Toshiya Kobayashi
Software Developer at IBM
Yokohama, Japan
Summary
🤩
Rockstar🎓
Top SchoolToshiya Kobayashi is a seasoned software developer with 15 years of experience specializing in back-end systems, business automation, and rule engines. Based in Yokohama, he spent over 15 years at Red Hat improving core projects like Drools, jBPM and Kogito—contributing features such as date-effective decision tables, lambda externalization, and performance fixes for constraint indexing. He brings full-stack experience from work on the jBPM web designer (including internationalization and Japanese translations) and practical integration expertise across Spring, Quarkus and OptaPlanner. His open-source contributions demonstrate a focus on correctness and precision (BigDecimal handling, expression language fixes) and on making complex BPM/DMN tooling more robust and usable. Now at IBM, he continues to apply deep domain knowledge in rule-based and process-driven systems to enterprise-grade software. Collectedly, his background blends low-level numeric and expression-language care with pragmatic engineering for cloud-native business automation.
15 years of coding experience
24 years of employment as a software developer
Bachelor of Arts (B.A.), Philosophy, Bachelor of Arts (B.A.), Philosophy at Kyoto University
Japanese, English
Stackoverflow
658reputation
3kreached
6answers
1question
Github Skills (39)
back-end-development10
utf10
jbpm10
processmaker10
bigdecimal10
drools10
mvel10
workflow-engine10
business-process-management10
dmn10
java10
rule-engine10
javas10
junit10
bpmn10
Programming languages (9)
Github contributions (5)
apache/incubator-kie-drools
Jan 2013 - Jan 2023
Drools is a rule engine, DMN engine and complex event processing (CEP) engine for Java.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1014 reviews, 400 commits, 845 PRs in 10 years 1 month
Contributions summary:Toshiya made multiple contributions to the Apache Drools project, focusing on improving the rule engine and related tooling. The commits include enhancements related to lambda externalization, particularly for features like "from" and "OOPath" clauses, and performance improvements for constraint indexing. They also addressed issues related to BigDecimal calculations and integration within the MVEL dialect.
droolsbusiness-rulesdmn-engineevent-processingcomplex-event-processing
mvel/mvel
Jan 2014 - Dec 2021
MVEL (MVFLEX Expression Language)
Role in this project:Back-end Developer
Back-end DeveloperContributions:12 reviews, 7 commits, 22 PRs in 7 years 11 months
Contributions summary:Toshiya primarily contributed to improving the MVEL expression language, focusing on bug fixes and enhancements. They addressed issues related to getter detection for boolean properties with internationalized names. The user also worked on number coercion, specifically preventing the conversion of certain numeric types to others to maintain precision. Furthermore, they enhanced the `getBestCandidate` method for BigDecimal arguments and fixed compound assignment operations for BigDecimal types.
expression-language
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