However, its history is not as widely known despite its critical importance in the Java ecosystem.
Maven Central, as part of the build automation tool Apache Maven, is the primary software registry and repository for Java components, libraries, and frameworks, as well as Java Virtual Machine (JVM) languages. It serves as the lifeblood of the Java development community, providing essential software dependencies and components for Java projects.
But how did Maven Central come into existence, and how did it grow to become the vital resource it is today?
In this blog post, we explore the evolution of Maven Central, highlighting its crucial role in the Java ecosystem and software development overall. We also discuss Sonatype's essential involvement and continual efforts to modernize this pivotal repository.
Maven: An origin story
To understand the history of Maven Central, we first delve into the origins of Apache Maven.
In the early 2000s, Maven began as a sub-project of Apache Turbine, which was part of the Jakarta Project hosted by the Apache Software Foundation. Maven reached its first critical milestone in July 2004 with the release of version 1.0.
Maven was one of the first systems to promote the following:
- binary reusability;
- convention over configuration; and
- declarative dependency management through Project Object Model (POM) files.
A Maven POM file is an XML file that describes the structure of a project, its dependencies, and metadata about the authors, licenses, and version control. A POM file with an artifact, such as a Java Archive (JAR) file, defines a format for hosting projects and allows the build system to identify and fetch them recursively.
Before the advent of Maven, most Java engineers used the Apache Ant build tool. Using Ant meant all necessary libraries, including every single library and its transitive dependencies, are stored in the version control system along with the source code. Designed in pre-AWS days, Apache Maven became a ground-breaking new system for downloading artifacts from a remote repository.
Maven also allowed users to publish to a repository in a custom format. This format made it easy for consumers to fetch any transitive dependencies.
The first Maven repository is what's known today as Maven Central. It's a community-lead repository where anyone can publish artifacts. By pulling dependencies from a central location you not only save on version-control storage space, but also gain the capability to manage dependencies more effectively from your build tool.
The Maven Central and Sonatype connection
Sonatype has hosted Maven Central for quite some time — but not from the very beginning.
Maven Central has a rich history of shifting homes to accommodate its growing needs. It began its journey at the Apache Software Foundation and shortly thereafter found a gracious host in Ibiblio, which supported Maven during its early expansion phases.
As Maven Central's demands began to strain Ibiblio's infrastructure, Jason Van Zyl purchased a machine and had it racked up at Contegix. Matthew Porter, founder and CEO of Contegix, provided significantly discounted bandwidth costs which really allowed the repository to continue growing without breaking the bank. This machine served Maven Central 24x7 for many years. When it was finally decommissioned in 2011, we published a bit of the story at the time.
With the evolution of Sonatype, founded by Van Zyl and Brian Fox in 2008, the day-to-day management of Maven Central was eventually entrusted to Fox and a dedicated team. Today, Engineering Manager Joel Orlina leads a technical operations team at Sonatype that supports the various services that make up today's Maven Central.
They manage all aspects of Maven Central, from user registrations to supporting Nexus instances, documenting procedures for users and publishers, maintaining the repository, and ensuring the seamless operation of the infrastructure and content delivery network (CDN). Their diligent work keeps Maven Central running smoothly.
The impact of Maven Central
According to Sonatype's co-founder and chief technology officer (CTO), Brian Fox, Maven Central in its infancy was a response to challenges posed by the Apache Maven build system.
In the early 2000s, many open source projects weren't built with Maven, which thus lacked the metadata necessary for search functionality that could make components readily accessible. To bridge this gap, the Java community needed a central repository to share component metadata.
This need led to the official coining of Maven Central in 2005. It served as a central hub where open source binaries and associated metadata could be distributed, enabling Java developers to manage their project dependencies effectively.
As the Java ecosystem continued to evolve, more build systems emerged, such as Gradle and Ivy. Still, Maven's metadata format became the de facto standard for all these tools. The ease of access to open source Java libraries, made available through Maven Central, further solidified its importance.
Beyond Java: Expanding the horizons
While Maven Central was initially conceived as a repository for Java libraries, it evolved to accommodate other JVM languages, such as Scala, which was made directly available beginning in early 2012.
Its expansion is a testament to the adaptability and indispensability of a central repository of open source software for multiple JVM languages.
Other milestones in the lead up to present-day Maven Central include the following:
- 2010: Sonatype provisions a new official Maven Central repository for users in Europe.
- 2014: The operations team at Sonatype implements SSL connectivity for Maven Central.
- 2018: Sonatype enhances SSL connectivity and implements HTTP/2 support for Maven Central.
- 2020: In the spirit of security and data integrity, Sonatype moves Maven Central to HTTPS.
Maven Central serves as a fundamental component in the software supply chain, crucial for various JVM languages. The ease of accessibility to a vast array of open source components has led to its adoption by other build tools, including Gradle, enabling interoperability between these tools.
