Hi All, I am exposing my process model as a service.I am able to call

Callback URL is another way to say "a mechanism to communicate back to the calling application".

1. So what kind of an application is going to call your process model (which you have exposed as a web service)?
2. Does the calling application have capability to receive an HTTP call?

In other words, you are building them a web service to start an appian process. If they need updates back to them, you need to establish a mechanism of communication. The easiest is for them to create an http service and give you the endpoint. From there, you would use the http smart node to communicate back to them. If they can't build an http call but insist on having updates on the web service call they made, then there are a number of things you can do.

Tell me more about what you are doing and the capability of the calling application and then I can help you to come up with a solution.

Callback URL is another way to say "a mechanism to communicate back to the calling application".

1. So what kind of an application is going to call your process model (which you have exposed as a web service)?
2. Does the calling application have capability to receive an HTTP call?

In other words, you are building them a web service to start an appian process. If they need updates back to them, you need to establish a mechanism of communication. The easiest is for them to create an http service and give you the endpoint. From there, you would use the http smart node to communicate back to them. If they can't build an http call but insist on having updates on the web service call they made, then there are a number of things you can do.

Tell me more about what you are doing and the capability of the calling application and then I can help you to come up with a solution.