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| 1 | +# Using the JetStream |
| 2 | + |
| 3 | +The [Jetstream](https://github.com/bluesky-social/jetstream) is a streaming service that provides information on activity on the ATProto network. |
| 4 | +You can consume the Jetstream using the `AtProtoJetstream` class. |
| 5 | + |
| 6 | +## Jetstream events |
| 7 | + |
| 8 | +`AtProtoJetstream` has three events you can subscribe to: |
| 9 | + |
| 10 | +* `ConnectionStateChanged` - fired when the state of the underlying WebSocket changes, typically on open and close. |
| 11 | +* `MessageReceived` - fired when a message has been received from the Jetstream, but has not yet been parsed. |
| 12 | +* `RecordReceived` - fired when a message has been parsed into a JetStream event. |
| 13 | + |
| 14 | +There are three types of Jetstream event that are passed to `RecordReceived`: |
| 15 | + |
| 16 | +* `AtJetstreamCommitEvent` - an event raised when a change happens to a record in a repo, creation, deletion or changes. For example a post is created, or a user profile is updated. |
| 17 | +* `AtJetstreamAccountEvent` - an event that has happened on an actor's account, activation or deactivation, with an optional status indicating if deactivation was performed by moderation. |
| 18 | +* `AtJetstreamIdentityEvent` - an event raised when an actor changes their handle |
| 19 | + |
| 20 | +## Consuming the Jetstream |
| 21 | + |
| 22 | +To connect to the Jetstream create a new instance of `AtProtoJetstream` and subscribe to the events you are interesting in reacting to. |
| 23 | + |
| 24 | +Typical use would be subscribing to the `RecordReceived` event, examining the event arguments and reacting accordingly to the wanted jetstream events. |
| 25 | + |
| 26 | +```c# |
| 27 | +using (var jetStream = new AtProtoJetstream()) |
| 28 | +{ |
| 29 | + jetStream.RecordReceived += (sender, e) => |
| 30 | + { |
| 31 | + string timeStamp = e.ParsedEvent.DateTimeOffset.ToLocalTime().ToString("G", CultureInfo.DefaultThreadCurrentUICulture); |
| 32 | + |
| 33 | + switch (e.ParsedEvent) |
| 34 | + { |
| 35 | + case AtJetstreamAccountEvent accountEvent: |
| 36 | + if (accountEvent.Account.Active) |
| 37 | + { |
| 38 | + Console.WriteLine($"ACCOUNT: {accountEvent.Did} activated at {timeStamp}"); |
| 39 | + } |
| 40 | + else |
| 41 | + { |
| 42 | + Console.WriteLine($"ACCOUNT: {accountEvent.Did} deactivated at {timeStamp}"); |
| 43 | + } |
| 44 | + break; |
| 45 | + |
| 46 | + case AtJetstreamCommitEvent commitEvent: |
| 47 | + Console.WriteLine($"COMMIT: {commitEvent.Did} executed a {commitEvent.Commit.Operation} in {commitEvent.Commit.Collection} at {timeStamp}"); |
| 48 | + break; |
| 49 | + |
| 50 | + case AtJetstreamIdentityEvent identityEvent: |
| 51 | + Console.WriteLine($"IDENTITY: {identityEvent.Did} changed handle to {identityEvent.Identity.Handle} at {timeStamp}"); |
| 52 | + break; |
| 53 | + |
| 54 | + default: |
| 55 | + break; |
| 56 | + } |
| 57 | + }; |
| 58 | +} |
| 59 | +``` |
| 60 | + |
| 61 | +If you want the raw messages from the jetstream subscribe to the `MessageReceived` event. |
| 62 | + |
| 63 | +> [!WARNING] |
| 64 | +> The Jetstream covers all ATProto events. The Commit events cover not only Bluesky record commits but any commits from a registered PDS, such as [WhiteWind](https://whtwnd.com) |
| 65 | +> blog records or [Tangled](https://blog.tangled.sh/intro) collaboration messages. This is why the `Record` property in `AtJetstreamCommit` is presented as a `JsonDocument`. |
| 66 | +> When deserializing this property to, for example, a `BlueskyRecord` you will encounter exceptions if you attempt it on a non-Bluesky defined record |
| 67 | +
|
| 68 | +Once you have a configured instance of `AtProtoJetstream` call `ConnectAsync` and processing will begin in the background, raising events as appropriate. |
| 69 | +When you are finished with the jetstream call `CloseAsync` |
| 70 | + |
| 71 | +```c# |
| 72 | +await jetStream.ConnectAsync(); |
| 73 | + |
| 74 | +await jetStream.CloseAsync(); |
| 75 | +``` |
| 76 | + |
| 77 | +The [Jetstream sample](https://github.com/blowdart/idunno.Bluesky/tree/main/samples/Samples.Jetstream) shows subscribing to both raw messages and events, |
| 78 | +writing the raw message and a break down of the event to the console.type. |
| 79 | + |
| 80 | +## Filtering commit events |
| 81 | + |
| 82 | +You can limit the commit events you receive by [DID](commonTerms.md#dids) or [Collection](commonTerms.md#records). You can configure the filters |
| 83 | +when creating of `AtProtoJetstream`: |
| 84 | + |
| 85 | +```c# |
| 86 | +using (var jetStream = new AtProtoJetstream( |
| 87 | + collections: ["app.bsky.feed.post"], |
| 88 | + dids: ["did:plc:ec72yg6n2sydzjvtovvdlxrk"]) |
| 89 | +{ |
| 90 | +} |
| 91 | +``` |
| 92 | + |
| 93 | +You can also change the `CollectionFilter` and `DidFilter` properties on a running instance. |
| 94 | + |
| 95 | +## Configuring AtProtoJetstream |
| 96 | + |
| 97 | +`AtProtoJetstream` has two configuration options, `options` and `webSocketOptions`. |
| 98 | + |
| 99 | +The `options` parameter on the constructor allows you to configure |
| 100 | + |
| 101 | +* `LoggerFactory` - The `ILoggerFactory` to use for logging |
| 102 | +* `UseCompression` - a flag indication whether compression should be used. This defaults to `true`. |
| 103 | +* `Dictionary` - the zst compression/decompression dictionary to use if compression is enabled. This defaults to a generated dictionary specific to the jetstream. |
| 104 | +* `TaskFactory` - the `TaskFactory` to use when creating new tasks. This allows you to configure `TaskScheduler` settings if needed. |
| 105 | +* `MaximumMessageSize` - the maximum size of messages you are willing to accept, in bytes. This defaults to 8096. |
| 106 | + |
| 107 | +The `webSocketOptions` parameter allows you to configure the underlying web socket client, |
| 108 | + |
| 109 | +* `Proxy` - A proxy to use, if supplied. |
| 110 | +* `KeepAliveInterval` - Sets the keep alive interval. |
| 111 | + |
| 112 | +The following code snippet demonstrates setting a `LoggerFactory` and a `Proxy` |
| 113 | + |
| 114 | +```c# |
| 115 | +using (var jetStream = new AtProtoJetstream( |
| 116 | + options: new JetstreamOptions() |
| 117 | + { |
| 118 | + LoggerFactory = loggerFactory |
| 119 | + }, |
| 120 | + webSocketOptions: new WebSocketOptions() |
| 121 | + { |
| 122 | + Proxy = new WebProxy(new Uri("http://localhost:8866")) |
| 123 | + })) |
| 124 | +{ |
| 125 | +} |
| 126 | +``` |
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