OpenTok.Net.Android

.NET for Android and .NET MAUI bindings for the Vonage OpenTok (Video API) Android SDK.

Packages

Two packages, from net8.0-android through net10.0-android:

Package	Native artifact	Use it when
OpenTok.Net.Android	com.opentok.android:opentok-android-sdk	Always — Session, Publisher, Subscriber and the rest of OpenTok's own API.
OpenTok.Net.webrtc.Dependency.Android	com.vonage:webrtc	Never referenced directly — a NuGet dependency of the package above, carrying the WebRTC engine OpenTok is built on.
OpenTok.Net.Transformers.Android	com.vonage:client-sdk-video-transformers plus com.vonage:mltransformers-ps16k	You want background blur, background replacement or audio noise suppression. Costs ~70 MB.

dotnet add package OpenTok.Net.Android

OpenTok.Net.webrtc.Dependency.Android comes along transitively; you never reference it yourself. It exists because com.vonage:webrtc's .aar is 243 MB (four ABIs' worth of the native WebRTC engine) — carrying it as a separate package keeps OpenTok.Net.Android itself a normal-sized package with a NuGet dependency on this one, instead of ~250 MB every time either changes.

OpenTok.Net.Transformers.Android does not come along, and does not depend on the binding either — add it yourself if you want it. It carries native payload and no managed API: the classes that use it (PublisherKit.VideoTransformer, SetVideoTransformers and friends) are in OpenTok.Net.Android, and the SDK loads the native transformers when one is constructed. Without it that construction compiles, links, and then returns null at runtime with MediaTransformerOpenTokTransformersLibraryNotLoaded. See src/OpenTok.Transformers.md.

using Com.Opentok.Android;

var publisher = new Publisher.Builder(context).Name("me").Build();
publisher.PublishAudio = true;
publisher.PublishVideo = true;
// publisher.View is a ready-made Android.Views.View — attach it into your layout to show the
// local camera preview. See samples/OpenTok.Sample.Android for a full MAUI example.

var session = new Session.Builder(context, apiKey, sessionId).Build();
session.StreamReceived += (s, e) => session.Subscribe(new Subscriber.Builder(context, e.Stream).Build());
session.Connect(token);

These are raw platform bindings — the full class-parse-generated surface, Com.Opentok.Android and friends, namespaced exactly as the Java package (com.opentok.android → Com.Opentok.Android, no rename). See tokbox.com/developer/sdks/android for the SDK's own API reference.

Two things in that snippet are this package's doing rather than class-parse's, and both exist because the generator loses information the Java API has:

• Build() returns Publisher, and the chain stays on Publisher.Builder. Java's covariant build() override and every fluent setter on Publisher.Builder are dropped along with their synthetic bridge methods, leaving only the inherited PublisherKit-typed versions — so this otherwise reads new Publisher.Builder(context).Build().JavaCast<Publisher>(), and the plain (Publisher) cast an author reaches for first throws. See src/OpenTok.Net.Android/Additions/.
• e.Stream, not e.P1. The .aar is compiled without javac -parameters, so every generated EventArgs would otherwise expose P0/P1/P2. See Transforms/Metadata.xml.

If you want one API across both platforms instead of the raw binding, see sbokatuk/OpenTok.Net — a cross-platform Session/Publisher/Subscriber and a MAUI video view over this package and its iOS counterpart.

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Requirements

• .NET 9 SDK with the android workload — global.json pins 9.0.100 (rollForward: latestFeature), which builds net8.0-android34.0 and net9.0-android35.0.
• .NET 10 SDK with the android workload (maui-android too, for the sample) — needed only for the net10.0-android36.0 leg and the sample app; not selected by this repository's global.json, so it always runs from a scratch global.json in a temporary directory (see build/BuildNugets.sh and the Sample section below for why: the SDK — and so the workload set — is resolved from the working directory).
• JDK 17 or newer on $JAVA_HOME before building anything that isn't just the binding libraries themselves — see "The JDK 17 requirement" below.

