Thermostat

Thermostat

This example presents an application with a client (think app running on your phone) that interacts with a device (a thermostat in your home) via an intermediary server (such as a server deployed on a public cloud).

The device can only establish outgoing connections, so the client needs this intermediary server to reach it.

This example shows how you can send requests "the other way around" with IceRPC, from the server-side of a connection to the client-side of this connection. The client sets the target temperature on the device (the technical term is "set point") by calling a service in the server that in turns forwards the call to a service in the device.

It also shows a very simple publish-subscribe setup with streams: the device sends a stream of readings to the server, and the server distributes these readings to the "subscribed" clients (all clients currently monitoring the device).

For simplicity and brevity, this example ignores authentication / security and supports only a single device at a time.

Interactions

---
title: Typical deployment
---
flowchart LR
    subgraph cloud [Public cloud]
        Server
    end
    subgraph home [Home network]
        Device
    end
    subgraph shop [Coffee shop]
        Client
    end
    Client -- port 4062 --> Server

    %% Put device on the right hand size
    Server ~~~ Device
    Device -- port 10000 --> Server

Loading

The arrows on the diagram indicate the client and server sides of the connection, not the flow of requests and responses.

Server implements two Slice interfaces using two separate services:

• Thermostat, the client-facing interface
• ThermoHome, the device-facing interface

Server also calls a service on the device that implements Slice interface ThermoControl.

Build and run

You can build the client, server and device with:

dotnet build

First start the Server program:

cd Server
dotnet run

In a separate terminal, start the Device program:

cd Device
dotnet run

Then in another window, start the Client program:

cd Client
dotnet run

You can start multiple instances of the Client program. When you start Client with no arguments (as shown above), it monitors the device until you press Ctrl+C or the Server shuts down.

You can also use Client to set a new target temperature ("set point") on the device. For example, you can change the set point to 70°F with:

cd Client
dotnet run set 70