Securing Containers
In Java EE, the component containers are responsible for providing application security. A container provides two types of security: declarative and programmatic. The following sections discuss these concepts in more detail.
Using Deployment Descriptors for Declarative Security
Declarative security expresses an application component’s security requirements using deployment descriptors. A deployment descriptor is an XML document with an .xml extension that describes the deployment settings of an application, a module, or a component. Because deployment descriptor information is declarative, it can be changed without the need to modify the source code. At runtime, the Java EE server reads the deployment descriptor and acts upon the application, module, or component accordingly.
This tutorial does not document how to write the deployment descriptors from scratch, only what configurations each example requires its deployment descriptors to define. For help with writing deployment descriptors, you can view the provided deployment descriptors in a text editor. Each example’s deployment descriptors are stored at the top layer of each example’s directory. Another way to learn how to write deployment descriptors is to read the specification in which the deployment descriptor elements are defined.
Deployment descriptors must provide certain structural information for each component if this information has not been provided in annotations or is not to be defaulted.
Different types of components use different formats, or schema, for their deployment descriptors. The security elements of deployment descriptors which are discussed in this tutorial include the following:
Enterprise JavaBeans components use an EJB deployment descriptor that must be named META-INF/ejb-jar.xml and must be contained in the EJB JAR file.
The schema for enterprise bean deployment descriptors is provided in the EJB 3.0 Specification (JSR-220), Chapter 18.5, Deployment Descriptor XML Schema, which can be downloaded from http://jcp.org/en/jsr/detail?id=220.
Security elements for EJB deployment descriptors are discussed in this tutorial in the section Using Enterprise Bean Security Deployment Descriptor Elements.
Web Services components use a jaxrpc-mapping-info deployment descriptor defined in JSR 109. This deployment descriptor provides deployment-time mapping functionality between Java and WSDL. In conjunction with JSR 181, JAX-WS 2.0 complements this mapping functionality with development-time Java annotations that control mapping between Java and WSDL.
The schema for web services deployment descriptors is provided in Web Services for Java EE (JSR-109), section 7.1, Web Services Deployment Descriptor XML Schema, which can be downloaded from http://jcp.org/en/jsr/detail?id=109.
Schema elements for web application deployment descriptors are discussed in this tutorial in the section Declaring Security Requirements in a Deployment Descriptor.
Web components use a web application deployment descriptor named web.xml.
The schema for web component deployment descriptors is provided in the Java Servlet 2.5 Specification (JSR-154), section SRV.13, Deployment Descriptor, which can be downloaded from http://jcp.org/en/jsr/detail?id=154.
Security elements for web application deployment descriptors are discussed in this tutorial in the section Declaring Security Requirements in a Deployment Descriptor.
Using Annotations
Annotations enable a declarative style of programming, and so encompass both the declarative and programmatic security concepts. Users can specify information about security within a class file using annotations. When the application is deployed, this information is used by the Application Server. Not all security information can be specified using annotations, however. Some information must be specified in the application deployment descriptors.
Annotations let you avoid writing boilerplate code under many circumstances by enabling tools to generate it from annotations in the source code. This leads to a declarative programming style, where the programmer says what should be done and tools emit the code to do it. It also eliminates the need for maintaining side files that must be kept up to date with changes in source files. Instead the information can be maintained in the source file.
In this tutorial, specific annotations that can be used to specify security information within a class file are described in the following sections:
The following are sources for more information on annotations:
JSR 175: A Metadata Facility for the Java Programming Language
JSR 181: Web Services Metadata for the Java Platform
JSR 250: Common Annotations for the Java Platform
The Java SE discussion of annotations
Links to this information are provided in Further Information about Security.
Using Programmatic Security
Programmatic security is embedded in an application and is used to make security decisions. Programmatic security is useful when declarative security alone is not sufficient to express the security model of an application. The API for programmatic security consists of two methods of the EJBContext interface and two methods of the servlet HttpServletRequest interface. These methods allow components to make business logic decisions based on the security role of the caller or remote user.
Programmatic security is discussed in more detail in the following sections: