#
# Although Istio proxies are able to automatically send spans, they need some
# hints to tie together the entire trace. Applications need to propagate the
# appropriate HTTP headers so that when the proxies send span information, the
# spans can be correlated correctly into a single trace.
#
# To do this, an application needs to collect and propagate headers from the
# incoming request to any outgoing requests. The choice of headers to propagate

            rootAttributes.put("xsi:schemaLocation", "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/application_" + version + ".xsd");
        } else if ("7".equals(version) || "8".equals(version)) {
            rootAttributes.put("xsi:schemaLocation", "http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/application_" + version + ".xsd");
        } else if ("9".equals(version) || "10".equals(version)) {

[[sec:building_swift_applications]]
== Building Swift applications

See the <<swift_application_plugin.adoc#swift_application_plugin,Swift Application Plugin>> chapter for more details, but here’s a quick summary of what you get:

 * `install` create a directory containing everything needed to run it
 * Shell and Windows Batch scripts to start the application

```Python hl_lines="9"
{!../../../docs_src/behind_a_proxy/tutorial004.py!}
```

and then it won't include it in the OpenAPI schema.

## Mounting a sub-application

If you need to mount a sub-application (as described in [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}) while also using a proxy with `root_path`, you can do it normally, as you would expect.

[[sec:building_cpp_applications]]
== Building {cpp} applications

See the <<cpp_application_plugin.adoc#cpp_application_plugin,{cpp} Application Plugin>> chapter for more details, but here’s a quick summary of what you get:

 * `install` create a directory containing everything needed to run it
 * Shell and Windows Batch scripts to start the application

COPY ./requirements.txt /app/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt

COPY ./app /app
```

### Bigger Applications

If you followed the section about creating [Bigger Applications with Multiple Files](../tutorial/bigger-applications.md){.internal-link target=_blank}, your `Dockerfile` might instead look like:

```Dockerfile hl_lines="7"
FROM tiangolo/uvicorn-gunicorn-fastapi:python3.9

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                for (SwiftApplication application : p.getComponents().withType(SwiftApplication.class)) {
                    DefaultTarget target = new DefaultTarget(application.getModule().get(), p.getProjectDir(), application.getSwiftSource());
                    swiftLanguageVersion = max(swiftLanguageVersion, application.getSourceCompatibility().getOrNull());

The client will get a **500 Internal Server Error** for that request, but the application will continue working for the next requests instead of just crashing completely.

### Bigger Errors - Crashes

Nevertheless, there might be cases where we write some code that **crashes the entire application** making Uvicorn and Python crash. 💥

                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {