Wording it that way makes it sound like webMethods is an end-point. It almost never is. It is the intermediary that facilitates interactions between 2 or more applications/systems. Based upon your most recent post, the integration is between NGA and SuccessFactors – facilitated by wM.
When we did SuccessFactors some time back, the interaction with them was file-based. They may have an HTTP-based interaction available now though. You’ll want to check on that.
You can use CloudStreams if you want (and have a license) for applications that expose an HTTP-based interface. It won’t help with file-based though. We have avoided CloudStreams in the past as it seemed to get in the way more than helped. We also avoid REST API Descriptors (RAD) and Web Service Descriptors (WSD) for the same reason. But certainly those tools can be helpful depending on your environment and team skill set.
The key is understanding the details of what the end-points expose – file exchange, DB table, message queue, XML over HTTP, JSON over HTTP, SOAP, REST, custom interface library (rare nowadays), etc. – and then which components within the wM IS environment can be used to interact with them.