DDevelopment & Design

Activiti – are you ready for BPMN 2.0?

  • bympr
  • March 27, 2011
  • 5 minute read
From the beginning of this year I got quite involved in project called Activiti. It’s a “light-weight workflow and Business Process Management (BPM) Platform” (according to creators. The project is led by JBPM creators – Tom Bayens and Joram Barrez and is backed by Alfresco and several other companies. I also contributed some small features :) Activiti has already made some noise in BPM world – check this, this, or this, and of course InfoQ.
So, what’s the fuss all about? What makes Activiti special? Of course – it depends what are you comparing it with. My experience involves mainly working with open source BPEL implementation, but I think some points remain valid.

So, here is my list of distinctive features:

BPMN 2.0 support I took quite a lot of time for this spec to arrive, but it’s finally here. The biggest step ahead comparing with BPMN 1.x is execution model – no more BPEL, you can use the same diagram for modelling and execution, and it has proper xsd schema! Of course, it won’t solve all round-trip headaches, but I think it’s quite important improvement. XML describing BPMN 2.0 process consists of nodes definitions and transition definitions: Activiti is one of the first BPM engines offering BPMN 2.0 support. Currently not all nodes are supported, but the list includes:
* exclusive and paralell gateways  

  • timer boundary and intermediate events (timer start event almost ready)    

  • various tasks: script, user, service, manual, rules, receive    

  • error events and handling them    

  • subprocesses (both embedded or not)     Not all of these nodes are fully defined in spec – e.g. it does not describe how service task invocation should look like. Therefore, Activiti comes with a set of custom extensions. They are meant to be as non-intrusive as possible – to make processes more portable. One of most commonly used are ones for describing service task behaviour: Another useful extension enables to associate html form and candidate user with user task: One of nice features of BPMN 2.0 is also providing xml schema for describing process diagram – aka Diagram Interchange. This enables good engines (such as Activiti ;)) to generate process diagram just on the basis of xml definition – which makes importing processes modelled in some external tool much easier. It looks like this: Maybe not too beautiful, but usable.

Goal of supporting full BPM cycle

Do you (still) believe that future tools for creating business processes will allow users to get rid of developers? I do not… Unless of course, business people will learn how to code ;) Otherwise what we’ll be left with are some nice zero-coding tools which look great on 15minutes (or event 2hours if they’re exprensive enough) but after running into real-life problems will demand extensive hacking.
Activiti pursues different goal, and proposes developing process cycle layer. Key points of this proposition are:

  • zero coding solutions won’t work
  • analysts are needed to model the process, developers are needed to create executable processes, and operations are needed to deploy and monitor them
  • each of these groups have their own set of tools which they’re familiar with
  • so let’s not reinvent the wheel but encourage them to collaborate but use their set of tools

So, how to achieve this? By creating another web application, of course ;) It’s name is Activiti Cycle and it’s meant to encourage collaboration between business, developers and operations, while allowing each of them to use their own, specific tools in their daily job. It’s more like a federated repository of BPM assets, such as Visio Diagrams, BPMN process definitions, maven process projects, deployment packages and so on. These artifacts can be linked, commented and tracked by various process stakeholders and also transformed.

Easy to embed and extend, also by quasi-REST API

One of biggest pains of BPEL based solutions is that they force you to integrate with the rest of you app using webservices. Fortunately, this is no longer the case. You can embed activiti engine in your (for example) Spring application just by importing few jars and configuring it as any other Spring component:
This is of course great for running processes that handle some Java tasks. What about user tasks? Activiti comes with decent webapps for handling human tasks and monitoring process state: Activiti Explorer – screens shows the list of tasks for a given user:  

Activiti Probe – screen shows monitoring process instance:  

But what if you want to/have to use some other frontend technology? Webapps that I mentioned before are really thin clients – all logic is hidden behind Activiti’s quasi-REST API (I use the word quasi not to be beaten by RESTafarians who will surely point out that Activiti API is just RPC over HTTP…). That means you can embed Activiti in you webapps/OSGi container/any other environment and integrate with frontend webapps using handy JSON/HTTP communication. Which looks more or less like this:

Using (defacto) standards When you create application using Activiti chances are high that you know many (if not all) building blocks & techniques:

  • development? Eclipse plugin & maven
  • connecting components together? you can choose: spring or (for JEE6 lovers) CDI
  • testing? just do your normal TDD (you do it, right? ;)) using Activiti JUnit testing utils

Eclipse plugin includes visual modeler, which enables you to draw executable BPMN 2.0 processes, and fill all needed properties:

It uses Diagram Interchange format, so process diagram layout will remain the same when displaying process diagram in other applications. Testing is also pretty easy, as Activiti comes with good JUnit support. One of small, but important features is ability to simulate the clock – very handy when dealing with long running tasks.

