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# Media Casting
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Media casting capabilities allow applications to discover, connect to, and stream content to Cast-enabled devices such as Chromecast, Android TV, and other Cast receivers.
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## Cast Device Discovery
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### Get Available Cast Sinks
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Retrieve list of available Cast devices on the network.
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```java { .api }
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public List<Map<String, String>> getCastSinks();
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```
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**Returns:** List<Map<String, String>> - List of available cast devices with ID and name pairs
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**Usage Example:**
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```java
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// ChromiumDriver is typically used through subclasses like ChromeDriver, EdgeDriver
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ChromiumDriver driver = ...; // Obtain from ChromeDriver, EdgeDriver, etc.
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// Get available cast devices
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List<Map<String, String>> castSinks = driver.getCastSinks();
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for (Map<String, String> sink : castSinks) {
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    String deviceId = sink.get("id");
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    String deviceName = sink.get("name");
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    System.out.println("Found device: " + deviceName + " (ID: " + deviceId + ")");
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}
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```
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## Cast Device Selection
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### Select Cast Sink
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Select a Cast device as the target for media operations.
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```java { .api }
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public void selectCastSink(String deviceName);
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```
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**Parameters:**
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- `deviceName` (String): Name of the target Cast device
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**Usage Example:**
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```java
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// Select a specific cast device
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driver.selectCastSink("Living Room TV");
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// Or select using device discovered from getCastSinks()
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List<Map<String, String>> sinks = driver.getCastSinks();
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if (!sinks.isEmpty()) {
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    String firstDevice = sinks.get(0).get("name");
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    driver.selectCastSink(firstDevice);
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}
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```
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## Screen Mirroring
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### Start Desktop Mirroring
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Mirror the entire desktop to a Cast device.
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```java { .api }
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public void startDesktopMirroring(String deviceName);
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```
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**Parameters:**
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- `deviceName` (String): Name of the target Cast device
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**Usage Example:**
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```java
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// Start mirroring desktop to Cast device
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driver.startDesktopMirroring("Living Room TV");
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// Application continues running while desktop is mirrored
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// User can see desktop content on the Cast device
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```
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### Start Tab Mirroring
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Mirror the current browser tab to a Cast device.
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```java { .api }
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public void startTabMirroring(String deviceName);
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```
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**Parameters:**
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- `deviceName` (String): Name of the target Cast device
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**Usage Example:**
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```java
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// Navigate to content to cast
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driver.get("https://video-streaming-site.com");
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// Start mirroring current tab
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driver.startTabMirroring("Bedroom Chromecast");
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// The current tab content will be displayed on the Cast device
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```
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### Stop Casting
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Stop active casting session to a specific device.
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```java { .api }
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public void stopCasting(String deviceName);
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```
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**Parameters:**
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- `deviceName` (String): Name of the Cast device to stop casting to
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**Usage Example:**
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```java
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// Stop casting to specific device
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driver.stopCasting("Living Room TV");
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// Or stop all active casting sessions
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List<Map<String, String>> sinks = driver.getCastSinks();
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for (Map<String, String> sink : sinks) {
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    driver.stopCasting(sink.get("name"));
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}
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```
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## Error Handling and Monitoring
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### Get Cast Issue Message
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Retrieve any error messages from active Cast sessions.
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```java { .api }
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public String getCastIssueMessage();
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```
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**Returns:** String - Error message if there are Cast session issues, empty string otherwise
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**Usage Example:**
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```java
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// Check for casting issues
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String issueMessage = driver.getCastIssueMessage();
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if (!issueMessage.isEmpty()) {
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    System.err.println("Cast error: " + issueMessage);
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    // Handle the error (retry, select different device, etc.)
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    driver.stopCasting("Problem Device");
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}
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```
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## Complete Casting Workflow
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```java
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import org.openqa.selenium.chromium.ChromiumDriver;
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import java.util.List;
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import java.util.Map;
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public class CastingExample {
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    public void demonstrateCasting() {
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        ChromiumDriver driver = new ChromiumDriver(commandExecutor, capabilities, "chrome");
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        try {
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            // Discover available Cast devices
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            List<Map<String, String>> devices = driver.getCastSinks();
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            if (devices.isEmpty()) {
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                System.out.println("No Cast devices found");
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                return;
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            }
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            // Display available devices
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            System.out.println("Available Cast devices:");
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            for (int i = 0; i < devices.size(); i++) {
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                Map<String, String> device = devices.get(i);
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                System.out.println((i + 1) + ". " + device.get("name"));
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            }
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            // Select first available device
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            String deviceName = devices.get(0).get("name");
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            driver.selectCastSink(deviceName);
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            // Navigate to content
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            driver.get("https://video-site.com/video/12345");
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            // Start tab mirroring
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            driver.startTabMirroring(deviceName);
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            // Monitor for issues
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            Thread.sleep(5000); // Wait for casting to establish
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            String issues = driver.getCastIssueMessage();
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            if (!issues.isEmpty()) {
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                System.err.println("Casting issues: " + issues);
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            }
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            // Continue with test or user interaction
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            // ...
