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// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
package com.microsoft.azure.sdk.iot.device.twin;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import java.util.Date;
import java.util.Map;
/**
* Representation of a single Twin metadata for the {@link TwinCollection}.
*
* The metadata is a set of pairs lastUpdated/lastUpdatedVersion for each
* property and sub-property in the Twin. It is optionally provided by
* the service and the clients can only ready it.
*
*
This class store the Date and Version for each entity in the {@link TwinCollection}.
*
*
For instance, the following is a valid TwinCollection with its metadata.
*
* {@code
* "$metadata":{
* "$lastUpdated":"2017-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":4,
* "MaxSpeed":{
* "$lastUpdated":"2017-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":3,
* "$lastUpdatedBy": "newconfig",
* "$lastUpdatedByDigest": "637570574076206429",
* "Value":{
* "$lastUpdated":"2017-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":5
* },
* "NewValue":{
* "$lastUpdated":"2017-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":5
* }
* }
* }
* }
*
*
* @see Understand and use device twins in IoT Hub
* @see Device Twin Api
*/
// Unchecked casts of Maps to Map are safe as long as service is returning valid twin json payloads. Since all json keys are Strings, all maps must be Map
@SuppressWarnings("unchecked")
public class TwinMetadata
{
// the entity last updated date and time in the TwinCollection
public static final String LAST_UPDATE_TAG = "$lastUpdated";
private Date lastUpdated;
// the entity last updated version in the TwinCollection
public static final String LAST_UPDATE_VERSION_TAG = "$lastUpdatedVersion";
private final Integer lastUpdatedVersion;
// the entity last updated by in the TwinCollection. Value is a configuration applied on the Twin.
public static final String LAST_UPDATED_BY = "$lastUpdatedBy";
private String lastUpdatedBy;
// the entity last updated by digest in the TwinCollection which represents service internal version for the applied configuration.
public static final String LAST_UPDATED_BY_DIGEST = "$lastUpdatedByDigest";
private String lastUpdatedByDigest;
/**
* CONSTRUCTOR
*
* This private constructor will receive and store the metadata parameters.
*
* @param lastUpdated the {@code String} with the date and time UTC of the last update on the entity. It can be {@code null}, empty or invalid.
* @param lastUpdatedVersion the {@code Integer} with the version of the last update on the entity. It can be {@code null}.
* @throws IllegalArgumentException If no valid parameter was provide and the class will be empty, or if the DateTime is invalid.
*/
TwinMetadata(String lastUpdated, Integer lastUpdatedVersion, String lastUpdatedBy, String lastUpdatedByDigest) {
if (!Tools.isNullOrEmpty(lastUpdated)) {
this.lastUpdated = ParserUtility.getDateTimeUtc(lastUpdated);
}
if (lastUpdatedBy != null) {
this.lastUpdatedBy = lastUpdatedBy;
}
if (lastUpdatedByDigest != null) {
this.lastUpdatedByDigest = lastUpdatedByDigest;
}
this.lastUpdatedVersion = lastUpdatedVersion;
if ((this.lastUpdatedVersion == null) && (this.lastUpdated == null)) {
throw new IllegalArgumentException("no valid data to create a TwinMetadata.");
}
}
/**
* CONSTRUCTOR (copy)
*
*
This private constructor will create a new instance of the TwinMetadata coping the information from the provided one.
*
* @param metadata the original {@code TwinMetadata} to copy.
*/
TwinMetadata(TwinMetadata metadata) {
if (metadata == null) {
throw new IllegalArgumentException("metadata to copy cannot be null");
}
this.lastUpdated = metadata.getLastUpdated();
this.lastUpdatedVersion = metadata.getLastUpdatedVersion();
this.lastUpdatedBy = metadata.getLastUpdatedBy();
this.lastUpdatedByDigest = metadata.getLastUpdatedByDigest();
}
/**
* Metadata extractor
*
*
This internal method will try to find $lastUpdated and $lastUpdatedVersion at the first
* level of the provided Map (Object), and create a new instance of the TwinMetadata with
* this information.
*
*
Once the provide Object can or cannot be a Map, and, if it is a Map, it can or cannot
* contains a valid metadata, this method contains the label try, which means that
* it can return a valid TwinMetadata or {@code null}.
