Return-Path: X-Original-To: apmail-incubator-general-archive@www.apache.org Delivered-To: apmail-incubator-general-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 2D9FB18B88 for ; Tue, 24 Nov 2015 19:40:42 +0000 (UTC) Received: (qmail 65617 invoked by uid 500); 24 Nov 2015 19:40:41 -0000 Delivered-To: apmail-incubator-general-archive@incubator.apache.org Received: (qmail 65373 invoked by uid 500); 24 Nov 2015 19:40:41 -0000 Mailing-List: contact general-help@incubator.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: general@incubator.apache.org Delivered-To: mailing list general@incubator.apache.org Received: (qmail 65361 invoked by uid 99); 24 Nov 2015 19:40:40 -0000 Received: from Unknown (HELO spamd4-us-west.apache.org) (209.188.14.142) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 24 Nov 2015 19:40:40 +0000 Received: from localhost (localhost [127.0.0.1]) by spamd4-us-west.apache.org (ASF Mail Server at spamd4-us-west.apache.org) with ESMTP id 7BE24C0845 for ; Tue, 24 Nov 2015 19:40:40 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at spamd4-us-west.apache.org X-Spam-Flag: NO X-Spam-Score: 0.002 X-Spam-Level: X-Spam-Status: No, score=0.002 tagged_above=-999 required=6.31 tests=[DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.001, URIBL_BLOCKED=0.001] autolearn=disabled Authentication-Results: spamd4-us-west.apache.org (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com Received: from mx1-us-east.apache.org ([10.40.0.8]) by localhost (spamd4-us-west.apache.org [10.40.0.11]) (amavisd-new, port 10024) with ESMTP id SqX4jK7BLQ4G for ; Tue, 24 Nov 2015 19:40:27 +0000 (UTC) Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by mx1-us-east.apache.org (ASF Mail Server at mx1-us-east.apache.org) with ESMTPS id 19332429A9 for ; Tue, 24 Nov 2015 19:40:27 +0000 (UTC) Received: by pabfh17 with SMTP id fh17so32388134pab.0 for ; Tue, 24 Nov 2015 11:40:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:content-type:mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to; bh=nRXXyt7+sOihZU+y2qdVmSoOZQb2+gIOw/YLJ8mBQlo=; b=Z1zZjDvfhTWnetcjHqfxcn6Ie5o9I1FITQmGkCiaJgFJlji8rWD5BZ0lUpoi7R47HN 0IxKO+akI6Jqsz8E6c6jVBY8w93wvv2nC81iqn3fIembdzimFQVW98U8nK4413VoW4aO ojjTQzsCzLQ151bmwv4n5yvTiI0iy59MDvVe3QpvHffeJmKnyNKOpSuFhrNXf8P8XPrZ K2u7h2+daTA+A/ZoLU/N2QsBh9pAw2fObZ/uVZOEwlTHVolsOqCvsKP6mLlu7L9GLQDY AHU0w1rKpVmZKWBe+skCWaSs2jn0CZ39D+0Qaw1LnFupuSH1vAJatWZ6TK/IlevtFFjb 8q0Q== X-Received: by 10.98.42.9 with SMTP id q9mr25219533pfq.142.1448394026420; Tue, 24 Nov 2015 11:40:26 -0800 (PST) Received: from [172.16.2.14] ([74.217.76.101]) by smtp.gmail.com with ESMTPSA id 70sm16001373pfr.2.2015.11.24.11.40.25 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 24 Nov 2015 11:40:25 -0800 (PST) Sender: Jarek Jarcec Cecho Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.1 \(3096.5\)) Subject: Re: [VOTE] Accept Kudu into the Apache Incubator From: Jarek Jarcec Cecho In-Reply-To: Date: Tue, 24 Nov 2015 11:40:24 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: general@incubator.apache.org X-Mailer: Apple Mail (2.3096.5) > [X] +1, accept Kudu into the Incubator (binding) Jarcec > On Nov 24, 2015, at 11:32 AM, Todd Lipcon wrote: >=20 > Hi all, >=20 > Discussion on the [DISCUSS] thread seems to have wound down, so I'd = like to > call a VOTE on acceptance of Kudu into the ASF Incubator. The proposal = is > pasted below and also available on the wiki at: > https://wiki.apache.org/incubator/KuduProposal >=20 > The proposal is unchanged since the original version, except for the > addition of Carl Steinbach as a Mentor. >=20 > Please cast your votes: >=20 > [] +1, accept Kudu into the Incubator > [] +/-0, positive/negative non-counted expression of feelings > [] -1, do not accept Kudu into the incubator (please state reasoning) >=20 > Given the US holiday this week, I imagine many folks are traveling or > otherwise offline. So, let's run the vote for a full week rather than = the > traditional 72 hours. Unless the IPMC objects to the extended voting > period, the vote will close on Tues, Dec 1st