concurrent_iterator

This expression is a cross between ‘concurrence’ and ‘iterator’.

Please look at the documentation of ‘iterator’ to learn more about the
common options between ‘iterator’ and ‘concurrent-iterator’.

              pdef = Ruote.process_definition :name => 'test' do
                concurrent_iterator :on_val => 'alice, bob, charly', :to_var => 'v' do
                  participant '${v:v}'
                end
              end

will be equivalent to

              pdef = Ruote.process_definition :name => 'test' do
                concurrence do
                  participant 'alice'
                  participant 'bob'
                  participant 'charly'
                end
              end

The ‘on’ and the ‘to’ attributes follow exactly the ones for the iterator
expression.

When there is no ‘to’, the current iterated value is placed in the variable
named ‘i’.

The variable named ‘ii’ contains the current iterated index (an int bigger
or egal to 0).

‘concurrent_iterator’ does not understand commands like
rewind/break/jump/… like ‘iterator’ does, since it fires all its
branches when applied.

:on and arrays

Given a workitem field named ‘x’ containing the array value
[ ‘a’, ‘b’, ‘c’ ] and a workitem field ‘y’ containing the string ‘a, b, c’,
this:

              concurrent_iterator :on_field => 'x', :to_f => 'xx' do
                # ...
              end

is equivalent to

              concurrent_iterator :on => '$f:x', :to_f => 'xx' do
                # ...
              end

is equivalent to

              concurrent_iterator :on => '${f:y}', :to_f => 'xx' do
                # ...
              end

:to_field and :to_f, :to_var and :to_v, :to

Those 4 lines are equivalent:

              concurrent_iterator :on => [ 'ceo', 'cto' ], :to_field => 'a' do ...
              concurrent_iterator :on => [ 'ceo', 'cto' ], :to_f => 'a' do ...
              concurrent_iterator :on => [ 'ceo', 'cto' ], :to => 'f:a' do ...
              concurrent_iterator :on => [ 'ceo', 'cto' ], :to => 'a' do ...

Those 3 lines are equivalent:

              concurrent_iterator :on => [ 'ceo', 'cto' ], :to_var => 'a' do ...
              concurrent_iterator :on => [ 'ceo', 'cto' ], :to_v => 'a' do ...
              concurrent_iterator :on => [ 'ceo', 'cto' ], :to => 'v:a' do ...

:times and :branches

Similarly to the iterator expression, the :times or the :branches attribute
may be used in stead of the ‘on’ attribute.

              pdef = Ruote.process_definition :name => 'test' do
                concurrent_iterator :times => 3 do
                  participant 'user${v:i}'
                end
              end

is equivalent to

              pdef = Ruote.process_definition :name => 'test' do
                concurrence do
                  participant 'user0'
                  participant 'user1'
                  participant 'user2'
                end
              end

ruote 2.3.0 and the citerator children

Prior to ruote 2.3.0, the concurrent-iterator only considered one child
expression:

              concurrent_iterator :times => 3 do
                participant 'al'
                participant 'bob' # 'bob' would never be reached
              end

So one had to write:

              concurrent_iterator :times => 3 do
                sequence do
                  participant 'al'
                  participant 'bob' # 'bob' would never be reached
                end
              end

Ruote 2.3.0 lifts that restriction.

options

the concurrent_iterator accepts the same options for merging as its bigger
brother, the concurrence expression.

:count, :merge (override, mix, isolate, stack, union, concat, deep, ignore),
:remaining (cancel, forget) and :over.

add branches

The ‘add_branches’/‘add_branch’ expression can be used to add branches
to a concurrent-iterator while it is running.

              concurrent_iterator :on => 'a, b, c' do
                sequence do
                  participant :ref => 'worker_${v:i}'
                  add_branches 'd, e', :if => '${v:/not_sufficient}'
                end
              end

In this example, if the process level variable ‘not_sufficient’ is set to
true, workers d and e will be added to the iterated elements.

Read more at the ‘add_branches’ expression description.

‘citerator’

‘citerator’ is an alias for ‘concurrent_iterator’.

              pdef = Ruote.process_definition :name => 'test' do
                citerator :on_val => 'alice, bob, charly', :to_var => 'v' do
                  participant '${v:v}'
                end
              end