system.net.httpClient() causes java.io.IOException while system.net.httpGet() works fine

[msella]

I am currently able to pull in data from the JIRA REST API using system.net.httpGet(), but when I try the same request with system.net.httpClient().get() I receive a java.io.IOException GOAWAY.

# Working request
url = "URL"
headers = {"Accept": "application/json"}
contentType = "application/json"
username = "USER"
password = “API_KEY”
response = system.net.httpGet(url = url, contentType = contentType, headerValues = headers, username = username, password = password)

# Broken request
url = "URL"
headers = {"Accept": "application/json"}
username = "USER"
password = “API_KEY”
response = system.net.httpClient().get(url = url, headers = headers, username = username, password = password)

I have checked for header differences between the two calls and found none. I also tried changing the redirect_policy which led to no improvement. Is there a difference with how the Java 11 HttpClient makes the connection with the API server that differs from the old system.net.httpGet() that might lead to this issue?

Note: This is on 8.0.17.

[PGriffith]

httpClient is using HTTP/2, which the target server is apparently not accepting and apparently not negotiating correctly. Unfortunately, the solution (telling HttpClient to only use HTTP/1) is not currently viable due to a bug:

[BUG-16787] system.net.httpClient() HttpClient.Version customizer

I need to set my http clients version, similar to: HttpClient.newBuilder() .version(Version.HTTP_1_1) so I defined a customizer function to set it, but I cannot for the life of me figure out what I need to import or define so that I can specify the version parameter needed in the .version method. Here is my callable, but I just cant seem to figure it out. def clientCustomizer(client): return client.version(HttpClient.Version.versionOf("HTTP_1_1")) If anyone has any ideas they are great…

Until that bug is fixed, you'll likely have to keep using httpGet.

[msella]

Thank you for the explanation - I’ll be looking out for an update in the future. In the meantime, is there a compatible library I could use to execute a “multipart/form-data” POST with? It’s the reason why I wanted to try using system.net.httpClient() in the first place. I don’t believe system.net.httpPost() will work.

[PGriffith]

Actually, httpClient doesn't do you any favors with multipart/form-data at present either (). I've seen customers use requests in Ignition directly; you can access pip to install it more easily using the method outlined here:

Procedure for installing python libraries from source

There’s actually a procedure you can use to use pip from within Jython to install packages, then link Ignition’s Jython lib to an-off-the-shelf Jython lib and use that…however, the article specifically calls out the twilio module as not working, because one of its dependencies, cffi, has C dependencies (IE, won’t work in Jython). For posterity, here’s the procedure, copied verbatim from an internal document: 0) On the server, install Java 8 if you haven’t already. Download the full Jython 2.…

[richardNZ15]

Hi @PGriffith is that [BUG-16787] still not fixed?
I’m on 8.1.17 and trying to use httpClient.post and i think i am running into the same problem in this thread.

This works:

resp = system.net.httpPost(url=postUrl, contentType="application/json", postData=payload, username="REDACTED", password="REDACTED", throwOnError=False)

This doesn’t:

client = system.net.httpClient()
response = client.post(url=postUrl, data=payload, username="REDACTED", password="REDACTED")

I get the following error:

com.inductiveautomation.ignition.common.script.JythonExecException
Traceback (most recent call last):
  File "<function:runAction>", line 81, in runAction
  File "<function:runAction>", line 67, in testSendMsg3
java.util.concurrent.ExecutionException: java.util.concurrent.ExecutionException: java.io.IOException: Can't get stream 1: java.io.EOFException: EOF reached while reading

	caused by org.python.core.PyException
Traceback (most recent call last):
  File "<function:runAction>", line 81, in runAction
  File "<function:runAction>", line 67, in testSendMsg3
java.util.concurrent.ExecutionException: java.util.concurrent.ExecutionException: java.io.IOException: Can't get stream 1: java.io.EOFException: EOF reached while reading

	caused by ExecutionException: java.io.IOException: Can't get stream 1: java.io.EOFException: EOF reached while reading
	caused by IOException: Can't get stream 1: java.io.EOFException: EOF reached while reading
	caused by EOFException: EOF reached while reading

Ignition v8.1.13 (b2021122109)
Java: Azul Systems, Inc. 11.0.13

[Kevin.Herron]

Your error message says you’re on 8.1.13.

Since 8.1.16 there is a version parameter you can set when using system.net.httpClient: system.net.httpClient - Ignition User Manual 8.1 - Ignition Documentation (inductiveautomation.com)

[richardNZ15]

Thanks Kevin,

My bad, i forgot what gateway i was testing this on. There are 5 gateways on this project and i updated all of them (except this one) to 8.1.17 recently.
I’ll try update it and see how we go with that new version option.
Cheers

Edit: Yep that worked fine forcing version to “HTTP_1_1”. Cheers