[AccessHeadersJava]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/AccessHeaders.java
 [AccessHeadersKotlin]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/kt/AccessHeaders.kt
 [PostStringJava]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PostString.java

---

But for this example, we'll use a very simple HTML document with some JavaScript, all inside a long string.

This, of course, is not optimal and you wouldn't use it for production.

In production you would have one of the options above.

But it's the simplest way to focus on the server-side of WebSockets and have a working example:

```Python hl_lines="2  6-38  41-43"

state of the world. It is regenerated (usually partially) on each configuration push (more on this below). Due to being a snapshot, most lookups are lock-free.

`PushContext` is built up by querying the above layers. For some simple use cases, this is as simple as storing something like `configstore.List(SomeType)`; in this case, the only difference from directly exposing the configstore is to snapshot the current state. In other cases, some pre-computations and indexes are computed to make...

* `allow_origins` - A list of origins that should be permitted to make cross-origin requests. E.g. `['https://example.org', 'https://www.example.org']`. You can use `['*']` to allow any origin.
* `allow_origin_regex` - A regex string to match against origins that should be permitted to make cross-origin requests. e.g. `'https://.*\.example\.org'`.

For example, there's an official <a href="https://hub.docker.com/_/python" class="external-link" target="_blank">Python Image</a>.

And there are many other images for different things like databases, for example for:

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>

* Share database connections.
* Enforce security, authentication, role requirements, etc.
* And many other things...

All these, while minimizing code repetition.

## First Steps

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable"

Let's first focus on the dependency.

Interceptors
============

Interceptors are a powerful mechanism that can monitor, rewrite, and retry calls. Here's a simple interceptor that logs the outgoing request and the incoming response.

```java
class LoggingInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
    Request request = chain.request();

    long t1 = System.nanoTime();

Now, let's imagine your organization gave you the `app/internal/admin.py` file.

It contains an `APIRouter` with some admin *path operations* that your organization shares between several projects.

For this example it will be super simple. But let's say that because it is shared with other projects in the organization, we cannot modify it and add a `prefix`, `dependencies`, `tags`, etc. directly to the `APIRouter`:

This release also contains a number of bug fixes to the feature set. Aspiring plugin authors can look at [sample-exec-plugin](https://github.com/ankeesler/sample-exec-plugin) as a way to get started.

                List.of("                           apple, banana, pear"));
        p2.put("trees", "fir, oak, maple");
        p1.update(p2);

        assertEquals(2, (Object) p1.size());
        Object o23 = p1.getComments("trees");
        assertEquals(List.of("#", "# List of trees", "#"), o23);
        Object o22 = p1.getProperty("trees");
        assertEquals("fir, oak, maple", o22);
        Object o21 = p1.getComments("fruits");