Send a request for new credentials at regular intervals.

Every five minutes, a message is sent via WebSocket to ask the
server for a refreshed JWT token.

lib/www/client/source/src/main.js

@@ -7,6 +7,8 @@ import vueDebounce from 'vue-debounce'
 import { mapMutations } from 'vuex';
 import { markdown, markdownInline } from './lib/markdown';
 import { geometryAsString } from './lib/utils';
+import { mapGetters } from 'vuex';
+
 
 Vue.config.productionTip = false
 
@@ -14,7 +16,7 @@ Vue.use(vueDebounce);
 
 Vue.filter('markdown', markdown);
 Vue.filter('markdownInline', markdownInline);
-Vue.filter('position', (str, item, opts) => 
+Vue.filter('position', (str, item, opts) =>
   str
   .replace(/@POS(ITION)?@/g, geometryAsString(item, opts) || "(position unknown)")
   .replace(/@DMS@/g, geometryAsString(item, {...opts, dms:true}) || "(position unknown)")
@@ -32,10 +34,16 @@ new Vue({
       user: null,
 
       wsUrl: "/ws",
-      ws: null
+      ws: null,
+      wsCredentialsCheckInterval: 300*1000, // ms
+      wsCredentialsCheckTimer: null
     }
   },
 
+  computed: {
+    ...mapGetters(["jwt"])
+  },
+
   methods: {
 
     markdown (value) {
@@ -85,6 +93,17 @@ new Vue({
         this.setServerConnectionState(false);
       });
 
+      if (this.wsCredentialsCheckTimer) {
+        clearInterval(this.wsCredentialsCheckTimer);
+        this.wsCredentialsCheckTimer = null;
+      }
+
+      this.wsCredentialsCheckTimer = setInterval( () => {
+        this.ws.send(JSON.stringify({
+          jwt: this.jwt
+        }));
+      }, this.wsCredentialsCheckInterval);
+
     },
 
     ...mapMutations(['setServerEvent', 'setServerConnectionState'])