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Defining @Configurable Attributes on Connectors

Like all Mule elements, connectors have attributes that can be assigned in Mule configuration XML files and set in the element’s property dialog. The @Configurable  DevKit annotation defines attributes on the connector that can be set when the connector is used. A @Connector can have any number of simple or complex @Configurable attributes.

Assumptions

You are familiar with Mule’s XML syntax for configuring elements.

Creating a @Configurable Attribute

The @Configurable annotation signals the generator to create a property configurable for each instance of your connector through XML syntax or a connector configuration dialog box. In addition to the @Configurable annotation, you need a public getter and a public setter.

For example:


         
      
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import org.mule.api.annotations.Configurable;
import org.mule.api.annotations.Connector;
 
@Connector(name = "myconnector")
public class MyConnector {
 
    @Configurable
    private String key;
 
    public String getKey(){
        return this.key;
    }
    public void setKey(String key) {
       this.key = key;
    }

Then configure the module or connector as follows:


         
      
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<myconnector:config key="myKey" />

Making an Attribute @Optional

@Configurable attributes are mandatory, unless marked with the @Optional annotation. @Optional @Configurable attributes may be omitted when using the connector.

For example:


         
      
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@Module(name = "mymodule")
public class MyModule {
  
    @Configurable
    @Optional
    private String key;
  
    public String getKey(){
        return this.key;
    }
    public void setKey(String key) {
       this.key = key;
    }

Then configure the connector as follows:


         
      
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<myconnector:config key="myKey" />
 The following is also valid since assigning a value is optional:

         
      
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<myconnector:config />

Adding a @Default Attribute Value

For @Optional configurable attributes, use the @Default annotation to specify a default value if the attribute is omitted. 

For example:


         
      
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@Module(name = "mymodule")
public class MyModule {
  
    @Configurable
    @Optional
    @Default("testKey")
    private String key;
  
    public String getKey(){
        return this.key;
    }
    public void setKey(String key) {
       this.key = key;
    }

Then the connector can be configured as follows:


         
      
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<myconnector:config key="myKey" />

If the key attribute is not present it will implicitly be assigned the value testKey as defined by the @Default annotation:


         
      
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<myconnector:config />

Customizing Attributes for Better Usability

You can (and should) use several annotations that control how the attribute appears in the property dialog in Studio and in your connector documentation:

  • @FriendlyName sets the attribute name shown in the property dialog

  • @Placement affects the position in the property dialog

  • @Summary provides a short description for the operation (used as a tooltip in Studio)

See Customizing Connector Integration with ESB and Studio for more on these annotations.

Complex Data Types and Configurable Attributes

DevKit supports configurable attributes of complex types, such as enumerated types and collections. See Handling Data Types for Configurable Properties for more details.