WSA

Web Services Architecture

Developers writing distributed applications need a way to provide:

• Security
• Message integrity
• Message confidentiality
• Authentication
• Authorization
• Non-repudiation
• Reliability
• Transactions
• Etc.

The Web Services Architecture (WSA) is a set of protocols that use XML and SOAP (a Web service protocol) to solve the problems that every distributed application written with Web services faces. They allow developers to save time and concentrate on writing software instead of worring about plumbing issues. It is important to understand how WSA works, because it will be used by Aviation Web Services that C3D Aero builds.

The best way to understand what WSA does is to think of the U.S. Post Office. You can place an addressed, stamped, and sealed envelope in a mailbox and you don’t have to worry about anybody looking inside it or how it will get to its destination. You also have the option to use additional services like certified mail.

Click to enlarge the WSA security protocols diagram below:

WS-Security

The most important WSA security protocol is WS-Security because the other security protocols use it. WS-Security uses a technology called XML Signature to provide message integrity. XML Signature uses an algorithm to create and encrypt a message digest which can be compared to the original message. If any modification of the message has occurred, the digest will not match.

WS-Security also provides message confidentiality. It uses a technology called XML Encryption and security tokens such as usernames and passwords, X.509 certificates, and Kerberos tickets to encrypt sections of XML documents.

Other WSA protocols

WSA contains more than just security protocols. WS-ReliableMessaging allows messages to be delivered in the presence of software and network failures. The WS-Addressing protocol defines Web service endpoints which allow message transmission through gateways and firewalls. WS-Routing allows a SOAP message to specify a virtualized path through a network.

Another protocol called WS-Attachments allows attached files (documents, pictures, sound, video, etc.) to be sent with SOAP messages. The WS-Transactions protocol allows applications using more than one Web service to coordinate changes.

There are more WSA protocols. However, a detailed discussion of each one is beyond the scope of this web page. The important thing to remember is that C3D Aero uses WSA protocols to build Aviation Web Services.