stella.xml

Class DOMSequence

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.ArrayList<Collection<DOMSequence.TaskElement>>

stella.xml.DOMSequence

All Implemented Interfaces:

Serializable, Cloneable, Iterable<Collection<DOMSequence.TaskElement>>, Collection<Collection<DOMSequence.TaskElement>>, List<Collection<DOMSequence.TaskElement>>, RandomAccess, DTDConstants

public class DOMSequence
extends ArrayList<Collection<DOMSequence.TaskElement>>
implements DTDConstants

An XML-parser-application interface to read sequencer files in XML format (see jaxp extension interface to first read in the file and parse it into a parse() method. Only after this method has been called, the DOM-sequence can be traversed with a call to it's iterator method. Note that this iterator delivers a collection of DOMSequence.TaskElements at calls to its next method. The Step as the top-level element of the sequence is only used to construct the list in the correct sequence. A dom sequence is a specialized list in the way that it only allows special elements. Concrete, if you add a sequencer step with one of the list's add method, the object added must be a collection of DOMSequence.TaskElements. The list's addAll method work only if the collection added is a dom sequence. In this case, the awkward checking of the individual elements, as done with the add methods, is not necessarry as a domsequence is believed to be constructed of the correct types.

Although removal and addition of sequencing steps is also possible after the list has been constructed and although this may happen in different threads it is impossible that addition and removal of elements happen at the same time, therfore no synchronization is necessary.

Grammer of the xml-file:
At the time of this writing, the DTD can be found at XMLSequencer.

The complete condition tells the sequencer when it should consider a task as finished. Note that this does not necessarily mean that all commands in this task have been completed. True and false denote some Triggers that should be set to the appropriate value as this task is ready to execute. If a Change element is present, its value is used to initiate an external change in the parameter cluster of the sequncer. The commands are command templates (e.g. MOVE_TELESCOPE) that the sequencer can translate to device-understandable commands at runtime. To allow the sequencer or, more precisely, the rendering helper class used to transform the command template into an actual command three possibilities are available. If the command carries an id attribute, this attribute is matched as a refernece to an element in the target actually observed. A common use is to reference here the Star-id in a DOMTarget. If this reference is not unique an (additional) ref attribute may be specified, which must point to a unique element in the element-tree below the element specified with the id-tag (or the entire document, if no id- tag is given). If the command needs external parameters, like the ambient temperature, additional Parameter elements may be given with the command template. The sequencer retrieves the current value of the stated parameter name out of its parameter list and passes it over to its rendering instance.

See Also:

XMLSequencer, Serialized Form