NEMO Scripting
The NEMO framework executes every experiment according to the script that defines it. Scripts handle every detail, from creating devices to logging data. Scripts are written in a language called Jython.

The Task Object
When writing a NEMO script, one variable, called task, will be predefined by the framework. task is a Java object that is created when an experiment is created (that is, when a user decides to run the experiment). task serves as an intermediary between the script and the NEMO framework. It provides functions for setting up the environment for an experiment and communicating with clients during an experiment.

The following functions are made available to script writers through task:

• setExperimentSize(numClients)


  Tells the task how many clients will be connecting to the server for this experiment. The experiment cannot start until exactly numClients clients are connected. This function must be called in the Pre-Start Phase.

  
  
• setStartFunction(aFunctionName)


  When the required number of clients have connected to the experiment and entered start mode, NEMO will make a call to the script function aFunctionName. This function might set the initial display, setup data handling, or prompt the subjects for input. This function must be called in the Pre-Start Phase.

  
  
• setExperimentName(aName)


  Every experiment has a unique name. When uploading a script to NEMO for future use, a name is supplied to identify the experiment. The name used when uploading must match the name passed to the function. This function must be called in the Pre-Start Phase.

  
  
• getDataType(aDataTypeName)


  Returns the DataType with the name aDataTypeName. The returned DataType is used later in the script by startDataSet to create a DataSet, which is used to log behavioral data. This function must be called in the Pre-Start Phase.

  
  
• addDevice(aDeviceName, aDeviceClassName, aHandlerFunction)


  Creates a device with the unique name aDeviceName using the class aDeviceClassName. Any communication from clients travels through the function given by aHandlerFunction. See more about devices here. This function must be called in the Pre-Start Phase.

  
  
• addDeviceProperty(aDeviceName, aPropertyName, aPropertyValue)


  This function allows a script writer to designate required configuration parameters for devices. See more about devices here. This function must be called in the Pre-Start Phase.

  
  
• startRun(aRunName)


  Runs are divisions in an experiment. A singe experiment may have any number of runs. Each run will be stored separately by NEMO while still being linked to the particular experiment. The run will be labeled with aRunName. The time at which this function is called will be stored with the run by NEMO.

  
  
• startDataSet(aDataTypeName, aClientID)


  A DataSet is a collection of data of the same DataType. A DataSet should be created for each client in the experiment. The call to this function requires the name of the DataType and the ID of a client. The name of the DataType can be found using the DataType returned by the call to getDatatType. This function will return a DataSet object, which will be used for logging and to end the DataSet.

  
  
• endDataSet(aDataSet)


  Ends the DataSet given by the parameter aDataSet. Once the DataSet has ended, no more data can be logged to it.

  
  
• endRun()


  Ends the current run. This method will fail if a run has not yet been started.

  
  
• endExperiment()


  Ends the entire experiment. No more data can be logged, and no more runs can be started. This method must be called to tell NEMO to store all logged data to the database!

The Pre-Start Phase
After a user chooses to run an experiment, NEMO pulls the script from the database and processes it. It is the responsibility of the script (and the script writer) to ensure that certain actions are taken to properly set up the experiment. Before the experiment starts, NEMO requires that a script specify the number of clients to expect, the name of the experiment, the start function, and the devices to be used.

The Pre-Start Phase is also a good time to set up any variables that may need to be used later in the script. This will cut down on time once the experiment starts. For example, this phase is a good time to get the necessary DataTypes from task.

Any part of the script that is not inside a class or function will be run in the Pre-Start Phase. Calls can be made to functions and classes, but only those that are explicitly called will be executed. As shown in the sample code on lines 481-514, calls are made to task.setExptSize, task.setExperimentName, task.setStartFunction, and others in the Pre-Start Phase. Note that a call is made on line 514 to construct an instance of a custom class (called ExampleClass).

Coordinating Clients
NEMO assigns a unique ID to each client that connects to the experiment. The IDs fall in the range 0 to numClients - 1. Client IDs are used when sending commands to clients, receiving communication from a particular client, and creating DataSets for logging data. When writing a script for a single-client experiment, client coordination is very straightforward (it will always be 0!); however, writing an experiment for 12 subjects can be cumbersome. It will be very important to ensure that commands go to the correct client and that events are attributed to the correct client.