One appendix to Chris note... there is an example application in the samples
repo where two edgent nodes are connected, in that case using a MQTT Broker.
You can run this example and see how it works, it can be found here:
https://github.com/apache/incubator-edgent-samples/tree/develop/apps/scripts/sensorAnalytics
One Application runs and simulates a sensor.
And the other application can communicates with the first one to send commands
to the first one.
Julian
Am 22.09.18, 14:43 schrieb "Christofer Dutz" <christofer.d...@c-ware.de>:
Oh dammit ... sorry not for responding to your email Tom (
Guess I was distracted by our PLC4X meetup.
Well I would like to agree with Julian: I doubt raw http is ideal for
inter-edgent-instance-communication.
The problem is that adding a http client could take care of the one side,
however you would need a server part on the other side.
So you would have to implement both sides and handle all the marshaling and
unmarshaling. I would strongly suggest to use a different transport.
Currently I know that the Kafka integration as well as MQTT. But both
require maintaining a third system.
I guess we never really had "directly linking two Edgent nodes" on our plan
... might be a good thing to support ... let me thing about the options ...
Chris
Am 22.09.18, 04:20 schrieb "Julian Feinauer" <j.feina...@pragmaticminds.de>:
Hi Tom,
first of, I'm no real expert for Edgent.
But my first question is, why do you need the HTTP Transport?
Edgent provides many transport layers that work out of the box and I'm
a bit unsure about HTTP.
For your direct question, sending should be fairly easy with libraries
like Apaches HTTP Client (http://hc.apache.org/httpclient-3.x/).
But on the receiving side it should be a bit more different as you
would need a HTTP Server Listening, e.g., based on a Custom Servlet in Jetty or
something.
Perhaps, if you give some more background on your use case I can try to
help you a bit more.
Best
Julian
Am 20.09.18, 21:55 schrieb "Tom G."
<tom.gelbl...@googlemail.com.INVALID>:
Dear Apache Edgent community,
I’m trying to figure out how to establish a HTTP connection between
two
Apache Edgent instances.
I want to tail an active file and send the appended records via
HTTP to
another Apache Edgent instance.
The second instance should receive these records via HTTP and write
them to
disk.
My code for the first instance looks like this:
package com.mycompany.app;
import org.apache.edgent.connectors.http.*;
import org.apache.edgent.connectors.file.*;
import org.apache.edgent.providers.direct.DirectProvider;
import org.apache.edgent.topology.TStream;
import org.apache.edgent.topology.Topology;
/**
* Edgent Application template.
*/
public class TemplateApp {
public static void main(String[] args) throws Exception {
//Create a provider
DirectProvider dp = new DirectProvider();
//Create a topology
Topology top = dp.newTopology();
//Build the topology
String watchedDir = "/tmp/test/";
//Read file
TStream<String> pathnames =
FileStreams.directoryWatcher(top, () ->
watchedDir, null);
TStream<String> lines =
FileStreams.textFileReader(pathnames);
//Insert filter here
lines.print();
//Insert ‘send data to HTTP server’ here
//Submit the topology
dp.submit(top);
}
}
How do I fill the gap after “//Insert ‘send data to HTTP server’
here” to
be able to send the records to the second instance?
How does the HTTP part of the second instance have to look like to
be able
to receive these records?
Best regards,
Tom
