Java Software Resources

Databases that Support a Java Software Interface

There are a variety of database options available:

• Oracle. I mention Oracle because it is, after all, the leading database. Oracle is free for software development, but deployment and commercial use requires a license and Oracle licenses are relatively expensive.
• For enterprise database support PostgreSQL provides an open source alternative to Oracle that is easier to install, easier to maintain and which provides very competitive performance.
  • pgAdmin is an open source PostgreSQL database administration tool.
• Apache Derby This database started its life as IBM's Cloudscape database. Derby is one of the most popular Java/embedded database systems, with a large user community. Derby is ACID compliant (which means that it's transaction safe). I am probably going to integrate Derby with the Trade Engine to track transactions.
• db40 is an object relational database. This database does not directly support SQL (since it uses objects, rather than tables). I've never drunk the object database Koolaid so I mention this database only in passing. I don't foresee ever using it.

JavaScript, Ajax and Data Visualization

Implementing the Web Browser based GUI for an intra-day market trading system written in Java has really demonstrated to me that Web based applications may have a server side core, but the client, Web browser side, is critical as well. Or at least critical if you want good user interaction. HTML forms provide at best a primitive user interface with awkward interactivity in many cases. This page provides links to a variety of JavaScript/Ajax client side resources that can be used to build "Rich Internet Applications".

JavaScript is a historical accident in many ways. The JavaScript language is an interesting language in its own right and is much more powerful and complicated than a simple scripting languages like Php. JavaScript was designed to run within a web browser, but it was not released with support classes and methods for client/server interaction.

Ajax evolved to provide this client/server interaction. Ajax is a label that has been attached to a set of techniques for interaction between the client Web browser and the server. The methodology that makes up Ajax evolved and some of the techniques, like Ajax hidden frames, are overly complex and awkward. Frameworks that can hide this awkwardness are particularly important.

The resources listed below target standard browsers like Firefox or (the horror) Microsoft's Internet Explorer. The platform that I have in mind has a Java Servlet engine (Tomcat) supporting the application and it would be possible to use a custom browser like Lobo, which supports the Java Swing GUI and Sun's JavaFX within the browser. However, this introduces yet another component to configure. Also, Lobo is experimental at the time this was written. Lobo is unlikely to become a browser standard because it would to be adopted by both Mozialla and Microsoft. Microsoft has the Silverlight framework that they are pushing, so it seems unlikely that this will happen.

As the list below shows, there's a staggering number of JavaScript/Ajax frameworks, all claiming to be the answer to your Ajax problems. Several of the open source frameworks are supported by commercial entities with business models that are not obvious to me. It would be best to avoid adopting a framework that became an orphan.

• Ajax Frameworks and Ajax Support

  • ExtJS
    The ExtJS JavaScript/AJAX software has been used very successfully by one of the internal LLNL GUI projects. ExtJS can be used to build very attractive, very fast Web based GUIs systems. The software is platform independent, which is not clear from their web site.
    • ExtGWT (for the Google Web Tool API)
      This is a Google Web Toolkit wrapper from the ExtJS people. However, ExtJS may be a better choice, since there is a huge collection of widgets and examples.
  • Designing Rich AJAX Web Interfaces With ZK
    ZK allows AJAX client and Servlet side interfaces to be created using XML and Java, which is presumably translated into JavaScript on the client side and Java on the Server (Servlet side). There is a nice set of demo applications, including one where radio buttons can be clicked on which immediately cause the web page to change. The software seems to be both professional and free, so I'm not sure what their business model is.
  • Bindows
    This is a commercial JavaScript package that is reasonably priced and has a lot of interesting "widgets" including a charting widget that runs on the client (e.g., the browser), offloading the processing needed for graphics display to the client.
  • Google Software
    Google apparently pioneered the initial Ajax technology in Web sites like Google Earth and GMail.
    • Google Web Tool Kit
    • Google Visualization API
  • Yahoo Software
    • The Yahoo User Interface Library
  • Appcelerator: Open Source Rich Internet Applications. Apparently there is an Eclipse plugin that helps develop Appcelerator applications. Since this is yet another open source JavaScript/Ajax company, I don't know what their business model is.
  • OpenLaszio.

