How would you build a custom solution based on the following requirements?

[Fabrizio Lamari]

Environment:

• SharePoint 2013/2016 on-premise environment

Requirements:

• Custom List form which needs to retrieve information based on filled inputs during edit > not after saving
• The information needs to be retrieved via Web Services from other internal applications > the authentication against the already present Web Services happens via Certificate Authentication and cannot be done client side
• Only users that have already access to the SharePoint site where the list with the custom form resides should have access to the functions to call the web services via custom form

My approach would be to create a custom Site or Application Page with code behind with WebMehtods that can be executed client side via JSOM.

Is this still the way to go or are there other more modern approach to implement such solutions?

I'm aware of the client-side solutions that can be build but we're not able to call the present web services from client-side and we don't want to build new web services that themselves calls the present one because doing thins we'll need to implement a whole new solutions which handels authentication too.

Thank you for your answers already in advance. I'm excited about your feedback ;)

Kind regards,

Fabrizio

[#2]

Then JSOM is not an option here....did you mean CSOM? If the backend part cannot be changed, I think you have two options here:
(1) Create a Full-Trust solution
(2) Create a Provider-Hosted Add-in

[#3]

Hi Juan Carlos,

Thank you for your reply.

I thought to follow the approach mentioned under the following two guides:

• WebMethods in SharePoint using JQuery
• How to call Server Side Method from jQuery/javascript using Ajax & JSON Parsing

These approaches are using JavaScript client-side (therefore I thought about JSOM = JavaScript Client Object Model) to call the server-side "WebMethods".

Do you think this is the right approach?

Kind regards,

Fabrizio