diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/NshmpMicronautServlet.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/NshmpMicronautServlet.java
new file mode 100644
index 0000000000000000000000000000000000000000..8178878370a40c0ec5123b855882b4923b577848
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/NshmpMicronautServlet.java
@@ -0,0 +1,51 @@
+package gov.usgs.earthquake.nshmp.internal.www;
+
+import org.reactivestreams.Publisher;
+
+import io.micronaut.core.type.MutableHeaders;
+import io.micronaut.http.HttpRequest;
+import io.micronaut.http.MutableHttpResponse;
+import io.micronaut.http.annotation.Filter;
+import io.micronaut.http.filter.HttpServerFilter;
+import io.micronaut.http.filter.ServerFilterChain;
+import io.reactivex.rxjava3.core.Flowable;
+import io.reactivex.rxjava3.schedulers.Schedulers;
+
+/**
+ * Custom NSHMP servlet implementation and URL helper class for Micronaut
+ * services.
+ *
+ * <p>This class sets custom response headers and provides a helper class to
+ * ensure serialized response URLs propagate the correct host and protocol from
+ * requests on USGS servers and caches that may have been forwarded.
+ *
+ * @author U.S. Geological Survey
+ */
+@Filter("/**")
+public class NshmpMicronautServlet implements HttpServerFilter {
+
+ /*
+ * Set CORS headers and content type.
+ *
+ * Because NSHMP services may be called by both the USGS website, other
+ * websites, and directly by 3rd party applications, responses generated by
+ * direct requests will not have the necessary header information that would
+ * be required by security protocols for web requests. This means that any
+ * initial direct request will pollute intermediate caches with a response
+ * that a browser will deem invalid.
+ */
+ @Override
+ public Publisher<MutableHttpResponse<?>> doFilter(
+ HttpRequest<?> request,
+ ServerFilterChain chain) {
+ return Flowable.just(chain).subscribeOn(Schedulers.io())
+ .switchMap(bool -> chain.proceed(request))
+ .doOnNext(res -> {
+ MutableHeaders headers = res.getHeaders();
+ headers.add("Access-Control-Allow-Origin", "*");
+ headers.add("Access-Control-Allow-Methods", "*");
+ headers.add("Access-Control-Allow-Headers", "*");
+ });
+ }
+
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseBody.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseBody.java
new file mode 100644
index 0000000000000000000000000000000000000000..650056c312352c118178816cca2e9d92bbcca6bc
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseBody.java
@@ -0,0 +1,213 @@
+package gov.usgs.earthquake.nshmp.internal.www;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.time.ZonedDateTime;
+
+import gov.usgs.earthquake.nshmp.internal.www.meta.Status;
+
+/**
+ * Generic wrapper around a web service response object that is typically
+ * serialized to JSON and sent back to requestor as an HttpResponse 'body'.
+ *
+ * <p>To create a response, use one of the three static builder methods:
+ * {@link Builder#error()}, {@link Builder#success()}, or
+ * {@link Builder#usage()}.
+ *
+ * @author U.S. Geological Survey
+ *
+ * @param <T> The request type
+ * @param <V> The response type
+ */
+public class ResponseBody<T, V> {
+
+ private final String name;
+ private final String date;
+ private final String status;
+ private final String url;
+ private final T request;
+ private final V response;
+ private final ResponseMetadata metadata;
+
+ private ResponseBody(Builder<T, V> builder) {
+ name = builder.name;
+ date = ZonedDateTime.now().format(WsUtils.DATE_FMT);
+ status = builder.status;
+ url = builder.url;
+ request = builder.request;
+ response = builder.response;
+ metadata = builder.metadata;
+ }
+
+ protected ResponseBody() {
+ date = null;
+ metadata = null;
+ name = null;
+ request = null;
+ response = null;
+ status = null;
+ url = null;
+ }
+
+ /**
+ * The date and time this request/response.
+ */
+ public String getDate() {
+ return date;
+ }
+
+ /**
+ * The metadata.
+ */
+ public ResponseMetadata getMetadata() {
+ return metadata;
+ }
+
+ /**
+ * The name of the service.
+ */
+ public String getName() {
+ return name;
+ }
+
+ /**
+ * The request object.
+ */
+ public T getRequest() {
+ return request;
+ }
+
+ /**
+ * The response object.
+ */
+ public V getResponse() {
+ return response;
+ }
+
+ /**
+ * The response status.
