## Una aplicación con callbacks { #an-app-with-callbacks }

Veamos todo esto con un ejemplo.

Imagina que desarrollas una aplicación que permite crear facturas.

Estas facturas tendrán un `id`, `title` (opcional), `customer` y `total`.

El usuario de tu API (un desarrollador externo) creará una factura en tu API con un request POST.

Luego tu API (imaginemos):

* Enviará la factura a algún cliente del desarrollador externo.

        final CreateForm form = new CreateForm();
        form.doc = new HashMap<>();
        form.doc.put("url", "https://example.com");
        form.doc.put("title", "Test");
        form.doc.put("custom_metadata", "custom value");
        form.doc.put("department", "Engineering");

        final java.lang.reflect.Field currentFormField = AdminSearchlistAction.class.getDeclaredField("currentForm");
        currentFormField.setAccessible(true);

        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }

        // Lifecycles cannot be cached as extensions might add custom lifecycles later in the execution.
        try {
            return registry != null
                    ? registry.stream().collect(Collectors.toMap(lf -> lf.id(), lf -> new Lifecycle(registry, lf)))

/**
 * Copies the Rest YAML test to the current projects test resources output directory.
 * This is intended to be be used from {@link RestResourcesPlugin} since the plugin wires up the needed
 * configurations and custom extensions.
 *
 * @see RestResourcesPlugin
 */
public class CopyRestTestsTask extends DefaultTask {
    private static final String REST_TEST_PREFIX = "rest-api-spec/test";

// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the [Scanner.Buffer]. When a scan stops, the reader may have

It used custom types in its declarations instead of standard Python types, but it was still a huge step forward.

It also was one of the first frameworks to generate a custom schema declaring the whole API in JSON.

nindent 10 }} {{- end }} resources: {{ toYaml .Values.makeUserJob.resources | indent 10 }} {{- end }} minio/templates/post-install-custom-command.yaml {{- if .Values.customCommands }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-custom-command-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-custom-command-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook":...

.Values.configPathmc }}certs {{ end }} resources: {{ toYaml .Values.makeUserJob.resources | indent 10 }} {{- end }} minio/templates/post-install-custom-command.yaml {{- if .Values.customCommands }} apiVersion: batch/v1 kind: Job metadata: name: {{ template "minio.fullname" . }}-custom-command-job namespace: {{ .Release.Namespace | quote }} labels: app: {{ template "minio.name" . }}-custom-command-job chart: {{ template "minio.chart" . }} release: {{ .Release.Name }} heritage: {{ .Release.Service }} annotations: "helm.sh/hook":...

        return ComponentUtil.getSearchEngineClient().update(ComponentUtil.getFessConfig().getIndexDocumentUpdateIndex(), id, field, value);
    }

    /**
     * Updates a document using a custom update request builder.
     *
     * @param id The document ID to update
     * @param builderLambda Consumer function to configure the update request builder
     * @return true if the update was successful, false otherwise

     * @param manager the persistent handle manager
     */
    public HandleReconnector(PersistentHandleManager manager) {
        this(manager, 3, 1000);
    }

    /**
     * Create a new handle reconnector with custom settings
     * @param manager the persistent handle manager
     * @param maxRetries maximum number of retry attempts
     * @param retryDelay base retry delay in milliseconds
     */