Good integration capabilities

Activiti comes with capabilities allowing for integration with three most popular open source integration frameworks:

  • Mule ESB – integration is written by MuleSoft
  • SpringIntegration, contributed by SpringSource
  • last but cetainly not least: Apache Camel – which is contributed by TouK ;) – it’s still work in progress, but I hope to write a blog post soon about integrating Camel & Activiti

This allows to build processes that are closer to orchestration than simple workflows, containing only (or mostly) human tasks. Each of these integration frameworks comes with a vast collection of adapters using all popular (and not so popular) communication protocols. This allows process engine to concentrate on the process, and not on the communication details.

Summary I think it’s quite impressive set of features for a product that is less than year old. And what are Activiti plans for the future? Tom Bayens recently announced that Activiti is going to support some sort of Adaptive Case Management – which is one of top buzzwords in process world. Other goals include:

  • asynchronous continuations
  • moving towards full support of BPMN 2.0
  • extending Activiti Cycle – check Bernd’s Ruecker screencast showing Activiti Cycle approach to handling collaboration between analysts, developers and admins – it’s quite impressive

As for me, I’m finishing adding support for start timer tasks and hope to post something on Activiti-Camel intergration and running Activiti in OSGi environment soon – especially Apache Servicemix – so stay tuned. If you’ve found Activiti interesting, please start with 10 minutes 

Getting started guide, and if you know Polish, you can also have a look at my slides from Warsaw JUG presentation Thanks for reading my first post on this blog – hope you liked it.

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DDevelopment & Design

Super Confitura Man

How Super Confitura Man came to be :)

Recently at TouK we had a one-day hackathon. There was no main theme for it, you just could post a project idea, gather people around it and hack on that idea for a whole day - drinks and pizza included.

My main idea was to create something that could be fun to build and be useful somehow to others. I’d figured out that since Confitura was just around a corner I could make a game, that would be playable at TouK’s booth at the conference venue. This idea seemed good enough to attract Rafał Nowak @RNowak3 and Marcin Jasion @marcinjasion - two TouK employees, that with me formed a team for the hackathon.

Confitura 01

The initial plan was to develop a simple mario-style game, with preceduraly generated levels, random collectible items and enemies. One of the ideas was to introduce Confitura Man as the main character, but due to time constraints, this fall through. We’ve decided to just choose a random available sprite for a character - hence the onion man :)

Confitura 02

How the game is played?

Since we wanted to have a scoreboard and have unique users, we’ve printed out QR codes. A person that would like to play the game could pick up a QR code, show it against a camera attached to the play booth. The start page scanned the QR code and launched the game with username read from paper code.

The rest of the game was playable with gamepad or keyboard.

Confitura game screen

Technicalities

Writing a game takes a lot of time and effort. We wanted to deliver, so we’ve decided to spend some time in the days before the hackathon just to bootstrap the technology stack of our enterprise.

We’ve decided that the game would be written in some Javascript based engine, with Google Chrome as a web platform. There are a lot of HTML5 game engines - list of html5 game engines and you could easily create a game with each and every of them. We’ve decided to use Phaser IO which handles a lot of difficult, game-related stuff on its own. So, we didn’t have to worry about physics, loading and storing assets, animations, object collisions, controls input/output. Go see for yourself, it is really nice and easy to use.

Scoreboard would be a rip-off from JIRA Survivor with stats being served from some web server app. To make things harder, the backend server was written in Clojure. With no experience in that language in the team, it was a bit risky, but the tasks of the server were trivial, so if all that clojure effort failed, it could be rewritten in something we know.

