Written questions -------------j2ee

j2ee part

1, the connection and difference between BS and CS.

C/S is the abbreviation of Client/Server. Servers usually use high-performance PCs, workstations or minicomputers, and use large database systems such as Oracle, Sybase, InFORMix or SQL Server. The client needs to install dedicated client software.

B/S is the abbreviation of Brower/Server. As long as a browser (Browser) is installed on the client computer, such as Netscape Navigator or Internet Explorer, the server installs databases such as Oracle, Sybase, InFORMix or SQL Server. Under this structure, the user interface is completely implemented through the WWW browser, and part of the transaction logic is implemented on the front end, but the main transaction logic is implemented on the server side. The browser exchanges data with the database through the Web Server.

The difference between C/S and B/S:

1. Different hardware environments:

  C/S is generally built on a dedicated network, a network environment in a small area, and a dedicated server is used to provide connection and data exchange services between local area networks.

  B/S is built on a wide area network and does not have to be specialized Network hardware environment, such as telephone Internet access, rental equipment. Information management. It has a stronger adaptability than C/S, generally as long as there is an operating system and a browser

2. For different security requirements,

  C/S is generally oriented to a relatively fixed user group, and has a strong ability to control information security. Generally, a highly confidential information system adopts a C/S structure. Part of the public information can be released through B/S.

  B/ S is built on a wide area network and has relatively weak control over security, and may be oriented to unknowable users.

3. different program architecture

  C/S programs can pay more attention to the process, multi-level verification of permissions, and less consideration for system running speed.

  B/S's multiple considerations for security and access speed are based on the need for more optimization. C/S has higher requirements. B/S structure program architecture is the trend of development, from MS .Net series BizTalk 2000 Exchange 2000, etc., to fully support the system built by network components. The JavaBean component technology pushed by SUN and IBM etc., make B/S more mature.

4. Software reuse of different

  C/S programs can inevitably consider the integrity, and the reusability of components is not as good as that of components under B/S requirements.

  The multiple structure of B/S pairs requires relatively independent functions of components. Better reuse. Just buy a dining table that can be reused instead of a stone table made on the wall

. Due to the integrity of system maintenance, different  

  C/S programs must be inspected as a whole to deal with problems and system upgrades. Upgrading is difficult. It may be to make a new system

  B/S component composition, and individual components can be replaced to achieve a system without Seam upgrade. System maintenance costs are minimized. Users can download and install themselves from the Internet to achieve upgrades.

5. Dealing with problems Different

  C/S programs can deal with fixed user planes, and in the same area, high security requirements are required, which are related to the operating system. They should all be the same system

  B/S built on the wide area network, facing different user groups, scattered regions , which is impossible for C/S. It has the least relationship with the operating system platform.

7. Different user interface

  C/S are mostly built on the Window platform, the performance methods are limited, and the programmers are generally required to be higher.

  B/S is built on the browser, and has a richer and more vivid way to communicate with users. And most of the difficulty is reduced, reducing the development cost.

8. Different information flow

  C/S programs are generally typical centralized mechanical processing, relatively low interactivity

  B/S information flow can be changed, BB BC BG and other information, flow changes, more like a trading center.

2. What is the difference between application server and WEB SERVER?

     Application server: Weblogic, Tomcat, Jboss

     WEB SERVER: IIS, Apache

3, what are the application servers?

     What is BEA WebLogic Server, IBM WebSphere Application Server, Oracle9i Application Server, jBoss, Tomcat

4, J2EE?

     Answer: Je22 is a multi-diered, distributed, and component-based enterprise application model proposed by Sun. In such an application system, it can be The functionality is divided into different components, which in turn can be on different computers and in corresponding tiers. The hierarchy includes client tier (clietn tier) components, web tier and components, Business tier and components, and enterprise information system (EIS) tier.

     An alternative answer: j2ee is CRUD.

5. Is J2EE a technology or a platform or a framework? What is J2EE

   J2EE itself is a standard, a standard platform for the development of enterprise distributed applications.

   J2EE is also a framework, including JDBC, JNDI, RMI, JMS, EJB, JTA and other technologies.

