chore(middleware-flexible-checksums): add RequestChecksumCalculation and ResponseChecksumValidation

Author: trivikr

packages/middleware-flexible-checksums/src/constants.ts

@@ -1,3 +1,45 @@
+/**
+ * Determines when a checksum will be calculated for request payloads.
+ */
+export enum RequestChecksumCalculation {
+  /**
+   * When set, a checksum will be calculated for all request payloads of operations
+   * modeled with the {@link httpChecksum} trait where `requestChecksumRequired` is `true`
+   * AND/OR a `requestAlgorithmMember` is modeled.
+   * {@link https://smithy.io/2.0/aws/aws-core.html#aws-protocols-httpchecksum-trait httpChecksum}
+   */
+  WHEN_SUPPORTED = "WHEN_SUPPORTED",
+
+  /**
+   * When set, a checksum will only be calculated for request payloads of operations
+   * modeled with the {@link httpChecksum} trait where `requestChecksumRequired` is `true`
+   * OR where a `requestAlgorithmMember` is modeled and the user sets it.
+   * {@link https://smithy.io/2.0/aws/aws-core.html#aws-protocols-httpchecksum-trait httpChecksum}
+   */
+  WHEN_REQUIRED = "WHEN_REQUIRED",
+}
+
+/**
+ * Determines when checksum validation will be performed on response payloads.
+ */
+export enum ResponseChecksumValidation {
+  /**
+   * When set, checksum validation MUST be performed on all response payloads of operations
+   * modeled with the {@link httpChecksum} trait where `responseAlgorithms` is modeled,
+   * except when no modeled checksum algorithms are supported by an SDK.
+   * {@link https://smithy.io/2.0/aws/aws-core.html#aws-protocols-httpchecksum-trait httpChecksum}
+   */
+  WHEN_SUPPORTED = "WHEN_SUPPORTED",
+
+  /**
+   * When set, checksum validation MUST NOT be performed on response payloads of operations UNLESS
+   * the SDK supports the modeled checksum algorithms AND the user has set the `requestValidationModeMember` to `ENABLED`.
+   * It is currently impossible to model an operation as requiring a response checksum,
+   * but this setting leaves the door open for future updates.
+   */
+  WHEN_REQUIRED = "WHEN_REQUIRED",
+}
+
 /**
  * Checksum Algorithms supported by the SDK.
  */