The way to describe this in OpenAPI, is to mark that field as **required**, because it will always be there.

Because of that, the JSON Schema for a model can be different depending on if it's used for **input or output**:

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

<img src="/img/tutorial/websockets/image02.png">

And your **FastAPI** application with WebSockets will respond back:

<img src="/img/tutorial/websockets/image03.png">

You can send (and receive) many messages:

<img src="/img/tutorial/websockets/image04.png">

And all of them will use the same WebSocket connection.

## Using `Depends` and others { #using-depends-and-others }

## Conflict Resolution

Conflicts in an open source project can take many forms, from someone having a bad day and using harsh and hurtful language in the issue queue, to more serious instances such as sexist/racist statements or threats of violence, and everything in between.

 * **RealConnection** is the socket and streams of an HTTP/1 or HTTP/2 connection. These are created on demand to fulfill HTTP requests. They may be reused for many HTTP request/response exchanges. Their lifetime is typically shorter than a connection pool.

 * **Exchange** carries a single HTTP request/response pair.

#!/bin/sh

#
# Copyright © 2015 the original authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

    /**
     * Check if cache needs refresh
     *
     * @return true if refresh needed
     */
    public boolean needsRefresh() {
        return isExpired() || hasChanges;
    }

    /**
     * Mark the cache as complete (full enumeration cached)
     */
    public void markComplete() {
        lock.writeLock().lock();
        try {
            this.isComplete = true;
            this.hasChanges = false;

  /**
   * @throws IllegalArgumentException if another entry in the bucket has the same key
   * @throws BucketOverflowException if this bucket has too many entries, which may indicate a hash
   *     flooding attack
   */
  private static void checkNoConflictInValueBucket(
      Object value, Entry<?, ?> entry, @Nullable ImmutableMapEntry<?, ?> valueBucketHead)

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