|
What is EJB container?- An EJB container will provide the runtime environment for EJB applications within the application server.
- It is responsible for all the operations of the EJB applications.
- The container acts as an intermediary action between the business logic of the bean and the rest of the world of the enterprise application.
- One or more EJB modules can be installed within a single EJB container.
- The role of EJB container is to perform transactional actions such as,
1. Starting a transaction.
2. Rollback a transaction or commit a transaction.
3. Managing various connection pools for the database resources.
4. Bean’s instance variables with corresponding data items which are stored in a database will be synchronized. Explain the four types of container that J2EE supports.EJB Container:
- An EJB container will provide the runtime environment for EJB applications within the application server.
- It is responsible for all the operations of the EJB applications.
- The container acts as an intermediary action between the business logic of the bean and the rest of the world of the enterprise application.
- One or more EJB modules can be installed within a single EJB container. The role of EJB container is to perform transactional actions such as,
1. Starting a transaction.
2. Rollback a transaction or commit a transaction.
3. Managing various connection pools for the database resources.
4. Bean’s instance variables with corresponding data items which are stored in a database will be synchronized.
Web Container:
- A web container implements a web component such as servlet container.
- A servlet container supports the operations of a servlet.
- It supports the web server operations and the client java operations such as JRE,maps the URL specific requests into servlet requests.
- The servlet cotainers have the ability to dynamically add or remove servlets from the system.
- Individual servlets will get registered by the servlet container.
- The servlet API is provided by different vendors for a specific servlet standard.
Application Client Container:
- An application client container includes set of java classes, libraries and the set of files that are needed and distributed among various java client applications which executes on their own JVMs.
- The ACC is responsible for managing the applications execution by providing all the system services that are needed for the execution of java client programs.
- It is light-weighted and communicates with different application servers.
Applet client container:
- Like application client container, applet container executes the client applications.
- The difference is an applet executes the application in a separate browser.
- They execute on their own JVMs.
- It supports the applet programming model.
- JEE client may use java plug-in to provide the required environment that executes the applet.
Developer classes vs. container classes.
- The developer classes are the classes that are authored by the developers
- The container classes are the classes which supports the container to manage the container specific functionality.Explain the difference between servers and containers.- The server receives the requests from client and sends the responses to the client.
- If it is a web server or EJB server, the request will be sent to the web container or to the EJB container.
- A web server responds requests over the web.
- The container creates the required objects pertaining to the requests and responses, and invokes the appropriate service methods.
- Containers also provide the communication support, life cycle management, multithreading support and declarative security.
- A container runs inside the web or application server which could produce dynamic content.
|
