WSO2 CEP - Publish Events Using Java Client

The last article: WSO2 CEP - Hello World!, explained how to set up WSO2 CEP with a simple event processor. This article shows you the way to send events to the CEP using a Java client. Actually it is nothing more than an HTTP client which can send the event to the CEP through HTTP request.

Step 0:

Follow the previous article and setup the CEP engine. This article uses the same event processor and receiver defined in the previous article to test the Java client.

Step 1:

Create a new simple Maven project in Eclipse.

Step 2:

Give the Group Id: "com.javahelps" and Artifact Id: "cepclient" and click on the "Finish" button.

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Prototype Design Pattern

Name: Prototype Design Pattern

Type: Creational Design Pattern

Purpose:

• Improving performance by cloning objects.
• Minimize complexity in object creation.

Sample Problem and Solution:

Consider a problem where you need a 64x64 grid Board class to represent a chess board. A possible design is provided here.

public class Cell {
    private String color;

    public Cell(String color) {
        this.color = color;

        // Make it time consuming task.
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
        }
    }

    public String getColor() {
        return color;
    }

    @Override
    public String toString() {
        return color.substring(0, 1);
    }
}

In this code, Thread.sleep is used to make the object creation as a time consuming operation.

public class Board {
    public static final int NO_OF_ROWS = 8;
    public static final int NO_OF_COLUMNS = 8;

    private final Cell[][] board;

    public Board() {
        this.board = new Cell[NO_OF_ROWS][NO_OF_COLUMNS];

        for (int row = NO_OF_ROWS - 1; row >= 0; row--) {
            for (int col = NO_OF_COLUMNS - 1; col >= 0; col--) {
                if ((row + col) % 2 == 0) {
                    board[row][col] = new Cell("WHITE");
                } else {
                    board[row][col] = new Cell("BLACK");
                }
            }
        }
    }

    public void print() {
        for (int row = 0; row < NO_OF_ROWS; row++) {
            for (int col = 0; col < NO_OF_COLUMNS; col++) {
                System.out.print(board[row][col] + " ");
            }
            System.out.println();
        }
    }
}

public class Main {

    public static void main(String[] args) {
        // Get the start time
        long startTime = System.currentTimeMillis();

        Board chessBoard = new Board();

        // Get the end time
        long endTime = System.currentTimeMillis();

        System.out.println("Time taken to create a board: " + (endTime - startTime) + " millis");

        // Print the board
        chessBoard.print();
    }

}

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