Started working on using default values in workflows.

frontend/src/js/page/wb-launch-workflow-page.js

@@ -113,12 +113,19 @@ class WBLaunchWorkflowPage extends Component {
 
     let prom = makeArvadosRequest(arvHost, arvToken,
       '/arvados/v1/workflows/' + workflowUuid);
-    prom = prom.then(xhr => this.setState({
-      'workflow': xhr.response,
-      'workflowDefinition': parseDefinition(xhr.response.definition),
-      'defaultProcessName': xhr.response.name + ' ' + (new Date().toISOString()),
-      'defaultProcessDescription': xhr.response.description
-    }));
+    prom = prom.then(xhr => {
+        const def = parseDefinition(xhr.response.definition);
+        const inputs = {};
+        const main = def['$graph'].find(a => (a.id === '#main'));
+        main.inputs.map(a => (inputs[a.id] = JSON.stringify(a.default)));
+        this.setState({
+        'workflow': xhr.response,
+        'workflowDefinition': def,
+        'defaultProcessName': xhr.response.name + ' ' + (new Date().toISOString()),
+        'defaultProcessDescription': xhr.response.description,
+        inputs
+      });
+    });
   }
 
   renderInput(inputSpec) {