# 2. GraphQL Subscription

The sequence diagram for GraphQL Subscriptions illustrates how to benefit from the event-driven architecture implemented in the GeoPard core. Upon any changes to the linked entities, the

GeoPard API promptly emits an event capturing the impacted entities and the corresponding operation (`INSERT`, `MODIFY`, `REMOVE`). The scope of these subscriptions is expansive, covering all entities such as Farm, Field, SatelliteImage, SoilDataset, AsAppliedDataset, YieldDataset, TopographyMap, Notes, etc. 

The GraphQL Subscription ([Request 1 or R1](/geopard-tutorials/api-docs/geopard-api-requests-overview/1.-subscription-get-events.md)) operates on a WebSocket where all events are delivered in almost real-time, ensuring immediate communication of any changes. 

{% hint style="danger" %}
The receiver of the subscription events should function as a basic service, responsible for routing the received events to a subsequent service where processing logic is applied. It is crucial that this receiver doesn't perform any processing tasks itself.
{% endhint %}

Moreover, should there be any missed or lost events, users have the capability to retrieve them. This is achieved by executing a GraphQL query tailored for a specific date range and entities (User, Farm, Field), effectively enabling a complete recovery of past events ([Request 2 or R2](/geopard-tutorials/api-docs/geopard-api-requests-overview/82.-query-restore-subscription-events.md)). This level of functionality ensures no information is lost, maintaining the integrity and consistency of user data.

<figure><img src="/files/Ta2tUZfp5yn6Z1PM4tla" alt=""><figcaption><p>Sequence diagram: Workk with Subscription Events</p></figcaption></figure>


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