1. If you opt for create a package via landing page , then it will automatically pick up the rule instances, data instances ( access group, operator id ) etc and create a product rule for you. You can then download the product jar and import it to any other environment.
2. If you opt for manually creating a product rule , then you have to define the components you want to be part of the application . For example, if you want to only package a single class rule or image rule then just create the RAP specifying the pzInsKey of the rule and you are set.
When there is a need to package a big application and loads of rules etc, packaging application is a better option.
However, for incremental releses ( mostly containing patch etc ) , creating a small product rule manually and just exporting the ruleset or rule will do good.
For more details, you can refer to the PDN components, Sashi had shead earlier.
sorry for my late respone, I've tried it ( using package landing page ).
But I want to make sure, How do I get data instances of class integration (external schema) not entered during export?
In my opinion , Class integration (external schema) requires just the class only, not the contents of the data table. But while export, The contents of the data from the table are exported by pega. Have you ever encountered this problem? thanks