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:

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

Constraints

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