*
*
For instance, for the following Map, this method will create a TwinMetadata with
* {@code lastUpdated = 2015-09-21T02:07:44.238Z} and {@code lastUpdatedVersion = 3}
*
*
* {@code
* "$lastUpdated":"2015-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":3,
* "Value":{
* "$lastUpdated":"2016-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":5
* },
* "NewValue":{
* "$lastUpdated":"2017-09-21T02:07:44.238Z",
* "$lastUpdatedVersion":5
* }
* }
*
*
* @param metadata the {@code Object} that may contains the metadata.
* @return A valid TwinMetadata instance it the provided metadata {@code Object} is a Map with
* data and version metadata, or {@code null} for the other cases.
* @throws IllegalArgumentException If no valid parameter was provide and the class will be empty, or if the DateTime is invalid.
*/
static TwinMetadata tryExtractFromMap(Object metadata) {
if (!(metadata instanceof Map)) {
return null;
}
String lastUpdated = null;
Integer lastUpdatedVersion = null;
String lastUpdatedBy = null;
String lastUpdatedByDigest = null;
for (Map.Entry entry : ((Map) metadata).entrySet()) {
String key = entry.getKey();
if (key.equals(LAST_UPDATE_TAG)) {
lastUpdated = (String) entry.getValue();
} else if (key.equals(LAST_UPDATE_VERSION_TAG)) {
if (!(entry.getValue() instanceof Number)) {
throw new IllegalArgumentException("Version in the metadata shall be a number");
}
lastUpdatedVersion = ((Number) entry.getValue()).intValue();
} else if (key.equals(TwinMetadata.LAST_UPDATED_BY)) {
lastUpdatedBy = entry.getValue().toString();
} else if (key.equals(TwinMetadata.LAST_UPDATED_BY_DIGEST)) {
lastUpdatedByDigest = entry.getValue().toString();
}
}
if ((lastUpdatedVersion != null) || !Tools.isNullOrEmpty(lastUpdated)) {
return new TwinMetadata(lastUpdated, lastUpdatedVersion, lastUpdatedBy, lastUpdatedByDigest);
}
return null;
}
/**
* Getter for lastUpdatedBy.
*
* @return the {@code String} representing the configuration LastUpdatedBy.
*/
public String getLastUpdatedBy() {
return this.lastUpdatedBy;
}
/**
* Getter for lastUpdatedByDigest.
*
* @return the {@code String} with the stored lastUpdatedByDigest.
*/
public String getLastUpdatedByDigest() {
return this.lastUpdatedByDigest;
}
/**
* Getter for lastUpdatedVersion.
*
* @return the {@code Integer} with the stored lastUpdatedVersion. It can be {@code null}.
*/
public Integer getLastUpdatedVersion() {
return this.lastUpdatedVersion;
}
/**
* Getter for lastUpdated.
*
* @return the {@code Date} with the stored lastUpdated. It can be {@code null}.
*/
public Date getLastUpdated() {
return this.lastUpdated;
}
/**
* Serializer
*
*
* Creates a {@code JsonElement}, which the content represents
* the information in this class in a JSON format.
*
* This is useful if the caller will integrate this JSON with JSON from
* other classes to generate a consolidated JSON.
*
*
* @return The {@code JsonElement} with the content of this class.
*/
JsonElement toJsonElement() {
JsonObject jsonObject = new JsonObject();
if (this.lastUpdated != null) {
jsonObject.addProperty(LAST_UPDATE_TAG, ParserUtility.dateTimeUtcToString(this.lastUpdated));
}
if (this.lastUpdatedVersion != null) {
jsonObject.addProperty(LAST_UPDATE_VERSION_TAG, this.lastUpdatedVersion);
}
if (this.lastUpdatedBy != null) {
jsonObject.addProperty(LAST_UPDATED_BY, this.lastUpdatedBy);
}
if (this.lastUpdatedByDigest != null) {
jsonObject.addProperty(LAST_UPDATED_BY_DIGEST, this.lastUpdatedByDigest);
}
return jsonObject;
}
/**
* Creates a pretty print JSON with the content of this class and subclasses.
*
* @return The {@code String} with the pretty print JSON.
*/
@Override
public String toString() {
return toJsonElement().toString();
}
}