com.microsoft.azure.sdk.iot.deps.twin

Class TwinMetadata

java.lang.Object

com.microsoft.azure.sdk.iot.deps.twin.TwinMetadata

public class TwinMetadata
extends Object

Representation of a single Twin metadata for the 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 TwinCollection.

For instance, the following is a valid TwinCollection with its metadata.

 
  "$metadata":{
      "$lastUpdated":"2017-09-21T02:07:44.238Z",
      "$lastUpdatedVersion":4,
      "MaxSpeed":{
          "$lastUpdated":"2017-09-21T02:07:44.238Z",
          "$lastUpdatedVersion":3,
          "Value":{
              "$lastUpdated":"2017-09-21T02:07:44.238Z",
              "$lastUpdatedVersion":5
          },
          "NewValue":{
              "$lastUpdated":"2017-09-21T02:07:44.238Z",
              "$lastUpdatedVersion":5
          }
      }
  }
 
 

See Also:

Understand and use device twins in IoT Hub, Device Twin Api

Field Summary

Fields

Modifier and Type	Field and Description
static String	LAST_UPDATE_TAG
static String	LAST_UPDATE_VERSION_TAG

Method Summary

Modifier and Type	Method and Description
Date	getLastUpdated() Getter for the lastUpdated.
Integer	getLastUpdatedVersion() Getter for the lastUpdatedVersion.
protected com.google.gson.JsonElement	toJsonElement() Serializer
String	toString() Creates a pretty print JSON with the content of this class and subclasses.
protected static TwinMetadata	tryExtractFromMap(Object metadata) Metadata extractor

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

LAST_UPDATE_TAG

public static final String LAST_UPDATE_TAG

See Also:

Constant Field Values

LAST_UPDATE_VERSION_TAG

public static final String LAST_UPDATE_VERSION_TAG

See Also:

Constant Field Values

Method Detail

tryExtractFromMap

protected static TwinMetadata tryExtractFromMap(Object metadata)

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 null.

For instance, for the follow Map, this method will create a TwinMetadata with lastUpdated = 2015-09-21T02:07:44.238Z and lastUpdatedVersion = 3

 
 "$lastUpdated":"2015-09-21T02:07:44.238Z",
 "$lastUpdatedVersion":3,
 "Value":{
     "$lastUpdated":"2016-09-21T02:07:44.238Z",
     "$lastUpdatedVersion":5
 },
 "NewValue":{
     "$lastUpdated":"2017-09-21T02:07:44.238Z",
     "$lastUpdatedVersion":5
 }
 
 

Parameters:

metadata - the Object that may contains the metadata.

Returns:

A valid TwinMetadata instance it the provided metadata Object is a Map with data and version metadata, or 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.

getLastUpdatedVersion

public Integer getLastUpdatedVersion()

Getter for the lastUpdatedVersion.

Returns:

the Integer with the stored lastUpdatedVersion. It can be null.

getLastUpdated

public Date getLastUpdated()

Getter for the lastUpdated.

Returns:

the Date with the stored lastUpdated. It can be null.

toJsonElement

protected com.google.gson.JsonElement toJsonElement()

Serializer

Creates a 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.

Returns:

The JsonElement with the content of this class.

toString

public String toString()

Creates a pretty print JSON with the content of this class and subclasses.

Overrides:

toString in class Object

Returns:

The String with the pretty print JSON.