation.

What is the official BLE way to do what I'm trying to do?

[Jim]

Yes, I came across this last night, and now have it working. I hadn't noticed it before because I'm not currently thinking of securing the communications, and rd_auth seemed like a security mechanism. It does precisely what I want. Thanks.

FYI, I would have called the two flavors of reading something like "read static" (your default), and "read dynamic" (where I implement the code to compute the result). This is similar to how you can implement accessors in languages like C#, Java, or Scala. They can be just values, or you can write code to dynamically compute the value.