Subscription Examples

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Understanding Subscriptions

In GraphQL, the subscription type is used to implement real-time functionality. Clients can subscribe to specific events and receive the associated data as it becomes available.

When opening a subscription your account including a session token gets registered for changes for 12 hours (time is subject for change). This means that a disconnection wont make your session miss messages. These messages will get notified after reconnecting within the 12 hour window.

Session handle

Every subscription can listen for a individual session token. This token makes sure that the client can have multiple individual subscriptions opened against the same type, which listens and acknowledges each message individually.

Limitations

Each account is limited to 10 opened subscriptions. When trying to exceed that limit a message will be shown and stop any further subscriptions.

Examples of Subscriptions

Note: When using subscriptions, only Id and entityChangeLocalId are available.

Important: Always include entityChangeLocalId in every subscription call. This enables you to resume from the last known point in the event of a disconnection.

This subscription will notify you of any changes or additions to contracts, providing the contract's Id:

subscription testSubscribeOnContractChange
{
  contract {
    id
    entityChangeLocalId
  }
}

This subscription will notify you if a specific contract, identified by its Id, changes:

subscription testSubscribeOnContractByIdChange
{
  contractById (id: "0e628534ef0143d6adfeeb631e3a4e3a") {
    id
    entityChangeLocalId
  }
}

Handle missed data

To manage events that occur while disconnecting over a longer time period, we provide queries that return EntityChange.

For example, if you are running a subscription on the entity Contract and you disconnect with the last row returned having:

Id: "a unique guid" entityChangeLocalId: 123

You can query for changes made after entityChangeLocalId: 123, like this:

query GetContractChanges
{
  contractChangesSync(lastEntityChangeLocalId: 123) {
    nodes {
      entityId
      localId
    }
  }
}

After a successful change sync, it's possible to go back subscribing on new changes.