## Metagnostic home
| # JNIPort for Dolphin Smalltalk
Goodies JNIPort Z-Kit ListTree Space Breakdown F.M.B. Ghoul Miscellanea Experiments Changes Prerequisites Licence | ## Introduction (This page is just an introduction, the complete documentation for JNIPort is here.) JNIPort allows Java code to be invoked from Dolphin Smalltalk. It acts as a bridge between the world of Smalltalk objects and a JVM where Java code is executing. What's the point? Well, with JNIPort you can: Supplement Smalltalk's libraries with the rather extensive Java libraries from Sun and other vendors. Use the normal (to a Smalltalker) interactive way of playing with objects and code in workspaces to learn about and prototype Java operations. Continue to use your legacy Java code as you migrate to a more grown-up language… This version of JNIPort is known not to work with the recently released Dolphin 6. JNIPort is very roughly comparable to the facilities built into Dolphin for interacting with COM and Active-X objects. There are some big differences, though, mostly caused by the differences between the Java object model and COM. As with Dolphin's COM wrappers, you talk to a Java object via a Smalltalk object that acts as a proxy for it. You can call Java methods via the proxy using a lowish-level API where you have to tell the proxy what the method name is, what the argument types are, and so on. Alternatively you can use a higher-level of wrapper methods that are either statically generated (as by the Dolphin Active-X Wizard), or created dynamically. There are significant differences from the way that Dolphin wraps COM too. One is that Java has type-precise introspection (and no equivalent of VB!), so there's much less “guesswork” involved in generating wrapper methods. Another is that Java classes are represented explicitly by wrapper objects (called class statics), so each proxy for a Java instance has both a Smalltalk class and a reference to the (shared) class static. The Smalltalk class defines the wrapper methods for calling the Java object's methods, and accessing its fields. The class static is the single member of a different Smalltalk class that has methods for using the “static” methods and fields of the Java class. The class static also has methods corresponding to the Java class's constructors, so it acts as a factory for new instances. (That means that from the point of view of a JNIPort programmer, Java classes really are objects!) ## A Damper A few warnings before you start to expect too much: JNIPort does not provide complete interoperability between Java and Smalltalk. For instance it is not possible to create Smalltalk subclasses of Java classes (or the other way around). The facilities for calling back from Java into Smalltalk are weak, slow, and clunky. JNIPort allows proper interaction with Java objects but it cannot magically give you the ability to redefine Java classes interactively too. This is evolving software; I expect that some of the design will change, so you should assume that interfaces, etc, will change in future versions. Naturally, I think the interfaces are fairly stable, or I wouldn't be releasing it to public view, but I promise nothing. I haven't yet thought much about how to deploy applications based on a mixture of Java and Smalltalk. It's clear that there would be problems – for instance the default Dolphin image stripper would remove needed wrapper classes. This is an area that needs further work. ## Documentation The software is complex enough to need documentation. I suggest that you start by looking at the overview, which also includes a very simple example, and possibly this walkthrough of installing and configuring JNIPort. You might also like to look at some more complete examples. I cannot, in honesty, fail to recommend a look at the problems and limitations of JNIPort. The complete documentation is listed here. ### Packages
Package sizes and versions
Name | Size | Version
--- | --- | ---
CU Java Quasi-UTF8 | 6715 | 1.00
CU JNI | 386963 | 1.09
CU JNI Helper | 15631 | 1.00
CU Java Base | 657908 | 1.31
CU Java Base Tests | 115959 | 1.03
CU Java Callbacks | 67406 | 1.10
CU Java Callback Tests | 44386 | 1.02
CU Java Wrapper Generation | 113967 | 1.06
CU Java Ghost Classes | 60579 | 1.10
CU Java Wrapper Generation Tests | 63357 | 1.01
CU Java Additional Wrappers | 180705 | 1.02
CU Java Status Monitor | 131671 | 1.23
CU Java History Page | 19345 | 1.06
CU Java Console Page | 23107 | 1.02
CU Java Wrapper Wizard | 69246 | 1.05
CU Java JRockit Patch | 16905 | 1.00
CU Java Examples | 8122 | 1.00
CU JNIPort | 1525 | 1.00
CU JNIPort Tests | 1352 | 1.00
Prerequisite packages' sizes and versions
Name | Size | Version
--- | --- | ---
CU Abstract Collections | 51193 | 4.02
CU Always | 5976 | 3.01
CU Anonymous Subclass | 2092 | 1.00
CU Binary Arrays | 6126 | 2.00
CU Collection Adaptors | 34195 | 1.02
CU Enhanced Scrolling Decorator | 13841 | 1.02
CU Form Layout | 27356 | 2.01
CU GDI Extensions | 10083 | 0.0004 (unpublished)
CU Ghost Classes | 7592 | 1.01
CU Graphics Base | 135733 | 0.0150
CU Package-relative File Locator | 11829 | 3.01
CU PluggableWeakSet | 5238 | 0.0002 (unpublished)
CU PolyViewer | 85322 | 1.03
CU PolyViewer Tools Base | 20325 | 0.0009 (unpublished)
CU Rolling Accumulator | 7243 | 2.00
CU Selection From List Presenter | 70640 | 1.04
CU Sortblocks | 16398 | 3.01
CU String Extensions | 6885 | 1.00
CU Tools Base | 34422 | 0.0009 (unpublished)
CU Varargs | 22545 | 2.02
CU Windows Shell Extensions | 4809 | 1.00

Copyright © Chris Uppal, 2003-2005

Java, JNI (probably), JVM (possibly), and God knows what else, are trademarks of Sun Microsystems, Inc.