diff --git a/frontend/src/js/arvados/process/wb-submit-container-request.js b/frontend/src/js/arvados/process/wb-submit-container-request.js
new file mode 100644
index 0000000..060b2c1
--- /dev/null
+++ b/frontend/src/js/arvados/process/wb-submit-container-request.js
@@ -0,0 +1,87 @@
+import makeArvadosRequest from 'make-arvados-request';
+import wbUuidsToCwl from 'wb-uuids-to-cwl';
+
+function wbParseWorkflowInputs(workflowDefinition, userInputs, errors) {
+  // first see if all inputs are parseable
+  const inputs = {};
+
+  const main = workflowDefinition['$graph'].find(a => (a.id === '#main'));
+
+  for (let k in userInputs) {
+    try {
+      let val = jsyaml.safeLoad(userInputs[k]);
+      val = wbUuidsToCwl(val);
+      k = k.split('/').slice(1).join('/');
+      inputs[k] = (val === undefined ? null : val);
+    } catch (exc) {
+      errors.push('Error parsing ' + k + ': ' + exc.message);
+    }
+  }
+
+  return inputs;
+}
+
+// params:
+//   arvHost, arvToken, inputs,
+//   projectUuid, workflowDefinition, workflowUuid
+//   processName, processDescription
+function wbSubmitContainerRequest(params) {
+
+  const { workflowDefinition, workflowUuid,
+    processName, processDescription, inputs,
+    arvHost, arvToken, projectUuid } = params;
+
+  // prepare a request
+  const req = {
+    name: processName,
+    description: processDescription,
+    owner_uuid: projectUuid,
+    container_image: 'arvados/jobs',
+    properties: {
+      template_uuid: workflowUuid
+    },
+    runtime_constraints: {
+      API: true,
+      vcpus: 1,
+      ram: 1073741824
+    },
+    cwd: '/var/spool/cwl',
+    command: [
+      'arvados-cwl-runner',
+      '--local',
+      '--api=containers',
+      '--project-uuid=' + projectUuid,
+      '--collection-cache-size=256',
+      '/var/lib/cwl/workflow.json#main',
+      '/var/lib/cwl/cwl.input.json'],
+    output_path: '/var/spool/cwl',
+    priority: 1,
+    state: 'Committed',
+    mounts: {
+      'stdout': {
+        kind: 'file',
+        path: '/var/spool/cwl/cwl.output.json'
+      },
+      '/var/spool/cwl': {
+        kind: 'collection',
+        writable: true
+      },
+      '/var/lib/cwl/workflow.json': {
+        kind: 'json',
+        content: workflowDefinition
+      },
+      '/var/lib/cwl/cwl.input.json': {
+        kind: 'json',
+        content: inputs
+      }
+    }
+  };
+
+  const prom = makeArvadosRequest(arvHost, arvToken,
+    '/arvados/v1/container_requests',
+    { method: 'POST', data: JSON.stringify(req) });
+
+  return prom;
+}
+
+export { wbParseWorkflowInputs, wbSubmitContainerRequest };
diff --git a/frontend/src/js/arvados/process/wb-uuids-to-cwl.js b/frontend/src/js/arvados/process/wb-uuids-to-cwl.js
index 6c0a3ff..cb1df7c 100644
--- a/frontend/src/js/arvados/process/wb-uuids-to-cwl.js
+++ b/frontend/src/js/arvados/process/wb-uuids-to-cwl.js
@@ -2,7 +2,7 @@ function wbUuidsToCwl(obj) {
   if (obj instanceof Array) {
     const res = [];
     for (let k in obj) {
-        res[k] = uuidsToCwl(obj[k]);
+        res[k] = wbUuidsToCwl(obj[k]);
     }
     return res;
   }
diff --git a/frontend/src/js/component/wb-workflow-input.js b/frontend/src/js/component/wb-workflow-input.js
new file mode 100644
index 0000000..473a611
--- /dev/null
+++ b/frontend/src/js/component/wb-workflow-input.js
@@ -0,0 +1,71 @@
+import { h, Component } from 'preact';
+import wbInputSpecInfo from 'wb-input-spec-info';
+import WBPathDisplay from 'wb-path-display';
+import { parseKeepRef } from 'wb-process-misc';
+
+class WBWorkflowInput extends Component {
+  render({ app, inputSpec, inputsDict, browseDialogRef }) {
+    const { isFile, isDirectory, isArray } = wbInputSpecInfo(inputSpec);
+
+    if (!isFile && !isDirectory)
+      return (
+        <div>
+          <input class="form-control w-100" type="text" placeholder={ inputSpec.label }
+            value={ inputsDict[inputSpec.id] }
+            onchange={ e => (inputsDict[inputSpec.id] = e.target.value) }></input>
+          <div class="mt-2 text-muted">{ inputSpec.doc }</div>
+        </div>
+      );
+
+    const button = (
+      <button class="btn btn-outline-primary"
+        onclick={ e => {
+          e.preventDefault();
+          browseDialogRef.current.show(
+            [].concat(isFile ? 'file' : []).concat(isDirectory ? 'directory' : []),
+            isArray,
+            v => {
+              inputsDict[inputSpec.id] = JSON.stringify(v);
+              this.setState({});
+            });
+        } }>
+        Browse...
+      </button>
+    );
+
+    let value = inputsDict[inputSpec.id];
+    if (value) {
+      try {
+        value = jsyaml.load(value);
+      } catch (_) {}
+    }
+
+    return (
+      <div>
+        <div class="input-group">
+          <input class="form-control w-100" type="text" placeholder={ inputSpec.label }
+            value={ inputsDict[inputSpec.id] }
+            onchange={ e => (inputsDict[inputSpec.id] = e.target.value) }></input>
+          <div class="input-group-append">
+            { button }
+          </div>
+        </div>
+        <div class="mt-2 text-muted">{ inputSpec.doc }</div>
+        { value ?
+          isArray ? (
+            <ul class="mb-0">
+              { value.map(path => (
+                <li>
+                  <WBPathDisplay app={ app } path={ parseKeepRef(path) } />
+                </li>
+              )) }
+            </ul>
+        ) : (
+          <WBPathDisplay app={ app } path={ parseKeepRef(value) } />
+        ) : null }
+      </div>
+    );
+  }
+}
+
+export default WBWorkflowInput;
diff --git a/frontend/src/js/page/wb-launch-workflow-page.js b/frontend/src/js/page/wb-launch-workflow-page.js
index cda3671..603ad5b 100644
--- a/frontend/src/js/page/wb-launch-workflow-page.js
+++ b/frontend/src/js/page/wb-launch-workflow-page.js
@@ -4,15 +4,12 @@ import WBNavbarCommon from 'wb-navbar-common';
 import WBArvadosCrumbs from 'wb-arvados-crumbs';
 import WBBrowseDialog from 'wb-browse-dialog';
 import WBTable from 'wb-table';
-import WBNameAndUuid from 'wb-name-and-uuid';
 import makeArvadosRequest from 'make-arvados-request';
 import { wbDisableControls, wbEnableControls } from 'wb-disable-controls';
 import linkState from 'linkstate';
 import wbParseWorkflowDef from 'wb-parse-workflow-def';
-import wbInputSpecInfo from 'wb-input-spec-info';
-import wbUuidsToCwl from 'wb-uuids-to-cwl';
-import { encodeURIComponentIncludingDots, parseKeepRef } from 'wb-process-misc';
-import WBPathDisplay from 'wb-path-display';
+import { wbParseWorkflowInputs, wbSubmitContainerRequest } from 'wb-submit-container-request';
+import WBWorkflowInput from 'wb-workflow-input';
 
