Please note - this project is incomplete and not ready for production use. The information here describes the design and technical goals of ActivityPubSharp, not the currently implemented functionality. Please see the issues tracker for detailed status.
ActivityPubSharp is a work-in-progress toolkit to support the use of ActivityPub in .NET applications. Multiple packages are available to fit any use case or application.
As the name suggests, ActivityPubSharp is focused on supporting ActivityPub rather than raw ActivityStreams or any other related standard. If there is ever a conflict between standards, then the ActivityPub spec will be followed.
At present, ActivityPubSharp does not intend to offer full JSON-LD support. The provided serialization code implements a minimum-viable approach that should support most use cases. At future, it will be possible to inject a user-provided compaction/normalization layer through DI.
Abstraction is a key goal of this project. The intent is that it should be relatively simple to integrate this library at any appropriate level of abstraction. A client-only app doesn't need tons of server-related code, and a server app shouldn't be bound to any particular web framework. To support this, a variety of NuGet packages are produced at increasing levels of abstraction. The main packages are as follows:
| Package | Description | Use Case |
|---|---|---|
| ActivityPubSharp.Types | Serializable type definitions for ActivityPub types. Includes utility classes to handle polymorphic properties. | You only need the ActivityPub object types, and nothing else. |
| ActivityPubSharp.Types.Proposed | Extended type definitions for proposed extensions to ActivityStreams. | You need to use the unreleased ActivityStreams extensions. |
| ActivityPubSharp.Types.Mastodon | Extended type definitions for integration with Mastodon. | You are communicating with a Mastodon server. |
| ActivityPubSharp.Types.W3ID | Extended type definitions for W3ID Security. This only includes the types - actual security logic is handled by ActivityPubSharp.Auth. | You need to secure communications using W3ID security. |
| ActivityPubSharp.Types.Schema | Extended type definitions for schema.org. | You integrate with an application that expects a schema, or you want to use a related technology like Microdata. |
| ActivityPubSharp.Auth | Authentication schemes used by common ActivityPub implementations. | You will communicate with an external host which requires signatures or other authentication. |
| ActivityPubSharp.Client | Implementation of the Client conformance class. Supports the client side of Client to Server interactions. | You are implementing (at least) the Client conformance class. |
| ActivityPubSharp.Server | Implementation of the Server conformance class. Supports the server side of Client to Server interactions. | You are implementing (at least) the Server conformance class. |
| ActivityPubSharp.Federation | Implementation of the Federated Server conformance class. Supports Server to Server interactions. | You are implementing (at least) the Federated Server conformance class. |
| ActivityPubSharp.AspNetCore | Extends Server package with bindings and middleware for ASP.NET Core. | You are implementing a server that will utilize ASP.NET. |
| ActivityPubSharp | Meta-package that includes all others. | You want ActivityPub with minimal effort, and can accept the library authors' default implementations and 3rd-party bindings. |
It is possible to use multiple of the Client, Server, and Federation packages simultaneously.
ActivityPubSharp utilizes Dependency Injection to easily support unique or extended use cases.
For example, included services all utilize the IJsonLdSerializer interface which enables user code to replace or modify the default JSON support.
User-accessible DI services and and options are described in the README for each individual package.
- .NET 7 (newer should work, but is untested)
- Any platform - no native code is used
- Minimal dependencies - software supply chain risks are real and very underrated. ActivityPubSharp is developed using minimal external dependencies, but without reinventing all the wheels.
- Modern .NET - ActivityPubSharp has set .NET 7 as the minimum supported version. This unfortunately excludes some projects, but is critical for System.Text.Json support.
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