+ */
+ public String getStatus() {
+ return status;
+ }
+
+ /**
+ * The URL used to call the service
+ */
+ public String getUrl() {
+ return url;
+ }
+
+ /**
+ * Create a new builder initialized to an error response.
+ *
+ * @param <T> The request type
+ * @param <V> The response type
+ */
+ public static <T, V> Builder<T, V> error() {
+ return new Builder<T, V>(Status.ERROR);
+ }
+
+ /**
+ * Create a new builder initialized to a success response.
+ *
+ * @param <T> The request type
+ * @param <V> The response type
+ */
+ public static <T, V> Builder<T, V> success() {
+ return new Builder<T, V>(Status.SUCCESS);
+ }
+
+ /**
+ * Create a new builder initialized to a usage response.
+ *
+ * @param <T> The request type
+ * @param <V> The response type
+ */
+ public static <T, V> Builder<T, V> usage() {
+ return new Builder<T, V>(Status.USAGE);
+ }
+
+ /**
+ * A {@code ResponseBody} builder.
+ *
+ * @param <T> The request type
+ * @param <V> The response type
+ */
+ public static class Builder<T, V> {
+
+ private String name;
+ private String status;
+ private String url;
+ private ResponseMetadata metadata;
+ private T request;
+ private V response;
+
+ private Builder(String status) {
+ this.status = status;
+ }
+
+ /**
+ * Set the metadata.
+ *
+ * @param metadata The servie metadata
+ */
+ public Builder<T, V> metadata(ResponseMetadata metadata) {
+ this.metadata = metadata;
+ return this;
+ }
+
+ /**
+ * Set the service name.
+ *
+ * @param name of the service being called
+ */
+ public Builder<T, V> name(String name) {
+ this.name = name;
+ return this;
+ }
+
+ /**
+ * Set the request object.
+ *
+ * @param request object
+ */
+ public Builder<T, V> request(T request) {
+ this.request = request;
+ return this;
+ }
+
+ /**
+ * Set the response object.
+ *
+ * @param response object
+ */
+ public Builder<T, V> response(V response) {
+ this.response = response;
+ return this;
+ }
+
+ /**
+ * Set the url used to call the service.
+ *
+ * @param url used to generate this response
+ */
+ public Builder<T, V> url(String url) {
+ this.url = url;
+ return this;
+ }
+
+ /**
+ * Returns a new Response
+ */
+ public ResponseBody<T, V> build() {
+ checkNotNull(metadata);
+ checkNotNull(name);
+ checkNotNull(request);
+ checkNotNull(response);
+ checkNotNull(url);
+ checkNotNull(status);
+ return new ResponseBody<T, V>(this);
+ }
+ }
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseMetadata.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseMetadata.java
new file mode 100644
index 0000000000000000000000000000000000000000..f526c118c7ebf0cc301e9ef66c1d285c7bedf188
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/ResponseMetadata.java
@@ -0,0 +1,18 @@
+package gov.usgs.earthquake.nshmp.internal.www;
+
+import gov.usgs.earthquake.nshmp.internal.AppVersion.VersionInfo;
+
+/**
+ * The response metadata with version info.
+ */
+public class ResponseMetadata {
+ public final VersionInfo[] repositories;
+
+ public ResponseMetadata(VersionInfo... repositories) {
+ this.repositories = repositories;
+ }
+
+ public VersionInfo[] getRepositories() {
+ return repositories;
+ }
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/WsUtils.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/WsUtils.java
new file mode 100644
index 0000000000000000000000000000000000000000..e45eb6f8da8150a5956fc5f1308132deb1956a40
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/WsUtils.java
@@ -0,0 +1,100 @@
+package gov.usgs.earthquake.nshmp.internal.www;
+
+import java.lang.reflect.Type;
+import java.time.format.DateTimeFormatter;
+import java.util.Optional;
+
+import com.google.common.collect.Range;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+
+import gov.usgs.earthquake.nshmp.gmm.GmmInput;
+import gov.usgs.earthquake.nshmp.gmm.GmmInput.Field;
+
+/**
+ * Web service utilities.
