About XRCE

X-Folders breaks physical and organisational boundaries allowing users across distributed virtual organizations to flexibly collaborate and share documents.

Context of X-Folders

The X-Folders system allows users across distributed virtual organizations to flexibly collaborate and share documents.

The paradigm underlying X-Folders is the well known circulation folder. It works on the same principle as the brown envelope in which users insert papers and specify the necessary recipients by writing their name(s) on its exterior. This envelope then flies magically from pigeon hole to pigeon hole and the final task, based on people's will and teamwork, is eventually performed. X-Folders builds on this, combining the same simplicity with all the power and benefits of interconnected computers, in terms of speed, distance bridging and support.

X-Folders provides more consistency than what users can have when e-mailing copies of documents across organizations and more flexibility than what traditional centralized workflow systems can offer. Problems of consistency can arise because of diverging versions of duplicated documents. Traditional workflow systems are so constraining that overhead can be very heavy for small processes that evolve frequently.

For example, if you are involved in the preparation of a proposal for a multi-organisational project, you would need to ensure that:

  • Relevant documents already stored in local heterogeneous Document Management Systems (DMS) will be accessible to all involved partners without the need for them to be copied into a centralized repository;
  • The project partners will be able to collaborate to construct documents in a safe and efficient manner;
  • External constraints such as deadlines will be respected;
  • The process guiding the work will be flexible, allowing it to evolve during the different partners' activities.
  • The concurrency control applied to the shared documents could evolve according to the documents' maturity, allowing it to be relaxed in the first phases and stronger in the later ones.

X-Folders is designed to address all these different issues quickly and efficiently.

How X-Folders Work ?

X-Folders uses the concept of Electronic Circulation Folders (ECF) as a "virtual" storage space for documents.

Users access documents in Document Repositories (DR) (such as Document Management Systems or in the simplest case directory structures of a file system). When an ECF is created, the user responsible for this task is able to insert documents from the local DR. This could either involve that the documents are physically copied from the user directory to a dedicated DR, or only that references (e.g. by the means of URL) to documents already in place in some others DR are created in the ECF.

The user can attach a simple routing process to an ECF. Each step within this process is defined by a set of tasks, the users involved and the documents required. Once the creator has completed his task, (s)he forwards the ECF, that is sent to the user(s) involved in the next step. These users may then insert new documents and add, modify or remove steps in the routing process. The modification of a step may require the addition, modification or removal of a task. On the other hand, the modification of a task may involve the addition or removal of some documents or a change in the task description. A major advantage of X-Folders as compared to more rigid workflow tools is that any user who presently "owns" an ECF is able to change both its content and its routing process.

When an ECF is forwarded to the next step, the system checks that all documents required for that step are accessible to the users involved. This is essential when working across remote teams. The physical distribution of the different partners means that documents may be located in a DR for which the user does not have access rights or, even worse, in a DR hidden behind a firewall. X-Folders addresses this issue by ensuring that inaccessible documents are physically migrated to a DR for which the user has the correct rights.

X-Folders also provides concurrency control mechanisms to handle problems potentially arising when several users are involved in the same step of a process, e.g. when a document is required by several users who do not share a common DR. This requires the document to be either first duplicated and then merged, or split into different pieces (e.g. sections) that can be handled separately by the different users.

When determining the way the folder is forwarded, two alternative operating modes can be specified. The first mode allows users within the next step to begin work as soon as one of the users in the current step has forwarded the folder. In this case, the tasks of the two steps may overlap. The second mode requires that all the users of the current step have forwarded the folder before the next step is activated.

Another interesting feature addresses the common problem of people's unavailability not being known in advance. For example, an ECF may be forwarded to a user who is unable to accept it due to holiday or sick leave. In these situations, a mechanism of timeout can be associated to any step, notifying the sender of the recipient's non acceptance of the folder. The sender can retrieve the ECF, alter the user's identity for the next step and then forward the folder again.

Finally, X-Folders supports nomadic operation. Even when disconnected from the network, a user is able to perform basic operations such as document modification and requests for the ECF to be forwarded. When a reconnection occurs synchronisation is automatically performed and the ECF is forwarded.

X-Folders is built on top of XRCE's Coordination Language Facility (CLF). This platform, developed internally, provides advanced features to build distributed applications and to deploy them over large scale distributed systems.

X-Folders is built on top of the CLF/Mekano framework

For more information on the X-Folders research project please contact Xerox Research Centre Europe
6 chemin de Maupertuis
38240 Meylan, France

Stefania Castellani or Fran├žois Pacull
Stefania.Castellani@xrce.xerox.com
Francois.Pacull@xrce.xerox.com