Generally, apps running in v3 are compatible in v4. However, there is greater emphasis on security in v4 so the following exceptions apply:
- Form Elements - Form labels and values now do not allow script execution to prevent possible cross-site scripting (XSS) vulnerabilities. Apps that depend on scripting will need to place such scripts into Custom HTML elements.
- Readonly Form Elements - Previously, form read-only field values are not editable in the browser, but get stored in the database upon form submission. In v4, read-only field values are no longer stored to prevent unintended modifications using client-side browser tools such as Browser Console, Firebug, etc.
- JSON API Request Methods – Previously, JSON API calls that modify the state of a process (e.g. start a process, complete an assignment, etc) support both HTTP GET and POST. In v4, only POST requests are supported to prevent cross-site request forgery (CSRF) attacks. Read-only API calls are unchanged. Please refer to the latest JSON API reference in the Knowledge Base at JSON API
- JSON API Responses – In v4, all JSON API calls respond with JSON responses only. Previously, failed authentication will redirect the request to a login page, but a failed authentication now would result in a JSON 401 response e.g.
- JSON API Authentication – The JSON API now supports basic authentication, so this would be the recommended authentication mechanism when combined with HTTPS.