Chapter 11. Securing Web ServicesDesign Strategies and Best Practices

Topics in This Chapter

• Web Services Security Protocols Stack

• Web Services Security Infrastructure

• Web Services Security Patterns

• Best Practices and Pitfalls

Web services provide XML standards-based technology for developing and deploying application components. They provide an ideal infrastructure solution for delivering cross-platform application-to-application communication and integration. Web services are increasingly used for enabling inter-enterprise communication, workflow, and collaboration, and for integrating business applications over a network. Enabling XML Web services enables interoperability among applications developed using heterogeneous environments such as J2EE, Microsoft .NET, CORBA, and C++.

Security in Web services can be implemented from the ground up in a loosely coupled and platform-independent way, ensuring secure communication and controlled access via authentication and authorization. This is achieved by applying rules and policies for access to exposed services and establishing a circle of trust among service providers, identity providers, and service requesters. Adopting XML-based security and other standards-based technologies provides the mechanisms for achieving the goals of end-to-end Web services security and also enabling interoperability among infrastructure providers. Applying security and establishing trust among Web services or between a Web service and its consumer has created newer challenges, some of which remain un-addressed by traditional security methods and technologies. Because Web services can be dynamically located, subscribed, and consumed using a wide range of heterogeneous applications, system platforms, devices, and so on, it is also the responsibility of the Web services provider to facilitate a standardized security mechanism that can be accessed by the service requesters using heterogeneous platforms and devices.

For example, in a healthcare Web services scenario, a patient viewing his or her medical records via Web services should not be constrained or impacted by whether he or she is using a Web browser client, a network accessible device, or a stand-alone application as long as the service requester client is able to view the secured information using a network with the required standards, secure message transport, and relevant message-level security mechanisms required by the Web service provider. Similarly, a patient's record may be viewed in a workflow by multiple participants, including a physician, lab specialist, pharmacist, insurance provider, and so on. The problem is that each participant may require access to a selected portion of the document without compromising the security of the patient's health record.

In Chapter 6, we discussed the Web services architectural goals, Web services security threats and vulnerabilities, security requirements, and evolving standards and technologies. When implementing Web services applications, the known security risks and threats are usually considered as security challenges that need to be addressed with safeguards and countermeasures prior to deployment. Otherwise they can affect numerous aspects of the overall Web services architecture, including security, availability, reliability, scalability, and manageability. Many of these security challenges are captured and addressed using a proven set of security design patterns and best practices that are applicable during the architectural and design phases of Web services development.

This chapter explores the Web services security design strategies, applied patterns, and best practices that contribute to building end-to-end security of Web services. This chapter adheres to the XML security specifications derived from industry-standard efforts and compliant vendor implementations for building XML Web services.