Got it. So this isn't considered bad form for RPC? Technically it isn't
RPC? In my case:
- Server implements rpc Link (stream UpLink) returns (stream DownLink) {}
- Client initiates connection
- Client waits for messages to come down from the server to be executed
- Clients parses the strings/bytes streamed down and uses a case statement
to execute commands
On Wed, Feb 7, 2018 at 12:04 PM, Carl Mastrangelo <[email protected]>
wrote:
> Yes, that is correct. (It's bidirectional because the word "stream" is in
> both the request (UpLink) and response (DownLink).)
>
> I mistakenly thought this was another thread (which I replied to
> yesterday) which had almost the same issue. Take a look at
> https://groups.google.com/d/msg/grpc-io/G4eYs1zNMjE/Yh2WJS7TBwAJ where I
> describe how to do what you want.
>
>
> On Wed, Feb 7, 2018 at 11:38 AM John Pearson <[email protected]>
> wrote:
>
>> I'm unclear on what the last part means: "That's why that issue, (and my
>> post), suggest treating the message as inverted requests and responses."
>>
>> Do you mean rpc Link (stream UpLink) returns (stream DownLink) {} ? With
>> a bidirectional stream?
>>
>> Thanks
>>
>>
>>
>> On Wed, Feb 7, 2018 at 11:27 AM, 'Carl Mastrangelo' via grpc.io <
>> [email protected]> wrote:
>>
>>> It's unlikely that gRPC will be able to have servers initiate
>>> connections / rpcs to clients. The initial headers need to be sent by the
>>> client to the server, and only the server can send trailers to indicate the
>>> RPC is done. But, after these two, the client and server are peers.
>>> That's why that issue, (and my post), suggest treating the message as
>>> inverted requests and responses.
>>>
>>>
>>>
>>> On Monday, February 5, 2018 at 8:55:46 PM UTC-8, John Pearson wrote:
>>>>
>>>> Question regarding bi-directional streaming:
>>>>
>>>> Is this issue(https://github.com/grpc/grpc-go/issues/484#
>>>> issuecomment-288880402) solved because of bidirectional rpc? -- it is
>>>> almost exactly the same as my use case.
>>>>
>>>>
>>>> On Mon, Feb 5, 2018 at 3:41 PM, 'Carl Mastrangelo' via grpc.io <
>>>> [email protected]> wrote:
>>>>
>>>>> Sounds like you want to use a client streaming rpc. The client will
>>>>> start an RPC, and periodically send messages to the server, which will
>>>>> never respond. This works well if the time between updates is small
>>>>> perhaps no more than a minute apart. If it's longer, it would be better
>>>>> to just make it unary because the connection will be at risk of being torn
>>>>> down by intermediary things.
>>>>>
>>>>> If you trust the hardware you are running on, a common way of authing
>>>>> would be client side certificates, but we leave the problem of certificate
>>>>> rotation and revocation up to you. In gRPC, auth is more commonly
>>>>> (always?) done at the RPC level. Each RPC would need an auth token, like
>>>>> a
>>>>> JWT.
>>>>>
>>>>> If you want a command and control style system, you'll need to use a
>>>>> bidirectional streaming RPC. This would let the client phone home, and
>>>>> wait for messages to come down from the server to be executed. The client
>>>>> must initiate the connection and the RPC, but after that each side is a
>>>>> peer.
>>>>>
>>>>> There are examples on how to do each style of these commands in the
>>>>> github repos. Look for "Route Guide" examples on how to do it in each
>>>>> language.
>>>>>
>>>>> On Sunday, February 4, 2018 at 5:37:40 PM UTC-8, [email protected]
>>>>> wrote:
>>>>>>
>>>>>> I manage a fleet of linux devices and I need a way to send
>>>>>> telemetry data(CPU, memory, drives, etc.) from devices to a centralized
>>>>>> server and also send commands(linux service restarts for example) from
>>>>>> server to devices to execute on the device. The 15 different linux
>>>>>> devices are bare metal boxes in 15 different locations access to WAN
>>>>>> with a
>>>>>> dynamic IP address. In a year the number of devices could jump to 100.
>>>>>>
>>>>>> I'm looking for suggestions on:
>>>>>> - how to gather telemetry data to send to grpc server
>>>>>> - how authenticate and identify devices
>>>>>> - how to run commands locally on each device and report back
>>>>>>
>>>>>> Thanks.
>>>>>>
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