at noon PST. >=20 > Thanks > -Todd > ----- >=20 > =3D Kudu Proposal =3D >=20 > =3D=3D Abstract =3D=3D >=20 > Kudu is a distributed columnar storage engine built for the Apache = Hadoop > ecosystem. >=20 > =3D=3D Proposal =3D=3D >=20 > Kudu is an open source storage engine for structured data which = supports > low-latency random access together with efficient analytical access > patterns. Kudu distributes data using horizontal partitioning and > replicates each partition using Raft consensus, providing low > mean-time-to-recovery and low tail latencies. Kudu is designed within = the > context of the Apache Hadoop ecosystem and supports many integrations = with > other data analytics projects both inside and outside of the Apache > Software Foundation. >=20 >=20 >=20 > We propose to incubate Kudu as a project of the Apache Software = Foundation. >=20 > =3D=3D Background =3D=3D >=20 > In recent years, explosive growth in the amount of data being = generated and > captured by enterprises has resulted in the rapid adoption of open = source > technology which is able to store massive data sets at scale and at = low > cost. In particular, the Apache Hadoop ecosystem has become a focal = point > for such =E2=80=9Cbig data=E2=80=9D workloads, because many = traditional open source > database systems have lagged in offering a scalable alternative. >=20 >=20 >=20 > Structured storage in the Hadoop ecosystem has typically been achieved = in > two ways: for static data sets, data is typically stored on Apache = HDFS > using binary data formats such as Apache Avro or Apache Parquet. = However, > neither HDFS nor these formats has any provision for updating = individual > records, or for efficient random access. Mutable data sets are = typically > stored in semi-structured stores such as Apache HBase or Apache = Cassandra. > These systems allow for low-latency record-level reads and writes, but = lag > far behind the static file formats in terms of sequential read = throughput > for applications such as SQL-based analytics or machine learning. >=20 >=20 >=20 > Kudu is a new storage system designed and implemented from the ground = up to > fill this gap between high-throughput sequential-access storage = systems > such as HDFS and low-latency random-access systems such as HBase or > Cassandra. While these existing systems continue to hold advantages in = some > situations, Kudu offers a =E2=80=9Chappy medium=E2=80=9D alternative = that can dramatically > simplify the architecture of many common workloads. In particular, = Kudu > offers a simple API for row-level inserts, updates, and deletes, while > providing table scans at throughputs similar to Parquet, a = commonly-used > columnar format for static data. >=20 >=20 >=20 > More information on Kudu can be found at the existing open source = project > website: http://getkudu.io and in particular in the Kudu white-paper = PDF: > http://getkudu.io/kudu.pdf from which the above was excerpted. >=20 > =3D=3D Rationale =3D=3D >=20 > As described above, Kudu fills an important gap in the open source = storage > ecosystem. After our initial open source project release in September = 2015, > we have seen a great amount of interest across a diverse set of users = and > companies. We believe that, as a storage system, it is critical to = build an > equally diverse set of contributors in the development community. Our > experiences as committers and PMC members on other Apache projects = have > taught us the value of diverse communities in ensuring both longevity = and > high quality for such foundational systems. >=20 > =3D=3D Initial Goals =3D=3D >=20 > * Move the existing codebase, website, documentation, and mailing = lists to > Apache-hosted infrastructure > * Work with the infrastructure team to implement and approve our code > review, build, and testing workflows in the context of the ASF > * Incremental development and releases per Apache guidelines >=20 > =3D=3D Current Status =3D=3D >=20 > =3D=3D=3D=3D Releases =3D=3D=3D=3D >=20 > Kudu has undergone one public release, tagged