Open Source Workflow Engines written in Java

• Bossa - Bossa is a workflow engine written in Java. The engine is very fast and lightweight, uses a very expressive Petri net notation to define workflows, does not require a RDBMS and is very simple to use and to integrate with java applications.
  
  Actually, it was designed to be embedded. Therefore, Bossa is organized as a library to be used by server side applications (especially web oriented ones) that need workflow services. We plan, in the future, to implement a shell over the current library to offer workflow services as a stand alone server.
  
      
• con:cern - con:cern is a workflow engine based on an extended case handling approach. A process is described as a set of activities with pre- and postconditions. An activity is executed when its preconditions are met. It manipulates the process item, thereby creating postconditions. The process flow is determined at run-time.
      
• Enhydra Shark - The Enhydra Shark project delivers a workflow server with a difference.
  
  Shark is an extendable workflow engine framework including a standard implementation completely based on WfMC specifications using XPDL (without any proprietary extensions !) as its native workflow process definition format and the WfMC "ToolAgents" API for serverside execution of system activities.
  
  The Enhydra JaWE graphical XPDL editor can be used to produce XPDL process definitions for Enhydra Shark !
  
      
• Freefluo - Freefluo is a workflow orchestration tool for web services initially developed by IT Innovation but now available to all from the Freefluo Sourceforge Site. It can handle WSDL based web service invocation. It supports two XML workflow languages, one based on IBMs WSFL and another named XScufl that is under development as part of the Taverna Sourceforge project.
  
  Freefluo is very flexible, at its core is a reusable orchestration framework that is not tied to any workflow language or execution architecture. Freefluo includes extension libraries that enable execution of workflows written in a subset of WSFL. Support exists for for discovery via standard UDDI and recording of provenance.
  
      
• jBPM - JBoss jBPM is a flexible, extensible workflow management system. Business processes, expressed in a simple and powerfull language and packaged in process archives, serve as input for the JBoss jBPM runtime server. JBoss jBPM bridges the gap between managers and developers by giving them a common language : the JBoss jBPM Process definition language (jPdl). This gives software project managers much more control on their software development efforts. After loading the process archive, users or systems perform single steps of the process. JBoss jBPM maintains the state, logs and performs all automated actions. JBoss jBPM combines easy development of workflow-applications with excellent enterprise application integration (EAI) capabilities. JBoss jBPM includes a web-application and a scheduler. JBoss jBPM can be used in the simplest environment like an ant task and scale up to a clustered J2EE application.
      
• JFlower - JFlower is workflow engine written in java, extendible with java plugins. The server parse xml document for execute jobs, and check conditions. The session data are stored on a database, so the server is fully scalable.
      
• JFolder - JFolder (formerly PowerFolder) is a complete application creation and production solution. You can develop many applications without writing any code, even scripting.
  
  JFolder contains features critical to many applications - including web pages, workflow, security, persistence, email, file management, and data access. In addition, new features can be added with little effort.
  
      
• Micro-Flow - The micro-workflow framework targets developers who want to separate the control and logic aspects in their programs, thus making them flow independent. A well-factored flow independent application facilitates change because the most frequent business changes translate into process changes, thus leaving the code intact. Flow independence also fosters reuse, because domain objects make fewer assumptions about the control context in which they operate.
  
  
      
• ObjectWeb Bonita - Bonita is a flexible cooperative workflow system, compliant to WfMC specifications, based on the workflow model proposed by the ECOO Team, which incorporates the anticipation of activities as a more flexible mechanism of workflow execution. Bonita is Open Source and is downloadable in LGPL License. The system provides:
  
  A comprehensive set of integrated graphical tools for performing the process conception and definition, the instantiation and control of this process, and the interaction with the users and other applications
  
  100% browser-based environment with Web Services integration that uses SOAP and XML Data binding technologies in order to encapsulate existing workflow business methods and publish them as a J2EE-based web services.
  