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            // Stop casting when done
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            driver.stopCasting(deviceName);
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        } catch (Exception e) {
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            System.err.println("Casting failed: " + e.getMessage());
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        } finally {
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            driver.quit();
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        }
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    }
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}
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```
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## Cast Command Constants
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```java { .api }
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// Command constants from AddHasCasting
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public static final String GET_CAST_SINKS = "getCastSinks";
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public static final String SET_CAST_SINK_TO_USE = "selectCastSink"; 
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public static final String START_CAST_TAB_MIRRORING = "startCastTabMirroring";
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public static final String START_CAST_DESKTOP_MIRRORING = "startDesktopMirroring";
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public static final String GET_CAST_ISSUE_MESSAGE = "getCastIssueMessage";
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public static final String STOP_CASTING = "stopCasting";
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```
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## Testing Cast-Enabled Applications
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### Test Cast Button Functionality
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```java
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// Navigate to a Cast-enabled web application
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driver.get("https://youtube.com/watch?v=example");
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// Verify cast button is present
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WebElement castButton = driver.findElement(By.className("ytp-cast-button"));
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assertTrue(castButton.isDisplayed());
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// Get available devices before clicking
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List<Map<String, String>> devicesBeforeClick = driver.getCastSinks();
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// Click cast button in application
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castButton.click();
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// Verify application shows available devices
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// (Application-specific verification logic)
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```
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### Test Cast Session Management
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```java
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// Start casting
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driver.selectCastSink("Test Device");
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driver.startTabMirroring("Test Device");
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// Verify no error messages
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String issues = driver.getCastIssueMessage();
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assertEquals("", issues);
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// Navigate to different content while casting
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driver.get("https://another-video-site.com");
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// Verify casting continues (no new error messages)
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issues = driver.getCastIssueMessage();
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assertEquals("", issues);
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// Stop casting and verify
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driver.stopCasting("Test Device");
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```
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## Network Requirements
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Cast functionality requires:
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1. **Network Discovery**: Chrome must be able to discover Cast devices on the local network
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2. **Multicast DNS**: mDNS must be enabled for device discovery
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3. **Network Permissions**: Appropriate network access permissions
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4. **Same Network**: Cast devices and Chrome must be on the same network segment
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## Limitations and Considerations
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1. **Null Handling**: Methods return empty collections/strings when casting is not available
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2. **Device Availability**: Cast devices may appear and disappear based on network conditions
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3. **Session Management**: Only one casting session per device is typically supported
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4. **Content Restrictions**: Some content may have casting restrictions (DRM, etc.)
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5. **Network Dependencies**: Casting requires stable network connectivity
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6. **Chrome Version**: Casting features may vary between Chrome versions
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## Error Scenarios
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Common error conditions:
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- **No Devices Found**: Network issues or no Cast devices on network
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- **Device Unavailable**: Selected device goes offline or becomes unavailable
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- **Content Restrictions**: Content provider blocks casting
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- **Network Issues**: Intermittent connectivity affects casting quality
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```java
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// Robust casting with error handling
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public boolean safeCast(ChromiumDriver driver, String deviceName, String url) {
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    try {
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        // Verify device is available
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        List<Map<String, String>> devices = driver.getCastSinks();
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        boolean deviceFound = devices.stream()
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            .anyMatch(device -> deviceName.equals(device.get("name")));
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        if (!deviceFound) {
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            System.err.println("Device not found: " + deviceName);
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            return false;
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        }
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        // Navigate and start casting
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        driver.get(url);
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        driver.selectCastSink(deviceName);
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        driver.startTabMirroring(deviceName);
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        // Check for immediate issues
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        Thread.sleep(2000);
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        String issues = driver.getCastIssueMessage();
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        if (!issues.isEmpty()) {
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            System.err.println("Cast issues: " + issues);
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            driver.stopCasting(deviceName);
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            return false;
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        }
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        return true;
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    } catch (Exception e) {
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        System.err.println("Casting error: " + e.getMessage());
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        try {
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            driver.stopCasting(deviceName);
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        } catch (Exception stopError) {
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            // Ignore stop errors
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        }
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        return false;
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    }
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}
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```
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## Best Practices
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1. **Device Verification**: Always verify devices are available before attempting to cast
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2. **Error Monitoring**: Regularly check for cast issues during sessions
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3. **Graceful Cleanup**: Always stop casting sessions when tests complete
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4. **Network Stability**: Ensure stable network conditions for reliable casting
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5. **Content Compatibility**: Verify content supports casting before starting sessions
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6. **Session Management**: Handle multiple device scenarios appropriately
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7. **User Experience**: Consider the user experience on both the browser and Cast device