Metro, Axis2, CFX

Metro

Metro is a high-performance, extensible, easy-to-use web service stack. The Metro web service stack is a part of the GlassFish community, but it can be also used outside GlassFish. It provides several transports and related technologies to provide efficient connectivity to different services:

HTTP transport

Metro can act as both a client and a server for HTTP. The HTTP web service can run inside any servlet container or anywhere on JavaSE6.

MTOM and XOP

These specifications enable optimized binary encodings of XML content within SOAP 1.2 payloads. XML structure is preserved in a text-based “XML Information Set” manifest, while enabling the document’s contents to be serialized to any binary encoding. These specifications enable encoding of XML content as MIME body parts and encapsulation of those parts – along with the associated XML Information Set manifest — within SOAP 1.2 envelopes. The specifications also describe how to encapsulate binary-encoded XML body parts directly within HTTP packets. The main point is that the size of the XML is reduced resulting in more optimal communication.

SOAP/TCP

SOAP over TCP transport enables highly efficient transmission of SOAP messages by using FastInfoset. Transport support in Metro is extensible. There are other transports available as well, including the in-VM transport, JMS transport, SMTP transport, etc.

Reliability, in Metro, ensures that the underlying system is able to recover from failures caused by messages that are lost or misordered in transit. Recovery is handled by the underlying system without involvement of consumer or provider application code.

Interoperable reliability is achieved by implementing the WS-ReliableMessaging specification. Turning on reliability, in Metro, when developing a web service, is simply a checkbox in a reliability panel in NetBeans.

Atomic transactions are a well-known means to ensure that all operations within a transaction boundary succeed or fail in a consistent manner. If even one operation fails then all other operations are aborted. Transactional support has been available in Java Enterprise Edition for a number of years on IIOP invocations. Metro enables transactional support for web services. Interoperable atomic transactions are enabled, in Metro, by implementing the WSCoordination and WS-AtomicTransactions specifications.

Web services, until now, have relied on transport-based security such as SSL to provide point-to-point security. Metro implements the WS-Security specification to provide interoperable message content integrity and confidentiality, even in the presence of intermediaries. In other words, WS-Security does not rely on transport-based security. WS-Security is a security option provided by Metro besides existing transport security which still may be used. Metro also provides an implementation of the WS-Trust specification as a means for issuing, renewing, and validating security tokens used by WS-Security, and to establish and broker trust relationships.

The core of Metro implements the JAX-WS API and serves as the foundation where all the higher-level features plugs in. The extensibility in this layer enables “pay as you go” model, where you’ll only pay the performance/complexity price for features that you use. The core also provides the basic interoperability features, such as WS-I Basic Profile, WS-I Attachments Profile, and WS-Addressing. Metro builds on top of libraries that are independently reusable outside the context of web services. Those include:

1. JAXB RI for the databinding layer

2. SAAJ for raw DOM access to SOAP messages

3. Woodstox for efficient XML parsing

4. XML stream buffer for efficient infoset buffering

Axis2

Axis2 is a clean and extensible Open Source web services platform with a configurable, modular architecture. The same business logic implementation in Axis2 offers both a SOAP endpoint and a REST interface. Otherwise the architecture is similar to Metro JAX-WS: Axis2 utilizes an XML pull parser, supports hot deployment and asynchronous web services, and can be extended to provide security and reliable messaging similar to WSIT. 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. Apache Axis2 is more efficient, more modular and more XML-oriented than the older version. It is carefully designed to support the easy addition of plug-in “modules” that extend their functionality for features such as security and reliability. The Modules currently available or under development include:

WS-ReliableMessaging - Supported by Apache Sandesha2

WS-Coordination and WS-AtomicTransaction - Supported by Apache Kandula2

WS-Security - Supported by Apache Rampart

WS-Addressing -Module included as part of Axis2 core

Apache Axis2 is built on Apache AXIOM , a new high performant, pull-based XML object model. Axis2 comes with many new features, enhancements and industry specification implementations.

The key features offered are as follows:

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, highly performant and is developer convenient.

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 Service 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.

Apache CFX

Apache CXF is an open source services framework. CXF helps you build and develop services using frontend programming APIs, like JAX-WS. These services can speak a variety of protocols such as SOAP, XML/HTTP, RESTful HTTP, or CORBA and work over a variety of transports such as HTTP, JMS or JBI. CXF includes a broad feature set, but it is primarily focused on the following areas:

Web Services Standards Support: CXF supports a variety of web service standards including SOAP, the Basic Profile, WSDL, WS-Addressing, WS-Policy, WS ReliableMessaging, and WS-Security.

Frontends: CXF supports a variety of “frontend” programming models. CXF implements the JAX-WS APIs (version 2.0 will be TCK compliant). It also includes a “simple frontend” which allows creation of clients and endpoints without annotations. CXF supports both contract first development with WSDL and code first development starting from Java.

Ease of use: CXF is designed to be intuitive and easy to use. There are simple APIs to quickly build code-first services, Maven plug-ins to make tooling integration easy, JAX-WS API support, Spring 2.0 XML support to make configuration a snap, and much more.

Binary and Legacy Protocol Support: CXF has been designed to provide a pluggable architecture that supports not only XML but also non-XML type bindings, such as JSON and CORBA, in combination with any type of transport.

Made by: Arpad Sebesi