The BZDev class library and applications

The BZDev class library supports discrete-event simulation, graphs and plotting, mathematical functions and numerical algorithms, 2D animation, 3D printing, writing graphics to output streams, integration of scripting with applications, additional Swing components, etc. This library, and several applications that use it, can be installed by visiting

https://billzaumen.github.io/bzdev/

The library uses 'factory' classes for configuring simulations and animations. Annotation processor makes it relatively easy to create a factory class and provide support for dynamic methods in which the types of a method's arguments are determined at run time instead of compile time. It also provides a Java-specific scripting language (ESP—Expression Sequence Processor) that can be used to run simulations and animations. It also provides an implementation of a secure authentication algorithm called Secure Basic Authentication for use with web servers.

The library is provided as a series of Java modules, each with its own JAR file. The source code is available on GitHub:

https://github.com/BillZaumen/libbzdev

All of the module and package names start with org.bzdev, which was chosen mainly for brevity.

There are also several applications and additional class libraries based on the BZDev class library. The more complex applications have web pages describing them. The libraries do not as the API documentation can be downloaded as part of an installation. These applications and libraries include

• cvrdecode—a utility for processing multiple images containing California digital vaccine records for COVID-19 vaccinations. The program extracts a minimum amount of information from the records and produces a CSV file showing the records in a table, sorted by name. It was intended as a utility for people running events were people would voluntarily email copies of their records. For the source code, please visit

  https://github.com/BillZaumen/cvrdecode/

• ecdb—a simple database example for scheduling events and emailing calendar appointments. For the source code, please visit

  https://github.com/BillZaumen/ecdb/

• epimodel—a Docker container providing a basic model of a pandemic. This code was written at the start of the COVID-19 pandemic during the lockdown. The initial model was written the first morning of the lockdown and it was then expanded and set up to be run using a web server in a Docker container. It can be used as a short coding example. For the source code, please visit

  https://github.com/BillZaumen/epimodel/

• epts—a graphics editor for creating paths and outputting the paths in a variety of formats. The output format can be controlled by templates, both built-in templates and user-supplied templates. For the source code, please visit

  https://github.com/BillZaumen/epts/

• evdisk—an application for managing a LUKS file system mounted via the loopback device, using GPG to encrypt the file systems password (this application does not use the library). For the source code, currently Linux specific, please visit

  https://github.com/BillZaumen/evdisk/

• gethdrs—a simple application for tracing HTTP and HTTPS headers, including showing series of HTTP redirects. For the source code, please visit

  https://github.com/BillZaumen/geth/

• libosgbatik—a Java service provider based on the Apache Batik project for adding SVG support to the output-stream graphics classes in the BZDev library. For the source code, please visit

  https://github.com/BillZaumen/osg-batik/

  The current package includes a stripped-down copy of Apache Batik because of an issue with Java modules: the Batik code duplicated some XML-related classes from packages whose names start with org.w3c and those classes cause a conflict that prevents the use of the standard Batik JAR files as Java automatic modules. When that issue is resolved, libosgbatik will be modified so that it just contains the classes specific to the libbzdev modules.
• librdanim—a small library providing classes that can be used for creating animations showing cars, bicycles, and pedestrians by using the org.bzdev.anim2d Java package. This package is particularly useful in the event of a car accident where an animation would help describe the situation (the author wrote it after being involved in a "fender bender" caused by an aggressive drive trying to pass by using a shoulder while the author was making a right turn from a right-turn-only lane onto a street with only a single lane in each direction). For the source code, please visit

  https://github.com/BillZaumen/librdanim/

  This library contain 1866 lines of source code (augmented by 3768 lines of code generated by an annotation processor used to create classes supporting factories). It is short enough and straightforward enough to be used as an example.
• libbikeshr—a simulation of a bicycle-sharing system, useful mainly as a modest-sized example of a simulation (4560 lines of code, excluding comments and blank lines). For the source code, please visit

  https://github.com/BillZaumen/libbikeshr/

• QRLauncher—an application that can extract URLs from QR codes and open the URLs using a browser or display the QR code's contents. THis application can also generate QR codes in a variety of formats including SVG and PostScript, with user-specified colors, sizes, and error-correction levels. For the source code, please visit

  https://github.com/BillZaumen/QRLauncher/

• webnail—a utility that can take a series of images scale them to fit in a specified bounding box, and generate zip files and web pages that can provide a slideshow. It includes a built-in web server that can be optionally used. For the source code, please visit

  https://github.com/BillZaumen/webnail/

  A Docker container can run webnail's internal web server. The web page

  https://hub.docker.com/r/wtzbzdev/webnail

  contains instructions.

While there is extensive API documentation, there are also several books currently in preparation or being planned that provides more of a tutorial.

Short utility programs

• transfertest.jar. This will provide a console with a drop location near the top of a window. If you drag and drop objects to that location, information about the data flavors the transfer provides will be displayed and may be saved to a file or printed. In the same directory in which transfertest.jar is placed, run the command

  
  ln -s /usr/share/bzdev/libbzdev-desktop.jar .
  	

  To run the utility, use

  
  java -jar transfertest.jar
  	

  or

  
  java -jar transfertest.jar default
  	

  The output can be printed or saved in a file. The 'default' option changes the text field representing the drop location to an uneditable text field and replaces its transfer handler. Without this option, new text may appear in the text field when a drag and drop operation completes.

https://github.com/BillZaumen/utils/

Links

• Computing the length of a Bézier path analytically.

Discussions and commenting

• add an issue using GitHub. All of the applications and libraries listed above have their source code on GitHub.
• visit https://fosstodon.org/@bzdev or just use the handle @bzdev@fosstodon.org in the usual way on any Mastodon server.

About the banner

Besides providing a name, the adjacent figure shows an orbit around a black hole (no electric charge and not spinning), with color changes denoting redshifts due to both the relativistic Doppler effect and time running at different rates at various distances from the center. It was produced by using the BZDev class library to

• solve differential equations numerically and use splines to represent the solutions.
• compute colors given a wavelength for a monochromatic light source.
• draw the image while expressing positions in units suitable to the problem domain (as opposed to pixels on a screen our output device).

About this web page

Readers may find the design kind of "old fashioned" as it uses hand-written HTML with a style sheet to control the layout, font-sizes, colors, etc. It was designed to load quickly (only a single, small image), and to be fully usable with a small screen width. That's useful if you are using an adjacent terminal window.