6. Please explain (or briefly describe) the following terms commonly used in J2EE

     web container: Provide an environment for the application components (JSP, SERVLET) in it, so that JSP, SERVLET can directly interact with the environment variable interface in the container , do not need to pay attention to other system problems. Mainly WEB server to achieve. For example: TOMCAT, WEBLOGIC, WEBSPHERE, etc. The interface provided by the container strictly follows the WEB APPLICATION standard in the J2EE specification. We call the WEB server that complies with the above standards the WEB container in J2EE.

     EJB container: Enterprise java bean container. More industry-specific. It provides various management functions to the component EJB running in it. As long as the EJB that meets the J2EE specification is put into the container, it will be managed efficiently by the container immediately. And system-level services can be obtained through ready-made interfaces. Such as mail service, transaction management.

     JNDI: (Java Naming & Directory Interface) JAVA naming directory service. The main functions provided are: to provide a directory system, so that applications in other places can leave their own indexes on it, so as to meet the functions of quickly finding and locating distributed applications.

     JMS: (Java Message Service) JAVA message service. Mainly realize the communication between various applications. Including point-to-point and broadcast.

     JTA: (Java Transaction API) JAVA transaction service. Provides various distributed transaction services. The application only needs to call the interface it provides.

     JAF: (Java Action FrameWork) JAVA security authentication framework. Provides a framework for some security controls. Let developers implement their own personalized security control policies through various deployments and customizations.     

     RMI/IIOP: (Remote Method Invocation /internet Object Request Intermediary Protocol) They are mainly used to invoke services remotely. For example, if there is a program running on a remote computer, it provides stock analysis services, and we can directly call it on the local computer. Of course, this is only through a certain specification to communicate between heterogeneous systems. RMI is specific to JAVA.

7. How to specify the size of memory for weblogic?

     (This question does not give a specific answer. It is only listed to tell the reader what problems may be encountered. You do not need to cover everything, you are proficient in everything.)

     In the script that starts Weblogic (located in the corresponding Domian startServerName in the server directory), add set MEM_ARGS=-Xms32m -Xmx200m, the minimum memory can be adjusted to 32M, the maximum is 200M      8.

How to set the hot start mode (development mode) and product release mode of weblogic?

Modify the startup mode of the corresponding server to one of the development or production modes. Or modify the service startup file or commenv file and add set PRODUCTION_MODE=true.

9. How to start without entering user name and password?

     Modify the service startup file and add WLS_USER and WLS_PW items. You can also add encrypted username and password to the boot.properties file.

10. After configuring the related information such as jms, ejb or connection pool for an application domain (or a website, Domain) in the weblogic management console, what file is it actually saved in?

     Save it in the config.xml file of this Domain , which is the server's core configuration file.

11. Talk about the default directory structure of a Domain in weblogic? For example, what directory should a simple helloWorld.jsp be placed in, then you can enter http://host:port number//helloword on the browser .jsp, you can see the running result? Another example is what should I do if I use a javaBean written by myself?

     Domain directory server directory applications, put the application directory in this directory, it can be accessed as an application, if it is a web application, The application directory needs to meet the requirements of the Web application directory. The jsp file can be placed directly in the application directory, and the Javabean needs to be placed in the classes directory of the WEB-INF directory of the application directory. Setting the default application of the server can be realized without inputting on the browser. application name.

12. What configuration files need to be involved in publishing ejb in weblogic

     Different types of EJB involve different configuration files, and the configuration files involved include ejb-jar.xml, weblogic-ejb-jar.xml CMP entity Bean generally also requires weblogic- cmp-rdbms-jar.xml

13. How to perform ssl configuration and client authentication configuration in weblogic or talk about j2ee (standard) for ssl configuration?

     In the default installation, DemoIdentity.jks and DemoTrust.jks KeyStore are used to implement SSL. You need to configure the server to use Enable SSL and configure its port. In product mode, you need to obtain the private key and digital certificate from the CA, create the identity and trust keystore, and load the obtained key and digital certificate. It is possible to configure whether this SSL connection is unidirectional or bidirectional.

14. How to view the EJBs that have been published in weblogic?

     You can use the management console to view all published EJBs in its Deployment