Building modular applications
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The document discusses the importance and challenges of building modular applications, emphasizing how modularity aids in managing complexity and scaling development teams. It highlights tools and best practices such as OSGi and Maven that simplify the process but also points out the complexities involved with dependencies and integration across modules. The speaker's background includes extensive experience in enterprise applications and open-source frameworks.
Building modular applications
- 1. Building modular applications Kamal Govindraj TenXperts Technologies
- 2. About Me Programming for 13 Years Architect @ TenXperts Technologies Trainer / Consultant @ SpringPeople Technologies Enteprise applications leveraging open source frameworks (spring,hibernate, gwt,jbpm..) Key contributor to InfraRED & Grails jBPM plugin (open source)
- 3. Agenda Importance of Moudlarity How to? Challenges Tools & best practices OSGI
- 4. Modularity Break application into smaller modules Interaction between module via interfaces Helps in dealing with complexity Break development into smaller teams Reuse Easier to maintain
- 5. Horizontal / Technology Presentation Catalog Inventory Inventory Order Service / Domain Persistence
- 6. Vertical / Functional Order Presentation Inventory Catalog Order Application Inventory Catalog
- 7. Vertical is better Scales better − Team size − Feature Separate concerns along the lines of business functionality Easier to maintain
- 8. Physical Vs Logical Logical separation provides most of the benefits Phyiscal separation issues − Performance overheads − Reduces reliability − Increased Complexity
- 9. Package guidelines Visible to other modules Visible to other modules Private classes / Not visible outside this module
- 10. Challenges Builds become more complex Changes across module boundaries are harder Integration issue Wiring the system together
- 11. Tools & Frameworks Maven − Simplifies multi module builds − Declarative dependency − Transitive dependency handling − Versioned
- 12. Maven in action
- 13. Dependency Injection Takes care of wiring together components from different modules The modules are loosely coupled depending only on the published interfaces Spring Framework / Google Guice / EJB 3.0 ..
- 14. Java module limitation Jar is the basic construct for defining modules Only a compile time construct − Modules are not preserved at run time No way to enforce strict separation Difficult to have multiple versions of same module in a vm Not easy to share modules across multiple applications
- 15. Runtime modularity OSGI − A mature specification & platform − Eclipse is built on OSGI − So are many of the application servers − Multiple implementations (Equinox, Felxi, Knopflerfish JSR 294 – Simple module system for Java
- 16. OSGI A module is a jar with metadata (MANIFEST file) − exported packages − Imported packages with versions − Other module dependecies with versions OSGI container − Manages module lifecycle − Resolve dependencies − Enforces strict separation
- 17. OSGI != modular OSGI can make a existing modular application work better Breaking up a system into well defined modules and maintaining it that way is the harder part Tools can help – but ...
- 18. Questions ?
- 19. Thank You.