> ## Documentation Index > Fetch the complete documentation index at: https://ai.easyaf.dev/llms.txt > Use this file to discover all available pages before exploring further. # AuthorizationServerMetadataClient > Discovers an RFC 8414 authorization server metadata document (or its OpenID Connect discovery document counterpart) over the handler-free `'OAuth'` named [Ht... ## Definition **Assembly:** Microsoft.OData.Mcp.Authentication.dll **Namespace:** Microsoft.OData.Mcp.Authentication.Outbound **Inheritance:** System.Object ## Syntax ```csharp theme={null} Microsoft.OData.Mcp.Authentication.Outbound.AuthorizationServerMetadataClient ``` ## Summary Discovers an RFC 8414 authorization server metadata document (or its OpenID Connect discovery document counterpart) over the handler-free `"OAuth"` named [HttpClient](https://learn.microsoft.com/dotnet/api/system.net.http.httpclient), probing the well-known candidates for a base URI in the order that prefers a Microsoft identity platform v2 document over its v1 counterpart. ## Remarks A new `"OAuth"` client is requested from [IHttpClientFactory](https://learn.microsoft.com/dotnet/api/system.net.http.ihttpclientfactory) on every call rather than cached, matching the "Two named HttpClients" table in `specs/v3/AUTHENTICATION.md`. Per `AUTH-14`, an Entra-style authorization server publishes both a v1 (OpenID Connect only) and a v2 (RFC 8414 and OpenID Connect) document at the same base URI; [Uri)](https://learn.microsoft.com/dotnet/api/microsoft.odata.mcp.authentication.outbound.authorizationservermetadataclient.candidatedocuments\(system.uri\)) orders the v2 candidates first so discovery never selects the v1 issuer when a v2 one is available. Response bodies are never logged. ## Examples ```csharp theme={null} var client = new AuthorizationServerMetadataClient(httpClientFactory, logger); var metadata = await client.DiscoverAsync(new Uri("https://login.microsoftonline.com/common"), cancellationToken); if (metadata is not null) { // metadata.TokenEndpoint is guaranteed non-null and absolute. } ``` ## Constructors ### .ctor Initializes a new instance of the [AuthorizationServerMetadataClient](https://ai.easyaf.dev/odata-mcp/api-reference/Microsoft/OData/Mcp/Authentication/Outbound/AuthorizationServerMetadataClient.md) class. #### Syntax ```csharp theme={null} public AuthorizationServerMetadataClient(System.Net.Http.IHttpClientFactory httpClientFactory, Microsoft.Extensions.Logging.ILogger logger) ``` #### Parameters | Name | Type | Description | | - | - | - | | `httpClientFactory` | `System.Net.Http.IHttpClientFactory` | The factory used to create the `"OAuth"` named client per call. | | `logger` | `Microsoft.Extensions.Logging.ILogger` | The logger this instance records non-fatal well-known outcomes and probe attempts to. | #### Exceptions | Exception | Description | | - | - | | `ArgumentNullException` | Thrown when *httpClientFactory* or *logger* is [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). | ### .ctor Inherited > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public Object() ``` ## Methods ### CandidateDocuments Builds the well-known authorization server metadata candidates for a base URI, in probe order. #### Syntax ```csharp theme={null} public static System.Collections.Generic.IReadOnlyList CandidateDocuments(System.Uri baseUri) ``` #### Parameters | Name | Type | Description | | - | - | - | | `baseUri` | `System.Uri` | The absolute authorization server base URI, such as an issuer or an authorization endpoint's origin and path. | #### Returns Type: `System.Collections.Generic.IReadOnlyList` Five candidates when *baseUri* carries a path beyond `/`: the versioned (v2) RFC 8414 document, the versioned OpenID Connect document, the unversioned RFC 8414 document, the RFC 8414 ยง3.1 path-prefixed document, and the unversioned OpenID Connect document, in that order. The path-prefixed candidate is omitted, leaving four candidates, when *baseUri* has no path beyond `/`. #### Exceptions | Exception | Description | | - | - | | `ArgumentNullException` | Thrown when *baseUri* is [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). | | `ArgumentException` | Thrown when *baseUri* is not an absolute URI. | #### Remarks A trailing `/` on *baseUri* is trimmed before any suffix is appended, so no candidate carries a doubled path separator. The versioned candidates are listed first so that an Entra-style authorization server, which publishes a v1 (OpenID Connect only) document at the unversioned base and a v2 (RFC 8414 and OpenID Connect) document under `/v2.0`, is discovered through its v2 issuer. ### DiscoverAsync