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| [](https://travis-ci.org/apache/distributedlog) |
| [](https://builds.apache.org/job/distributedlog-nightly-build/) |
| [](https://coveralls.io/github/apache/distributedlog?branch=master) |
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| # Apache DistributedLog |
| |
| Apache DistributedLog (DL) is a *high-throughput*, *low-latency* replicated log service, offering |
| *durability*, *replication* and *strong consistency* as essentials for building |
| reliable _real-time_ applications. |
| |
| ## Status |
| |
| _Apache DistributedLog project graduated from Incubator at July 2017. It is now a sub-project of Apache BookKeeper._ |
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| ## Features |
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| #### High Performance |
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| DL is able to provide *milliseconds* latency on *durable* writes with a large number |
| of concurrent logs, and handle high volume reads and writes per second from |
| thousands of clients. |
| |
| #### Durable and Consistent |
| |
| Messages are persisted on disk and replicated to store multiple copies to |
| prevent data loss. They are guaranteed to be consistent among writers and |
| readers in terms of *strict ordering*. |
| |
| #### Efficient Fan-in and Fan-out |
| |
| DL provides an efficient service layer that is optimized for running in a multi- |
| tenant datacenter environment such as _Mesos_ or _Yarn_. The service layer is able |
| to support large scale writes (fan-in) and reads (fan-out). |
| |
| #### Various Workloads |
| |
| DL supports various workloads from *latency-sensitive* online transaction |
| processing (OLTP) applications (e.g. WAL for distributed database and in-memory |
| replicated state machines), real-time stream ingestion and computing, to |
| analytical processing. |
| |
| #### Multi Tenant |
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| To support a large number of logs for multi-tenants, DL is designed for I/O |
| isolation in real-world workloads. |
| |
| #### Layered Architecture |
| |
| DL has a modern layered architecture design, which separates the *stateless |
| service tier* from the *stateful storage tier*. To support large scale writes (fan- |
| in) and reads (fan-out), DL allows scaling storage independent of scaling CPU |
| and memory. |
| |
| ## First Steps |
| |
| * *Concepts*: Start with the [basic concepts](http://bookkeeper.apache.org/distributedlog/docs/latest/basics/introduction) of DistributedLog. |
| This will help you to fully understand the other parts of the documentation, |
| including [setup](http://bookkeeper.apache.org/distributedlog/docs/latest/deployment/cluster), |
| [integration](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/api/main.html) and |
| [operation guide](http://bookkeeper.apache.org/distributedlog/docs/latest/admin_guide/main.html). |
| It is highly recommended to read this first. |
| * *Quickstarts*: [Run DistributedLog](http://bookkeeper.apache.org/distributedlog/docs/latest/start/quickstart) on your local machine |
| or follow the tutorial to [write a simple program](http://bookkeeper.apache.org/distributedlog/docs/latest/tutorials/basic-1) to interact with _DistributedLog_. |
| * *Setup*: The [docker](http://bookkeeper.apache.org/distributedlog/docs/latest/deployment/docker) and [cluster](http://bookkeeper.apache.org/distributedlog/docs/latest/deployment/cluster) setup guides show how to deploy DistributedLog stack. |
| * *User Guide*: You can checkout our guides about the [basic concepts](http://bookkeeper.apache.org/distributedlog/docs/latest/basics/introduction) and the [Core Library API](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/api/core) or [Proxy Client API](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/api/proxy) |
| to learn how to use DistributedLog to build your reliable real-time services. |
| |
| ## Next Steps |
| |
| * *Design Documents*: Learn about the [architecture](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/architecture/main), |
| [design considerations](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/design/main) and |
| [implementation details](http://bookkeeper.apache.org/distributedlog/docs/latest/user_guide/implementation/main) of DistributedLog. |
| * *Tutorials*: You can check out the [tutorials](http://bookkeeper.apache.org/distributedlog/docs/latest/tutorials/main) on how to build real applications. |
| * *Admin Guide*: You can check out our guides about how to [operate](http://bookkeeper.apache.org/distributedlog/docs/latest/admin_guide/main) the DistributedLog Stack. |
| |
| ## Get In Touch |
| |
| ### Report a Bug |
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| For filing bugs, suggesting improvements, or requesting new features, help us out by [opening a jira](https://issues.apache.org/jira/browse/DL). |
| |
| ### Need Help? |
| |
| [Subscribe](mailto:distributedlog-user-subscribe@bookkeeper.apache.org) or [mail](mailto:distributedlog-user@bookkeeper.apache.org) the [distributedlog-user@bookkeeper.apache.org](mailto:distributedlog-user@bookkeeper.apache.org) list - Ask questions, find answers, and also help other users. |
| |
| [Subscribe](mailto:distributedlog-dev-subscribe@bookkeeper.apache.org) or [mail](mailto:distributedlog-dev@bookkeeper.apache.org) the [distributedlog-dev@bookkeeper.apache.org](mailto:distributedlog-dev@bookkeeper.apache.org) list - Join developement discussions, propose new ideas and connect with contributors. |
| |
| [Join us on Slack](https://getdl-slack.herokuapp.com/) - This is the most immediate way to connect with DistributedLog committers and contributors. |
| |
| ## Contributing |
| |
| We feel that a welcoming open community is important and welcome contributions. |
| |
| ### Contributing Code |
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| 1. See [Developer Guide](https://cwiki.apache.org/confluence/display/DL/Developer+Guide) to get your local environment setup. |
| |
| 2. Take a look at our [open issues](https://issues.apache.org/jira/browse/DL). |
| |
| 3. Review our [coding style](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=65867477) and follow our [code reviews](https://github.com/apache/distributedlog/pulls) to learn about our conventions. |
| |
| 4. Make your changes according to our [code review workflow](https://cwiki.apache.org/confluence/display/DL/Contributing+to+DistributedLog#ContributingtoDistributedLog-ContributingCodeChanges). |
| |
| 5. Checkout the list of [project ideas](https://cwiki.apache.org/confluence/display/DL/Project+Ideas) to contribute more features or improvements. |
| |
| ### Improving Website and Documentation |
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| 1. See [website/README.md](/website/README.md) on how to build the website. |
| |
| 2. See [docs/README.md](/docs/README.md) on how to build the documentation. |
| |
| ## About |
| |
| Apache DistributedLog is an open source project of The Apache Software Foundation (ASF). The Apache DistributedLog project originated from [Twitter](https://twitter.com/). |