Statistics

During the whole Confitura day there were 69 unique players (69 QR codes were used), and 1237 games were played. The final score looked like this:

  1. Barister Lingerie 158 - 1450 points
  2. Boilerdang Custardbath 386 - 1060 points
  3. Benadryl Clarytin 306 - 870 points

And the obligatory scoreboard screenshot:

Confitura 03

Obstacles

The game, being created in just one day, had to have problems :) It wasn’t play tested enough, there were some rough edges. During the day we had to make a few fixes:

  • the server did not respect the highest score by specific user, it was just overwritting a user’s score with it’s latest one,
  • there was one feature not supported on keyboard, that was available on gamepad - turbo button
  • server was opening a database connection each time it got a request, so after around 5 minutes it would exhaust open file limit for MongoDB (backend database), this was easily fixed - thou the fix is a bit hackish :)

These were easily identified and fixed. Unfortunately there were issues that we were unable to fix while the event was on:

  • google chrome kept asking for the permission to use webcam - this was very annoying, and all the info found on the web did not work - StackOverflow thread
  • it was hard to start the game with QR code - either the codes were too small, or the lighting around that area was inappropriate - I think this issue could be fixed by printing larger codes,

Technology evaluation

All in all we were pretty happy with the chosen stack. Phaser was easy to use and left us with just the fun parts of the game creation process. Finding the right graphics with appropriate licensing was rather hard. We didn’t have enough time to polish all the visual aspects of the game before Confitura.

Writing a server in clojure was the most challenging part, with all the new syntax and new libraries. There were tasks, trivial in java/scala, but hard in Clojure - at least for a whimpy beginners :) Nevertheless Clojure seems like a really handy tool and I’d like to dive deeper into its ecosystem.

Source code

All of the sources for the game can be found here TouK/confitura-man.

The repository is split into two parts:

  • game - HTML5 game
  • server - clojure based backend server

To run the server you need to have a local MongoDB installation. Than in server’s directory run: $ lein ring server-headless This will start a server on http://localhost:3000

To run the game you need to install dependencies with bower and than run $ grunt from game’s directory.

To launch the QR reading part of the game, you enter http://localhost:9000/start.html. After scanning the code you’ll be redirected to http://localhost:9000/index.html - and the game starts.

Conclusion

Summing up, it was a great experience creating the game. It was fun to watch people playing the game. And even with all those glitches and stupid graphics, there were people vigorously playing it, which was awesome.

Thanks to Rafał and Michał for great coding experience, and thanks to all the players of our stupid little game. If you’d like to ask me about anything - feel free to contact me by mail or twitter @zygm0nt

Recently at TouK we had a one-day hackathon. There was no main theme for it, you just could post a project idea, gather people around it and hack on that idea for a whole day - drinks and pizza included.

My main idea was to create something that could be fun to build and be useful somehow to others. I’d figured out that since Confitura was just around a corner I could make a game, that would be playable at TouK’s booth at the conference venue. This idea seemed good enough to attract >Conclusion

DDevelopment & Design

Need to make a quick json fixes – JSONPath for rescue

From time to time I have a need to do some fixes in my json data. In a world of flat files I do this with grep/sed/awk tool chain. How to handle it for JSON? Searching for a solution I came across the JSONPath. It quite mature tool (from 2007) but I haven't hear about it so I decided to share my experience with others.

First of all you can try it without pain online: http://jsonpath.curiousconcept.com/. Full syntax is described at http://goessner.net/articles/JsonPath/



But also you can download python binding and run it from command line:
$ sudo apt-get install python-jsonpath-rw
$ sudo apt-get install python-setuptools
$ sudo easy_install -U jsonpath

After that you can use inside python or with simple cli wrapper:
#!/usr/bin/python
import sys, json, jsonpath

path = sys.argv[1]

result = jsonpath.jsonpath(json.load(sys.stdin), path)
print json.dumps(result, indent=2)

… you can use it in your shell e.g. for json:
{
"store": {
"book": [
      {
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
      },
      {
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
      },
      {
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
      },
      {
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
      }
    ],
"bicycle": {
"color": "red",
"price": 19.95
    }
  }
}

You can print only book nodes with price lower than 10 by:
$ jsonpath '$..book[?(@.price

Result:
[
  {
"category": "reference",
"price": 8.95,
"title": "Sayings of the Century",
"author": "Nigel Rees"
  },
  {
"category": "fiction",
"price": 8.99,
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"author": "Herman Melville"
  }
]

Have a nice JSON hacking!From time to time I have a need to do some fixes in my json data. In a world of flat files I do this with grep/sed/awk tool chain. How to handle it for JSON? Searching for a solution I came across the JSONPath. It quite mature tool (from 2007) but I haven't hear about it so I decided to share my experience with others.