ExtensionService (api 5.2-SNAPSHOT API)

```
public interface ExtensionService
```
Interface for registering DataExtensions.
Obtaining instance: - Obtain instance with getInstance(). - Make sure to catch a possible NoClassDefFoundError in case Plan is not installed - Catch IllegalStateException in case ExtensionService is not enabled
Registering DataExtension: - Register your DataExtension with register(DataExtension) - Catch a possible IllegalArgumentException in case the DataExtension implementation is invalid.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static class ExtensionService.Holder

Method Summary

All Methods Static Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`static ExtensionService`	`getInstance()`	Obtain instance of ExtensionService.
`java.util.Optional<Caller>`	`register(DataExtension extension)`	Register your `DataExtension` implementation.
`void`	`unregister(DataExtension extension)`	Unregister your `DataExtension` implementation.

- Method Detail
  - getInstance
```
static ExtensionService getInstance()
```
    Obtain instance of ExtensionService.
    
    Returns:
    
    ExtensionService implementation.
    
    Throws:
    
    java.lang.NoClassDefFoundError - If Plan is not installed and this class can not be found or if older Plan version is installed.
    
    java.lang.IllegalStateException - If Plan is installed, but not enabled.
  - register
```
java.util.Optional<Caller> register(DataExtension extension)
```
    Register your DataExtension implementation.
    You can use ExtensionExtractor.validateAnnotations() in your Unit Tests to prevent IllegalArgumentExceptions here at runtime.
    
    Parameters:
    
    extension - Your DataExtension implementation, see DataExtension for requirements.
    
    Returns:
    
    Optional Caller that can be used to call for data update in Plan database manually - If the Optional is not present the user has disabled the extension in Plan config.
    
    Throws:
    
    java.lang.IllegalArgumentException - If an implementation violation is found.
  - unregister
```
void unregister(DataExtension extension)
```
    Unregister your DataExtension implementation.
    This method should be used if calling methods on the DataExtension suddenly becomes unavailable, due to plugin disable for example.
    
    Parameters:
    
    extension - Your DataExtension implementation that was registered before.