if you are going to integrate any system with ServiceNow, before proposing any solution try to ask few questions:
1. Is it really required to do so ? Don't we have any OOB product within ServiceNow which can be used as alternate solution? If yes, can't we migrate the data within ServiceNow and onboard/encourage the business users to use it?
If Now, questions are followed:
2. Do we have OOB features available which can be use easily to integrate the solutions? For ex: Integration hub, Devops change management, CMDB/discovery/event management using graph connector etc.
3. Will it be bi-directional ?
4. how much data flow ? will it be continuous data flow or based on user use basis?
5. Which product provided by ServiceNow can be full fill most of the requirement?
6. If you are using custom solution, is there any possibilities to increase the usage in upcoming year?
7. DO we need custom application to prevent the security or not?
8. Use ServiceNow coding standard to built the custom solution. For example: use import set mechanism to insert data in ServiceNow.
9. build the solution which can be easily extend in future and write the functions which can be re-utilized.
10. If you are building the financial portal integration then take extra pre-caution to handle the data security.
11. for automation try to implement Flow designer and create your own custom actions and spoke to use it. (if it is not available in SN).
12. Is it cost effective ? how much you can save by implementing the automation.
Challenges you may face like on authentication, handling the large amount of data flow, live data update etc.
There are more but for now i am recalling those points only.
These all are based on my experience and implementation.
