Philip Hazel was 51 when he began the Exim message transfer agent (MTA) project in 1995, which led to the Perl-Compatible Regular Expressions (PCRE) project in 1998. At 80, he's maintained PCRE, and its successor PCRE2, for more than 27 years. For those doing the math, that's a year longer than LWN has been in publication. Exim maintenance was handed off around the time of his retirement in 2007. Now, he is ready to hand off PCRE2 as well, if a successor can be found. Hazel's tenure as a free-software developer is exceptional, if not record-breaking in its length. Linus Torvalds began working on Linux in 1991 as a college student and is still leading its development 33 years later with no signs of slowing. However, as Hazel wrote in his technical memoir From Punched Cards To Flat Screens, he began contributing to free software "nearer the end than the start" of his career. This LWN.net subscription-only content has been made available to you by an LWN subscriber. For more details, see the original source.
Early Career and Introduction to Computers
At the beginning of his career, Philip Hazel was introduced to computers during his undergraduate years when the University of Cape Town received an International Computers and Tabulators (ICT) 1301. He immersed himself in the basics of programming by attending lectures and reading manuals. This initial exposure laid the foundation for what would be a long and distinguished career in software development.
Description: The ICT 1301 computer that sparked Hazel’s interest in the field of computing.
Hazel moved to the University of Cambridge as a PhD student, where he had access to multiple computer systems including Titan, IBM 1130, IBM 360, and PDP-7. His fluency in Manchester Autocode, akin to Titan Autocode, granted him an early opportunity to delve deeper into software development, eventually leading to his role at Cambridge Computing Service in 1971.
During his tenure at Cambridge, Hazel worked on various systems, gained significant experience, and started the Experimental Internet Mailer (Exim) project in 1995. Its creation was spurred by the limitations and difficulties Hazel faced while programming existing mail transfer agents like Sendmail and Smail.
The Birth and Evolution of Exim
Exim, conceptualized in 1995, began as a solution to the complexities Hazel faced while managing emails at Cambridge. He sought to create an MTA that leveraged modern operating systems, utilized standard C compilers, and could handle TCP/IP networks comprehensively. By November 1995, Exim could send and receive emails, leading to its initial implementation by colleagues. The Exim project quickly gained ground and saw contributions from many users, prompting Hazel to switch the licensing to GPL and making it more accessible for adoption across various systems.
Over time, Exim became a globally recognized MTA, finding its way to many commercial and open-source environments. This success was something Hazel did not initially foresee but reflected the increasing reliance on and trust in free software solutions.
Regular Expressions and PCRE
Regular expressions significantly impact message management in MTAs. Hazel initially adopted a regular expression library written by Henry Spencer for Exim but found it inadequate when compared to Perl’s pattern-matching features. Consequently, he embarked on creating Perl-Compatible Regular Expressions (PCRE), a standalone library providing advanced regex capabilities.
PCRE became a cornerstone in many applications, including Apache HTTPD and Postfix MTA, due to its utility in processing complex regex patterns. Hazel further evolved this project into PCRE2, recognizing the need for extended features that the original API could not support.
Transitioning and Looking Ahead
At 80, Hazel feels it is time to pass the mantle of PCRE2 maintenance to new hands, ideally with the capacity to enhance and sustain the project. Although still uncertain about the future of PCRE2’s stewardship, Hazel remains open to supporting the new maintainers during the transition phase.
In reflecting on his extensive career, Hazel notes the incredible journey from the non-digital era to today’s highly advanced computing landscape. His advice to emerging software developers is to consider the long-term maintenance demands of their projects and the importance of building robust testing frameworks.
Description: Philip Hazel guiding new developers in the seemingly ever-evolving world of software.
Remember these 3 key ideas for your startup:
Long-term Vision and Maintenance: The effort to maintain software far exceeds initial development. Prioritize sustainability and continuous improvement processes. For a deeper understanding, read about how to determine realistic goals for a project.
Adaptation and Flexibility: Embrace the need for regular updates and rewrites to adapt to the changing technological landscape and user requirements. Check out this guide on how and why to prepare for a change freeze.
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