Features & Benefits

Metro provides interoperability between Java Web Services and Microsoft's Windows Communication Foundation. It focuses on enterprise class features such as security, reliable messaging, and atomic transactions.

Interoperability is accomplished by implementing a number of WS-*specifications and holding plugfests where Sun and Microsoft engineers work together testing our respective implementations of those specifications.

Metro enterprise features fall into four main categories: messaging, metadata, security, and quality-of-service (QoS), as shown in the following figure.

Starting with the core XML support built into the Java platform, we use or extend existing features and add new support for metadata, messaging, security, and quality-of-service. Each of these areas has a number of specifications used by Sun and Microsoft to guide our implementations.

Don't let the list of specifications intimidate you. The specifications are for Sun and Microsoft engineers. Programmers using Project Tango are presented with a simple programming model: they use JAX-WS and NetBeans. NetBeans is used to configure reliable messaging and security (note that transactions are specified using existing annotations). Programmers who want to use something other than NetBeans can consult WSDL samples that show how to add policies for configuration.

From a functional point-of-view the main features enabled by the above specifications are:

• Bootstrapping communication (WS-MetaDataExchange)
• Securing communication (WS-SecurityPolicy, WS-Security, WS-Trust)
• Optimizing communication (MTOM, WS-SecureConversation)
• Enabling reliability (WS-ReliableMessaging)
• Enabling atomic transactions (WS-Coordination, WS-AtomicTransactions)

The following list gives a broad overview of the main areas and specifications to give you a good idea of how interoperability is accomplished.

• Messaging
  • SOAP: Support for the SOAP wire protocol is built into JAX-WS.
  • MTOM: JAX-WS also includes support for Message Transmission Optimization Mechanism (MTOM) for optimizing the wire format of SOAP messages.
  • WS-Addressing: supports normalized web service addresses, enabling multiple transports to be used (besides HTTP). JAX-WSA (i.e., JSR 261), the Java APIs for W3C Web Services Addressing is available in the Java Web Services Developer Pack now.
• Metadata
• WSDL: Support for the Web Services Description Language is built into JAX-WS.
• WS-Policy: Policies express and handle requirements and capabilities of web service consumers and providers.
• WS-MetadataExchange: "WS-MEX" is a protocol to enable a consumer to obtain a service's metadata (i.e., its WSDL and policies). Think of it as a bootstrap mechanism for communication.
• Security
• WS-SecurityPolicy: Defines specific policies (i.e., assertions) that describe how messages are secured.
• WS-Security: Provides message content integrity and confidentiality (even in the presence of intermediaries).
• WS-Trust: Provides methods for issuing, renewing, and validating security tokens used by WS-Security. It also provides ways to establish and broker trust relationships
• WS-SecureConversation: Can be viewed as a security optimization (i.e., better message level security and efficiency in multiple-message exchanges).
• QoS
• WS-ReliableMessaging: Enables a messaging system to recover from failures caused by messages that are lost or misordered in transit.
• WS-Coordination: A framework for providing protocols that coordinate the actions of distributed applications. Used by WS-AtomicTransactions.
• WS-AtomicTransactions: Supports two phase commit semantics such that either all operations invoked within an atomic transaction succeed or are all rolled back.