Summary

---

We have considered servlets and how they fit into the multi-tiered J2EE infrastructure. J2EE and servlets offer a wide range of services through the range of APIs provided. Servlets have a range of advantages in enterprise web applications such as security, cross-platform and cross-server portability, protocol flexibility, as well as a wide range of J2EE APIs available for the servlet developer to make use of.

In the chapter we examined the J2EE container architecture and the web container architecture in particular. We saw that containers manage and provide services for the components they contain. Web applications and components, and their place in the web architecture were also discussed.

We noted that the Tomcat web server/container is the reference implementation of the Servlet 2.3 specifications, although there are many other implementations of the specifications too, which means that we can choose the one best suited to the needs of our web application.

We finished the chapter by considering the range of possibilities that business web applications could encompass, and examined the roles that servlets had to play in such applications. The variety of roles we saw illustrated the versatility of these components.

In the next chapter we will look at the Servlet 2.3 API in detail. We will see the recent developments in the API and start to develop and run servlets using the Tomcat reference implementation.

A

applet container, 10

• J2EE container architecture illustrated, 9

application container, 10

• J2EE container architecture illustrated, 9

architectures

• J2EE container architecture, 7

• tiered architectures, 5

• web server-web container relationship, 15

auction e-business

• servlet based application, 26

authentication

• using servlets with JAAS, 21

authorization

• using servlets with JAAS, 21

B

bus network topology, 2

business tier

• tiered architectures, 6

C

Catalina

• servlet container, Tomcat, 14

CGI (Common Gateway Interface)

• servlets and benefits of using, 17

client containers

• J2EE container architecture, 9

• servlet communication, 13

client tier

• applet container, 10

• application container illustrated, 10

• J2EE container architecture illustrated, 9

• tiered architectures, 6

communication

• servlet-client communication, 13

components

• J2EE web components, 11

containers

• J2EE container architecture, 7

• types in J2EE container architecture, 8

CORBA (Common Object Broker Request Architecture), 5

D

database connectivity

• using servlets with, 20

E

e-commerce store

• servlet based application, 24

EJB (Enterprise JavaBean) container, 11

• J2EE container architecture illustrated, 8

Enterprise Architecture, 2

• networks, 2

• protocols, 3

H

HTTP (Hypertext Transfer Protocol), 4

J

J2EE (Java 2.0 Platform Enterprise Edition)

• builds on J2SE, 1

J2EE connector architecture

• using servlets with, 19

J2EE container architecture, 7

• client containers, 9

• container types, 8

• illustrated, 8

J2EE platform

• tiered architectures, 6

J2EE web components

• Java servlets, 11

• JavaServer Pages (JSP) components, 19

• web tier, 11

J2SE (Java 2 Platform, Standard Edition)

• built on by J2EE, 1

JAAS (Java Authentication and Authorization Service

• using servlets with, 21

Java servlets

• J2EE web component, 11

JavaMail

• using servlets with, 21

javax.servlet package

• protocol flexibility, 18

javax.servlet.http package

• protocol flexibility, 18

JAXP (Java API for XML Processing)

• using servlets with, 22

JMS (Java Message Service)

• using servlets with, 20

JNDI (Java Naming and Directory Interface)

• using servlets with, 21

JSP (JavaServer Pages)

• J2EE web components, 19

JTS (Java Transaction Service)

• using servlets with, 20

L

legacy system interface

• servlet based application, 28

M

messaging in J2EE

• servlets and, 20

middle tier

• containers, 10

• EJB container, 11

• J2EE container architecture illustrated, 8

• tiered architectures, 6

• web container, 11

• web server-web container relationship, 15

N

networks

• bus topology, 2

• description, 2

• ring topology, 2

• star topology, 2

P

packages

• javax.servlet package, 18

• javax.servlet.http package, 18

presentation tier see web tier, 6

protocols

• definition, 3

• HTTP, 4

• layered protocols, 3

• Servlet API flexibility, 18

• TCP/IP, 4

R

reservation system

• servlets roles within, discussed, 22

ring network topology, 2

RMI (Remote Method Invocation)

• RPC implemented in RMI, 5

RPC (Remote Procedure Calls)

• definition, 4

• implemented in RMI, 5

• reasons against using, 4

S

sales e-business

• servlet based application, 26

security

• using servlets with JAAS, 21

server tier see middle tier.

Servlet 2.3 API

• protocol flexibility, 18

servlet based applications

• discussion, 24

• e-commerce store, 24

• legacy system interface, 28

• sales and auction e-business, 26

• web services, 30

Servlet specification implementation, 13

• Tomcat, 14

servlets

• !see also Java servlets.

• benefits of using, 17

• client communication, 13

• communication times/places, 12

• database connectivity, using with, 20

• J2EE Connector Architecture, using with, 19

• JAAS, using with, 21

• JavaMail, using with, 21

• JMS, using with, 20

• JTS, using with, 20

• lifecycle, 12

• roles in web applications, 22

• using with JAXP, 22

• using with JNDI, 21

star network topology, 2

T

TCP/IP (Transmission Control Protocol/Internet Protocol), 4

tiered architectures, 5

• J2EE platform, 6

Tomcat

• Servlet specification implementation, 14

• web site, 14

W

web applications

• servlet based applications, 24

• servlets roles in, 22

web container, 11

• J2EE container architecture illustrated, 8

• web server relationship, 15

web server

• web container relationship, 15

web services

• servlet based application, 30

web tier

• J2EE web components, 11

• tiered architectures, 6

---