JavaFBP

Java Implementation of "Classical" Flow-Based Programming (FBP)

General web site on Flow-Based Programming: https://jpaulm.github.io/fbp/ .

Latest release is v4.1.14. The jar file - javafbp-4.1.14.jar - can be obtained from the Releases folder, or from build/libs. Note: The Maven 'shield' below may show an earlier release. If you click on the Maven shield below, select Download, then jar.

This implementation is a kit for building JavaFBP projects. For a number of sample networks, go to https://github.com/jpaulm/javafbp/tree/master/src/main/java/com/jpaulmorrison/fbp/resourcekit/examples .

For your own projects, include the JavaFBP jar file in the Build Path property for the project.

General

General web site for "classical" FBP:

• https://jpaulm.github.io/fbp

In computer programming, flow-based programming (FBP) is a programming paradigm that defines applications as networks of "black box" processes, which exchange data across predefined connections by message passing, where the connections are specified externally to the processes. These black box processes can be reconnected endlessly to form different applications without having to be changed internally. FBP is thus naturally component-oriented.

FBP is a particular form of dataflow programming based on bounded buffers, information packets with defined lifetimes, named ports, and separate definition of connections.

JavaFBP Syntax and Component API:

• https://jpaulm.github.io/fbp/jsyntax.htm

An automatically generated Javadoc can also be browsed at http://jpaulm.github.io/javafbp/ . Unfortunately this isn't very useful for someone planning to use JavaFBP components, so we have built an FBP-specific Component Attributes List, which can be displayed by clicking on http://htmlpreview.github.io/?https://github.com/jpaulm/javafbp/blob/master/compList.html - see below.

<!-- ## Running your JavaFBP project under Eclipse **Add the current JavaFBP jar file to the `External Jar Files` tab in your project's `Java build path` properties.** In your component source, you will need the following import statement: import com.jpaulmorrison.fbp.core.engine.*; Note: the **core** level was added in the last repackaging of JavaFBP. -->

MySQL Support

Two components are available for reading and writing MySQL tables, respectively: ReadJDBC and WriteJDBC, in core.components.jdbc. These dynamically load the most recent MySQL jar file, and use reflection to execute SQL services.

If you are looking for an application using these components, it can be found in the FBP-ETL repository. This application of course uses the JavaFBP jar file as a dependency.

If you get a message saying "No suitable driver found", try restarting the MySQL service in services.msc.

JavaFBP-WebSockets

There is also a small GitHub project called javafbp-websockets, which contains two generalized components supporting WebSockets ( https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API ), and a simple test component and network - it can be found at https://github.com/jpaulm/javafbp-websockets .

<!--## Prerequisites for rebuilding JavaFBP or derivative The project requires Gradle for (re)building. You can download the corresponding package from the following URL: http://www.gradle.org Windows and Linux users should follow the installation instructions on the Maven website. OSX users (using Brew, http://brew.sh) can install Maven by executing the following command: brew install gradle ## Eclipse IDE Integration with Gradle You can generate an Eclipse project using the following command: gradle eclipse If you already created an Eclipse project you can run: gradle cleanEclipse Eclipse You need to install a Gradle plugin for Eclipse as explained here: https://github.com/spring-projects/eclipse-integration-gradle/ Then import a generated project in Eclipse, right (ctrl for OSX) click on the project in Eclipse -> Configure -> Convert to Gradle Project. After the conversion you can Right (ctrl for OSX) click on the project -> Gradle -> Task Quick Launcher and type `build`. You may have to go to the project Properties and select Java Build Path/Source; remove whatever is there and select `JavaFBP/src/main/java`; then close Eclipse, and reopen it. <!-- ## Building and/or running from command line The latest jar file can simply be downloaded from the latest release in JavaFBP GitHub Releases, or it can be rebuilt , by running the following command: gradle build As a result a `javafbp-x.x.x.jar` file will be created in the `build/libs` directory. It will include the JavaFBP core (runtime) and all the examples from the source code (sub-package `com.jpmorrsn.fbp.resourcekit.examples`). **`resourcekit` is now in the hierarchy, as of version v4.0.1** . The generated code shown above is a standard JavaFBP network, and can be executed as described below. -->

Running a network

Default connection size

JavaFBP recommends using a small connection size for debugging, and a larger one for production. In the latest version of JavaFBP, this is specified in the <user>.JavaFBPProperties.xml file - <defaultcapacity> tag.

