Approvals via REST HOWTO

Last modified 23 Mar 2021 14:06 +01:00

The following approval-related operations are currently available via REST service:

  • starting an approval process,

  • determining the status of the approval process.

The following is doable, but currently only using an unsupported "hack", basically for demonstration purposes only:

  • approving or rejecting an item (i.e. the actual decision making).

In this document we’ll show how to carry out these operations.

Starting an approval process

In midPoint the approval process is started automatically when an operation requiring approval is started. I.e. there’s no special "start an approval process" method.

Let us illustrate this on an example.

This is user peter:

<user xmlns="http://midpoint.evolveum.com/xml/ns/public/common/common-3"
    oid="cac0694d-62d8-441b-a277-0a33b8caa0f7">
    <name>peter</name>
</user>

This is role sensitive that we want to assign to peter:

<role xmlns="http://midpoint.evolveum.com/xml/ns/public/common/common-3"
    oid="d4930444-c5e5-4710-af96-19f79eb078cb">
    <name>sensitive</name>
</role>

The role has an approver, named paul:

<user xmlns="http://midpoint.evolveum.com/xml/ns/public/common/common-3"
    oid="3b5b5d18-b1d9-4125-b435-a5d3aece8546">
    <name>paul</name>
    <assignment>
        <targetRef oid="d4930444-c5e5-4710-af96-19f79eb078cb" type="RoleType" relation="approver"/>
    </assignment>
    <assignment>
        <targetRef oid="00000000-0000-0000-0000-000000000004" type="RoleType"/> <!--  Superuser, to avoid authorization issues -->
    </assignment>
    <credentials>
        <password>
            <value>5ecr3t</value>
        </password>
    </credentials>
</user>

Paul has an assignment to role sensitive with a relation of approver, so it is an approver for all assignments of that role.

Now let’s start the approval process. We will do that by assigning role special to user peter.

curl.exe -v --user administrator:5ecr3t -H "Content-Type: application/xml" -X PATCH http://localhost:8080/midpoint/ws/rest/users/cac0694d-62d8-441b-a277-0a33b8caa0f7 -d @assign-sensitive-role.xml
+
assign-sensitive-role.xml
<objectModification
         xmlns="http://midpoint.evolveum.com/xml/ns/public/common/api-types-3"
         xmlns:t="http://prism.evolveum.com/xml/ns/public/types-3"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns:c="http://midpoint.evolveum.com/xml/ns/public/common/common-3">
    <t:itemDelta>
        <t:modificationType>add</t:modificationType>
        <t:path>assignment</t:path>
        <t:value xsi:type="c:AssignmentType">
            <c:targetRef oid="d4930444-c5e5-4710-af96-19f79eb078cb" type="c:RoleType">
                <!-- sensitive -->
            </c:targetRef>
        </t:value>
    </t:itemDelta>
</objectModification>

The above XML is sent to the REST service and it will be applied (as an object delta) to object cac0694d-62d8-441b-a277-0a33b8caa0f7, i.e. peter. It has one item delta, in particular creation of an assignment to d4930444-c5e5-4710-af96-19f79eb078cb i.e. to the sensitive role.

The response is then like this:

HTTP/1.1 204
Date: Thu, 25 Oct 2018 12:31:26 GMT

I.e. the operation was successful.

Determining the status of the approval process

The approval processes are represented as case objects. So they can be retrieved just like any other using the REST search operation. An example:

get-approval-cases-for-peter.bat
curl.exe -v --user administrator:5ecr3t -H "Content-Type: application/xml" -X POST "http://localhost:8080/midpoint/ws/rest/cases/search" -d @get-approval-cases-for-peter.xml
+
get-approval-cases-for-peter.xml
<q:query xmlns:q="http://prism.evolveum.com/xml/ns/public/query-3">
    <q:filter>
        <q:and>
            <q:ref>
                <q:path>objectRef</q:path>
                <q:value oid="cac0694d-62d8-441b-a277-0a33b8caa0f7"></q:value>        <!-- peter -->
            </q:ref>
            <q:equal> <!-- optional -->
                <q:path>state</q:path>
                <q:value>open</q:value>
            </q:equal>
        </q:and>
    </q:filter>
</q:query>

The above search query returns all approval processes and the whole requests that deal with the user cac0694d-62d8-441b-a277-0a33b8caa0f7 i.e. peter and are still waiting to be resolved (state=open condition).

Formally, state is an URI. It can have both unqualified and qualified forms, e.g. open vs http://midpoint.evolveum.com/xml/ns/public/common/case-3#open. In theory, you would need to check for both, using e.g. OR filter clause. But practically, midPoint currently uses the unqualified form.

There are two kinds of approval-related cases:

  1. Operation-level cases, covering the whole operation. Each operation can consist of one or more elementary actions, like "add assignment to role R1", "add assignment to role R2", "remove assignment of role R3". Operation cases have the Operation request archetype.

  2. Individual approval cases; each covering a single elementary action, like "add assignment to role R1". Each such task corresponds to a single approval process. These have the Approval case archetype.

You can use a filter on archetypeRef to differentiate between these two kinds; returning only what you need.

Approving or rejecting a work item

It is currently not possible to approve or reject a work item via REST directly. And it never was. As described here there was always an unsupported "hack" that allowed it. The following is an attempt to port that hack to 4.x. DO NOT USE THIS in production.

+
Missing/incomplete feature

This is a missing or incomplete feature of midPoint and/or of other related components. We are perfectly capable to implement, fix and finish the feature, just the funding for the work is needed. Please consider the possibility for supporting development of this feature by means of midPoint Platform subscription. If you already are midPoint Platform subscriber and this feature is within the goals of your deployment you may be able to use your subscription to endorse implementation of this feature.

Having understood the above, let us describe the hack. This will approve the work item:

approve-work-item.bat
curl.exe --user administrator:5ecr3t -H "Content-Type: application/xml" -X POST "http://localhost:8080/midpoint/ws/rest/rpc/executeScript" --data-binary @approve-work-item.xml

(--data-binary is there because otherwise the lines in script got concatenated, at least sometimes on Windows)

approve-work-item.xml
<?xml version="1.0"?>
<s:executeScript xmlns:s="http://midpoint.evolveum.com/xml/ns/public/model/scripting-3" xmlns:c="http://midpoint.evolveum.com/xml/ns/public/common/common-3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <s:action>
        <s:type>execute-script</s:type>
        <s:parameter>
            <s:name>script</s:name>
            <c:value xsi:type="c:ScriptExpressionEvaluatorType">
                <c:code>
                    import com.evolveum.midpoint.schema.util.WorkItemId
                    import com.evolveum.midpoint.xml.ns._public.common.common_3.*

                    caseOid = '492f3ff0-b0c7-4e97-86ff-730dc2bd8529' /* this is the OID of the approval case */
                    localId = 4                                      /* this is 'local' work item ID */
                    workItemId = WorkItemId.create(caseOid, localId)

                    output = new AbstractWorkItemOutputType(prismContext)
                        .outcome('http://midpoint.evolveum.com/xml/ns/public/model/approval/outcome#approve')

                    midpoint.workflowService.completeWorkItem(workItemId, output, midpoint.currentTask, midpoint.currentResult)
                </c:code>
            </c:value>
        </s:parameter>
        <s:parameter>
            <s:name>forWholeInput</s:name>
            <c:value>true</c:value>
        </s:parameter>
    </s:action>
</s:executeScript>

Unfortunately, the approval/rejection is logged under administrator account. It is not possible to use non-admin account to carry out this action, because Groovy script execution requires the strongest authorization (because of the security implications). But, as said, this is more-or-less for demonstration purposes.