Accessing a DataShareExtensionAbility from the FA Model

Overview

Regardless of the FA model or stage model, the data read/write function consists of the client and server.

• In the FA model, the client uses DataAbilityHelper to provide external APIs, and the server uses DataAbility to provide database read and write services.

• In the stage model, the client uses DataShareHelper to provide external APIs, and the server uses DataShareExtensionAbility to provide database read and write services

If the client uses the FA model whereas the server is upgraded to the stage model, the client cannot access the server.

To resolve this issue, the system provides a solution on the framework side for smooth evolution.

Basic Principles

A compatible method is that DataAbilityHelper determines whether to call the DataShareHelper APIs based on the URI prefix (either DataAbility or DataShare). However, this method requires modification to the URI in the original client code.

Instead of manual modification, the system adopts the following processing:

1. The system attempts to start the DataAbility based on the URI passed in. If the startup fails, the system converts the URI prefix to DataShare and attempts to start the DataShareExtensionAbility.

2. If the URI does not map to any DataAbility or DataShareExtensionAbility, the startup fails. Otherwise, either the DataAbility or DataShareExtensionAbility is started.

Constraints

1. When you switch a DataAbility to a DataShareExtensionAbility, only the URI prefix can be modified.

   

2. The DataShareHelper class implements only certain APIs of DataAbilityHelper. For details about the APIs, see the table below.

   Table 1 API compatibility when the FA model accesses a DataShareExtensionAbility of the stage model

   API	Provided by DataAbilityHelper	Provided by DataShareHelper	Compatible
   on	Yes	Yes	Yes
   off	Yes	Yes	Yes
   notifyChange	Yes	Yes	Yes
   insert	Yes	Yes	Yes
   delete	Yes	Yes	Yes
   query	Yes	Yes	Yes
   update	Yes	Yes	Yes
   batchInsert	Yes	Yes	Yes
   getType	Yes	No	No
   getFileTypes	Yes	No	No
   normalizeUri	Yes	Yes	Yes
   denormalizeUri	Yes	Yes	Yes
   openFile	Yes	No	No
   call	Yes	No	No
   executeBatch	Yes	No	No