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> ## 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's 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 (page 918).

> - Web Services components use a `jaxrpc-mapping-info` deployment descriptor defined in JSR 109. This deployment descriptor provides deployment time Java`<->`WSDL mapping functionality. In conjunction with JSR 181, JAX-WS 2.0 will complement this mapping functionality with development time Java annotations that control Java, WSDL mapping.

> 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 (page 959).

> - 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 (page 959).

> ### 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 can either be used by or overridden by the application deployment descriptor.

> 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:

> - Declaring Security Requirements Using Annotations (page 957)
> - Using Enterprise Bean Security Annotations (page 917)

> The following are sources for more information on annotations:

> - JSR 175: A Metadata Facility for the Java Programming Language, which can be viewed at
>   `http://jcp.org/en/jsr/detail?id=175`.
> - JSR 181: Web Services Metadata for the Java Platform, which can be viewed at
>   `http://jcp.org/en/jsr/detail?id=181`.
> - JSR 250: Common Annotations for the Java Platform, which can be viewed at
>   `http://jcp.org/en/jsr/detail?id=250`.
> - The Java SE discussion of annotations can be viewed at
>   `http://java.sun.com/j2se/1.5.0/docs/guide/language/annotations.html`.

> ### 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:

> - Accessing an Enterprise Bean Caller's Security Context (page 900)
> - Working with Security Roles (page 947).