If the URI in a request does not match the URI of the cached resource on Dynamic Route for CDN (DCDN) nodes, you can create a URI rewrite rule to overwrite the URI in the request. Then, the request can be redirected to the final URI.
Background information
The HTTP 302 status code, also known as the Found message, indicates that the requested resource has temporarily relocated. After you add a URI rewrite rule, DCDN nodes can add the new URI of the resource to the Location header in the HTTP 302 response message. After the client receives the message, the client sends a request to the new URI.
After you add a URI rewrite rule, DCDN nodes return the HTTP 302 status code to clients by default if the requested resource has relocated. You can also set the HTTP status code to 303 or 307. To change the HTTP status code, submit a ticket.
| HTTP status code | Definition | Processing method | Use scenario |
|---|---|---|---|
| 302 | Found | GET requests remain unchanged. Requests that use other request methods may be changed to GET. | A web page is temporarily inaccessible due to unknown reasons. In this case, search engines do not update the URL to the web page. |
| 303 | See Other | GET requests remain unchanged. Requests that use other request methods are changed to GET. The message body is dropped. | Redirect PUT and POST requests to prevent frequent redirections that are caused by a page refresh. |
| 307 | Temporary Redirect | Both the request method and message body remain unchanged. | A web page is temporarily inaccessible due to unknown reasons. In this case, search engines do not update the URL to the web page. If the website supports requests that use request methods other than GET, the HTTP 307 status code is returned instead of the HTTP 302 status code. |
Scenarios
A resource on the origin server is moved to a different URL, and the URL of the resource that is cached on the DCDN nodes is updated. However, a client sends a request to the original URL. In this case, DCDN nodes must rewrite the URL in the request. This way, the request can be redirected to the new URL. For example, an image file is moved from the /download/ directory to the /image/ directory.
Procedure
- Click Add. In the Rewrite dialog box, configure the URI to Be Rewritten, Target URI, and Executing Rules parameters.
Parameter Description URI to Be Rewritten Enter a URI that starts with a forward slash (/). The URI cannot contain http:// or domain names. You can use Perl Compatible Regular Expressions (PCRE) to specify the URI, for example, ^/hello$. Target URI Enter a URI that starts with a forward slash (/). The URI cannot contain http:// or domain names. Example: /index.html. Executing Rules Redirect and Break are supported. - Redirect: If the URI in a request matches the current rule, DCDN returns a 302 status code and the request is redirected to the final URI. After the current rule is executed, the request is matched against other rules.
- Break: If the URI in a request matches the current rule, DCDN returns a 302 status code and the request is redirected to the final URI. After the current rule is executed, other rules are skipped.
Configuration examples
A client sends a request to http://example.aliyundoc.com/hello, and the request contains /hello. DCDN nodes add a new URI http://example.aliyundoc.com/index.html to the Location header in the HTTP 302 response message and return the response message
to the client. Then, the client sends a request to http://example.aliyundoc.com/index.html.