Software Development

Generating MS Project Plans with MPXJ

27 Nov 2011 6 min read +DE 12 comments

Contents

Lately needed to create a project plan for a company who was doing some migrations. In this migrations a lot of different systems (about 200) and ressources (about 200 people) where involved. There were about 30 tasks which all had a different duration and different people involved depending on the system for which they were performed. First we thought about doing it the hard way: preparing a template for one system, copy&pasting it 200 times, then adjusting the values as needed. But due to frequent changes in the plan soon this turned out as unmanageable work effort.
So I was looking for some solution to automatically generate the plan.

I found this great java library, which makes it easy to read and write project plans: http://mpxj.sourceforge.net/

Download

First download the necessary files. The mpxj library is mandatory, the poi library you need to read mpp-Project-Files.

Setting up eclipse

Create a new Java Project
Add the mpxj and poi libraries to the buildpath as external archives

Create a basic project plan

Here is the example code to generate a basic project plan with tasks and subtasks and dependencies between the tasks

import java.util.Calendar;
import java.util.Calendar;

import net.sf.mpxj.Duration;
import net.sf.mpxj.ProjectFile;
import net.sf.mpxj.RelationType;
import net.sf.mpxj.Resource;
import net.sf.mpxj.Task;
import net.sf.mpxj.TimeUnit;
import net.sf.mpxj.mpx.MPXWriter;

public class MpxjExample {

	static Task pre = null;

	public static void main(String[] args) throws Exception {

		// writes the project-data-structure into a mpx-XML-File
		MPXWriter mpxwriter = new MPXWriter();

		// base data-structure for project files
		ProjectFile projectfile = new ProjectFile();

		// filling the project with some dummy data
		// here you can easily use your real data extracted
		// from a database or a csv-file
		int personcount = 1;
		for (int i = 1; i <= 10; i++) {

			// the same task as in ms project
			Task task = projectfile.addTask();
			task.setName("Example Task " + i);

			Task presub = null;
			// add some subtasks
			for (int j = 1; j <= 10; j++) {
				
				Task subtask = task.addTask();
				subtask.setName("Sub Task " + j);

				// set the subtasks duration, every subtask will take 4 hours in
				// the example
				subtask.setDuration(Duration.getInstance(4, TimeUnit.HOURS));

				// add resources to the subtask
				// in this example we will add only one resource to every task
				// 1. add the resource to the general projectfile
				Resource res = projectfile.addResource();
				res.setName("Person " + personcount);
				personcount++;

				// associate the resource with the current task
				subtask.addResourceAssignment(res);
				
				// concatenate the subtasks, so that one subtask is performed after
				// another on the timeline
				// the first task has no predecessor
				if (j == 1) {
					presub = subtask;
				} else {
					subtask.addPredecessor(presub, RelationType.FINISH_START, Duration
							.getInstance(0, TimeUnit.HOURS));
					presub = subtask;
				}
			}

			// concatenate the tasks, so that one main task is performed after
			// another on the timeline
			// the first task has no predecessor
			if (i == 1) {
				//set the startdate of the project
				Calendar rightNow = Calendar.getInstance();
				rightNow.set(2012, 1, 1);
				task.setStart(rightNow.getTime());
				pre = task;
			} else {
				task.addPredecessor(pre, RelationType.FINISH_START, Duration
						.getInstance(0, TimeUnit.HOURS));
				pre = task;
			}
		}

		//writing the project file
		mpxwriter.write(projectfile, "exampleproject.mpx");

	}
}

Opening the file in MS Project

At my tries there popped up an error message, but if you click to ignore the warnings the file builds up normally and then you can save it under a normal mpp-file. With the mpp-file saved by MS Project no error messages pop up.

Sometimes MS Project crashed when opening the mpx-file, but next time it worked. I think there is some problem with MS Project parsing files which have not set all values. But trying it another time for me always worked.

Adding several resources to a task

I don’t know if this is the right way to do, but for me it worked. As long as you proceed this way. If i did it otherwise, the total project times did not fit in the end.

you need to know (in the code) how many resources will be added to the task
add the time the task takes and divide it through the count of resources added (the more people work on the task in parallel the faster it is finished)
add the resources

Here is the example code

import java.util.Calendar;
import java.util.Calendar;

import net.sf.mpxj.Duration;
import net.sf.mpxj.ProjectFile;
import net.sf.mpxj.RelationType;
import net.sf.mpxj.Resource;
import net.sf.mpxj.Task;
import net.sf.mpxj.TimeUnit;
import net.sf.mpxj.mpx.MPXWriter;

public class MpxjExample2 {

	static Task pre = null;
	static final int respertask = 3;

	public static void main(String[] args) throws Exception {

		// writes the project-data-structure into a mpx-XML-File
		MPXWriter mpxwriter = new MPXWriter();

		// base data-structure for project files
		ProjectFile projectfile = new ProjectFile();

		// filling the project with some dummy data
		// here you can easily use your real data extracted
		// from a database or a csv-file
		int personcount = 1;
		for (int i = 1; i <= 10; i++) {

			// the same task as in ms project
			Task task = projectfile.addTask();
			task.setName("Example Task " + i);

			Task presub = null;
			// add some subtasks
			for (int j = 1; j <= 10; j++) {
				
				Task subtask = task.addTask();
				subtask.setName("Sub Task " + j);
				
				//this time we add three resources per task
				subtask.setDuration(Duration.getInstance(((float)4/(float)respertask), TimeUnit.HOURS));
				for(int k = 1; k <= respertask; k++) {
					
					
				// add resources to the subtask
				// 1. add the resource to the general projectfile
				Resource res = projectfile.addResource();
				res.setName("Person " + personcount);
				personcount++;

				// associate the resource with the current task
				subtask.addResourceAssignment(res);
				}
				// set the subtasks duration, every subtask will take 4 hours in
				// the example
				

				
				
				// concatenate the subtasks, so that one subtask is performed after
				// another on the timeline
				// the first task has no predecessor
				if (j == 1) {
					presub = subtask;
				} else {
					subtask.addPredecessor(presub, RelationType.FINISH_START, Duration
							.getInstance(0, TimeUnit.HOURS));
					presub = subtask;
				}
			}

			// concatenate the tasks, so that one main task is performed after
			// another on the timeline
			// the first task has no predecessor
			if (i == 1) {
				//set the startdate of the project
				Calendar rightNow = Calendar.getInstance();
				rightNow.set(2012, 1, 1);
				task.setStart(rightNow.getTime());
				pre = task;
			} else {
				task.addPredecessor(pre, RelationType.FINISH_START, Duration
						.getInstance(0, TimeUnit.HOURS));
				pre = task;
			}
		}

		//writing the project file
		mpxwriter.write(projectfile, "exampleproject2.mpx");

	}
}

Example Java Classes

MpxjExample.java
MpxjExample2.java

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