Vennila Sundar Rajan

Vennila Sundar Rajan

United Kingdom
7K followers 500+ connections

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About

As a Solutions Architect at J.P. Morgan, I work on modernizing legacy financial systems…

Activity

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Experience

  • J.P. Morgan Graphic

    J.P. Morgan

    Glasgow, Scotland, United Kingdom

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    Glasgow, United Kingdom

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    London, United Kingdom

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    Coventry, United Kingdom

Education

  • University of Leicester Graphic

    University of Leicester

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    Activities and Societies: Microsoft Ltd., Google, Inc.

    This course focuses on the algorithmic basis techniques underlying cloud computing. It equips students with the understanding and practical skills required to achieve the best outcome of the theoretical knowledge gained so far.

    Explains from basic to advanced concepts of cloud computing in order to design & build an efficient software for rapid growing technologies and the demands dominated by the economical pressure.

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Licenses & Certifications

Courses

  • Advanced System Design

    CO7205

  • Advanced Web Technologies

    CO7215

  • Distributed Systems and Applications

    CO7090

  • Financial Services Information Systems

    CO7218

  • Internet & Cloud Computing

    CO7219

  • Personal and Group Skills

    CO7210

  • Service-Oriented Architectures

    CO7214

  • Web Technologies

    CO7098

Projects

  • Hobby Project 1 for Learning - Monolithic to Modular Monolith Transformation

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    Re-architecting E-Commerce Platform: Journey from Monolith to Modular Monolith

    Experimental architecture transformation project demonstrating incremental modernization strategy for a simulated e-commerce platform without the operational overhead of microservices.


    Traditional monolithic application with 200K+ LOC experiencing scaling bottlenecks, deployment risks, and team velocity issues. Goal: Enable independent module development while maintaining single deployment unit…

    Re-architecting E-Commerce Platform: Journey from Monolith to Modular Monolith

    Experimental architecture transformation project demonstrating incremental modernization strategy for a simulated e-commerce platform without the operational overhead of microservices.


    Traditional monolithic application with 200K+ LOC experiencing scaling bottlenecks, deployment risks, and team velocity issues. Goal: Enable independent module development while maintaining single deployment unit benefits.

    Architecture Process:
    Phase 1: Domain Analysis & Boundary Definition

    Applied Domain-Driven Design (DDD) principles to identify bounded contexts
    Mapped 6 core domains: User Management, Product Catalog, Order Processing, Payment, Inventory, Notification
    Created context mapping to identify upstream/downstream dependencies

    Phase 2: Module Extraction Strategy

    Established module interface contracts using hexagonal architecture
    Implemented internal API gateways for inter-module communication
    Defined clear module ownership and dependency rules (no circular dependencies)

    Phase 3: Incremental Refactoring

    Strangler Fig pattern to gradually extract modules
    Started with least-dependent module (Notification Service)
    Moved shared database to module-specific schemas with defined integration points

    Phase 4: Module Isolation

    Enforced module boundaries using ArchUnit for compile-time validation
    Implemented module-level CI/CD pipelines for independent testing
    Created module-specific feature flags for controlled rollouts

    Phase 5: Observability & Monitoring

    Added distributed tracing within monolith using OpenTelemetry
    Module-level metrics and dashboards
    Performance comparison: 40% faster deployment, 60% reduction in merge conflicts

    Tech Stack: Spring Boot 3.x, Maven multi-module, PostgreSQL (schema-per-module), Redis, OpenTelemetry, Arch Unit


    Outcome: Successfully demonstrated that modular monoliths can provide 80% of microservices benefits while avoiding distributed system complexity.

  • Hobby Project 2 for Learning : Modular Monolith to Microservices

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    "The Distribution Phase" - Building on the modular monolith foundation, selectively extracting modules into microservices based on independent scaling needs, team autonomy requirements, and technology diversification.

    Established Rules:

    Module Independence: Each module has clear API boundaries
    No Direct Database Access: Modules cannot query other module's tables
    Explicit Dependencies: Module dependencies must be declared in Maven/Gradle
    Interface Segregation: Thin…

    "The Distribution Phase" - Building on the modular monolith foundation, selectively extracting modules into microservices based on independent scaling needs, team autonomy requirements, and technology diversification.

    Established Rules:

    Module Independence: Each module has clear API boundaries
    No Direct Database Access: Modules cannot query other module's tables
    Explicit Dependencies: Module dependencies must be declared in Maven/Gradle
    Interface Segregation: Thin, focused APIs between modules
    No Circular Dependencies: Enforced at build time

    Module Communication:

    Synchronous: Internal REST-like APIs (Spring @FeignClient pattern)
    Asynchronous: Internal event bus using Spring Events initially
    Data Access: Schema-per-module in same database

  • Monolith → Modular Monolith → Microservices ~ Hobby Project for Learning

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    The Problem with the Monolith
    Simple Analogy:
    "Imagine you have a massive IKEA warehouse where everything is in one giant room - furniture, utensils, decorations, all mixed together. When you want to find a lamp, you have to navigate through the entire warehouse. When one team wants to reorganize the furniture section, they accidentally bump into the utensils section. That was our monolith."
    The Problem: Our Giant Messy Monolith
    Picture this: we had a Spring Boot application that…

    The Problem with the Monolith
    Simple Analogy:
    "Imagine you have a massive IKEA warehouse where everything is in one giant room - furniture, utensils, decorations, all mixed together. When you want to find a lamp, you have to navigate through the entire warehouse. When one team wants to reorganize the furniture section, they accidentally bump into the utensils section. That was our monolith."
    The Problem: Our Giant Messy Monolith
    Picture this: we had a Spring Boot application that had been growing for 5 years. It was huge - 250,000 lines of code, one massive codebase, one database with 150+ tables. Fifteen teams were all working in the same repository, stepping on each other's toes constantly. We had 45 merge conflicts every single week. It was chaos.
    The business pain was real. We could only deploy twice a week, and each deployment took 45 minutes. Worse, if something broke, it took us 4 hours to figure out what went wrong because everything was so tangled together. When Black Friday came and we needed more servers for inventory, we had to scale the entire application - even the parts that didn't need it. Super wasteful.
    New developers? They needed a full month just to understand the codebase before they could be productive. That's expensive.

    So the Project is taking a messy e-commerce application and transforming it step-by-step into a modern, scalable architecture. The cool part? We improved deployment speed by 400%, cut costs by 40%, and made developers way more productive.

    Step 1: Making a Modular Monolith First
    Each module had:

    Its own database schema (no more stepping on each other)
    Its own tests (faster to run)
    Its own code ownership (one team responsible)
    Clear APIs (documented contracts)

    Step 2: Selective Microservices - Only When Necessary

    Step 3: Building the Microservices Platform

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Languages

  • English

    Full professional proficiency

  • Tamil

    Native or bilingual proficiency

  • Telugu

    Limited working proficiency

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