Add function to report devices activity

central_backend/src/logs/log_entry.rs

@@ -0,0 +1,17 @@
+use crate::devices::device::DeviceId;
+use crate::logs::severity::LogSeverity;
+
+#[derive(serde::Serialize, serde::Deserialize, Debug, Clone)]
+pub struct LogEntry {
+    /// If no device is specified then the message comes from the backend
+    pub device_id: Option<DeviceId>,
+    pub time: u64,
+    pub severity: LogSeverity,
+    pub message: String,
+}
+
+impl LogEntry {
+    pub fn serialize(&self) -> anyhow::Result<String> {
+        Ok(serde_json::to_string(self)?)
+    }
+}