+ *
+ * @author U.S. Geological Survey
+ */
+public class WsUtils {
+
+ public static final DateTimeFormatter DATE_FMT = DateTimeFormatter.ofPattern(
+ "yyyy-MM-dd'T'HH:mm:ssXXX");
+
+ public static <T, E extends Enum<E>> T checkValue(E key, T value) {
+ if (value == null) {
+ throw new IllegalStateException("Missing [" + key.toString() + "]");
+ }
+
+ return value;
+ }
+
+ /* Constrain all doubles to 8 decimal places */
+ public static final class DoubleSerializer implements JsonSerializer<Double> {
+ @Override
+ public JsonElement serialize(Double d, Type type, JsonSerializationContext context) {
+ double dOut = Double.valueOf(String.format("%.8g", d));
+ return new JsonPrimitive(dOut);
+ }
+ }
+
+ /* Convert NaN to null */
+ public static final class NaNSerializer implements JsonSerializer<Double> {
+ @Override
+ public JsonElement serialize(Double d, Type type, JsonSerializationContext context) {
+ return Double.isNaN(d) ? null : new JsonPrimitive(d);
+ }
+ }
+
+ public static final class ConstraintsSerializer implements JsonSerializer<GmmInput.Constraints> {
+ @Override
+ public JsonElement serialize(
+ GmmInput.Constraints constraints,
+ Type type,
+ JsonSerializationContext context) {
+ JsonArray json = new JsonArray();
+
+ for (Field field : Field.values()) {
+ Optional<?> opt = constraints.get(field);
+ if (opt.isPresent()) {
+ Range<?> value = (Range<?>) opt.orElseThrow();
+ Constraint constraint = new Constraint(
+ field.id,
+ value.lowerEndpoint(),
+ value.upperEndpoint());
+ json.add(context.serialize(constraint));
+ }
+ }
+
+ return json;
+ }
+ }
+
+ public static final class EnumSerializer<E extends Enum<E>> implements JsonSerializer<E> {
+ @Override
+ public JsonElement serialize(E src, Type type, JsonSerializationContext context) {
+ JsonObject jObj = new JsonObject();
+ jObj.addProperty("value", src.name());
+ jObj.addProperty("display", src.toString());
+
+ return jObj;
+ }
+ }
+
+ @SuppressWarnings("unused")
+ private static class Constraint {
+ final String id;
+ final Object min;
+ final Object max;
+
+ Constraint(String id, Object min, Object max) {
+ this.id = id;
+ this.min = min;
+ this.max = max;
+ }
+ }
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/EnumParameter.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/EnumParameter.java
new file mode 100644
index 0000000000000000000000000000000000000000..2e0956fef9f521de38c04d6e3363bea23b41388c
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/EnumParameter.java
@@ -0,0 +1,22 @@
+package gov.usgs.earthquake.nshmp.internal.www.meta;
+
+import java.util.Set;
+
+/**
+ * An enum parameter.
+ *
+ * @author U.S. Geological Survey
+ *
+ * @param <E> The enum type
+ */
+public final class EnumParameter<E extends Enum<E>> {
+
+ private final String label;
+ private final Set<E> values;
+
+ public EnumParameter(String label, Set<E> values) {
+ this.label = label;
+ this.values = values;
+ }
+
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/Status.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/Status.java
new file mode 100644
index 0000000000000000000000000000000000000000..b41c20599cad92cd3c5213a48e28d7f1c93d4276
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/Status.java
@@ -0,0 +1,18 @@
+package gov.usgs.earthquake.nshmp.internal.www.meta;
+
+/**
+ * Service request status identifier.
+ *
+ * @author U.S. Geological Survey
+ */
+public class Status {
+
+ /** Error reponse status. */
+ public static final String ERROR = "error";
+
+ /** Success reponse status. */
+ public static final String SUCCESS = "success";
+
+ /** Usage reponse status. */
+ public static final String USAGE = "usage";
+}
diff --git a/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/StringParameter.java b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/StringParameter.java
new file mode 100644
index 0000000000000000000000000000000000000000..14a5ab1f4e8a8841be577d6f704a9fad3867fc44
--- /dev/null
+++ b/src/main/java/gov/usgs/earthquake/nshmp/internal/www/meta/StringParameter.java
@@ -0,0 +1,20 @@
+package gov.usgs.earthquake.nshmp.internal.www.meta;
+
+import java.util.Set;
+
+/**
+ * A string parameter.
+ *
+ * @author U.S. Geological Survey
+ */
+public class StringParameter {
+
+ public final String label;
+ public final Set<String> values;
+
+ public StringParameter(String label, Set<String> values) {
+ this.label = label;
+ this.values = values;
+ }
+
+}