honnix / jaxo

wrap all Java XML stuffs as OSGi service, well, not all

Introduction

JAXP, JAXB, JAXWS, these XML stuffs can not work well together with OSGi due to class loading strategy. Also nearly all of them are not thread-safe and have critical performance problem if without proper pooling.

Core Bundle

The core bundle wraps latest implementations, pools, and finally provides services.

One should note that this bundle is absolutely not high configurable since we believe JAXP and JAXB is completely over engineered and nobody would ever configure it as it is supposed to be, so either you like this project or you think it sucks.

One good example is javax.xml.parser.DocumentBuilderFactory, by default we set it as namespace awared, and no validation enabled. The reason is, if someone ask you to use JAXP or JAXB, they surely want you to use damn namespace because it is both cool and zhuangbilable, so why not eanbling it by default; and you certainly can validate the DOM after it is built, so validation is no disabled.

This bundle is not an implementation of OSGi Service Platform Service Compendium 702 XML Parser Service Specification. One of the most important reason is checked exception which is a completely failure design of JAXP and JAXP. It just sucks. Another reason is this specification is too simple to be used in reality. So forget about it.

Build and Run

> mvn clean install

> mvn pax:provision

Details

com.honnix.jaxo.core

This bundle provides following OSGi services:

• CoreService

  This service uses ThreadLocal to cache DocumentBuilder, XPath, etc. The client only needs to get and use without concerning about return back.

• PoolableCoreSerivce

  This service uses object pool to cache DocumentBuilder, XPath, etc. Since this is a pool, the client needs to get, use and then return it back, otherwise the object will be lost.

  For each kind of pool, it can be configured separately through standard OSGi ConfigAdmin service. Each configuration key is prefixed with the class name, for example:

  • javax.xml.parsers.DocumentBuilder.maxIdle=4
  • javax.xml.parsers.DocumentBuilder.minIdle=2
  • javax.xml.parsers.DocumentBuilder.maxActive=6
  • javax.xml.parsers.DocumentBuilder.maxWait=100
  • javax.xml.parsers.DocumentBuilder.timeBetweenEvictionRunsMillis=100
  • javax.xml.parsers.DocumentBuilder.minEvictableIdleTimeMillis=1000
  • javax.xml.xpath.XPath.maxIdle=4
  • javax.xml.xpath.XPath.minIdle=2
  • javax.xml.xpath.XPath.maxActive=6
  • javax.xml.xpath.XPath.maxWait=100
  • javax.xml.xpath.XPath.timeBetweenEvictionRunsMillis=100
  • javax.xml.xpath.XPath.minEvictableIdleTimeMillis=1000

  For what these configurations mean, please refer to Apache Commons Pool.

  Currently, following types of objects can be configured:

  • javax.xml.parsers.DocumentBuilder
  • javax.xml.parsers.SAXParser
  • javax.xml.xpath.XPath
  • javax.xml.transform.Transformer
  • javax.xml.validation.Validator

  service.pid equals to service name, and if not configured, default values provided by Apache Commons Pool will be used.

com.honnix.jaxo.example

This bundle acts as an example of how to use services. It is very simple, so just read through the source code. One thing need to mention is maven dependency. The client should define dependencies:

<dependency>
  <groupId>com.honnix.jaxo</groupId>
  <artifactId>com.honnix.jaxo.core</artifactId>
  <version>${release.version}</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>xml-apis</groupId>
  <artifactId>xml-apis</artifactId>
  <version>1.4.01</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>javax.xml.bind</groupId>
  <artifactId>jaxb-api</artifactId>
  <version>2.2.6</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>javax.xml.ws</groupId>
  <artifactId>jaxws-api</artifactId>
  <version>2.2.8</version>
  <scope>provided</scope>
</dependency>

And the client should not delegate javax.xml to bootstrap class loader.

Acknowledgement

Quality ensured by Travis CI.