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Subscribe request format

Subscribe requests must be sent as JSON in text frames, one request per frame.

Example of subscribe request​


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{
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"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
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"action": "subscribe",
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"topic": "block_digests",
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"parameters": {
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"start_block_height": "99,416,580"
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}
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}

Example of successful response​


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{
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"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786"
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}

Example of failed response​


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{
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"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
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"error": {
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"code": 400,
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"message": "invalid message"
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}
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}

Example of messages provided by subscription (if successful)​


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{
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"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
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"payload": {
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"id": "0x1234...",
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"height:": "123456789",
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"timestamp": "2025-01-02T10:00:00Z"
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}
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}

Example of messages provided by subscription (if error)​


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{
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"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
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"error": {
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"code": 500,
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"message": "access node is not responsible"
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}
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}

Request fields:​

NameTypeMandatoryDescription
subscription_idUUIDNOOptional unique identifier for the subscription. Server will generate one if omitted
actionSTRINGYESAction to perform. Must be subscribe to initiate a subscription
topicSTRINGYESThe topic to subscribe to, such as blocks, block_digests, etc.
parametersSTRINGNOAdditional parameters for the subscription, such as start_block_id, start_block_height

You can use subscription_id as a client-generated identifier to track responses asynchronously. If you don't provide subscription_id, the server will generate one and include it in the response.

The order of params is not significant.

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