There was also an "OpenID" specification. That tried to solve the same thing as **OpenID Connect**, but was not based on OAuth2.

So, it was a complete additional system.

It is not very popular or used nowadays.

## OpenAPI { #openapi }

OpenAPI (previously known as Swagger) is the open specification for building APIs (now part of the Linux Foundation).

   * specification.
   *
   * <p>This escaper substitutes {@code 0xFFFD} for non-whitespace control characters and the
   * character values {@code 0xFFFE} and {@code 0xFFFF} which are not permitted in XML. For more
   * detail see section <a href="http://www.w3.org/TR/2008/REC-xml-20081126/#charsets">2.2</a> of
   * the XML specification.
   *

        """
        The OAuth 2 specification doesn't define the challenge that should be used,
        because a `Bearer` token is not really the only option to authenticate.

        But declaring any other authentication challenge would be application-specific
        as it's not defined in the specification.

        For practical reasons, this method uses the `Bearer` challenge by default, as

/**
 * Base class for SMB Witness Protocol RPC messages as defined in MS-SWN specification.
 * This class extends DcerpcMessage to provide witness-specific RPC operations.
 */
public abstract class WitnessRpcMessage extends DcerpcMessage {

    // MS-SWN Witness Protocol Interface UUID and Version
    /** Witness Protocol Interface UUID from MS-SWN specification */

{* ../../docs_src/request_forms/tutorial001_an_py310.py hl[9] *}

For example, in one of the ways the OAuth2 specification can be used (called "password flow") it is required to send a `username` and `password` as form fields.

The <dfn title="specification">spec</dfn> requires the fields to be exactly named `username` and `password`, and to be sent as form fields, not JSON.

  @VisibleForTesting long refreshDuration;
  @VisibleForTesting @Nullable TimeUnit refreshTimeUnit;

  /** Specification; used for toParseableString(). */
  private final String specification;

  private CacheBuilderSpec(String specification) {
    this.specification = specification;
  }

  /**
   * Creates a CacheBuilderSpec from a string.
   *
   * @param cacheBuilderSpecification the string form

  @VisibleForTesting long refreshDuration;
  @VisibleForTesting @Nullable TimeUnit refreshTimeUnit;

  /** Specification; used for toParseableString(). */
  private final String specification;

  private CacheBuilderSpec(String specification) {
    this.specification = specification;
  }

  /**
   * Creates a CacheBuilderSpec from a string.
   *
   * @param cacheBuilderSpecification the string form

/// note | Technical details

In the OpenAPI specification it is called the [Operation Object](https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#operation-object).

///

It has all the information about the *path operation* and is used to generate the automatic documentation.

As you see, the method names now have the tag and then the function name, now they don't include information from the URL path and the HTTP operation.

### Preprocess the OpenAPI Specification for the Client Generator { #preprocess-the-openapi-specification-for-the-client-generator }

The generated code still has some **duplicated information**.

For optimal production setup MinIO recommends Linux kernel version 4.x and later.

## Erasure Code (Multiple Drives / Servers)

| Item                                                            | Specification |
|:----------------------------------------------------------------|:--------------|
| Maximum number of servers per cluster                           | no-limit      |