Web applications and web services - OSGi in Action - page 493

Table 15.2 Parameters supported by the Web URL Handler

Parameter Description

Desired symbolic name for the resulting WAB.

Bundle-SymbolicName

Bundle-Version

Version of the resulting WAB. The value of this parameter must fol-
low OSGi versioning syntax.

Bundle-ManifestVersion

Desired bundle manifest version. Currently, the only valid value for
this parameter is 2 .

List of packages on which the WAR file depends.

Import-Package

Web-ContextPath

Context path from which the servlet container should serve content
from the resulting WAB. If the input JAR is already a WAB, this
parameter is optional but may be used to override the context path.
Otherwise, it must be specified.

In the first half of this chapter, we've looked at a range of web-application technolo-
gies and shown how they can be integrated with OSG i. We've highlighted a number of
themes:

Using the HTTP Service to provide static and dynamic content

■

The benefits modularity brings at execution time due to improved memory
consumption from the use of shared classes

■

Flexible collaboration between functional units due to the use of service patterns

■

Converting WAR -style applications to WAB s using OSG i R4.2 Enterprise features

■

In the second half of this chapter, we'll turn our attention to making OSG i services avail-
able across process boundaries—that is, how to build distributed OSG i applications.

15.2 Providing and consuming web services

Until this point in the topic, all your applications have resided in a single JVM process;
but this is rarely the case for web-based applications. The entire ethos of internet-based
development is predicated on distributed processes communicating over network pro-
tocols. You saw how to do this at a low level in chapter 3, where you built a simple telnet
implementation. But this is the early twenty-first century, and the zeitgeist for distributed
computing today is web services. In this section, we'll investigate OSG i-based technolo-
gies for communicating between JVM processes using web-service protocols.
Obviously, we'll only be able to scratch the surface of distributed computing,
because the topic is too large and complex to cover in a single section of a chapter.
Instead of going into a lot of detail about specific web-service protocols or technologies,
we'll introduce you to some of the key features of the Remote Services specification,
which is another specification in the OSG i R4.2 Enterprise specification.
The Remote Services specification and its sibling specifications, Remote Services
Admin and SCA Configuration Type, provide a comprehensive model for building dis-
tributed computer systems in OSG i. Their key purpose is to provide a common model