# Data Management
For structured data, the Data service supports creating and manipulating [JSON](https://www.json.org) documents. Not only can these documents contain data, but they can also be configured to contain a certain level of logic. To achieve this, documents created with the data service rely on a *data schema*, which dictates the document's structure and behaviour.
{% content-ref url="manage-data/data-service" %}
[data-service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/data-service)
{% endcontent-ref %}
Extra horizon services also provide storage for files that don't adhere to a particular structure, like images or zipped files. This service is called the `files service`, and allows storage and retrieval of a large variety of files.
{% content-ref url="manage-data/file-service" %}
[file-service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/file-service)
{% endcontent-ref %}
## Structured data
As previously mentioned, storage of structured data with ExH services relies on the `data service`. This service stores data in structured *documents* and uses *data schemas* to determine the structure of these documents. Documents can also adapt to a configurable logic, which is also determined in the document's schema.
#### Data schemas
Before creating a new document, the data service requires a *data schema*. The purpose of a data schema is twofold: It dictates the *data structure* of a document, as well as the *behavior logic* of that same document. ExH data schemas are inspired by [JSON-schemas](http://json-schema.org) and adhere to the same syntax.
**Data structure**
The primary function of a data schema is to ensure documents that are created with the `data service` are uniformly structured. Data schemas use *properties* to dictate the data structure that is accepted to create the resulting document.
**Configurable logic**
Secondly, data schemas allow configuration of the behavior logic of a document, similar to a [finite-state machine](https://en.wikipedia.org/wiki/Finite-state_machine). This means that the document can possess one of a limited amount of states, and change between these states based on the configuration provided. Similar to properties, the states and transitions of a document are configured in its data schema.
**Finite-state machines**
A traffic light could be considered a finite-state machine. It can exist in three **states**: green, orange and red.\
Changing from one state to another is called a **transition**. In the case of a traffic light, that would mean it has three transitions: changing from green to orange, changing from orange to red, and changing from red back to green.
#### Documents
After configuring a data schema, any number of documents can be created that follow its structure. These documents will exist in the states that are defined by the schema's *statuses*, and follow the logic configured in the schema's *transitions*. As previously mentioned, transitioning a document between statuses can trigger actions such as sending a mail, or tasks that interact with other services.
{% content-ref url="manage-data/data-service" %}
[data-service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/data-service)
{% endcontent-ref %}
## Unstructured data
While structured data is handled by the [Data Service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/data-service), some file types don't gain any significant benefit from being structured with JSON. Storing and retrieving unstructured data with ExH services can be done with the [File Service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/file-service).
#### Files
The `files service` provides a way of storing data without imposing a structure on it by way of schemas. This means the `files service` allows the storage of a variety of file types with unstructured content, such as images and streams. Storing a file with this service will return a *file token*, which can be used as a reference to that file for further interaction. The `files service` stores uploaded files together with metadata that describes the file, such as the name of the file, the file size and the file type.
{% content-ref url="manage-data/file-service" %}
[file-service](https://docs.extrahorizon.com/extrahorizon/services/manage-data/file-service)
{% endcontent-ref %}
---
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