here > https://github.com/cloudera/kudu/tree/kudu0.5.0-release >=20 > This initial release was not performed in the typical ASF fashion -- = no > source tarball was released, but rather only convenience binaries made > available in Cloudera=E2=80=99s repositories. We will adopt the ASF = source release > process upon joining the incubator. >=20 >=20 > =3D=3D=3D=3D Source =3D=3D=3D=3D >=20 > Kudu=E2=80=99s source is currently hosted on GitHub at > https://github.com/cloudera/kudu >=20 > This repository will be transitioned to Apache=E2=80=99s git hosting = during > incubation. >=20 >=20 >=20 > =3D=3D=3D=3D Code review =3D=3D=3D=3D >=20 > Kudu=E2=80=99s code reviews are currently public and hosted on Gerrit = at > http://gerrit.cloudera.org:8080/#/q/status:open+project:kudu >=20 > The Kudu developer community is very happy with gerrit and hopes to = work > with the Apache Infrastructure team to figure out how we can continue = to > use Gerrit within ASF policies. >=20 >=20 >=20 > =3D=3D=3D=3D Issue tracking =3D=3D=3D=3D >=20 > Kudu=E2=80=99s bug and feature tracking is hosted on JIRA at: > https://issues.cloudera.org/projects/KUDU/summary >=20 > This JIRA instance contains bugs and development discussion dating = back 2 > years prior to Kudu=E2=80=99s open source release and will provide an = initial seed > for the ASF JIRA. >=20 >=20 >=20 > =3D=3D=3D=3D Community discussion =3D=3D=3D=3D >=20 > Kudu has several public discussion forums, linked here: > http://getkudu.io/community.html >=20 >=20 >=20 > =3D=3D=3D=3D Build Infrastructure =3D=3D=3D=3D >=20 > The Kudu Gerrit instance is configured to only allow patches to be > committed after running them through an extensive set of pre-commit = tests > and code lints. The project currently makes use of elastic public = cloud > resources to perform these tests. Until this point, these resources = have > been internal to Cloudera, though we are currently investing in moving = to a > publicly accessible infrastructure. >=20 >=20 >=20 > =3D=3D=3D=3D Development practices =3D=3D=3D=3D >=20 > Given that Kudu is a persistent storage engine, the community has a = high > quality bar for contributions to its core. We have a firm belief that = high > quality is achieved through automation, not manual inspection, and = hence > put a focus on thorough testing and build infrastructure to ensure = that > bar. The development community also practices review-then-commit for = all > changes to ensure that changes are accompanied by appropriate tests, = are > well commented, etc. >=20 > Rather than seeing these practices as barriers to contribution, we = believe > that a fully automated and standardized review and testing practice = makes > it easier for new contributors to have patches accepted. Any new = developer > may post a patch to Gerrit using the same workflow as a seasoned > contributor, and the same suite of tests will be automatically run. If = the > tests pass, a committer can quickly review and commit the contribution = from > their web browser. >=20 > =3D=3D=3D Meritocracy =3D=3D=3D >=20 > We believe strongly in meritocracy in electing committers and PMC = members. > We believe that contributions can come in forms other than just code: = for > example, one of our initial proposed committers has contributed solely = in > the area of project documentation. We will encourage contributions and > participation of all types, and ensure that contributors are = appropriately > recognized. >=20 > =3D=3D=3D Community =3D=3D=3D >=20 > Though Kudu is relatively new as an open source project, it has = already > seen promising growth in its community across several organizations: >=20 > * '''Cloudera''' is the original development sponsor for Kudu. > * '''Xiaomi''' has been helping to develop and optimize Kudu for a new > production use case, contributing code, benchmarks, feedback, and > conference talks. > * '''Intel''' has contributed optimizations related to their hardware > technologies. > * '''Dropbox''' has been experimenting with Kudu for a machine = monitoring > use case, and