submit-a-message.md

Submit a message

ConsensusMessageSubmitTransaction() submits a message to a topic. If you are trying to submit a message to a private topic, you will need the associated submitKey to successfully submit messages to it.

Constructor	Description
ConsensusMessageSubmitTransaction()	Initializes a ConsensusMessageSubmitTransaction object

new ConsensusMessageSubmitTransaction()

Basic

Methods	Type	Description
setTopicID(<topic>	TopicID	The ID of the topic to submit a message to
setMessage(<message>)	byte[ ]	The message to submit in byte format. Max size of the transaction (including signatures) is 6144 bytes.
setMessage(<message>)	String	The message to submit in string format

Example

{% tabs %} {% tab title="Java" %}

//Submits a message to a public topic 
new ConsensusMessageSubmitTransaction()
    .setTopicId(topicId)
    .setMessage("hello, HCS! " + i)
    .build(client)
    .execute(client)
    .getReceipt(client);

{% endtab %}

{% tab title="JavaScript" %}

//Submits a message to a public topic 
await new ConsensusSubmitMessageTransaction()
    .setTopicId(topicId)
    .setMessage("hello, HCS! " + i)
    .build(client)
    .execute(client)
    .getReceipt(client);

{% endtab %} {% endtabs %}

Advanced

Submit a message to a private topic

To submit a message to a private topic, you will need access to the the submitKey. The submitKey is a property set at the time the topic is created and can be modified. If you do not have the appropriate submitKey, you will not be able to submit messages to that topic.

{% tabs %} {% tab title="Java" %}

new ConsensusMessageSubmitTransaction()
     .setTopicId(topicId)
     .setMessage(message)
     .build(hapiClient)
     // The transaction is automatically signed by the payer.
     // Due to the topic having a submitKey requirement, additionally sign the transaction with that key.
    .sign(submitKey)
    .execute(hapiClient)
    .getReceipt(hapiClient);

{% endtab %}

{% tab title="JavaScript" %}

await new ConsensusSubmitMessageTransaction()
     .setTopicId(topicId)
     .setMessage(message)
     .build(hapiClient)
     // The transaction is automatically signed by the payer.
     // Due to the topic having a submitKey requirement, additionally sign the transaction with that key.
    .sign(submitKey)
    .execute(hapiClient)
    .getReceipt(hapiClient);

{% endtab %} {% endtabs %}

You can view the complete example here.