  A Third Generation Worflow engine based in the activity anticipation model. This flexibility allows a considerable increase of speed in the design and development phases of cooperative applications
  
      
• OpenSymphony OSWorkflow - OSWorkflow is fairly different from most other workflow systems available, both commercially and in the open source world. What makes OSWorkflow different is that it is extremely flexible. This can be hard to grasp at first, however. For example, OSWorkflow does not mandate a graphical tool for developing workflows, and the recommended approach is to write the xml workflow descriptors by hand.
      
• OpenWFE - OpenWFE is an open source workflow engine. It is implemented in Java, and is available under the BSD license.
  OpenWFE not only features a workflow engine, but also a full fledged Business Process Management Suite. OpenWFE contains these features and many more:
  
  a worklist component for storing workitems (tasks) for participants,
  an APRE component, allowing you to implement automated agents into your work flows,
  Droflo, our web-based flow designer,
  and a well-documented REST interface and several libraries to access it, with more on the way.
  
  OpenWFE can run completely standalone without any Application Server, requiring only a Java SDK (1.4.x) or better.
      
• Syrup - Syrup is an adaptive Workflow system with a difference. Like any other Workflow solution, Syrup can be used to describe the tasks, procedural steps, required input and output information and tools needed for each step in a business process [1]. To be able to do this, Syrup provides five basic concepts: Tasks, Links, Workflows, Workers and the WorkSpace. Additionally, the minimal core is build in such a way that integrating Syrup into an existing infrastructure poses a minimal challenge to developers.
  
  Syrup can overcome the von Neumann bottleneck that stops traditional software systems from scaling [2].
  
      
• Taverna - The Taverna project aims to provide a language and software tools to facilitate easy use of workflow and distributed compute technology within the eScience community. As a component of the EPSRC funded my Grid project, Taverna is available freely under the terms of the GNU Lesser General Public License (LGPL).
      
• The Open for Business Workflow Engine - The Open for Business Workflow Engine is based on the WfMC and OMG specifications. The Workflow Engine is a member of the Services Framework, and is tightly integrated with the Entity Engine. It uses the entities found in entitymodel_workflow.XML for definition information and entitymode_workeffort for runtime storage. All changes to a process or activity are persisted real-time. Therefore, the engine does not run in a thread, it is simply a group of APIs and common objects which handle the flow. When a change to the workflow is made, the engine then processes that change. When finished, the engine returns. Hence, if the application does crash, or the system reboots, the workflow will continue right where it left off upon restart.
  
  The Workflow Engine is not designed for processing flow of a web site. This is a common misconception. Web site flow is controlled by the Control Servlet. Workflow is the processing of manual and automatic activities to fulfill a specific goal.
  
  OFBiz Workflow Engine uses XPDL as its process definition language.
  
      
• Twister - Twister's aim is to provide a new generation, easily integrable, B2B oriented workflow solution in Java, based on the latest specification efforts in this field. The process engine is based on the BPEL business process specifications and Web Services standards.
      
• XFlow - XFlow is a pure J2EE platform for building, executing and managing business processes and workflows. It is a basis for building collaborative applications as well as integrating processes across an enterprise. XFlow has a small footprint but is extremely powerful. It is designed to be easy to use from the development, deployment and management standpoints.
  
  XFlow runs within an EJB and servlet container. JBoss 4.0 (with bundled Tomcat) is the container used in this implementation. The architecture supports distributed and parallel processes within an organizations firewall as well as across organizational boundaries.
  
  
      
• YAWL - YAWL can be considered a very powerful workflow language, built upon experiences with languages supported by contemporary workflow management systems. While not a commercial language itself it encompasses these languages, and, in addition, has a formal semantics. Such an approach is in contrast with e.g. WfMCs XPDL which takes commonalities between various languages as a starting point and does not have formal semantics. Its design hopefully allows YAWL to be used for the purposes of the study of expressiveness and interoperability issues.
  
  At this stage YAWL supports the control-flow perspective and the data perspective.