WEBVTT 00:00.080 --> 00:03.650 Let's see how to monitor topics with Actigraph. 00:03.680 --> 00:07.640 For that, we will use the topics that you have just created in this section. 00:07.640 --> 00:11.420 And we're going to create quite a lot of publishers and subscribers, you will see. 00:11.450 --> 00:12.530 First what I'm going to do. 00:12.530 --> 00:14.390 So I have some open terminals. 00:14.390 --> 00:20.960 I'm just going to start an activity graph for example from that one okay I start activity graph with 00:20.960 --> 00:22.490 this comment. 00:23.990 --> 00:25.910 And again I'm going to put this full screen. 00:25.910 --> 00:27.170 You see now it's empty. 00:27.200 --> 00:30.650 We have no node running on the graph. 00:30.650 --> 00:33.920 So I'm going to start a publisher. 00:33.920 --> 00:42.380 So Ross to run my let's start the Cplusplus robot news station. 00:42.380 --> 00:50.450 And let's start Ross to run my Python smartphone. 00:51.380 --> 00:51.890 Okay. 00:51.920 --> 00:54.740 You can see the communication is already working. 00:54.740 --> 00:58.820 We are going to go to Active Graph and let's refresh. 00:58.850 --> 01:04.310 You see I have nodes only and you can see I have my robot news station node my smartphone node. 01:04.310 --> 01:05.660 And then I have a topic. 01:05.660 --> 01:12.760 So this is a topic robot news with the arrow that says that this is a publisher and this is the subscriber. 01:12.760 --> 01:14.950 And actually we can have a better view for that. 01:14.950 --> 01:20.110 If you click on nodes, topics, all you can refresh if needed. 01:20.110 --> 01:22.870 And now you can see that the robot news is a topic. 01:22.870 --> 01:29.980 So the box here is a topic the robot news station is publishing to the topic, and that one the smartphone 01:29.980 --> 01:34.270 is receiving data from the topic, so it's subscribing to the topic. 01:34.300 --> 01:34.570 Okay. 01:34.600 --> 01:39.370 And with this view you can see we can already see what's happening in the graph. 01:39.370 --> 01:44.800 So if for example, you see that communication doesn't work, you can open the graph. 01:44.800 --> 01:49.810 And maybe you see that the publisher is not publishing to the same topic as the subscriber is subscribing 01:49.840 --> 01:52.570 to, and then you can fix that in your code. 01:52.600 --> 01:53.140 Okay. 01:53.170 --> 01:57.670 Now let's go back to the terminal and let's add another publisher. 01:57.670 --> 02:03.100 So let's start to run my my Python or C plus plus. 02:03.100 --> 02:07.360 So they are all the same robot new station. 02:07.360 --> 02:14.310 The thing is I'm not going to start the node like that because it's going to have the same name as that 02:14.310 --> 02:14.760 one. 02:14.760 --> 02:18.210 And you know that we can't have two nodes with the same name. 02:18.210 --> 02:26.340 So I will have to do a Ross args and then dash r node and let's rename it. 02:26.370 --> 02:30.060 Let's just name it station two okay. 02:30.060 --> 02:33.510 So we have robot new station and this one is going to be station two. 02:33.900 --> 02:34.980 You see already. 02:34.980 --> 02:37.740 So we have the C plus plus one and the Python one here. 02:37.740 --> 02:43.440 You see already on this subscriber we receive the data from both publishers. 02:43.440 --> 02:49.950 And we can verify that if we refresh you have the station two that is also publishing on the robot news 02:49.950 --> 02:50.760 topic. 02:50.970 --> 02:51.570 Okay. 02:51.570 --> 02:56.670 So all the subscribers here, only one receive all the data from all the publishers. 02:57.120 --> 03:00.330 We can add yet another. 03:00.750 --> 03:13.890 So that's going to be here another publisher Ross to run my pi PG with robot new station Ross args dash 03:13.920 --> 03:15.540 r node. 03:15.540 --> 03:18.960 Let's call it station three. 