design - Schema extension for SCIM 2.0 -

we have identity provider user registry, , soap web service applications read/write user profiles. plan add scim interface well.

we find core user schema covers basic set of attributes, our existing system has different naming convention same attributes.

for example, usertelephonenumber, userstreetaddr1 , on.

considering large number of applications using naming convention, continue same scim 2.0.

given can extend core user schema,

1) can opt not using attributes core schema ? if payload includes these attributes, can ignore them on server side, , process custom schema attributes ?

an example user document -

    {         "schemas":    [ "urn:scim:schemas:core:2.0:user",                      urn:scim:schemas:extension:customattrs:2.0:user"],          "id": "2819c223-7f76-453a-919d-413861904646",          "urn:scim:schemas:extension:customattrs:2.0:user": {             "userfirstname": "fname",             "userlastname": "lname",          "usertelephonenumber": "1231231234      }     } 

2) can define new resource , define new core schema.

which of these options cleaner way ?

if don't plan use core schemas, why use scim @ all?

scim discourage having multiple attributes mean same thing.

i suggest create mapping between attributes , scim core (and enterprise extension) attributes. if there not map 2 schemas, should create extension.