 class WBLaunchWorkflowPage extends Component {
   constructor(...args) {
@@ -43,156 +40,40 @@ class WBLaunchWorkflowPage extends Component {
     });
   }
 
-  renderInput(inputSpec) {
-    const { app } = this.props;
-
-    const { isFile, isDirectory, isArray } = wbInputSpecInfo(inputSpec);
-
-    if (!isFile && !isDirectory)
-      return (
-        <div>
-          <input class="form-control w-100" type="text" placeholder={ inputSpec.label }
-            value={ this.state.inputs[inputSpec.id] }
-            onchange={ e => (this.state.inputs[inputSpec.id] = e.target.value) }></input>
-          <div class="mt-2 text-muted">{ inputSpec.doc }</div>
-        </div>
-      );
-
-    const button = (
-      <button class="btn btn-outline-primary"
-        onclick={ e => {
-          e.preventDefault();
-          this.browseDialogRef.current.show(
-            [].concat(isFile ? 'file' : []).concat(isDirectory ? 'directory' : []),
-            isArray,
-            v => {
-              this.state.inputs[inputSpec.id] = JSON.stringify(v);
-              this.setState({});
-            });
-        } }>
-        Browse...
-      </button>
-    );
-
-    let value = this.state.inputs[inputSpec.id];
-    if (value) {
-      try {
-        value = jsyaml.load(value);
-      } catch (_) {}
-    }
-
-    return (
-      <div>
-        <div class="input-group">
-          <input class="form-control w-100" type="text" placeholder={ inputSpec.label }
-            value={ this.state.inputs[inputSpec.id] }
-            onchange={ e => (this.state.inputs[inputSpec.id] = e.target.value) }></input>
-          <div class="input-group-append">
-            { button }
-          </div>
-        </div>
-        <div class="mt-2 text-muted">{ inputSpec.doc }</div>
-        { value ?
-          isArray ? (
-            <ul class="mb-0">
-              { value.map(path => (
-                <li>
-                  <WBPathDisplay app={ app } path={ parseKeepRef(path) } />
-                </li>
-              )) }
-            </ul>
-        ) : (
-          <WBPathDisplay app={ app } path={ parseKeepRef(value) } />
-        ) : null }
-      </div>
-    );
-  }
-
   submit() {
     // first see if all inputs are parseable
-    const inputs = {};
-    const errors = [];
-
-    const { workflowDefinition } = this.state;
-    const main = workflowDefinition['$graph'].find(a => (a.id === '#main'));
-
-    for (let k in this.state.inputs) {
-      try {
-        let val = jsyaml.safeLoad(this.state.inputs[k]);
-        val = wbUuidsToCwl(val);
-        k = k.split('/').slice(1).join('/');
-        inputs[k] = (val === undefined ? null : val);
-      } catch (exc) {
-        errors.push('Error parsing ' + k + ': ' + exc.message);
-      }
-    }
+    const { app, workflowUuid } = this.props;
+    const { arvHost, arvToken, currentUser } = app.state;
+    const { workflowDefinition, projectUuid,
+      processName, processDescription,
+      defaultProcessName, defaultProcessDescription } = this.state;
 
