Misc : Microsoft Open Specifications

Microsoft publishes a list of open specifications that enable inter-operability over here.

These include a number of specifications that describe ADFS and WAP (Web Application Proxy).

These include:

• [MS-ADFSPIP]: Active Directory Federation Services and Proxy Integration Protocol
• [MS-ADFSOAL]: Active Directory Federation Services OAuth Authorization Code Lookup Protocol
• [MS-ADFSPP]: Active Directory Federation Service (AD FS) Proxy Protocol  
• [MS-ADFSWAP]: Active Directory Federation Service (AD FS) Web Agent Protocol

The MS-ADFSPIP document describes the interface between ADFS and WAP.

There are tons of questions on the forum around "Do I have to use WAP as the proxy. Can I use any reverse proxy or a load balancer or F5 or Netscaler etc. ?"

You can as long as the proxy you want to use implements the standards.

Good luck with getting your vendor to confirm that they do and to demonstrate this fact.

In addition, your vendor may also need to comply with the rules around

[MS-OFBA]: Office Forms Based Authentication Protocol

if e.g. the request is 

• from a Microsoft Office application that relies on the Office Forms Based Authentication (OFBA) Protocol
• from non-Microsoft-Office clients accessing services that implement the OFBA protocol [MS-OFBA] that rely on ADFS for authentication

It also needs to ensure that the correct claims are set e.g.

http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork

which is "True" is accessing ADFS directly or "False" if accessing via WAP.

My advice : Just use the WAP - much less stressful - :-).

Enjoy!