# Multi-HAP Design Objectives


- Modular management: A well-designed application is generally managed in a modular manner, where modules are loosely coupled. In light of this, the multi-HAP mechanism is designed, allowing you to divide services into multiple modules and store each module in an independent HAP file. For example, If you are developing a payment application and its home screen consists of multiple modules, such as the scan, pay, messaging, and finance modules, you can implement the logic of the home screen for managing other modules in the entry-type HAP file, and implement specific modules in feature-type HAP files. The feature-type HAP files are independent. You can develop and test each of them separately, and then integrate them with the entry-type HAP file.

- Flexible deployment: You can combine multiple HAP files and deploy them on different devices. Assume that an application contains one entry-type HAP file (**Entry.hap**) and two feature-type HAP files (**Feature1.hap** and **Feature2.hap**). The **Entry.hap** file can be deployed on device A and device B, the **Feature1.hap** file can be deployed only on device A, and the **Feature2.hap** can be deployed only on device B. In this way, you can easily combine the **Entry.hap** and **Feature1.hap** files and deploy them on device A, and combine the **Entry.hap** and **Feature2.hap** files and deploy them on device B.

- On-demand loading: You can load modules only when they are needed, reducing the package size. Specifically, you can configure some HAP files of an application to be loaded on demand. For example, if some features are not used during application startup, you can configure them to be loaded only when they are needed, rather than being loaded at startup. This can reduce the size of the application package to some extent.

- Easier resource sharing: The resources (including public resource files and public pages) and shared objects (.so library files) required by multiple HAP files can be stored in an independent HAP file. In this way, other HAP files can obtain the resources and files by accessing the HAP, which reduces the size of the application package to some extent.