|Developer(s)||Apache Software Foundation|
|Stable release||1.6.2 / April 17, 2012|
|Written in||Java and C|
|License||Apache License 2.0|
Axis2 not only provides the capability to add Web services interfaces to Web applications, but can also function as a standalone server application.
Why Apache Axis2 
A new architecture for Axis2 was introduced[by whom?] during the August 2004 Axis2 Summit in Colombo, Sri Lanka. The new architecture on which Axis2 is based is more flexible, efficient and configurable in comparison to Axis1.x architecture. Some well-established concepts from Axis 1.x, like handlers etc., have been preserved in the new architecture.
Apache Axis2 not only supports SOAP 1.1 and SOAP 1.2, but it also has integrated support for the widely popular REST style of Web services. The same business-logic implementation can offer both a WS-* style interface as well as a REST/POX style interface simultaneously.
Axis2/Java has support for Spring Framework.
Axis2/C seems to be abandoned in 2009.
Axis2 comes with many new features, enhancements and industry specification implementations. Key features offered include:
Axis2 Features 
Apache Axis2 includes support for following standards:
- WS - ReliableMessaging - Via Apache Sandesha2
- WS - Coordination - Via Apache Kandula2
- WS - AtomicTransaction - Via Apache Kandula2
- WS - SecurityPolicy - Via Apache Rampart
- WS - Security - Via Apache Rampart
- WS - Trust - Via Apache Rampart
- WS - SecureConversation - Via Apache Rampart
- SAML 1.1 - Via Apache Rampart
- SAML 2.0 - Via Apache Rampart
- WS - Addressing - Module included as part of Axis2 core
Further, Axis2 offers following features and characteristics.
- Speed - Axis2 uses its own object model and StAX (Streaming API for XML) parsing to achieve significantly greater speed than earlier versions of Apache Axis.
- Low memory foot print - Axis2 was designed ground-up keeping low memory foot print in mind.
- AXIOM - Axis2 comes with its own light-weight object model, AXIOM, for message processing which is extensible, optimized for performance, and simplified for developers.
- Hot Deployment - Axis2 is equipped with the capability of deploying Web services and handlers while the system is up and running. In other words, new services can be added to the system without having to shut down the server. Simply drop the required Web service archive into the services directory in the repository, and the deployment model will automatically deploy the service and make it available for use.
- Asynchronous Web services - Axis2 now supports asynchronous Web services and asynchronous Web services invocation using non-blocking clients and transports.
- MEP Support - Axis2 now comes handy with the flexibility to support Message Exchange Patterns (MEPs) with in-built support for basic MEPs defined in WSDL 2.0.
- Flexibility - The Axis2 architecture gives the developer complete freedom to insert extensions into the engine for custom header processing, system management, and anything else you can imagine.
- Stability - Axis2 defines a set of published interfaces which change relatively slowly compared to the rest of Axis.
- Component-oriented Deployment - You can easily define reusable networks of Handlers to implement common patterns of processing for your applications, or to distribute to partners.
- Transport Framework - We have a clean and simple abstraction for integrating and using Transports (i.e., senders and listeners for SOAP over various protocols such as SMTP, FTP, message-oriented middleware, etc.), and the core of the engine is completely transport-independent.
- WSDL support - Axis2 supports the Web Services Description Language, version 1.1 and 2.0, which allows you to easily build stubs to access remote services, and also to automatically export machine-readable descriptions of your deployed services from Axis2.
- Add-ons - Several Web services specifications have been incorporated including WSS4J for security (Apache Rampart), Sandesha for reliable messaging, Kandula which is an encapsulation of WS-Coordination, WS-AtomicTransaction and WS-BusinessActivity.
- Composition and Extensibility - Modules and phases improve support for composability and extensibility. Modules support composability and can also support new WS-* specifications in a simple and clean manner. They are however not hot deployable as they change the overall behavior of the system.
Axis2 Modules 
Axis2 modules provides QoS features like security, reliable messaging, etc.
- Apache Rampart module - Apache Rampart modules adds WS - Security features to Axis2 engine
- Apache Sandesha module - An implementation of WS - Reliable Messaging specification
Related technologies 
- Apache Axis
- Apache CXF - other Apache web services framework (old XFire & Celtix)
- Java Web Services Development Pack - web services framework
- XML Interface for Network Services - RPC/web services framework
- Web Services Invocation Framework - Java API for invoking Web services
- AlchemySOAP - C++ open source SOAP-based web services framework
Axis2 Books 
- Quickstart Apache Axis2.
- Apache Axis Homepage at the Apache Software Foundation
- Apache Axis2/Java at the Apache Software Foundation
- Apache Axis2/C at the Apache Software Foundation
- Apache Axis2 Module Page
- Web services using Apache Axis2
- How to run an Axis2 client running against a Windows Web Server - Rob Austin
- "Axis2, Middleware for Next Generation Web Services". Proceedings of the IEEE International Conference on Web Services. ICWS '06. CiteSeerX: 10.1.1.62.1740.
- Axis2 Tutorial