OSGi Configuration

What is OSGi Configuration? 

• In the Context of software development, Osgi stands for(Open Services Gateway Initiative).
• OSGi is a modular framework for building Java applications, allowing them to be dynamically composed of smaller, reusable components called bundles.
• When you want to give some input to your Bundle means your Java file like you give for the component you write Osgi Configuration.
• Basically Osgi Configuration Used in Run Modes. 

How Osgi Configuration look like?

• Go to the System Console.
• and than ConfigManager.

Osgi Configuration Fields

Save Osgi Configuration as a Node

• In crxde (Content Repository Extreme Development Environment). All the OSGI configurations are stored under (/apps/sling/config or /apps/system/config) by default.

What is the need or purpose of using Osgi Configuration?

• Basically Osgi Configuration Used in Run Modes.
• for eg:
• If our requirement is in Dev environment we want different configuration, In Stage environment we want different configuration & In Production environment we want different configuration then we will use Osgi Configuration. 

How to Create Osgi Configuration?

• First of all we write Interface for Osgi Service.
• for eg:

• Second step, we write a class it means implemented class for Osgi Service
• for eg:

 

 

In this class we are used few Specific annotation let's discuss what are these annotation and why we will use?

 

• @Component annotation make services from a simple class.
• @ObjectClassDefinition(name = "", description = " ")
• @ObjectClassDefinition this is used to generate Osgi Configuration fields.
• for eg:

• @Designate  annotation this is used to generate designate element in the meta type resource for an @ObjectClassDefinition.
• It means it will generate for this 

• using the annotative declarative services .

• we have to create a inner Interface class inside that you have to use public @interface this syntax.

• Inside that there is 
• @AttributeDefinition(name = "", description = "", type = AttributeType.STRING)
• Basically this @AttributeDefination annotation will be using on particular method and you pass some parameters this is used to generate your fields.
• you will be seeing here I used @AttributeDefinition which have name and than the description and then type.
• This Type is defined which kind of filled it is so, I define the STRING.
• It means the filled will be string type.
• Then I define a method this method will return whatever, the value this filled have and you can give default value.

for eg:

• Now we have Four fields

1. First Name
2. Last Name
3. Employee ID
4. Address

This is by default value.

Now let's, see how we can use it?

• with the help of @Activate annotation method we can use.

What is the purpose of @Activate annotation? 

• When you want to be load or executed at the time of this service initiation or to deploy this bundle you will write in activate.

I will display this value inside a component.

• we create a sling Model.
• for eg:

1. Interface of Sling Model

2. Sling Model to call Osgi Service.

 

3.Inside Slightly

4.After Deployment the value is on page

In short, 

1)We have a OSGI Configuration that is residing in the OSGI Service.

2)We are calling the OSGI Service from the Sling Model.

3)We are calling the Sling Model using from Sightly/HTL.

Please feel free to comment in case of any mistake I am also learning.

Thanks

Matri Sharma