has been contributing bug reports and product feedback. > * '''Dremio''' is working on integration with Apache Drill and = exploring > using Kudu in a production use case. > * Several community-built Docker images, tutorials, and blog posts = have > sprouted up since Kudu=E2=80=99s release. >=20 >=20 >=20 > By bringing Kudu to Apache, we hope to encourage further contribution = from > the above organizations as well as to engage new users and = contributors in > the community. >=20 > =3D=3D=3D Core Developers =3D=3D=3D >=20 > Kudu was initially developed as a project at Cloudera. Most of the > contributions to date have been by developers employed by Cloudera. >=20 >=20 >=20 > Many of the developers are committers or PMC members on other Apache > projects. >=20 > =3D=3D=3D Alignment =3D=3D=3D >=20 > As a project in the big data ecosystem, Kudu is aligned with several = other > ASF projects. Kudu includes input/output format integration with = Apache > Hadoop, and this integration can also provide a bridge to Apache = Spark. We > are planning to integrate with Apache Hive in the near future. We also > integrate closely with Cloudera Impala, which is also currently being > proposed for incubation. We have also scheduled a hackathon with the = Apache > Drill team to work on integration with that query engine. >=20 > =3D=3D Known Risks =3D=3D >=20 > =3D=3D=3D Orphaned Products =3D=3D=3D >=20 > The risk of Kudu being abandoned is low. Cloudera has invested a great = deal > in the initial development of the project, and intends to grow its > investment over time as Kudu becomes a product adopted by its customer > base. Several other organizations are also experimenting with Kudu for > production use cases which would live for many years. >=20 > =3D=3D=3D Inexperience with Open Source =3D=3D=3D >=20 > Kudu has been released in the open for less than two months. However, = from > our very first public announcement we have been committed to = open-source > style development: >=20 > * our code reviews are fully public and documented on a mailing list > * our daily development chatter is in a public chat room > * we send out weekly =E2=80=9Ccommunity status=E2=80=9D reports = highlighting news and > contributions > * we published our entire JIRA history and discuss bugs in the open > * we published our entire Git commit history, going back three years = (no > squashing) >=20 >=20 >=20 > Several of the initial committers are experienced open source = developers, > several being committers and/or PMC members on other ASF projects = (Hadoop, > HBase, Thrift, Flume, et al). Those who are not ASF committers have > experience on non-ASF open source projects (Kiji, open-vm-tools, et = al). >=20 > =3D=3D=3D Homogenous Developers =3D=3D=3D >=20 > The initial committers are employees or former employees of Cloudera. > However, the committers are spread across multiple offices (Palo Alto, = San > Francisco, Melbourne), so the team is familiar with working in a > distributed environment across varied time zones. >=20 >=20 >=20 > The project has received some contributions from developers outside of > Cloudera, and is starting to attract a ''user'' community as well. We = hope > to continue to encourage contributions from these developers and = community > members and grow them into committers after they have had time to = continue > their contributions. >=20 > =3D=3D=3D Reliance on Salaried Developers =3D=3D=3D >=20 > As mentioned above, the majority of development up to this point has = been > sponsored by Cloudera. We have seen several community users = participate in > discussions who are hobbyists interested in distributed systems and > databases, and hope that they will continue their participation in the > project going forward. >=20 > =3D=3D=3D Relationships with Other Apache Products =3D=3D=3D >=20 > Kudu is currently related to the following other Apache projects: >=20 > * Hadoop: Kudu provides MapReduce input/output formats for integration > * Spark: Kudu integrates with Spark via the above-mentioned input = formats, > and