io.scalecube.services.api.ServiceMessage Maven / Gradle / Ivy
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package io.scalecube.services.api;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.StringJoiner;
public final class ServiceMessage {
/** Default data format. */
public static final String DEFAULT_DATA_FORMAT = "application/json";
/** Qualifier header. */
public static final String HEADER_QUALIFIER = "q";
/**
* This is a system header which used by transport for serialization and deserialization purpose.
* It is not supposed to be used by application directly and it is subject to changes in future
* releases.
*/
public static final String HEADER_DATA_TYPE = "type";
/** Data format header. */
public static final String HEADER_DATA_FORMAT = "dataFormat";
/** Error type header. */
public static final String HEADER_ERROR_TYPE = "errorType";
/** Request method header. */
public static final String HEADER_REQUEST_METHOD = "requestMethod";
/** Null value for error type. */
public static final int NULL_ERROR_TYPE = -1;
private final Map headers;
private Object data;
/** Instantiates empty message for deserialization purpose. */
ServiceMessage() {
headers = new HashMap<>(2);
}
private ServiceMessage(Builder builder) {
this.data = builder.data;
this.headers = Collections.unmodifiableMap(new HashMap<>(builder.headers));
}
/**
* Instantiates new message with the same data and headers as at given message.
*
* @param message the message to be copied
* @return a new message, with the same data and headers
*/
public static Builder from(ServiceMessage message) {
return ServiceMessage.builder().data(message.data()).headers(message.headers());
}
/**
* Instantiates new message with error qualifier for given error type and specified error code and
* message.
*
* @param qualifier origin qualifier.
* @param errorType the error type to be used in message qualifier.
* @param errorCode the error code.
* @param errorMessage the error message.
* @return builder.
*/
public static ServiceMessage error(
String qualifier, int errorType, int errorCode, String errorMessage) {
return ServiceMessage.builder()
.qualifier(qualifier)
.header(HEADER_ERROR_TYPE, String.valueOf(errorType))
.data(new ErrorData(errorCode, errorMessage))
.build();
}
/**
* Instantiates new empty message builder.
*
* @return new builder
*/
public static Builder builder() {
return new Builder();
}
/**
* Returns the message headers.
*
* @return message headers
*/
public Map headers() {
return headers;
}
/**
* Returns header value by given header name.
*
* @param name header name
* @return the message header by given header name
*/
public String header(String name) {
Objects.requireNonNull(name, "header name");
return headers.get(name);
}
/**
* Returns message's qualifier.
*
* @return qualifier string
*/
public String qualifier() {
return header(HEADER_QUALIFIER);
}
/**
* Returns data format of the message data.
*
* @return data format of the data
*/
public String dataFormat() {
return header(HEADER_DATA_FORMAT);
}
/**
* Returns data format of the message data or default one.
*
* @return data format of the data or default one
*/
public String dataFormatOrDefault() {
final var dataFormat = dataFormat();
return dataFormat != null ? dataFormat : DEFAULT_DATA_FORMAT;
}
/**
* Return the message data, which can be byte array, string or any type.
*
* @param data type
* @return payload of the message or null if message is without any payload
*/
public T data() {
// noinspection unchecked
return (T) data;
}
public boolean hasData() {
return data != null;
}
/**
* Verify that this message contains data.
*
* @param dataClass the expected class of the data
* @return true if the data is instance of the dataClass
*/
public boolean hasData(Class dataClass) {
if (dataClass == null) {
return false;
}
if (dataClass.isPrimitive()) {
return hasData();
} else {
return dataClass.isInstance(data);
}
}
/**
* Describes whether the message is an error.
*
* @return result
*/
public boolean isError() {
return headers.containsKey(HEADER_ERROR_TYPE);
}
/**
* Returns error type. Error type is an identifier of a group of errors.
*
* @return error type if set otherwise {@value NULL_ERROR_TYPE}.
*/
public int errorType() {
String errorType = headers.get(HEADER_ERROR_TYPE);
if (errorType == null) {
return NULL_ERROR_TYPE;
}
try {
return Integer.parseInt(errorType);
} catch (NumberFormatException e) {
throw new IllegalStateException("Error type must be a number");
}
}
/**
* Returns request method header.
*
* @return request method, or null if such header doesn't exist.
*/
public String requestMethod() {
return headers.get(HEADER_REQUEST_METHOD);
}
@Override
public String toString() {
return new StringJoiner(", ", "ServiceMessage" + "[", "]")
.add("headers(" + headers.size() + ")")
.add("data=" + data)
.toString();
}
public static class Builder {
private final Map headers = new HashMap<>(2);
private Object data;
private Builder() {}
/**
* Setter for {@code data}.
*
* @param data data (optional)
* @return this
*/
public Builder data(Object data) {
this.data = data;
return this;
}
/**
* Setter for {@code dataType}.
*
* @deprecated in future releases will be dropped without replacement
* @param dataType data type; no null
* @return this
*/
@Deprecated
public Builder dataType(Class dataType) {
Objects.requireNonNull(dataType, "dataType");
headers.put(HEADER_DATA_TYPE, dataType.getName());
return this;
}
/**
* Setter for {@code dataFormat}.
*
* @param dataFormat data format
* @return this
*/
public Builder dataFormat(String dataFormat) {
headers.put(HEADER_DATA_FORMAT, dataFormat);
return this;
}
/**
* Setter for header {@link #HEADER_DATA_FORMAT}. Does nothing if input {@code dataFormat} is
* null or {@code headers} already contains value for {@link #HEADER_DATA_FORMAT}.
*
* @param dataFormat data format, optional
* @return self
*/
public Builder dataFormatIfAbsent(String dataFormat) {
if (dataFormat == null) {
return this;
}
headers.putIfAbsent(HEADER_DATA_FORMAT, dataFormat);
return this;
}
/**
* Returns {@code headers}.
*
* @return headers
*/
private Map headers() {
return headers;
}
/**
* Setter for {@code headers}.
*
* @param headers headers; not null
* @return this
*/
public Builder headers(Map headers) {
Objects.requireNonNull(headers, "headers").forEach(this::header);
return this;
}
/**
* Setter for header key-value pair.
*
* @param key header name; not null
* @param value header value; not null
* @return this
*/
public Builder header(String key, String value) {
Objects.requireNonNull(key, "header name");
Objects.requireNonNull(value, "header value");
headers.put(key, value);
return this;
}
/**
* Setter for header key-value pair.
*
* @param key header name; not null
* @param value header value; not null
* @return this
*/
public Builder header(String key, Object value) {
Objects.requireNonNull(key, "header name");
Objects.requireNonNull(value, "header value");
headers.put(key, value.toString());
return this;
}
/**
* Setter for {@code qualifier}.
*
* @param qualifier qualifier; not null
* @return this
*/
public Builder qualifier(String qualifier) {
return header(HEADER_QUALIFIER, Objects.requireNonNull(qualifier, "qualifier"));
}
/**
* Setter for {@code qualifier}.
*
* @param namespace namespace; not null
* @param action action; not null
* @return this
*/
public Builder qualifier(String namespace, String action) {
return qualifier(
Qualifier.asString(
Objects.requireNonNull(namespace, "namespace"),
Objects.requireNonNull(action, "action")));
}
public ServiceMessage build() {
return new ServiceMessage(this);
}
}
}
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