Changeset 7477

Timestamp:

10/24/2013 08:51:38 PM (13 years ago)

Author:

r-a-y

Message:

Set better HTTP headers for activity RSS feeds.

Previously, BP's RSS feeds would use WP's native HTTP headers set in the
WP::send_headers() method. This would cause BuddyPress to inherit WP
feed's "ETag" and HTTP status headers.

When trying to refresh BP's RSS feeds, this would not work correctly due
to BP relying on WP's post last modified date instead of BP's activity last
updated date. This would lead to a HTTP 304 Not Modified status header
being sent by WP, meaning the client (browser, RSS reader) would not fetch
the latest items from the activity stream.

This commit sets the appropriate HTTP headers for BP's activity RSS feeds
and uses a new, internal class method - http_headers() - to set them.

Fixes #5213.

File:

• trunk/bp-activity/bp-activity-classes.php (modified) (2 diffs)

trunk/bp-activity/bp-activity-classes.php

@@ -1271 +1271 @@
         }
 
-        /** OUTPUT ***************************************************************/
-
-        /**
-         * Output the RSS feed.
+        /**
+         * Sets various HTTP headers related to Content-Type and browser caching.
+         *
+         * Most of this class method is derived from {@link WP::send_headers()}.
+         *
+         * @since BuddyPress (1.9.0)
          *
          * @access protected
          */
-        protected function output() {
+        protected function http_headers() {
                 // set up some additional headers if not on a directory page
                 // this is done b/c BP uses pseudo-pages
@@ -1288 +1290 @@
                 }
 
-                header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ), true );
+                // Set content-type
+                @header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ), true );
+
+                // Cache-related variables
+                $last_modified      = mysql2date( 'D, d M Y H:i:s O', bp_activity_get_last_updated(), false );
+                $modified_timestamp = strtotime( $last_modified );
+                $etag               = md5( $last_modified );
+        
+                // Set cache-related headers
+                @header( 'Last-Modified: ' . $last_modified );
+                @header( 'Pragma: no-cache' );
+                @header( 'ETag: ' . '"' . $etag . '"' );
+        
+                // First commit of BuddyPress! (Easter egg)
+                @header( 'Expires: Tue, 25 Mar 2008 17:13:55 GMT');
+        
+                // Get ETag from supported user agents
+                if ( isset( $_SERVER['HTTP_IF_NONE_MATCH'] ) ) {
+                        $client_etag = wp_unslash( $_SERVER['HTTP_IF_NONE_MATCH'] );
+        
+                        // Remove quotes from ETag
+                        $client_etag = trim( $client_etag, '"' );
+        
+                        // Strip suffixes from ETag if they exist (eg. "-gzip")
+                        if ( $etag_suffix_pos = strpos( $client_etag, '-' ) ) {
+                                $client_etag = substr( $client_etag, 0, $etag_suffix_pos );
+                        }
+
+                // No ETag found
+                } else {
+                        $client_etag = false;
+                }
+        
+                // Get client last modified timestamp from supported user agents
+                $client_last_modified      = empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ? '' : trim( $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
+                $client_modified_timestamp = $client_last_modified ? strtotime( $client_last_modified ) : 0;
+        
+                // Set 304 status if feed hasn't been updated since last fetch
+                if ( ( $client_last_modified && $client_etag ) ?
+                                 ( ( $client_modified_timestamp >= $modified_timestamp ) && ( $client_etag == $etag ) ) :
+                                 ( ( $client_modified_timestamp >= $modified_timestamp ) || ( $client_etag == $etag ) ) ) {
+                        $status = 304;
+                } else {
+                        $status = false;
+                }
+        
+                // If feed hasn't changed as reported by the user agent, set 304 status header
+                if ( ! empty( $status ) ) {
+                        status_header( $status );
+        
+                        // cached response, so stop now!
+                        if ( $status == 304 ) {
+                                exit();
+                        }
+                }
+        }
+
+        /** OUTPUT ***************************************************************/
+
+        /**
+         * Output the RSS feed.
+         *
+         * @access protected
+         */
+        protected function output() {
+                $this->http_headers();
                 echo '<?xml version="1.0" encoding="' . get_option( 'blog_charset' ) . '"?'.'>';
         ?>