Maven Central by the numbers
Over the years, Maven Central has experienced exponential growth in consumption. The statistics are staggering, with billions of downloads each year, and a repository size that has far outgrown its humble beginnings.
While housing over half a million projects with over 12 million total project versions, Maven Central fielded an estimated one trillion requests in 2023.
As we unveiled in our recently published 9th annual State of the Software Supply Chain report, the Maven Central ecosystem has been experiencing 28% year-over-year project growth and 25% year-over-year download growth.
With the Sonatype team as its stewards, Maven Central continues to be a driving force for open source software.
Growing and protecting the ecosystem
As the popularity of Maven Central continued to grow, the repository faced a few challenges.
Bandwidth and the Bintray shutdown
One notable moment in Maven Central's history involved surges in bandwidth and requests. The repository experienced a significant increase in activity, primarily due to the onboarding of new publishers and an influx of publishing activity.
This uptick in usage, which was much higher than the typical month-to-month increases, presented a unique challenge.
A noteworthy incident in this regard was the shutdown of JFrog Bintray, a prominent alternative repository to Maven Central. The sudden announcement left many open source publishers without a home for their projects, leading to panic and an influx of new projects looking to migrate.
Sonatype responded quickly to help users who suddenly needed to migrate from Bintray. They reached out to the community and offered support, resources, and migration assistance for projects affected by the Bintray shutdown. This proactive approach helped maintain the integrity of the software supply chain, emphasizing the importance of responsible open source development.
Validation and metadata
One of the distinguishing features of Maven Central is its rigorous validation and metadata requirements for published artifacts.
In addition to the name and version, publishers must provide detailed information about the artifact, including descriptions, licenses, developer information, software configuration management (SCM) URLs, and more. While this may seem burdensome initially, it plays a critical role in ensuring the integrity and safety of the Java ecosystem.
In his The Secret Life of Maven Central presentation, Joel Orlina described the Maven Central publisher experience as follows:
- "Sonatype Nexus Repository serves as a caching proxy, and there's actually functionality in the professional version that ensures a certain level of quality for the components before you can actually publish them. Are your components well-formed? Do you have a complete set of metadata around them? Are you providing sources and Javadocs? Do you have PGP signatures? This is actually the area of the Maven ecosystem where my team and I receive the most interaction with customers, because we raise a non-trivial bar for people to vault over before they can even publish. We're not letting you in unless you can actually meet these requirements."
By adhering to these requirements, developers and users can have confidence in the software they consume from Maven Central, especially in the context of recent security concerns like Log4Shell, the Log4j exploit, which remains an ongoing problem.
A crucial aspect of Maven Central's history is its dedication to security.
In January 2021, Sonatype discovered a novel software supply chain attack of malicious brandjacking components in Maven Central. This attack involved threat actors pushing fake artifacts into repositories, potentially compromising the security of unsuspecting users.
Remarkably, Maven Central remained unscathed by this attack. This is rooted in the strong validation and metadata requirements enforced by the repository. Unlike some other ecosystems where anyone can publish without clear namespaces, Maven Central's stringent requirements help protect users from downloading potentially harmful artifacts.
When it comes to security and management, Maven Central has implemented measures to ensure the safety and integrity of its artifacts. From May 2021 onward, all staged repositories on OSS Repository Hosting (OSSRH) are scanned automatically as they're published to Maven Central. Developers receive reports via email providing details on security issues in their dependencies for things released through OSSRH.
This proactive approach to security helps maintain the trust of the developer community in using Maven Central.
Modernization efforts by Sonatype
In recent years, Sonatype has been actively working to modernize Maven Central to meet the evolving needs of developers and the broader software industry.
One of the primary goals is to provide a more unified and user-friendly experience for both publishers and consumers. This involves consolidating various aspects of the Maven Central ecosystem, from publishing to access, into a single coherent experience.
In March 2023, Sonatype released Maven Central with a new design and new features to improve security and vulnerability detection for developers using the repository.
Additionally, Sonatype remains focused on improving identity management, enabling developers to log in, update information, and access new features seamlessly.
With Sonatype's continued support and the growing demand for open source components, Maven Central is poised to remain a vital resource for developers worldwide.
Maven Central and Sonatype: Driving the software development landscape
Maven Central's journey epitomizes evolution, adaptation, and unwavering commitment under the guidance of Sonatype. From its inception as a Java repository to its present role as an indispensable resource for diverse JVM languages and build tools, Maven Central's enduring significance reflects its resilience.
This ecosystem, fostering open source collaboration, transcended its roots as a repository of Java libraries to become a comprehensive asset for developers across multiple languages, enriched by myriad contributions, including those from Sonatype.
Sonatype's dedication to open source innovation, evident in its Maven Central stewardship, democratizes software development by providing a secure, reliable, and efficient platform for open source component distribution.
Maven Central's story is not merely about a repository. It's a tale of a community that champions open source, of developers committed to accelerating software development. Sonatype, through its stewardship of Maven Central, contributes to shaping the future of software development.