invoice_wkf.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>

    <record model="workflow.activity" id="act_to_send">
      <field name="wkf_id" ref="account.wkf"/>
      <field name="name">to_send</field>
      <field name="action">write({'state':'to_send'})</field>
      <field name="kind">function</field>
    </record>

    <record model="workflow.activity" id="act_to_valid">
      <field name="wkf_id" ref="account.wkf"/>
      <field name="name">to_valid</field>
      <field name="action">action_to_valid()</field>
      <field name="kind">function</field>
    </record>

    <record model="workflow.transition" id="t_draft_to_valid">
      <field name="act_from" ref="account.act_draft"/>
      <field name="act_to" ref="act_to_valid"/>
      <field name="signal">invoice_to_valid</field>
    </record>

    <record model="workflow.transition" id="t_valid_to_send">
      <field name="act_from" ref="act_to_valid"/>
      <field name="act_to" ref="act_to_send"/>
      <field name="signal">invoice_to_send</field>
    </record>

    <record model="workflow.transition" id="t_send_to_pro2">
      <field name="act_from" ref="act_to_send"/>
      <field name="act_to" ref="account.act_proforma2"/>
      <field name="signal">invoice_proforma2</field>
    </record>

    <record model="workflow.transition" id="account.t4">
      <field name="act_from" ref="act_to_send"/>
      <field name="act_to" ref="account.act_open"/>
      <field name="signal">invoice_open</field>
    </record>

    <record model="workflow.transition" id="t_send_to_cancel">
      <field name="act_from" ref="act_to_send"/>
      <field name="act_to" ref="account.act_cancel"/>
      <field name="signal">invoice_cancel</field>
    </record>

    <record model="workflow.transition" id="t_valid_to_cancel">
      <field name="act_from" ref="act_to_valid"/>
      <field name="act_to" ref="account.act_cancel"/>
      <field name="signal">invoice_cancel</field>
    </record>

  </data>
</openerp>