Java Reference
In-Depth Information
After having been introduced to the theory and practical design of software deployment in gen-
eral, and Java deployment in particular, we will delve into more details by describing a particu-
lar Java deployment solution, the
Java Network Launching Protocol (JNLP)
. This third part of
the topic has been designed to be immediately accessible to programmers who need quick and
practical advice on JNLP technology. Although it is the natural complement to the first two
parts of the topic, the discussion has been kept focused on programming details in this third
part, reducing the importance of any previous knowledge of the other (more design-oriented)
parts of the topic.
This chapter introduces the technology using practical examples. Chapter 9, “The Protocol,”
discusses the protocol from a top-down perspective; whereas Chapter 10, “Defining the Client
Environment,” describes the XML elements in JNLP files. Chapter 11, “Runtime Client
Services,” illustrates the JNLP API that offers services to JNLP-launched applications. Chapter
12, “Server-side Support,” gives details about the server-side support of the protocol. Finally,
Chapter 13, “A Complete Example,” discusses a complete real-world example. In Appendix A,
“A Little Handbook for Deployment,” there is a part dedicated to JNLP adoption; whereas the
entire Appendix B, “The JNLP Specification,” is devoted to the Java Network Launching
Protocol specification.
An Introduction For Developers
Before starting our journey into the JNLP world, it is important to point out some basic things
that will probably save you a lot of time and frustration in the near future.
As with any deployment technology (and JNLP is no exception), one can identify three differ-
ent environments. The
production
environment is where developers build their programs. The
deployment
environment is where others, helped by deployment servers (we will use normal
Web servers such as Apache), will put developers' programs packed for distribution. Finally,
the third environment consists of
clients
,the end-users who run the applications on their com-
puters.
Let's better examine these environments as they pertain to software development:
•
Development
. You will probably use an Integrated Development Tool (IDE) for develop-
ing Java code and JAR files—such as Kawa, JBuilder, Forte, VisualAge, and so on. Of
course, you can always use the standard JDK, possibly with the help of some scripts. In
this case, you will need some Java libraries, other application-specific resources such as
icons, plus the
jarsigner
tool (or something similar) in order to sign JAR files should
you need to develop trusted applications.
