[#1]

The information in this article applies to:

Product: Metastorm BPM
Version: 9.x

Issue

• What protocols does Metastorm BPM use for communication?

Resolution

• Metastorm BPM's native web client connects to a Metastorm service using Metastorm's internal ECL. This can use either TCP or HTTP and is implemented via .NET remoting, rather than WCF. TCP uses port 4001; for example, tcp://machinename:4001/ECL.
  
  Note that direct programming access against the internal ECL is unsupported for 3rd party clients. They should use the SDK/ECL.WS when communicating with the MBPM engine. This uses standard WCF protocols that allow support for transport/message level security and also allow Metastorm BPM to support Windows Single Sign-On (SSO) and non-SSO environments.

[#2]

Can you provide any recommenation as to why we should (or shouldn't) use tcp instead of http?

[#3]

The TCP protocol in this case provides better performance for a small system, but at the point you are needing to handle greater volumes of user and user requests you should be looking at the HTTP protocol. If you want to secure the channel between the Web Server and Engine you would need to use HTTPS. You can't accomplish the equivalent with the TCP protocol.

More information can be found in the Administration Guide

[#4]

Adding to what Todd said, HTTP protocol is required if you are targeting a Single Sign On configuration. Generally, TCP is higher performance but only for a small number of users and only when not using SSO. HTTP is more scalable and required if you are using SSO (regardless of the number of users).