Versioning

Each package's version is <native artifact version>.<binding revision> — OpenTokVersion/ OpenTokBindingRevision and WebrtcVersion/WebrtcBindingRevision in Directory.Build.props. The two packages sit on independent native version lines (OpenTok's own SDK releases vs. Vonage's WebRTC engine releases), so there is no single version stamped across both — build/pins.sh resolves each from Directory.Build.props for shell scripts, and build/BuildNugets.sh --suffix ... appends a prerelease suffix to both when needed. The package set itself lives in build/packages.tsv, in dependency order (webrtc before opentok) — adding a package means adding a row there and a project under src/, nothing else keeps a second copy of the list. NuGet.config's local-artifacts source points at artifacts/, so the package tests, the device tests and the sample all restore the packed .nupkg rather than the projects — they exercise exactly what gets published.

How this repository works

Nothing native is committed to this repository: AndroidMavenLibrary resolves both .aar files straight from Maven Central for net9.0-android35.0/net10.0-android36.0, cached under ~/.cache/dotnet-android/MavenCacheDirectory. net8.0-android34.0 uses a different path — that SDK pack has no AndroidMavenLibrary support at all, so src/OpenTok.Binding.props downloads the same .aars directly with an MSBuild DownloadFile target instead. See the comments there for why this matters: the unsupported item is silently ignored rather than erroring, so a build using it on net8 "succeeds" with an empty few-KB binding assembly and no error anywhere in the log.

No single .NET SDK builds net8, net9 and net10 for Android, so build/BuildNugets.sh packs twice (the installed SDK's band, then a net10 pass from a scratch global.json) and merges the results — see build/merge-packages.py.

The webrtc split, and why it is a NuGet dependency rather than a project reference

OpenTok.Net.Android binds opentok-android-sdk directly. Its public API (custom video renderers, connection stats, texture-backed frames) hands back a handful of com.vonage.webrtc types, so those need real C# bindings too — provided by OpenTok.Net.webrtc.Dependency.Android, referenced as a packed NuGet dependency, not a bare project reference. That distinction matters: .NET for Android's Java dependency verification (XA4241/XA4242) reads a referenced NuGet package's own metadata to know what it provides, but does not look inside a same-solution project reference's own Maven declarations — so with a plain ProjectReference the build fails, reporting com.vonage:webrtc and its own transitive dependencies as unsatisfied even though the referenced project binds them. Packing the dependency first and referencing the .nupkg (see src/OpenTok.Net.Android/OpenTok.Net.Android.csproj's own comment) is what makes verification work — and is also what keeps the 243 MB .aar out of OpenTok.Net.Android's own package.

Several of com.vonage:webrtc's own transitive Java dependencies (Guava, in particular) are extremely common Android dependencies in their own right — a plain MAUI app's dependency graph already pulls in some of them on its own. Where that collision was observed (Guava, error_prone_annotations), src/OpenTok.Net.webrtc.Dependency.Android/OpenTok.Net.webrtc.Dependency.Android.csproj resolves them through the same canonical Xamarin.Google.* NuGet packages the rest of the ecosystem uses, so NuGet's normal single-version resolution deduplicates them instead of two copies colliding at dex time (R8: Type ... is defined multiple times). See that file's own comments for the specifics.

The JDK 17 requirement

opentok-android-sdk's own classes.jar is compiled to Java 17 class file format. Building against it — anything that compiles generated Java glue for a bound listener interface, which is any real app, not the binding libraries themselves — needs a JDK new enough to read that class file. net9.0-android35.0/net10.0-android36.0 pick up whatever JDK the environment's $JAVA_HOME already points to; net8.0-android34.0's tooling does not, by default, which is why tests/OpenTok.Net.Android.DeviceTests and samples/OpenTok.Sample.Android both fall back to $JAVA_HOME explicitly for that one target framework (see either project's own comment). Make sure $JAVA_HOME (or an explicit -p:JavaSdkDirectory=...) points at JDK 17 or newer before building an app — not just packing the libraries — against this SDK version.