+    const errors = [];
+    const inputs = wbParseWorkflowInputs(workflowDefinition,
+      this.state.inputs, errors);
     if (errors.length > 0) {
       this.setState({ errors });
       return;
     }
 
-    // prepare a request
-    const { app, workflowUuid } = this.props;
-    const { processName, processDescription,
-      defaultProcessName, defaultProcessDescription,
-      projectUuid } = this.state;
-    const { arvHost, arvToken, currentUser } = app.state;
-    const req = {
-      name: processName || defaultProcessName,
-      description: processDescription || defaultProcessDescription,
-      owner_uuid: projectUuid || currentUser.uuid,
-      container_image: 'arvados/jobs',
-      properties: {
-        template_uuid: workflowUuid
-      },
-      runtime_constraints: {
-        API: true,
-        vcpus: 1,
-        ram: 1073741824
-      },
-      cwd: '/var/spool/cwl',
-      command: [
-        'arvados-cwl-runner',
-        '--local',
-        '--api=containers',
-        '--project-uuid=' + (projectUuid || currentUser.uuid),
-        '--collection-cache-size=256',
-        '/var/lib/cwl/workflow.json#main',
-        '/var/lib/cwl/cwl.input.json'],
-      output_path: '/var/spool/cwl',
-      priority: 1,
-      state: 'Committed',
-      mounts: {
-        'stdout': {
-          kind: 'file',
-          path: '/var/spool/cwl/cwl.output.json'
-        },
-        '/var/spool/cwl': {
-          kind: 'collection',
-          writable: true
-        },
-        '/var/lib/cwl/workflow.json': {
-          kind: 'json',
-          content: workflowDefinition
-        },
-        '/var/lib/cwl/cwl.input.json': {
-          kind: 'json',
-          content: inputs
-        }
-      }
-    };
+    const params = {
+      arvHost, arvToken, inputs,
+      processName: processName || defaultProcessName,
+      processDescription: processDescription || defaultProcessDescription,
+      projectUuid: projectUuid || currentUser.uuid,
+      workflowUuid, workflowDefinition
+    }
 
     wbDisableControls();
-    let prom = makeArvadosRequest(arvHost, arvToken,
-      '/arvados/v1/container_requests',
-      { method: 'POST', data: JSON.stringify(req) });
+    let prom = wbSubmitContainerRequest(params);
     prom = prom.then(xhr => {
       wbEnableControls();
       route('/process/' + xhr.response.uuid);
     });
-
-    // throw Error('Not implemented');
+    prom = prom.catch(exc => {
+      wbEnableControls();
+      this.setState({ errors: [ exc.message ] });
+    });
   }
 
   render({ app, workflowUuid },
@@ -254,16 +135,12 @@ class WBLaunchWorkflowPage extends Component {
               <WBTable columns={ [ 'Name', 'Value'] }
                 rows={ workflowDefinition.$graph.find(a => (a.id === '#main')).inputs.map(it => [
                   it.label || it.id,
-                  this.renderInput(it)
+                  ( <WBWorkflowInput app={ app } inputSpec={ it }
+                    inputsDict={ this.state.inputs }
+                    browseDialogRef={ this.browseDialogRef } /> )
                 ]) } />
             </div>
 
-            <div class="form-group">
-              <button class="btn btn-success" onclick={ e => { e.preventDefault(); this.submit(); } }>
-                Submit
-              </button>
-            </div>
-
             { errors.length > 0 ? (
               <div class="form-group">
                 { errors.map(err => (
@@ -273,6 +150,12 @@ class WBLaunchWorkflowPage extends Component {
                 ))}
               </div>
             ) : null }
+
+            <div class="form-group">
+              <button class="btn btn-success" onclick={ e => { e.preventDefault(); this.submit(); } }>
+                Submit
+              </button>
+            </div>
           </form>) : <div>Loading...</div> }
       </div>
     );