Ch 2 – Application Assembly and Deployment

1. Ch 2 – Application Assembly and Deployment COSC 617 Jeff Schmitt September 14, 2006

2. Assembly Assembly of an application or component is the process of • collecting all of the elements required (source code, datafiles, configuration files) into a • structured format that can be • deployed to the server environment.

3. Deployment Deployment of a component or application is the process of • actually installing the runnable codethe runtime environment, which involves • making the code available to the server and • resolving resource references in the assembly with the resources actually on the server

4. Application Components J2EE supports various types of application components • Java Servlet API • JavaServer Pages API • JavaServer Faces API • Enterprise Java Beans API • Configuration Files – configure components and external resources needed • Deployment Descriptors – a configuration file for the application itself

5. J2EE Terminology Component – • a functional element of an application that runs within a container and makes use of runtime resources provided by the container (such as security mgmt, transation mgmt, etc) • One or more Java classes plus component-specific resources (properties, files, images) • 5 flavors: application clients, applets, web, EJB resource adapters

6. J2EE Terminology - 2 Module • Collections of components of the same type, to be run inside the corresponding container type • Contains component-specific classes plus any class libraries needed, and other cross-component resources such as datafiles, HTML documents and image files • Contains a standard XML deployment descriptor for external resource references and configuration details

7. Enterprise Application Archive • .ear file • A set of one or more modules, collectively containing all components of the app. • These modules contain • all of the components of the application • a deployment descriptor • Packaged into .jar files (java archive) • A particular layout

8. Assembling Applications • Getting all the application modules together in the right package structure • Deployment descriptor: application.xml – references all the modules which make up an application • Modules can be • EJB in an ejb-jar file • Web modules in a war file

9. JNDI Configuration Services • Assets are located at runtime using JNDI lookups in the namespace of the application server • Examples: • JMS message queues • JCA resource adapters • DataSource for MySql or Oracle database • Other J2EE components

10. JNDI Naming Conventions • Runtime assets are given names within the java:comp/env namespace in the JNDI service java:comp – J2EE components /env – component runtime environment • Coordination required among component code, deployment descriptors, application server • Example: java:comp/dev/jdbc/myDS • Referenced in source code • Configured in deployment descriptor • Actual asset is available in Container

11. Two-level Name Resolution • Assign an independent name when configuring within application server • Link this asset name to the name specified in the component deployment descriptor • Benefits • Allows flexibility • Allows sharing assets among components running on same server

12. Deploying Applications • After application assembly comes application deployment • Application server has an internal JNDI directory • Resource and component references are linked through JNDI • Classloading model – more than one JVM • Assign a separate classloader to each deployed application • Physical deployment – vendor specific details in special configuration files

13. Component Modules Component deployment descriptors specify • Module descriptive information, eg. name • Component elements (EJB web or resource connector) • Configuration data for component services (security services, lifecycle services, persistence services) • Resource and component dependencies (JDBC DataSources, JavaMail Sessions, session EJB, entity EJB)

14. Example • EJB Module descriptor • Component elements, configuration, resource component external resources needed • Web module descriptor • Servlet mapping – how to recognize certain file names, which refer to servlet instead of file. Example: *.do /viewprofile • Session timeouts • Resource declarations to be resolved by the applic server. Example: EJB’s

15. Application Assemblies • Application archive is just a .jar file with files stored in specific locations • Categories of information • Application descriptive information (name) • Module references – location of module .jar file in the application archive • Application security roles- control specific user’s access to components and their operations

16. Steps in Deploying J2EE Applications • Adjust deployment descriptors • Local environmental issues, default settings, maximum number of items, etc. • Perform server-specific configuration • Physical configuration of runtime assets not specified in J2EE since application servers implement services in many ways • Configure required assets in application server • Module deployment descriptor links to assets in app server

17. Deploying J2EE Apps (cont.) • Generate container-specific classes • Contaner-specific classes not specified in J2EE specification • Each server provides its own tools or processes for generating these classes • JBoss automatically generates EJB interface implementations • WebLogic povides command-line tool for generating container-specific classes