work is progressing on support for Spark Data Frames and Spark = SQL. >=20 >=20 >=20 > The Kudu team has reached out to several other Apache projects to = start > discussing integrations, including Flume, Kafka, Hive, and Drill. >=20 >=20 >=20 > Kudu integrates with Impala, which is also being proposed for = incubation. >=20 >=20 >=20 > Kudu is already collaborating on ValueVector, a proposed TLP spinning = out > from the Apache Drill community. >=20 >=20 >=20 > We look forward to continuing to integrate and collaborate with these > communities. >=20 > =3D=3D=3D An Excessive Fascination with the Apache Brand =3D=3D=3D >=20 > Many of the initial committers are already experienced Apache = committers, > and understand the true value provided by the Apache Way and the = principles > of the ASF. We believe that this development and contribution model is > especially appropriate for storage products, where Apache=E2=80=99s > community-over-code philosophy ensures long term viability and > consensus-based participation. >=20 > =3D=3D Documentation =3D=3D >=20 > * Documentation is written in AsciiDoc and committed in the Kudu = source > repository: >=20 > * https://github.com/cloudera/kudu/tree/master/docs >=20 >=20 >=20 > * The Kudu web site is version-controlled on the =E2=80=98gh-pages=E2=80= =99 branch of the > above repository. >=20 > * A LaTeX whitepaper is also published, and the source is available = within > the same repository. > * APIs are documented within the source code as JavaDoc or C++-style > documentation comments. > * Many design documents are stored within the source code repository = as > text files next to the code being documented. >=20 > =3D=3D Source and Intellectual Property Submission Plan =3D=3D >=20 > The Kudu codebase and web site is currently hosted on GitHub and will = be > transitioned to the ASF repositories during incubation. Kudu is = already > licensed under the Apache 2.0 license. >=20 >=20 >=20 > Some portions of the code are imported from other open source projects > under the Apache 2.0, BSD, or MIT licenses, with copyrights held by = authors > other than the initial committers. These copyright notices are = maintained > in those files as well as a top-level NOTICE.txt file. We believe this = to > be permissible under the license terms and ASF policies, and confirmed = via > a recent thread on general@incubator.apache.org . >=20 >=20 >=20 > The =E2=80=9CKudu=E2=80=9D name is not a registered trademark, though = before the initial > release of the project, we performed a trademark search and = Cloudera=E2=80=99s > legal counsel deemed it acceptable in the context of a data storage = engine. > There exists an unrelated open source project by the same name related = to > deployments on Microsoft=E2=80=99s Azure cloud service. We have been = in contact > with legal counsel from Microsoft and have obtained their approval for = the > use of the Kudu name. >=20 >=20 >=20 > Cloudera currently owns several domain names related to Kudu = (getkudu.io, > kududb.io, et al) which will be transferred to the ASF and redirected = to > the official page during incubation. >=20 >=20 >=20 > Portions of Kudu are protected by pending or published patents owned = by > Cloudera. Given the protections already granted by the Apache License, = we > do not anticipate any explicit licensing or transfer of this = intellectual > property. >=20 > =3D=3D External Dependencies =3D=3D >=20 > The full set of dependencies and licenses are listed in > https://github.com/cloudera/kudu/blob/master/LICENSE.txt >=20 > and summarized here: >=20 > * '''Twitter Bootstrap''': Apache 2.0 > * '''d3''': BSD 3-clause > * '''epoch JS library''': MIT > * '''lz4''': BSD 2-clause > * '''gflags''': BSD 3-clause > * '''glog''': BSD 3-clause > * '''gperftools''': BSD 3-clause > * '''libev''': BSD 2-clause > * '''squeasel''':MIT license > * '''protobuf''': BSD 3-clause > * '''rapidjson''': MIT > * '''snappy''': BSD 3-clause > * '''trace-viewer''': BSD 3-clause > * '''zlib''': zlib license > * '''llvm''': University of Illinois/NCSA