2 files changed, 16 insertions, 6 deletions
diff --git a/gr-zeromq/include/gnuradio/zeromq/pub_sink.h b/gr-zeromq/include/gnuradio/zeromq/pub_sink.h
index cef6a82a54..d9410c48cf 100644
--- a/gr-zeromq/include/gnuradio/zeromq/pub_sink.h
+++ b/gr-zeromq/include/gnuradio/zeromq/pub_sink.h
@@ -22,11 +22,17 @@ namespace zeromq {
  * \ingroup zeromq
  *
  * \details
- * This block acts a a streaming sink for a GNU Radio flowgraph
- * and writes its contents to a ZMQ PUB socket.  A PUB socket may
+ * This block acts as a streaming sink for a GNU Radio flowgraph
+ * and writes its contents to a ZMQ PUB socket. A PUB socket may
  * have subscribers and will pass all incoming stream data to each
- * subscriber.  Subscribers can be either another gr-zeromq source
- * block or a non-GNU Radio ZMQ socket.
+ * subscriber with a matching key. If the publisher's key is set to
+ * "GNURadio", the following example subscriber keys will match: "G",
+ * "GN", .., "GNURadio". In other words, the subscriber must contain
+ * the first set of characters from the publisher's key. If the subscriber
+ * sets an empty key "", it will accept all input messages from the
+ * publisher (including the key itself if one is set). Subscribers
+ * can either be another gr-zeromq source block or a non-GNU Radio
+ * ZMQ socket.
  */
 class ZEROMQ_API pub_sink : virtual public gr::sync_block
 {
@@ -42,13 +48,15 @@ public:
      * \param timeout  Receive timeout in milliseconds, default is 100ms, 1us increments.
      * \param pass_tags Whether sink will serialize and pass tags over the link.
      * \param hwm High Watermark to configure the socket to (-1 => zmq's default)
+     * \param key Prepend a key/topic to the start of each message (default is none)
      */
     static sptr make(size_t itemsize,
                      size_t vlen,
                      char* address,
                      int timeout = 100,
                      bool pass_tags = false,
-                     int hwm = -1);
+                     int hwm = -1,
+                     const std::string& key = "");
 
     /*!
      * \brief Return a std::string of ZMQ_LAST_ENDPOINT from the underlying ZMQ socket.
diff --git a/gr-zeromq/include/gnuradio/zeromq/sub_source.h b/gr-zeromq/include/gnuradio/zeromq/sub_source.h
index 88d286b3b8..c2be39e615 100644
--- a/gr-zeromq/include/gnuradio/zeromq/sub_source.h
+++ b/gr-zeromq/include/gnuradio/zeromq/sub_source.h
@@ -39,13 +39,15 @@ public:
      * \param timeout  Receive timeout in milliseconds, default is 100ms, 1us increments.
      * \param pass_tags Whether source will look for and deserialize tags.
      * \param hwm High Watermark to configure the socket to (-1 => zmq's default)
+     * \param key Subscriber filter key. Leave empty to pass all messages.
      */
     static sptr make(size_t itemsize,
                      size_t vlen,
                      char* address,
                      int timeout = 100,
                      bool pass_tags = false,
-                     int hwm = -1);
+                     int hwm = -1,
+                     const std::string& key = "");
 
     /*!
      * \brief Return a std::string of ZMQ_LAST_ENDPOINT from the underlying ZMQ socket.