Building locally

./build/BuildNugets.sh
dotnet test tests/OpenTok.Net.Android.PackageTests

OpenTok.Net.Android restores OpenTok.Net.webrtc.Dependency.Android from the local-artifacts NuGet source (artifacts/, see NuGet.config) — building it directly, on its own, only works once that dependency has already been packed there. ./build/BuildNugets.sh packs both, in the right order (see "Versioning" above); after that, iterating on a single project directly is fine, e.g.:

dotnet build src/OpenTok.Net.Android/OpenTok.Net.Android.csproj -f net9.0-android35.0

Tests

Everything runs against the packed .nupkg in artifacts/, not the build output, because the failure modes worth catching here are packaging ones — most importantly the net8 "empty shell" trap above, which builds with 0 errors and 0 warnings.

• tests/OpenTok.Net.Android.PackageTests (plain xUnit, runs anywhere) asserts the package layout — a real binding assembly and the native .aars for every target framework — and, through the metadata reader, the API itself: the core Com.Opentok.Android types exist, OpenTok.Net.Android depends on OpenTok.Net.webrtc.Dependency.Android rather than embedding its .aar, and SubscriberKit's two onDisconnected overloads (see src/OpenTok.Net.Android/Transforms/Metadata.xml) still carry the distinct names that keep them from colliding. A binding that failed to generate still packs cleanly; these are what notice.
• tests/OpenTok.Net.Android.DeviceTests is a bare Android app (no MAUI, no test framework) that consumes the packed package and drives the raw binding on an emulator: resolve the Java entry points out of the packaged .aars, construct a Session and a Publisher (no credentials — nothing here connects a session or joins anything), toggle publish audio/video, tear down. It reports a single OPENTOK_E2E_DONE PASS/FAIL line to logcat, which .github/scripts/run-emulator-tests.sh turns into an exit code.

Run the emulator suite locally, with an emulator already booted:

./build/BuildNugets.sh
OPENTOK_DEVICE_RID=android-arm64 ./.github/scripts/run-emulator-tests.sh 2.34.1.1 net9.0-android35.0

CI

.github/workflows/build.yml is a reusable workflow — pack builds both packages, validate runs the package tests, sample builds the MAUI sample against them, and e2e runs the emulator suite on net8.0-android34.0 and net10.0-android36.0 (the two extremes: net8's .aars arrive through the DownloadFile fallback, and net10's assets are grafted in by the merge step, so those are the two that could each break alone). .github/workflows/pr.yml calls it on every pull request, then publishes a beta build of both packages to nuget.org (skipped for forked PRs, which get no OIDC token for this repository). .github/workflows/release.yml does the same on a v* tag push, then creates a GitHub release. Both publish jobs use nuget.org trusted publishing (OIDC, no long-lived API key) against the nuget.org environment.

Sample

samples/OpenTok.Sample.Android is a MAUI app built straight against the packages — no cross-platform façade — that connects to a session, publishes this device's camera and microphone, and subscribes to the first remote stream: API key / session id / token entry, Connect / Disconnect / Publish, local and remote video, and a status log. It is deliberately the same flow and the same layout as samples/OpenTok.Sample.iOS in the iOS binding repository, so the two can be read side by side and the only differences are the ones the SDKs actually force.

Running it needs a Vonage Video API key, session id and token. Everything up to Connect works without them.

It also carries a small custom MAUI handler hosting whatever native view OpenTok hands back (see its OpenTokVideoView.cs for why a container rather than a wrapped SurfaceView — unlike Agora's SDK, OpenTok hands a ready-made View out of Publisher/Subscriber rather than wanting one supplied in). That handler is exactly what OpenTok.Net.Maui packages, if you would rather not write it.

It consumes the packed OpenTok.Net.Android package from ./artifacts (see NuGet.config), so pack first. It targets net10.0-android36.0 and needs the .NET 10 SDK with the maui-android workload, which this repository's global.json does not select — hence the scratch directory:

./build/BuildNugets.sh
cd /tmp && dotnet new globaljson --sdk-version 10.0.100 --force
dotnet build <repo>/samples/OpenTok.Sample.Android/OpenTok.Sample.Android.csproj

OpenTok.Net.Android.sln deliberately contains the binding projects and the tests but not the sample, so dotnet build OpenTok.Net.Android.sln does not require the MAUI workload.

Licence

MIT — see LICENSE. Vonage's own SDK is distributed under its own SDK licence terms.