# Populating values from external sources

**External Data Source (EDS)** is an Eximee mechanism that makes it possible to feed form components with data coming from outside the form itself (e.g. from backend services or dictionaries). Thanks to EDS, components can dynamically fetch and display current information while the application is being filled out, instead of relying only on statically defined values.

For components, we can define the following external data sources:

| Source type                | Source description                                                                                                                                                                                                                                                                                                                                   |
| -------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **DICTIONARY**             | Data fed from a dictionary. Description in: [Attaching a dictionary data source](/documentation/documentation-en/budowanie-aplikacji/interfejs-uzytkownika/formularze/praca-z-komponentami-bazowymi/zasilanie-wartosciami-z-zewnetrznych-zrodel/podpiecie-slownikowego-zrodla-danych.md).                                                            |
| **ENTRY\_SERVICE**         | A service for the application. Description in: [Example of hooking it up in a page or application service component](/documentation/documentation-en/budowanie-aplikacji/interfejs-uzytkownika/formularze/praca-z-komponentami-bazowymi/zasilanie-wartosciami-z-zewnetrznych-zrodel/podpiecie-uslugi-na-poziomie-strony-lub-calego-wniosku.md).      |
| **EXIT\_SERVICE**          | A service for the application. Description in: Example of hooking it up in a page or application service component.                                                                                                                                                                                                                                  |
| **EXTERNAL\_SECTION**      | A service providing the content of a section for direct embedding in the application.                                                                                                                                                                                                                                                                |
| **PAGE\_SERVICE**          | A service for the application page. Description in: [Example of hooking it up in a page or application service component](/documentation/documentation-en/budowanie-aplikacji/interfejs-uzytkownika/formularze/praca-z-komponentami-bazowymi/zasilanie-wartosciami-z-zewnetrznych-zrodel/podpiecie-uslugi-na-poziomie-strony-lub-calego-wniosku.md). |
| **SERVICE**                | A service corresponding to a key-value map. Description in: [Example of hooking it up in a service component](/documentation/documentation-en/budowanie-aplikacji/interfejs-uzytkownika/formularze/praca-z-komponentami-bazowymi/zasilanie-wartosciami-z-zewnetrznych-zrodel/przyklad-podpiecia-w-komponencie-uslugi.md).                            |
| **SUGGESTER\_SERVICE**     | <p>Suggester (description in: <a href="/pages/e818e37fe0802508312996067a878530015709ad">Suggester integration</a>). Available only for the Text Field component.</p><p>Availability of the functionality depends on the license and may not be available in all implementations.</p>                                                                 |
| **UNPARK\_ENTRY\_SERVICE** | A service triggered when the application is unparked.                                                                                                                                                                                                                                                                                                |

*Example uses of EDS:*

* **Lists from external services:** Selection fields (e.g. *Combobox*) can automatically be populated with a list of options fetched from an external service (Service Proxy), e.g. a list of products or SWIFT codes from an external system.
* **Local dictionaries:** Values can come from *dictionaries* defined in the Eximee Library – e.g. a list of countries, document types – shared between different applications.
* **Suggester (hint service):** Text fields can use special services of type *Suggester*, which suggest or correct the entered value.
* **Page/application services:** EDS also includes services associated with the entire application or page (so-called *Page Service*, *Entry Service*, *Exit Service*), which can fetch data for multiple fields at once (e.g. loading customer data when the application opens).

{% hint style="info" %}
Demo application: demoUslugi
{% endhint %}


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