Running on DOS

You will have downloaded the JavaFBP jar file earlier, so do a gradle build for your project, to make sure the compiled classes (.class files) are in the 'bin' directory.

Now position the current directory to your own project, using cd, and enter the following into the DOS window:

  java -cp "<JavaFBP directory>/javafbp-x.y.z.jar;." <program class name> 
  

where x.y.z is the version of the JavaFBP jar file. Note the final ;.... or you can place .; in front of the jar file name.

Program class name must be the fully qualified network name.

You must also make sure that java can find any class files that your main line needs, by specifying the necessary jar files, and class directories using the -cp/-classpath parameter.

Here is a test command you can run (changing x.y.z to the current version number, of course), using networks and components provided by the JavaFBP project. Note that the bin folder is not uploaded to GitHub, so you will have to compile any networks to be tested to the bin folder (or add them to your own jar file):

Do a cd command to your downloaded JavaFBP project, then enter

 java -cp ".;build/libs/javafbp-x.y.z.jar" com.jpaulmorrison.fbp.resourcekit.examples.networks.Copy1    
 

For your own project, you will probably have to add more directories to the classpath parameter - remember to provide the whole directory name.

Running on *nix

Replace the ';' in the -cp parameter with ":" for *nix.

Running in Eclipse

Go to Properties/Java Build Path for your project; click on Add External Jars, add your JavaFBP jar file to the list, and then hit Apply and OK.

Select Debug for your project.

<!-- ### Set up some data Nearly forgot - we need to give it some data: ReadFile handles any sequential file. In this case the file reader's IIP names at a CSV file (https://en.wikipedia.org/wiki/Comma-separated_values ), and the selected records will appear in a separate window. -->

Checking your setup

Here is a simple command-line test that can be run to test that everything is working.

Position to the javafbp directory; then enter

java -cp ".;build/libs/javafbp-x.y.z.jar" com.jpaulmorrison.fbp.resourcekit.examples.networks.MergeandSort

where x.y.z is the current version number of JavaFBP.

Alternatively, if you position to your own bin folder, you might code something like

java -cp ".;C:\users\<you>\downloads\javafbp-x.y.z.jar" <name of class to be run>

Here is a picture of MergeandSort, drawn using DrawFBP:

This network contains 4 processes:

• 2 occurrences of GenerateTestData,
• a Sort process - a very simple-minded Sort, which can only handle up to 9,999 information packets
• a text display component, which invokes Java Swing to display the sorted data in a scroll pane.

The outputs of the two GenerateTestData processes are merged on a "first come, first served" basis. During the run you should see a scroll pane with the sorted data scrolling down.

At the end of the run, you should see:

Run complete.  Time: x.xxx seconds
Counts: C: 150, D: 153, S: 300, R (non-null): 304, DO: 0

where the counts are respectively: creates, normal drops, sends, non-null receives, and drops done by "drop oldest".

Warning!

Care must be taken if combining LoadBalance (with substreams) and SubstreamSensitiveMerge in a divergent-convergent pattern - this pattern is one of the warning signals for deadlocks anyway. The problem is described in more detail under https://github.com/jpaulm/javafbp/issues/8.

Tracing and other options

To trace JavaFBP services and/or lock usage, set the appropriate parameter(s) in JavaFBPProperties.xml in the <user> directory to true:

• tracing
• tracelocks

e.g.

<?xml version="1.0"?> 
<properties> 
<tracing>true</tracing>
<tracelocks>false</tracelocks>
<defaultcapacity>...</defaultcapacity>    (as of v4.1.3)
</properties> 

These traces will appear in the project directory (in GitHub if running Eclipse) under the name xxxx-fulltrace.txt, where xxxx is the name of the network being run. Subnets have their own trace output files.

Values for defaultcapacity are as follows:

• PRODUCTION (currently 10)
• DEBUG (currently 1)
• any number
• defaultcapacity not specified - defaults to DEBUG v