# # Xposed Module and Host Channel

> This is a solution that uses system out-of-order broadcasting to send and receive data between the Module App and the Host App.

Condition that needs to be met

The Module App and the Host App need to remain alive, otherwise communication cannot be established.

## # Basic Usage

> The basic usage of the `wait` and `put` methods is described here.

By using `dataChannel` to realize the communication bridge between the Module App and the Host App, the principle is to send and receive system out-of-order broadcasts.

> The Module App example is as follows

    // Get from the Host App of the specified package name
    dataChannel(packageName = "com.example.demo").wait<String>(key = "key_from_host") { value ->
        // Your code here.
    }
    // Send to the Host App with the specified package name
    dataChannel(packageName = "com.example.demo").put(key = "key_from_module", value = "I am module")

> The Host App example is as follows

    // Get from the Module App
    dataChannel.wait<String>(key = "key_from_module") { value ->
        // Your code here.
    }
    // Send to the Module App
    dataChannel.put(key = "key_from_host", value = "I am host")

You can leave the `value` of `dataChannel` unset to only notify the Module App or Host App to call back the `wait` method.

> The Module App example is as follows

    // Get from the Host App of the specified package name
    dataChannel(packageName = "com.example.demo").wait(key = "listener_from_host") {
        // Your code here.
    }
    // Send to the Host App with the specified package name
    dataChannel(packageName = "com.example.demo").put(key = "listener_from_module")

> The Host App example is as follows

    // Get from the Module App
    dataChannel.wait(key = "listener_from_module") {
        // Your code here.
    }
    // Send to the Module App
    dataChannel.put(key = "listener_from_host")

Pay Attention

The receiver needs to stay alive to receive the communication data.

Tips

For more functions, please refer to YukiHookDataChannel.

## # Determine Module App and Host App Version Match

> Through the communication bridge function, `YukiHookAPI` also provides a solution for you to determine whether the Module App matches the Host App version after the user updates the Module App.

We only need to call the `checkingVersionEquals` method to achieve this function.

Bidirectional judgment can be performed between the Module App and the Host App.

You can check in the Module App whether the Host App of the specified package name matches the version of the current Module App.

> The following example

    // Get from the Host App of the specified package name
    dataChannel(packageName = "com.example.demo").checkingVersionEquals { isEquals ->
        // Your code here.
    }

You can also determine in the Host App whether it matches the current Module App version.

> The following example

    // Get from the Module App
    dataChannel.checkingVersionEquals { isEquals ->
        // Your code here.
    }

Condition of method callback

The Host App and Module App must be stay alive, and after activating the Module App restart the Hook target Host App object in scope.

Tips

For more functions, please refer to YukiHookDataChannel.

## # Rules for Callback Event Response

Only examples used in Module App are listed here, the same `key` in the Host App is always not allowed to be created repeatedly.

Pay Attention

In the Module App and Host App, each key callback event corresponding to dataChannel is not allowed to be repeatedly created, if repeated, the previous callback event will be replaced by the newly added callback event.

When used in the Module App, it cannot be repeated in the same Activity, and the same key in different Activity is allowed to be repeated.

> The following example

    class MainActivity : AppCompatActivity() {

        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            // Callback event A
            dataChannel(packageName = "com.example.demo").wait(key = "test_key") {
                // Your code here.
            }
            // Callback event B
            dataChannel(packageName = "com.example.demo").wait(key = "test_key") {
                // Your code here.
            }
            // Callback event C
            dataChannel(packageName = "com.example.demo").wait(key = "other_test_key") {
                // Your code here.
            }
        }
    }

    class OtherActivity : AppCompatActivity() {

        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            // Callback event D
            dataChannel(packageName = "com.example.demo").wait(key = "test_key") {
                // Your code here.
            }
        }
    }

In the above example, the callback event A will be replaced by the callback event B, the `key` of the callback event C is not repeated with others, and the callback event D is in another Activity, So the final callback events B, C, and D can all be created successfully.

Pay Attention

A callback event with the same key will only call back the callback event registered in the Activity that the current Module App is displaying, such as test_key in the above, if OtherActivity is being displayed, then test_key in MainActivity will not be called back.

The same key registers dataChannel in the same Activity but different Fragment, they will still be called back in the current Activity at the same time.

In a Module App, you can only use Context of Activity to register dataChannel, you cannot use dataChannel in Application and Service.

If you want to use dataChannel in Fragment, use activity?.dataChannel(...).

## # Security Instructions

In the Module environment, you can only receive communication data sent by the Host App with the specified package name and only send it to the Host App with the specified package name.

Pay Attention

In order to further prevent broadcast abuse, the API in the communication data will automatically specify the package name of the Host App and Module App to prevent other apps from monitoring and using broadcast to make overrun behaviors.