1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

//! # Nakadion
//!
//! A client for the [Nakadi](http://nakadi.io) Event Broker.
//!
//! ## Summary
//!
//! `Nakadion` is client that connects to the Nakadi Subscription API. It
//! does all the cursor management so that users can concentrate on
//! implementing their logic for processing events. The code implemented
//! to process events by a user does not get in touch with the internals of Nakadi.
//!
//! `Nakadion` processes batches of events from Nakadi on a worker per partition basis.
//! A worker new is spawned for each new partion discovered. These workers are guaranteed
//! to be run ona single thread at a time. To process batches of events a
//! handler factory has to be implemented which is creates handlers that are executed by the
//! workers.
//!
//! `Nakadion` is almost completely configurable with environment variables.
//!
//! Please have a look at the documentation of [Nakadi](http://nakadi.io)
//! first to become comfortable with the concepts of Nakadi.
//!
//! ## How to use
//!
//! 1. Implement a `BatchHandler` that contains all your batch processing logic
//! 2. Implement a `Handlerfactory` creates handlers for the workers.
//! 3. Configure `Nakadion`
//! 4. Hand your worker factory over to `Nakadion`
//! 5. Consume events!
//!
//! ## How Nakadion works
//!
//! ### Load balancing
//!
//! A started instance connects to the Nakadi Event Broker with one active connection. Due to
//! Nakadi`s capability of automatically distributing partitions among clients Nakadion does
//! not need to track concurrently consuming clients. In most use cases it does not make
//! any sense to have more clients running than the number partitions assigned
//! to an event type.
//!
//! ### Consuming events
//!
//! Nakadi delivers events in batches. Each batch contains the events of a single partition
//! along with a cursor that is used for reporting progress to Nakadi.
//!
//! To consume events with `Nakadion` one has to implement a `BatchHandler`. This `BatchHandler`
//! provides the processing logic and is passed the bytes containing the events of a batch.
//!
//! `Nakadion` itself does not do any deserialization of events. The `BatchHandler` is responsible
//! for deserializing events. Nevertheless there is a `TypedBatchHandler` for convinience
//! that does the deserialization of events using `serde`.
//!
//! When `Nakadion` receives a batch it just extract the necessary data from
//! the bytes received over the network and then delagates the batch
//! to a dispatcher which spawns workers that are then passed the batch.
//!
//! This means `Nakadion` itself does not have any knowledge of the events contained in a batch.
//!
//! ### Buffering batches and maximizing throughput
//!
//! `Nakadion` has an unbounded buffer for events. When looking at how Nakadi works it turns
//! out that a bounded buffer is not necessary.
//!
//! Nakadi has a timeout for committing the cursors of batches. This tiemout is 60 seconds.
//! Furthermore Nakadi has a configuration parameter called `max_uncommitted_events`.
//! With this paramteter which can be configured for `Nakadion` one can steer how many
//! events can be at most in `Nakadion`s buffers. In conjunction with a
//! `CommitStrategy` one can optimize for maximum throughput and keep the amount
//! of buffered events under control.
//!
//! ### Logging
//!
//! `Nakadion` does verbose logging when connecting to a stream and when a stream is closed. The
//! reason is that this information can be quite important when probles arise. A reconnect
//! happens roughly every full hour unless configured otherwise on Nakadi's side.
//!
//! `Nakadion` also logs a message each time a new worker is created and each time a worker is
//! shut down.
//!
//! Othrwise `Nakadion` only logs problems and errors.
//!
//! So in the end your log files will not be flodded with messages from `Nakadion`.
//!
//! ### Metrics
//!
//! `Nakadion` provides an interface for attaching metrics libraries. Metrics are especially
//! useful when optimizing for maximum throughput since one can see what
//! effect (especially on cursors) the different possible settings have.
//!
//! ### Performance
//!
//! Nakadion is not meant to be used in a high performance scenario. It uses synchronous IO.
//! Nevertheless it is easily possible to consume tens of thousands events per second depending
//! on the complexity of your processing logic.
#[macro_use]
extern crate failure;
#[macro_use]
extern crate hyper;
#[macro_use]
extern crate log;
#[macro_use]
extern crate serde;
extern crate serde_json;

extern crate reqwest;
extern crate uuid;

extern crate chrono;

extern crate backoff;

extern crate url;

#[cfg(feature = "metrix")]
extern crate metrix;

pub mod auth;

mod nakadi;

pub use nakadi::api;
pub use nakadi::consumer;
pub use nakadi::handler::*;
pub use nakadi::metrics;
pub use nakadi::model::{EventType, FlowId, PartitionId, StreamId, SubscriptionId};
pub use nakadi::streaming_client;
pub use nakadi::{CommitStrategy, Nakadion, NakadionBuilder, NakadionConfig, SubscriptionDiscovery};

pub use nakadi::publisher;

pub use nakadi::events;