03:19.860 --> 03:26.540 Okay, has been started and now we see we have three publishers on that topic. 03:26.570 --> 03:29.630 Now let's add another subscriber for example. 03:29.810 --> 03:33.800 So I'm gonna open a new new terminal. 03:33.830 --> 03:35.960 Let's move that here. 03:36.110 --> 03:41.690 Ross to run my, for example, CBP package with smartphone. 03:41.690 --> 03:45.530 And because we already have a smartphone node I'm going to rename. 03:45.530 --> 03:52.430 Also Ross Arcs are going to rename the node to smartphone two. 03:55.010 --> 03:55.790 Okay. 03:55.820 --> 04:01.130 And you see that node is also receiving all the data from all the publishers. 04:01.160 --> 04:03.320 Okay, I can refresh. 04:03.320 --> 04:09.290 And you see I have my smartphone two here that also receives all the data from all the publishers. 04:09.290 --> 04:12.770 And now let's go back to the terminal I'm going to do here. 04:12.800 --> 04:15.860 I'm going to start Ross to run. 04:15.890 --> 04:20.300 I'm going to start a publisher but this time. 04:20.300 --> 04:28.950 So I'm going to rename, of course, the node and let's say station four. 04:28.950 --> 04:32.370 And this time I'm also going to remap the topic. 04:32.370 --> 04:37.200 So another R the topic is robot news. 04:37.200 --> 04:42.180 Let's say my news okay. 04:42.180 --> 04:45.810 So this one is publishing to a my news topic now. 04:45.810 --> 04:48.690 And it's not going to be received by those subscribers. 04:48.690 --> 04:50.250 We can verify that. 04:51.300 --> 04:52.170 And you see here. 04:52.170 --> 04:55.680 So maybe you have those boxes checked okay. 04:55.710 --> 04:57.570 That syncs and live topics. 04:57.660 --> 04:59.340 You can uncheck those. 04:59.340 --> 05:04.170 And now you see the station four is publishing to my news. 05:04.170 --> 05:06.270 And you see that it's completely different. 05:06.270 --> 05:09.180 So those two topics are not the same. 05:09.510 --> 05:13.500 And so those two subscribers will not receive anything from that topic. 05:13.500 --> 05:15.960 And thus they will not receive anything from the station. 05:15.960 --> 05:22.140 Four now let's say we want to add the smartphone three that will listen to that topic. 05:22.140 --> 05:25.170 My news I can create here. 05:26.040 --> 05:30.030 For example, let's split that again. 05:30.150 --> 05:36.290 Press to run my by PG with smartphone. 05:37.400 --> 05:49.730 Let's do Ross AGS dash R, let's rename to Smart phone three and let's also rename the topic. 05:49.730 --> 05:56.060 So Robot News My news and make sure it's the same as here. 05:56.570 --> 05:57.890 Let's run that. 05:58.460 --> 06:00.170 You can see this is already working. 06:00.170 --> 06:02.840 We received some data here which is from that publisher. 06:02.840 --> 06:05.660 And we can verify here. 06:05.930 --> 06:06.350 Okay. 06:06.380 --> 06:09.500 So you see we have two topics and we have many nodes. 06:09.500 --> 06:14.090 But by using different topic names you can see that those three nodes are only going to publish to that 06:14.090 --> 06:14.570 one. 06:14.570 --> 06:18.320 And it's only going to be received by those two nodes here. 06:18.320 --> 06:22.550 And then whatever you publish on the my news topic is going to be received here by the smart phone. 06:22.580 --> 06:22.850 Three. 06:22.850 --> 06:24.740 So we have two different communications here. 06:24.770 --> 06:25.130 All right. 06:25.130 --> 06:30.590 So with this example I started a lot of nodes, lots of different configurations just to show you that 06:30.590 --> 06:34.310 with nodes and topics you can do a lot of different things. 06:34.310 --> 06:40.700 And with renaming the nodes and topics at runtime, you can already make your application quite dynamic.