Add a simple nanomsg pubsub example

Makefile

@@ -2,23 +2,29 @@
 
 GPRBUILD=`which gprbuild`
 GPRCLEAN=`which gprclean`
-EXECUTABLE=build/pipeline
 
-all: $(EXECUTABLE)
+all: build/pipeline build/pubsub
 clean:
 	$(GPRCLEAN) -Ppipeline
+	$(GPRCLEAN) -Ppubsub
 
-check: all build/c_pipeline
+check: all build/c_pipeline build/c_pubsub
 	./t/bin/bats ./t/*.bats
 
 generated:  build/generated/nanomsg_nn_h.ads
 
-build/pipeline:  generated
+build/pipeline: pipeline.adb
 	$(GPRBUILD) -Ppipeline
 
+build/pubsub: pubsub.adb
+	$(GPRBUILD) -Ppubsub
+
 build/c_pipeline: contrib/pipeline.c
 	$(CC) -lnanomsg -o build/c_pipeline contrib/pipeline.c
 
+build/c_pubsub: contrib/pubsub_client.c
+	$(CC) -lnanomsg -o build/c_pubsub contrib/pubsub_client.c
+
 build/generated/nanomsg_nn_h.ads:
 	(cd build/generated && gcc -fdump-ada-spec /usr/include/nanomsg/nn.h)
 

contrib/pubsub_client.c

@@ -0,0 +1,28 @@
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <nanomsg/nn.h>
+#include <nanomsg/pubsub.h>
+
+int client (const char *url, const char *name)
+{
+  int sock = nn_socket (AF_SP, NN_SUB);
+  assert (sock >= 0);
+  // TODO learn more about publishing/subscribe keys
+  assert (nn_setsockopt (sock, NN_SUB, NN_SUB_SUBSCRIBE, "", 0) >= 0);
+  assert (nn_connect (sock, url) >= 0);
+  while (1)
+    {
+      char *buf = NULL;
+      int bytes = nn_recv (sock, &buf, NN_MSG, 0);
+      assert (bytes >= 0);
+      printf ("CLIENT (%s): RECEIVED %s\n", name, buf);
+      nn_freemsg (buf);
+    }
+  return nn_shutdown (sock, 0);
+}
+
+int main (const int argc, const char **argv)
+{
+   return client ("tcp://127.0.0.1:5018", argv[1]);
+}

pubsub.adb

@@ -0,0 +1,59 @@
+--
+--  Pubsub demo with nanomsg
+--
+
+with Ada.Calendar,
+   Ada.Calendar.Formatting;
+with Ada.Text_IO;
+with Interfaces.C,
+   Interfaces.C.Strings;
+
+with nanomsg_nn_h;
+
+procedure Pubsub is
+   pragma Linker_Options ("-lnanomsg");
+
+   use nanomsg_nn_h;
+   use Interfaces.C,
+      Interfaces.C.Strings;
+
+   use Ada.Text_IO;
+
+   NN_PROTO_PUBSUB : constant := 2;
+   NN_PUB : constant := (NN_PROTO_PUBSUB * 16 + 0);
+   NN_SUB : constant := (NN_PROTO_PUBSUB * 16 + 1);
+
+   NN_SUB_SUBSCRIBE : constant := 1;
+   NN_SUB_UNSUBSCRIBE : constant := 2;
+
+   subtype C_Socket is int;
+
+   Socket : constant C_Socket := nn_socket (AF_SP, NN_PUB);
+   Status : int;
+
+   procedure Publish_Tick (Bound_Socket : in C_Socket) is
+      Bytes_Sent : int := 0;
+      Buffer : constant String := Ada.Calendar.Formatting.Image (Ada.Calendar.Clock);
+   begin
+      Bytes_Sent := nn_send (Bound_Socket,
+                           To_C (Buffer)'Address,
+                           unsigned_long (Buffer'Last),
+                           0);
+      Put_Line ("Sent" & int'Image (Bytes_Sent));
+   end Publish_Tick;
+begin
+   Put_Line ("Running pubsub server");
+   Put_Line ("Socket " & int'Image (Socket));
+
+   Status := nn_bind (Socket,
+                      New_String ("tcp://127.0.0.1:5018"));
+
+   Put_Line ("Status: " & int'Image (Socket));
+
+   loop
+      Publish_Tick (Socket);
+      delay 2.0;
+   end loop;
+
+   Status := nn_shutdown (Socket, 0);
+end Pubsub;

pubsub.gpr

@@ -0,0 +1,12 @@
+with "shared";
+
+project Pubsub is
+   for Main use ("pubsub.adb");
+
+   for Source_Dirs use Shared'Source_Dirs;
+   for Object_Dir use Shared'Object_Dir;
+   for Exec_Dir use Shared'Exec_Dir;
+
+   package Compiler renames Shared.Compiler;
+end Pubsub;
+

t/pubsub.bats

@@ -0,0 +1,15 @@
+#!/usr/bin/env bats
+
+@test "Simple pubsub" {
+   ./build/pubsub &
+   server=$!
+
+   sleep 1
+
+   ./build/c_pubsub client0 &
+   client0=$!
+
+   sleep 2
+
+   kill $server $client0
+}