Enum ClientRegistration 

pub enum ClientRegistration {
    None,
    Dynamic,
    DynamicOrMetadataDocument,
    MetadataDocument,
}

How a client is expected to register with an authorization server.

Not a bitmask because the three states are a progression, not a set: a client that treats 2026-07-28 as “both work” would send a Dynamic Client Registration request to a server that has been told to deprecate it, and a server that rejects it looks like a broken server rather than a wrong client.

Variants

None

The revision specifies no authorization framework at all.

2024-11-05. Its vendored changelog has no authorization entry, so a client that registers against an OAuth server is doing something the revision never asked for.

Dynamic

RFC 7591 Dynamic Client Registration.

2025-03-26 and 2025-06-18. The framework was introduced here (2025-03-26 changelog §1, PR #133) with no alternative registration mechanism named, so this is what those revisions’ servers implement.

DynamicOrMetadataDocument

Both, with Client ID Metadata Documents recommended.

2025-11-25 changelog §8 (SEP-991, PR #1296) adds Client ID Metadata Documents as a recommended registration mechanism and does not deprecate Dynamic Client Registration, so a client may use either. Prefer Self::preferred over “either” when choosing.

MetadataDocument

Client ID Metadata Documents; Dynamic Client Registration deprecated.

2026-07-28 changelog §4 (PR #2858) deprecates RFC 7591 “in favor of” Client ID Metadata Documents, keeping it only “for backwards compatibility with authorization servers that do not support” them. So this is a preference with a fallback, not a removal — see Self::supports_dynamic.

Implementations

impl ClientRegistration

pub const fn supports_dynamic(self) -> bool

Whether a client may register through RFC 7591.

true even for Self::MetadataDocument: the deprecation is a statement about what the spec prefers, and the spec keeps the mechanism for servers that do not implement the replacement. A client that refused outright would fail against those servers, and a server that implements only RFC 7591 is not misconfigured.

pub const fn supports_metadata_document(self) -> bool

Whether a client may register with a Client ID Metadata Document.

pub const fn preferred(self) -> Option<Self>

The mechanism to try first.

Metadata documents wherever they exist, because a client that leads with the mechanism its own revision deprecates is doing the wrong thing against a server that supports both. Falls back to dynamic registration only where documents are not defined, so this never returns Self::None for a revision that can register at all.

pub const fn fallback(self) -> Option<Self>

What to try after self did not work, or None at the end of the list.

The second half of Self::preferred: a client has to be able to fall back, and Self::MetadataDocument is precisely the revision whose servers may still implement only RFC 7591.

pub const fn application_type_required(self) -> bool

Whether application_type must be sent during registration.

2026-07-28 changelog §8 (SEP-837): clients “MUST specify an appropriate application_type during Dynamic Client Registration to avoid OpenID Connect redirect URI conflicts”. A MUST, so this is about revisions that require the field, not about ones that tolerate it.

Trait Implementations

impl Clone for ClientRegistration

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ClientRegistration

impl Debug for ClientRegistration

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ClientRegistration

fn default() -> Self

Returns the “default value” for a type.

impl Eq for ClientRegistration

impl Hash for ClientRegistration

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for ClientRegistration

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for ClientRegistration

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for ClientRegistration

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for ClientRegistration