Hedera Consensus Service gRPC API

The Hedera Consensus Service (HCS) gRPC API is a public mirror node managed by Hedera for the testnet. It offers the ability to subscribe to HCS topics and receive messages for the topic subscribed.

Hedera Consensus Service Mainnet Mirror Node Access
To gain access to the Hedera managed mirror node for mainnet, please complete this form.

HCS Mirror Node Endpoints:
hcs.testnet.mirrornode.hedera.com:5600 
hcs.mainnet.mirrornode.hedera.com:5600
Community supported mirror node information can be found here:
Mirror Nodes
/mainnet/mirror-nodes
Build a Mirror Node Client
Constructor
Description
MirrorClient(<endpoint>)
Initializes the MirrorClient object
Java
JavaScript
Java
final MirrorClient mirrorClient = new MirrorClient(MIRROR_NODE_ADDRESS);
JavaScript
const mirrorClient = new MirrorClient(mirrorNodeAddress);
Concurrent Subscription Limit
A single client can make a maximum of 5 concurrent subscription calls per connection. 
Subscribe to a topic
Constructor
Description
MirrorConsensusTopicQuery()
Initializes the MirrorConsensusTopicQuery object
Method
Type
Description
setTopicId(<topicId>)
ConsensusTopicId
ID of the topic
subscribe(<mirrorClient, onNext, onError>)
MirrorClient, Consumer<MirrorConsensusTopicResponse>, Consumer<Throwable>
Subscribe to a topic
setStartTime(<startTime>)
Instant
The time to start receiving messages from the topic
setEndTime(<endTime>)
Instant
The time to stop receiving messages from the topic
setLimit(<limit>)
long
The limit to the number of messages to receive for that topic
Java
JavaScript
Java
new MirrorConsensusTopicQuery()
    .setTopicId(topicId)
    .subscribe(mirrorClient, resp -> {
        String messageAsString = new String(resp.message, StandardCharsets.UTF_8);
​
        System.out.println(resp.consensusTimestamp + " received topic message: " + messageAsString);
    },
        // On gRPC error, print the stack trace
        Throwable::printStackTrace);
JavaScript
new MirrorConsensusTopicQuery()
    .setTopicId(topicId)
    .subscribe(
        consensusClient,
        (message) => console.log(message.toString()),
        (error) => console.log(`Error: ${error}`)
    );

REST API

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Constructor	Description
`MirrorClient(<endpoint>)`	Initializes the MirrorClient object

Constructor	Description
`MirrorConsensusTopicQuery()`	Initializes the MirrorConsensusTopicQuery object

Method	Type	Description
`setTopicId(<topicId>)`	ConsensusTopicId	ID of the topic
`subscribe(<mirrorClient, onNext, onError>)`	MirrorClient, Consumer<MirrorConsensusTopicResponse>, Consumer<Throwable>	Subscribe to a topic
`setStartTime(<startTime>)`	Instant	The time to start receiving messages from the topic
`setEndTime(<endTime>)`	Instant	The time to stop receiving messages from the topic
`setLimit(<limit>)`	long	The limit to the number of messages to receive for that topic