About Cobalt pipeline

Murali Achar

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Mar 25, 2021, 12:33:14 AM3/25/21

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Hello,

I would like to know more about Cobalt pipeline used in Fuchsia OS

Communication Protocol ( over TCP/IP) between client and server

Data package format used for cobalt ( json? compressed/uncompressed, encrypted)

Typical Size/over-head

Suitability for NB-IoT network ( considering limited bandwitdth)

Appreciate your feedback

Warm Regards,

Murali

Shai Barack

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Mar 25, 2021, 1:01:21 AM3/25/21

to Murali Achar, discuss

Hi Murali,

I am far from being the expert on Cobalt. That said, here are some resources that can get you started while we wait for hopefully someone more informed than me to chime in.

https://fuchsia.googlesource.com/cobalt

https://fuchsia.googlesource.com/fuchsia/+/master/src/cobalt/README.md

https://fuchsia.dev/reference/fidl/fuchsia.cobalt

From looking at build definitions I'm assuming that Cobalt uses gRPC, which is roughly speaking protocol buffer (aka protobuf or proto) wire format over HTTPS.

I haven't seen an analysis of Cobalt's network performance in quantitative terms such as data overhead.

I don't have experience working with Narrowband IoT so I can't answer the qualitative question.

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Seth Ladd

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Mar 25, 2021, 3:32:42 PM3/25/21

to Shai Barack, Zach Bush, Cameron Dale, Murali Achar, discuss

cc @Zach Bush @Cameron Dale

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Cameron Dale

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Mar 25, 2021, 4:05:59 PM3/25/21

to Seth Ladd, Alex Zani, Shai Barack, Zach Bush, Murali Achar, discuss

On Wed, Mar 24, 2021 at 9:33 PM Murali Achar <amur...@gmail.com> wrote:
Hello,

I would like to know more about Cobalt pipeline used in Fuchsia OS

Communication Protocol ( over TCP/IP) between client and server

HTTP to a backend server at Google called Clearcut. You can see the implementation here:

https://fuchsia.googlesource.com/cobalt/+/refs/heads/master/src/lib/clearcut/uploader.h

Data package format used for cobalt ( json? compressed/uncompressed, encrypted)

Protocol Buffer messages, serialized. They contain doubly encrypted values that represent the metrics that were collected. The implementation in use today is here:

https://fuchsia.googlesource.com/cobalt/+/refs/heads/master/src/uploader/shipping_manager.h#277

However, this is implemented as an interface, so if you wanted to upload to a different server or using a different format, you can create and use a new implementation of this:

https://fuchsia.googlesource.com/cobalt/+/refs/heads/master/src/uploader/shipping_manager.h#32

Typical Size/over-head

I can't say what this might be, added @Alex Zani in case he has more information.

Suitability for NB-IoT network ( considering limited bandwitdth)

The older Cobalt 1.0 implementation in fuchsia.cobalt uses more bandwidth than our newer Cobalt 1.1 implementation in fuchsia.metrics (perhaps 10x more). So if bandwidth is a concern, you will definitely want to use Cobalt 1.1, which aggregates all metrics on the device for at least an hour before sending them to the server.