    According to the web site: the only run-anywhere, no-lock-in rich internet platoform. There's even a book, Laszlo in Action which is the definitive guide to Open Laszlo.

    Frameworks like OpenLaszio seem to be geared toward a Web browser based application. In such an application, the back end serves only as a database from which to fetch and update data.

    In contrast, a market trading application has a large body of software (thousands of lines of multi-threaded Java code) running as a Servlet. The Web brower simply serves and a control front end.

    Laszlo is a Servlet which supports the brower interaction. It's not clear that it would be easy or even possible to build a complex application that simply used Laszlo as a front end.

    Finally, one problem is that Laszlo seems to use Flash, which doesn't work terribly well on Linux.

• Ajax Infrastructure

  • JSON Java object format Historically, Ajax uses XML to communicate between the client and the server. JSON is an object format that can be used instead of XML.
  • Apache JetSpeed
    JetSpeed supports portal implementation. A portal provides a common and updating view of a set of data to multiple viewers using Web browsers (or even cell phones). This may be a way to build a Web browser based GUI for a market trading system where multiple browsers need the same, consistent, view of the trading system state.
  • jMaki
    This site publishes JavaScript and Servlet software that can be used to build connectors between different Java script applications and provide update to distributed Web browser clients.

• JavaScript Infrastructure

  • Prototype
    Prototype JavaScript Framework is a JavaScript extension that provides utilities to compensate for the shortcomings of JavaScript.
  • Dojo
    According to Wikipedia(ATW): "The Dojo Toolkit is a modular open source JavaScript toolkit (or library), designed to ease the rapid development of JavaScript or Ajax based applications and web sites." Feature set includes charting.. more info.
    • Nexaweb's Dojo.E Dojo development environment.
  • XMLHttpRequest
    underlies Ajax which build on the standard POST and GET HTTP requests.
  • Getting Started with Ajax by A list Apart
    A list apart is a popular, W3C-respecting web developer site for more high-brow web-devs..

• Charting in Java and Javascript

  • gChart Client-side charting for GWT
  • JFreeChart This software was developed and is maintained by Object Refinery Limited. There is a Servlet based charting package that mimics Google's charting package, but seem to run on the local servlet container (rather than requiring rendering on a Google server).
  • ASE Java Chart and Graph Component Library
  • PlotKit - Javascript Chart plotting
  • MochiKit - PlotKit requires MochiKit. The motto of MochiKit is _MochiKit makes Javascript suck less!

• Other JavaScrip and Data Visualization Resources

  • Max Kiesler Web Visualization
  • Firebug: a firefox web page development plug-in.
  • Processing
    According to the web page:
    Processing is an open source programming language and environment for people who want to program images, animation, and interactions. It is used by students, artists, designers, researchers, and hobbyists for learning, prototyping, and production. It is created to teach fundamentals of computer programming within a visual context and to serve as a software sketchbook and professional production tool. Processing is developed by artists and designers as an alternative to proprietary software tools in the same domain.

Java Development and Build

• YourKit
  Yes, Virgina, Java does have memory leaks.
  Although Java's dynamic allocation and garbage collection avoids many of the memory problems found in C++, a Java program can still have memory leaks. A project I worked on had a particularly nasty one. We finally found it using YourKit.
• Artifactory
  Artifactory is a Maven 2 enterprise repository. It offers advanced proxying, caching and security facilities to provide a robust, reproducible and independent build environment when using Maven. Artifactory is being used by clients ranging from small startup teams to international corporate teams employing distributed development, thus improving the development experience for tens of thousands of developers. Artifactory exposes a robust artifacts management platform using rich Ajax web UI and can be run out-of-the-box with a simple "unzip and launch".

Acknowledgments

Thanks go to Sebastian Thomas, who contributed to this web page.