Working with Sequences

What is a sequence?

A sequence is used to supply the next number from a defined sequence. It is designed to be used when you are building a form to create some form of new document, e.g. an application form. The sequence can be used to give each application a unique sequential id. Sequences are stored in the Ebase repository database.

Once a sequence has been created, it can be used by any number of forms.

How to use a sequence

The sequence is used via the sequence FPL script command which sets the $NEXT_SEQUENCE_ID system variable. For example, to create a new unique id for an application form, we would use the following FPL commands:

FPL:

API based language (Javascript):

sequence APPLICATIONS;

set APPLICATION_ID = $NEXT_SEQUENCE_ID;

var next = system.sequenceManager.sequence("APPLICATIONS");

fields.APPLICATION_ID.value = next;

where APPLICATIONS is the name of the sequence and APPLICATION_ID is the form field for the unique id.

Creating and editing a sequence

Sequences are created and maintained by clicking in the hierarchy tree panel (IT Elements -> Sequences).

· Sequence name is name by which the sequence is referenced in the sequence FPL command or API SequenceManager.sequence() method.

· Start of range is the lowest number within the sequence.

· End of range is the highest possible number within the sequence. When this number is reached, the sequence command will fail and the form will be terminated.

· Increment is the number by which the next document id should be incremented each time a new sequence is assigned.

· Next document id is the number to be used when the sequence is next accessed.

Click the icon to add a new sequence and the icon to delete selected sequences.

Sequences and transactionality

Sequences are incremented using a separate transaction from the main Ebase form execution. When the sequence FPL command or API SequenceManager.sequence() method is issued, a new sequence number is immediately assigned and the Ebase sequences database table is updated. If there is a subsequent failure in a script, the sequence will not be rolled back. It is therefore possible that there will be gaps in the sequence of documents created using a sequence.

Importing/exporting sequences

When sequences are selected for export, all sequence definitions are exported; it is not possible to export single definitions. Similarly an import will replace all sequence definitions and will also import the Most recent Document id, which could potentially compromise data integrity on the importing system. For these reasons, sequences are not automatically included in an export file when a form is exported with all related elements.

Sequence definitions should be created manually on the import target system.