[NIFI-1860] Backward compatibility for Site-to-Site client

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0, 1.0.0-Beta
• Component/s: Core Framework
• Assignee: Koji Kawamura
• Reporter: Koji Kawamura
• Created: 09/May/16 05:45
• Updated: 04/Aug/16 21:23
• Resolved: 09/May/16 12:25

Description

NIFI-1554 has moved /nifi-api/controller to /nifi-api/site-to-site/ .
However, Site-to-Site client is not updated yet, and it still sends a request to /nifi-api/controller to obtain information for Site-to-Site.

EndpointConnectionPool.java

    private ControllerDTO refreshRemoteInfo() throws IOException {
        final boolean webInterfaceSecure = clusterUrl.toString().startsWith("https");
        final NiFiRestApiUtil utils = new NiFiRestApiUtil(webInterfaceSecure ? sslContext : null);
        final ControllerDTO controller = utils.getController(apiUri + "/controller", commsTimeout);

We can simply change the URL to "/site-to-site", but if we do so, old version of NiFi won't be able to communicate with the new version of NiFi via Site-to-Site.
Possible approaches to provide backward compatibility are:

• A. keep the old endpoint and let it respond with 301 Moved Permanently
• B. add a ContainerRequestFilter to modify requested url
• C. Jetty Rewrite Handler http://www.eclipse.org/jetty/documentation/current/rewrite-handler.html

Similarly when new version of NiFi tries to communicate with old version of NiFi, it has to send request to /controller, instead of /site-to-site. For this scenario, adding retry logic in new version of SIte-to-SIte client would be sufficient.

1. Send request to /site-to-site
2. If response code is 404 or 405, then retry sending request to /controller