Breathing new life into JSP with OSGi!

1 minute read


  • JSP!!! What’s the meaning of this?
  • Bytecode is Better
  • Initial Problems
  • Compiling
  • Designing a Solution
  • Key Java EE OSGi Bundles
  • Jasper*
  • Compilation -
  • OSGi Support - org.osgi.framework.wiring
  • Phidias
  • Liferay JSP Compiler
  • Some Details
  • Demo Time

JSP!!! What’s the meaning of this?

  • Isn’t JSP a dead tech?
  • Enterprises use JSP a lot
    • find -type f -regex .*\.jspf? | wc -l
      • Eclipse = 59
      • Liferay = 1696
      • Liferay Plugins = 669

Bytecode is Better

  • Compiled to Bytecode view templates still most efficient server side
    • w.r.t. memory consumption and performance
    • Other _compiled to bytecode_ view tech not as widely known
      • Play Scala Templates
      • Google Soy Templates

Initial Problems

  • Java EE instantiation model (ServiceLoader, Class.forName, TCCL)
  • Limitations to the existing JSP servlet impls required ugly hacks
  • Compilation dependencies lead to complex runtime dependencies


  • Traditionally - JDT _load the world_ compilation strategy
    • JDT is not a small dependency
  • Other compilation options non-existent
  • OSGi had no way to natively support compilation process

Designing a Solution

  • Re-use existing tech when possible
  • Use JDK compiler API (since Java 6)
  • Avoid lots of hacks
  • Keep a small footprint
  • Limit usage requirements

Key Java EE OSGi Bundles

  • Key API/RIs are OSGi bundles ** Servlet ** JSP ** JSTL ** EL


  • Proven and stable
  • Has limited dependencies
  • Recently solved issues enabling easier OSGi use

Thanks Glassfish!

Java SE Support -

  • Since Java SE 6
  • Full blown compiler support
  • .. complicated to use

OSGi Support - org.osgi.framework.wiring

  • Since Core R4.3
  • Deep classloader & wiring resource access


  • Small OSS bundle which crosses
    • org.osgi.framework.wiring
  • Provides simplified OSGi aware compiler support
  • Alpha (0.3.4)

Liferay JSP Compiler

  • Extends Jasper with custom
    • JSP compiler which uses Phidias
    • JSP servlet which transparently handles classloading concerns

Some Details

  • Entire JSP support ~ 1.3MB
  • Most modern versions of JSP, JSTL, EL available
  • No need to declare any JSP related imports in JSP enabled bundles
  • No need to include any libs or standard TLDs
  • No need to WAB your bundles
    • Can use regular old jar layout + web fragment subtree
      • Place JSPs in META-INF/resources/

OSGi Aware Compilation

  • Does this open the door for other interesting topics?
    • Limit compile time view of the world to public APIs?