I have seen developers discussing different ways to integrate third party applications with Siebel. Hope this nicely elaborated article will help you understanding this better.
I have asked industry experts to share their ideas on to this and now publishing responses with you. More ideas are open. Lets discuss this and provide your expert suggestion in comment section.
Responses of industry expert:
Read what Joan Martí Peraire says about intgrating siebel with third party appication.
In order to integrate Siebel with external application, what I can share, from my own experience, is that there are two options that …

You might have heard about Batch Mode flag or noticed while working on workflow policies.

Why required?
1. New WF Policy and wants it to work as per the conditions specified for the policy.
2. Old Policy ,changes in condition

Steps:
1. Navigate to “Administration – Server Management -> Jobs” view
2. Click on New.
3. Component/Job = “Generate Triggers”
4. Now, in the Job Parameters applet, you need to provide the following four parameters:
 a) EXEC : TRUE
 b) Remove : FALSE
 c) Privileged User : “Database Table Owner Name”
 d) Privileged User Password : “Table Owner Password
5. Click on Start.
6. After few seconds, refresh the view (by clicking on “Execute Query” button), you will …

Today I faced a issue during the maintenance release. One of the application user told me that emails fro Siebel application has stopped working.
I looked into Email and found that Email was fired with the help of work flow policy.
Now I have two paths.
1. The condition of email firing was satisfied.
2. Email is stuck somewhere in between
Condition was ok, so jumped into the second option
S_ESCL_STATE ——– S_ESCL_REQ
First looked for S_ESCL_STATE to find the record , but as we set “Duration” was set to “0″ (Zero) so no issue of finding record …

Post is getting update.
sorry for inconvinence