Spring webflow start flow and event from a external link (p.e. confirmation email) - spring

Question

App send a confirmation email when an user register a new account. That email contain a link which must start a specific eventId for a flow which got several events. Link redirect properly to flow but I don't get this flow start on confirmation eventId, always it starts on first eventId called login.
url: ....aio/spring/login?_eventId=confirmation&code=cmFmYWVscnVpenRhYmFyZXNAZ21haWwuY29t
I have read possible solutions using externalRedirect and others commands written on flow rules but I don't need that way.
Login flow
<view-state id="login" view="login.xhtml">
<transition on="entry" to="connect"/>
<transition on="recoveryPass" to="recovery" />
</view-state>
<action-state id="connect">
<evaluate expression="login.connect()" />
<transition on="yes" to="finish" />
<transition on="no" to="login" />
</action-state>
<view-state id="recovery" view="recovery.xhtml" model="loginFields">
<transition on="return" to="login" />
<transition on="sendPass" to="recoveryPass" />
</view-state>
<action-state id="recoveryPass">
<evaluate expression="login.recoveryPass()" />
<transition on="yes" to="login" />
<transition on="error" to="error" />
</action-state>
<action-state id="confirmation">
<on-entry>
<set name="confirmationCode" value="requestParameters.code" type="string" />
</on-entry>
<evaluate expression="login.confirmation(confirmationCode)" />
<transition on="yes" to="confirmationOk" />
<transition on="no" to="noUserFound" />
<transition on="error" to="error" />
</action-state>
<view-state id="confirmationOk" view="confirmation.xhtml">
<!--<set name="viewScope.code" value="found" /> -->
</view-state>
<view-state id="noUserFound" view="confirmation.xhtml">
<!--<set name="viewScope.code" value="notFound" />-->
</view-state>
<end-state id="finish" />
<subflow-state id="error" subflow="error">
</subflow-state>

Answer 1

eventId is not same as state id - eventId is required for transitioning in a current state(action/view) of an ongoing flow and not for launching a new flow. The reason why you are landing on login could be that login-flow xml might be mapped to /login mapping and view-state with id login is the start state(by default first state in flow definition file will be start state) of login flow. You need to have a decision state as on start state to redirect to a state based on some conditional parameter whether you need to go to login state or confirmation state.
EDIT:
For example, if code parameter is present only when request is from email, then your flow definition could be like:
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">
<input name="code" type="java.lang.String">
<decision-state id="checkFlowStart">
<if test="code == null" then="login" else="confirmation"/>
</decision-state>
<view-state id="login" view="login.xhtml">
<transition on="entry" to="connect"/>
<transition on="recoveryPass" to="recovery" />
</view-state>
....

Answer 2

Have you considered make a particular state (implementation in that state) as a different flow. When using in the main flow it can be used as sub-flow and whereas it gives you a freedom to be launched as a separate flow as well.
The parameter from the main flow can be passed as inputs to the sub-flow. Below is an example I am trying to explain myself
Main Flow
<view-state></view-state>
<action-state></action-state>
<!-- This is the re-usable flow which can be used within this flow and can be
launched independently -->
<sub-flow>
<input/>
</sub-flow>
Another spring flow - can be plugged in from another flow or used independently
<input/>
<action-state></action-state>
<end-state></end-state>