Probes [Uri)](https://learn.microsoft.com/dotnet/api/microsoft.odata.mcp.authentication.outbound.authorizationservermetadataclient.candidatedocuments\(system.uri\)) in order and returns the first candidate that resolves to a usable metadata document. #### Syntax ```csharp theme={null} public System.Threading.Tasks.Task DiscoverAsync(System.Uri baseUri, System.Threading.CancellationToken cancellationToken) ``` #### Parameters | Name | Type | Description | | - | - | - | | `baseUri` | `System.Uri` | The absolute authorization server base URI to discover metadata for. | | `cancellationToken` | `System.Threading.CancellationToken` | The token that cancels the request. | #### Returns Type: `System.Threading.Tasks.Task` The first candidate's parsed document, or [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) when every candidate is non-fatally unusable (missing, unparseable, or lacking a `token_endpoint`). #### Exceptions | Exception | Description | | - | - | | `ArgumentNullException` | Thrown when *baseUri* is [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). | | `ArgumentException` | Thrown when *baseUri* is not an absolute URI. | | `OutboundDiscoveryException` | Thrown when a probe times out, fails at the transport, or returns a 5xx status, after one retry. | #### Examples ```csharp theme={null} var metadata = await client.DiscoverAsync(new Uri("https://login.microsoftonline.com/common"), cancellationToken); ``` #### Remarks Every probe is attempted over `http` only when its host is loopback; discovery stops at the first candidate with a `token_endpoint`, so a later candidate (such as the legacy v1 document) is never requested once an earlier one has already succeeded. ### Equals Inherited Virtual > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public virtual bool Equals(object obj) ``` #### Parameters | Name | Type | Description | | - | - | - | | `obj` | `object?` | - | #### Returns Type: `bool` ### Equals Inherited > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public static bool Equals(object objA, object objB) ``` #### Parameters | Name | Type | Description | | - | - | - | | `objA` | `object?` | - | | `objB` | `object?` | - | #### Returns Type: `bool` ### GetHashCode Inherited Virtual > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public virtual int GetHashCode() ``` #### Returns Type: `int` ### GetType Inherited > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public System.Type GetType() ``` #### Returns Type: `System.Type` ### MemberwiseClone Inherited > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} protected internal object MemberwiseClone() ``` #### Returns Type: `object` ### ReferenceEquals Inherited > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public static bool ReferenceEquals(object objA, object objB) ``` #### Parameters | Name | Type | Description | | - | - | - | | `objA` | `object?` | - | | `objB` | `object?` | - | #### Returns Type: `bool` ### ToString Inherited Virtual > [!NOTE] > > Inherited from `object` #### Syntax ```csharp theme={null} public virtual string ToString() ``` #### Returns Type: `string?` ### TryGetAsync Attempts to fetch and parse the authorization server metadata document at a well-known URL. #### Syntax ```csharp theme={null} public System.Threading.Tasks.Task TryGetAsync(System.Uri url, System.Threading.CancellationToken cancellationToken) ``` #### Parameters | Name | Type | Description | | - | - | - | | `url` | `System.Uri` | The absolute authorization server metadata URL. | | `cancellationToken` | `System.Threading.CancellationToken` | The token that cancels the request. | #### Returns Type: `System.Threading.Tasks.Task` The parsed document on a `200` response with a well-formed body carrying an absolute `token_endpoint`; otherwise [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) after a 401, 403, 404, unparseable body, a document without a usable `token_endpoint`, or any other non-retryable non-success status. #### Exceptions | Exception | Description | | - | - | | `ArgumentNullException` | Thrown when *url* is [`null`](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). | | `ArgumentException` | Thrown when *url* is not an absolute URI, or is an `http` URI whose host is not loopback. | | `OutboundDiscoveryException` | Thrown when the request times out, fails at the transport, or returns a 5xx status, after one retry. | #### Examples ```csharp theme={null} var metadata = await client.TryGetAsync(new Uri("https://login.microsoftonline.com/common/v2.0/.well-known/oauth-authorization-server"), cancellationToken); ``` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.