Github user kevdoran commented on a diff in the pull request:
https://github.com/apache/nifi-minifi-cpp/pull/114#discussion_r127531375
--- Diff: libminifi/src/RemoteProcessorGroupPort.cpp ---
@@ -150,6 +194,87 @@ void
RemoteProcessorGroupPort::onTrigger(core::ProcessContext *context, core::Pr
return;
}
+void RemoteProcessorGroupPort::refreshRemoteSite2SiteInfo() {
+ if (this->host_.empty() || this->port_ == -1 || this->protocol_.empty())
+ return;
+
+ std::string fullUrl = this->protocol_ + this->host_ + ":" +
std::to_string(this->port_) + "/nifi-api/controller/";
--- End diff --
I looked into it further and found out that `/controller` is a NiFi 0.x
endpoint. The `/site-to-site` endpoint was introduced in NiFi 1.x, and NiFi 1.x
maps `/controller` to `/site-to-site` so that NiFi 0.x instances can
communicate with NiFI 1.x instances.
I wasn't sure what minifi-cpp should do. `/controller` currently works for
both major versions of NiFi, but there is no guarantee it will forever, and
`/controller` is not documented in the 1.x REST API, making the intended
behavior of this client code a little less obvious/discoverable for future
developers (it was not obvious to me just from the API documentation). The
`/site-to-site` endpoint is documented, but would not be available on 0.x NiFi
instances.
I decided to look at the minifi-java implementation. It uses the
site-to-site client module from NiFi, which has this behavior: It tries
`/site-to-site` first, and if it gets a 404 (resource not found) error, then it
falls back to `/controller`. From
[SiteToSiteRestAPiClient](https://github.com/apache/nifi/blob/master/nifi-commons/nifi-site-to-site-client/src/main/java/org/apache/nifi/remote/util/SiteToSiteRestApiClient.java):
```java
private ControllerDTO getController() throws IOException {
try {
HttpGet get = this.createGetControllerRequest();
return ((ControllerEntity)this.execute(get,
ControllerEntity.class)).getController();
} catch (SiteToSiteRestApiClient.HttpGetFailedException var3) {
if(404 == var3.getResponseCode()) {
logger.debug("getController received NOT_FOUND, trying to
access the old NiFi version resource url...");
HttpGet get = this.createGet("/controller");
return ((ControllerEntity)this.execute(get,
ControllerEntity.class)).getController();
} else {
throw var3;
}
}
}
private HttpGet createGetControllerRequest() {
HttpGet get = this.createGet("/site-to-site");
get.setHeader("x-nifi-site-to-site-protocol-version",
String.valueOf(this.transportProtocolVersionNegotiator.getVersion()));
return get;
}
```
That seems like a reasonable approach for minifi-cpp as well. I'm
interested in hearing thoughts from others. @apiri - should we try to keep
compatibility with 0.x NiFi's in this implementation? If not, we could just go
with `/site-to-site` in this implementation.
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