Implement a custom content resolver

You can implement your own content resolvers based on the default resolvers.

When the PSDK detects a new opportunity, the PSDK iterates through the registered content resolvers looking for one that is capable of resolving that opportunity. The first one that returns true is selected for resolving the opportunity. If no content resolver is capable, then that opportunity is skipped. Because the content resolving process is usually asynchronous, the content resolver is responsible for notifying the PSDK when the process has completed.

Create a custom AdvertisingFactory instance and override createContentResolver.
For example:

new AdvertisingFactory() {
    ....
    @Override
    public ContentResolver createContentResolver(MediaPlayerItem item) {
        Metadata metadata = _mediaPlayer.getCurrentItem().getResource().getMetadata();
        if (metadata != null) {
            if (metadata.containsKey(DefaultMetadataKeys.AUDITUDE_METADATA_KEY.getValue())) {
                return new AuditudeResolver(getActivity().getApplicationContext());
            } else if (metadata.containsKey(DefaultMetadataKeys.JSON_METADATA_KEY.getValue())) {
                return new MetadataResolver();
            } else if (metadata.containsKey(DefaultMetadataKeys.CUSTOM_AD_MARKERS_METADATA_KEY.getValue())) {
                return new CustomAdMarkersContentResolver();
            } else if (metadata.containsKey(CustomAdResolver.CUSTOM_METADATA_KEY)) {
                return new CustomAdResolver();
            }
        }
        return null;
    }
    ....
}

// register the custom advertising factory with media player
advertisingFactory = createCustomAdvertisingFactory();
mediaPlayer.registerAdClientFactory(advertisingFactory);

Pass an AdvertisingMetadata object to the PSDK as follows:
1. Create an AdvertisingMetadata object and MetadataNode object.
2. Save the AdvertisingMetadata object to MetadataNode.
```
MetadataNode result = new MetadataNode();
result.setNode(DefaultMetadataKeys.ADVERTISING_METADATA.getValue(), advertisingMetadata);
```
Create a custom ad resolver class that extends the ContentResolver class.
1. In the custom ad resolver, override this protected function:
```
void doResolveAds(Metadata metadata, PlacementOpportunity placementOpportunity)
```
  Metadata contains your AdvertisingMetada. Use it for the following TimelineOperation vector generation.
2. For each placement opportunity, create aVector<TimelineOperation>. The vector can be empty, but not null. This sample TimelineOperation provides a structure for AdBreakPlacement:
```
AdBreakPlacement(
    AdBreak.createAdBreak(ads, // Vector<Ad>
                          time, // Ad Break start time. Note: local time on the timeline
                          duration, // Ad Break duration
                          tag()  // An arbitrary string value that can be attached to the AdBreak object.
                         ),
    placementInformation  // Retrieved from PlacementOpportunity
)
```
3. After ads are resolved, call one of the following functions:
  - If the ad resolve succeeds: notifyResolveComplete(Vector<TimelineOperation> proposals)
  - If the ad resolve fails: notifyResolveError(Error error)
  For example, if it fails:
```
Metadata metadata = new MetadataNode();
metadata.setValue("NATIVE_ERROR_CODE", exception.getCause().toString());
error.setMetadata(metadata);
```

This sample custom ad resolver makes an HTTP request to the ad server and receives a JSON response.

public class CustomAdResolver extends ContentResolver {
    ...
    @Override
    protected void doResolveAds(Metadata metadata, PlacementOpportunity placementOpportunity) {
        ...
        if (resolveSuccess == true) {
            notifyResolveComplete(Vector<TimelineOperation> proposals);
        }
        else {
            notifyResolveError(Error error);
        }
    }
    ...
}

Sample JSON ad server response for a live stream:

{    "response": {
        "breaks": [
            {
                "start": 0,
                "ads": [
                    {
                        "id": 1001,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/geico/playlist.m3u8",
                            "duration": 30000,
                            "id": "asset1",
                            "resource_type": ""
                        },
                        "companion_assets": {
                        }
                    }
                ]
            },
            {
                "start": -1,
                "ads": [
                    {
                        "id": 1003,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/priceline/playlist.m3u8",
                            "duration": 30000,
                            "id": "asset3",
                            "resource_type": ""
                        },
                        "companion_assets": {
                        }
                    }
                ]
            }
        ]
    }
}

Sample JSON ad server response for VOD:

{    "response": { 
        "breaks": [
            {
                "start": 0,
                "ads": [
                    {
                        "id": 1001,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/geico/playlist.m3u8",
                            "duration": 30000,
                            "id": "asset1",
                            "resource_type": ""
                        },
                        "companion_assets": { 
                        }
                    },
                    {
                        "id": 1002,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/crescent/playlist.m3u8",
                            "duration": 15000,
                            "id": "asset2",
                            "resource_type": ""
                        },
                        "companion_assets": {
                         }
                    }
                ]
            },
            {
                "start": 50000,
                "ads": [
                    {
                        "id": 1003,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/priceline/playlist.m3u8",
                            "duration": 30000,
                            "id": "asset3",
                            "resource_type": ""
                        },
                        "companion_assets": {
                        }
                    }
                ]
            },
            {
                "start": 100000000,
                "ads": [
                    {
                        "id": 1004,
                        "primary_asset": {
                            "url": "http://venkat-test.s3.amazonaws.com/ads/camry/playlist.m3u8",
                            "duration": 15000,
                            "id": "asset4",
                            "resource_type": ""
                        },
                        "companion_assets": {
                        }
                    }
                ]
            }
        ]
    }
}