Odoo Activity View

<record id="view_activity_example_form" model="ir.ui.view">
<field name="name">activity.example.form</field>
<field name="model">activity.example</field>
<field name="arch" type="xml">
<form string="Study roadmap record">
<sheet>
<group>
<field name="name"></field>
</group>
</sheet>
<div class="oe_chatter">
<field name="message_ids" widget="mail_thread"></field>
<field name="activity_ids" widget="mail_activity"></field>
</div>
</form>
</field>
</record>