Open Source (BSD-alike) > * '''bitshuffle''': MIT > * '''boost''': Boost license > * '''curl''': MIT > * '''libunwind''': MIT > * '''nvml''': BSD 3-clause > * '''cyrus-sasl''': Cyrus SASL license (BSD-alike) > * '''openssl''': OpenSSL License (BSD-alike) >=20 > * '''Guava''': Apache 2.0 > * '''StumbleUpon Async''': BSD > * '''Apache Hadoop''': Apache 2.0 > * '''Apache log4j''': Apache 2.0 > * '''Netty''': Apache 2.0 > * '''slf4j''': MIT > * '''Apache Commons''': Apache 2.0 > * '''murmur''': Apache 2.0 >=20 >=20 > '''Build/test-only dependencies''': >=20 > * '''CMake''': BSD 3-clause > * '''gcovr''': BSD 3-clause > * '''gmock''': BSD 3-clause > * '''Apache Maven''': Apache 2.0 > * '''JUnit''': EPL > * '''Mockito''': MIT >=20 > =3D=3D Cryptography =3D=3D >=20 > Kudu does not currently include any cryptography-related code. >=20 > =3D=3D Required Resources =3D=3D >=20 > =3D=3D=3D Mailing lists =3D=3D=3D >=20 > * private@kudu.incubator.apache.org (PMC) > * commits@kudu.incubator.apache.org (git push emails) > * issues@kudu.incubator.apache.org (JIRA issue feed) > * dev@kudu.incubator.apache.org (Gerrit code reviews plus dev = discussion) > * user@kudu.incubator.apache.org (User questions) >=20 >=20 > =3D=3D=3D Repository =3D=3D=3D >=20 > * git://git.apache.org/kudu >=20 > =3D=3D=3D Gerrit =3D=3D=3D >=20 > We hope to continue using Gerrit for our code review and commit = workflow. > The Kudu team has already been in contact with Jake Farrell to start > discussions on how Gerrit can fit into the ASF. We know that several = other > ASF projects and podlings are also interested in Gerrit. >=20 >=20 >=20 > If the Infrastructure team does not have the bandwidth to support = Gerrit, > we will continue to support our own instance of Gerrit for Kudu, and = make > the necessary integrations such that commits are properly = authenticated and > maintain sufficient provenance to uphold the ASF standards (e.g. via = the > solution adopted by the AsterixDB podling). >=20 > =3D=3D Issue Tracking =3D=3D >=20 > We would like to import our current JIRA project into the ASF JIRA, = such > that our historical commit messages and code comments continue to = reference > the appropriate bug numbers. >=20 > =3D=3D Initial Committers =3D=3D >=20 > * Adar Dembo adar@cloudera.com > * Alex Feinberg alex@strlen.net > * Andrew Wang wang@apache.org > * Dan Burkert dan@cloudera.com > * David Alves dralves@apache.org > * Jean-Daniel Cryans jdcryans@apache.org > * Mike Percy mpercy@apache.org > * Misty Stanley-Jones misty@apache.org > * Todd Lipcon todd@apache.org >=20 > The initial list of committers was seeded by listing those = contributors who > have contributed 20 or more patches in the last 12 months, indicating = that > they are active and have achieved merit through participation on the > project. We chose not to include other contributors who either have = not yet > contributed a significant number of patches, or whose contributions = are far > in the past and we don=E2=80=99t expect to be active within the ASF. >=20 > =3D=3D Affiliations =3D=3D >=20 > * Adar Dembo - Cloudera > * Alex Feinberg - Forward Networks > * Andrew Wang - Cloudera > * Dan Burkert - Cloudera > * David Alves - Cloudera > * Jean-Daniel Cryans - Cloudera > * Mike Percy - Cloudera > * Misty Stanley-Jones - Cloudera > * Todd Lipcon - Cloudera >=20 > =3D=3D Sponsors =3D=3D >=20 > =3D=3D=3D Champion =3D=3D=3D >=20 > * Todd Lipcon >=20 > =3D=3D=3D Nominated Mentors =3D=3D=3D >=20 > * Jake Farrell - ASF Member and Infra team member, Acquia > * Brock Noland - ASF Member, StreamSets > * Michael Stack - ASF Member, Cloudera > * Jarek Jarcec Cecho - ASF Member, Cloudera > * Chris Mattmann - ASF Member, NASA JPL and USC > * Julien Le Dem - Incubator PMC, Dremio > * Carl Steinbach - ASF Member, LinkedIn >=20 > =3D=3D=3D Sponsoring Entity =3D=3D=3D >=20 > The Apache Incubator --------------------------------------------------------------------- To unsubscribe, e-mail: general-unsubscribe@incubator.apache.org For additional commands, e-mail: general-help@incubator.apache.org