Legion Web Interface

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Simplified inner organization of Legion Web Interface

This layer was developed to ease the access to the grid for researchers through the generation and host of web interfaces. These interfaces include:

  • A custom task submission form per project
  • A monitoring page that shows the list of submitted tasks with their progress.
  • Tools to share the tasks between users of the same research group or project.

The interfaces are generated within the same application through a series of guided steps commonly known as “wizard”. This task, done by the administrator, is easier than developing a custom interface for each project. The steps include a graphical form editor for the custom task submission page as an alternative to entering the XML form specification directly. When the end user opens the task submission page for a project, the xml representation of the form, either generated by the graphical form editor or entered directly, is rendered to display the HTML components which will let the user to specify the parameters and input files for a custom task.

Another important step required by the wizard is entering a “config.xml” template. This file is required by LWS in order to break down the task in many smaller computing units and must be compliant to “config.xml” specification when interpreted. This template is entered directly by the system administrator at project creation stage and interpreted after each task submission. The interpreter supports the replacement of Form and Project variables and the interpretation of simple mathematical expressions and computing a split function with these variables.

LWI was developed using the Java programming language. The reason for choosing the latter has to do with the robustness of the platform. The inner structure is based on the MVC pattern in order to produce a maintainable product. The business logic is encapsulated in the “Services” component. The “DAO” component and “Web Service Consumer” provide the data access layer to LWI. The MySQL database is accessed with the help of the MyBatis ORM framework. Apache Axis, a widely adopted Web Service library for Java is used to interact with the LWS layer via the SwA standard. The client-side Form Editor was developed using the Google Web Toolkit (used for compiling a subset of Java into Javascript code) because of the useful widgets available and the ease provided by the object oriented programming. Go here for more details about the Architecture of Legion Framework.


Legion Projects

The concept of a project in Legion Framework encompasses both: a group of users and the application that they run on the Grid. This application must be batch-kind and capable of performing the computation of any computing unit. The executable files, custom task submission form, and related configuration is to be specified at the Project creation stage and they are susceptible of further modification without any risk to broke the compatibility after tasks began to been sent. Fore more details go to Legion Projects.

Creation Wizard

In order to create a project one must follow a 6 steps project creation wizard. A review of these steps is presented in Creation Wizard.

Template Interpreter

Legion Web Interface has a default template interpreter for generating the 'config.xml' file required by Legion Web Services. The latter is a Task Creation Descriptor, and thus must contain information which is present only in the task submission form each time a task is created. For more details go to Template Interpreter. Nevertheless the generated file should be compliant with the Config.xml Syntax.

Working example

A complete example of a project creation in Legion Web Interface is shown here .

User Roles

There are 3 scopes for user roles in Legion Web Interface. More details.

Legion Web Interface usage

Check the User Home for a quick view of the Home page for users. If you are interested in administrative home page have a look here instead.


Go to Installing Legion Web Interface for more details about the installation.


If you want to develop extensions for Legion Web Interface, you could have a look at the analysis class diagram here .

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Legion Web Interface
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