Invoke Process

Invoke Process

Type: invoke-process  ·  Package: Core Activities v1.0.8

Runs another published process from Zoan Cloud as part of the current process, passes it input data and receives its results back. It is the way to reuse a whole process across projects: signing in to a portal, looking up a customer in the ERP or sending a report is built and published once, and other processes invoke it.

The invoked process runs inside the same execution, not as a separate one. That is why what it returns stays alive: if the login process returns the already authenticated browser session, the calling process keeps working in that same tab.

Invoke Process or Invoke Playbook?

• Invoke Playbook: runs another playbook from the same project, from its file.
• Invoke Process: runs a process published in Zoan Cloud, which may come from another project and has its own version history.

How it works

1. Looks up in Zoan Cloud the current published version of the process set in process, in the same environment where the robot runs. It downloads it the first time and keeps it on the machine for later runs.
2. Loads the activity packages that process needs and runs its entry playbook, passing it the values of input.
3. The invoked process runs with its own variable space: it does not see or modify the caller’s variables.
4. When it finishes, its outputs are mapped to variables of the current process according to outputs.
5. If the invoked process fails, this activity fails with the same error (catchable with Try / Catch).

Required parameters

Parameter	Type	Default	Description
process	string	—	The published process to run, by name. Its current published version is always invoked; no version is pinned.

Optional parameters

Parameter	Type	Default	Description
input	Dictionary	—	Values the invoked process receives, as name: value pairs. The names are the input arguments of its main playbook.
outputs	Dictionary	—	{ processOutput: callerVariable } mapping. Only the invoked process’s output arguments (Out or In/Out) cross over; names that are not valid variables or that the process doesn’t return are ignored.

Output

This activity does not return a value of its own: what the invoked process produces reaches the variables set in outputs. Since it runs in the same execution, an output can be a live object (a browser session, an application window) that the current process keeps using. When it finishes successfully, Process '…' completed. is logged.

Choosing the process in the Designer

If you are signed in to Zoan Cloud from the Designer and have an environment selected, process shows the list of processes published in that environment. When you pick one, the input and outputs editors are filled with the inputs and outputs that process declares.

Without a session, process is a free text field where you type the process name: you can keep designing, and the name is resolved anyway when the process runs on a robot.

Example

A published process, Supplier portal login, opens the browser, signs in and returns the page session. Another process invokes it and keeps working in the same tab:

Invoke Process
  process = "Supplier portal login"
  input   = { user: "robot01" }
  outputs = { page: portalPage }
Page Navigate   page = portalPage   url = "https://suppliers.example.com/invoices"
Extract Structured Data   page = portalPage   selector = (#invoices)   → output: invoices

• input: the invoked process receives user as an input variable.
• outputs: the invoked process’s page output is stored in the current process’s portalPage variable.

Always the current version

The process is invoked by name, not by a fixed version. When you publish a new version of the invoked process, every process that calls it uses that version on its next run, without republishing them. Keep in mind that a change to its inputs or outputs affects all of them.

Each process has its own variables

Communication happens only through input (to the invoked process) and outputs (back). Only the output arguments (Out or In/Out) the invoked process declares in its Arguments panel cross over; its internal variables do not.

The variable that receives an output (portalPage in the example) must be declared in the current process. If it is not, that output is not assigned and a warning in the log says so. Any valid variable name works, including one-letter names (x, n).

Requires a connection to Zoan Cloud

The process is resolved in Zoan Cloud at run time. It works on connected robots and in the Designer when you are signed in and have an environment selected. Also, a headless process cannot invoke a Windows process.

Common errors

Message	Cause and fix
Process not found: '…'	There is no published version with that name in the environment where the robot runs. Check the exact name and that the process is published in that environment.
Process '…' is a Windows process and cannot be invoked from a headless process. …	A headless process tried to invoke a Windows one. Run the calling process on a Windows robot, or make the invoked process headless.
Could not resolve process '…': Zoan Cloud answered HTTP …	Zoan Cloud answered with an error other than “does not exist” (for example, missing permissions or a service failure). Check the robot account’s permissions; if it is a temporary failure, wrap the invocation in a Retry.
Could not prepare process '…' (…). See the Runner log for details.	The process exists, but it could not be downloaded or prepared on the robot. The details are in the Runner log; check the machine’s connection and disk space.
invoke-process is not supported in this host (no process resolver configured).	The execution has no connection to Zoan Cloud (for example, the Designer without a signed-in session). Sign in to Zoan Cloud from the Designer and pick an environment, or run it on a connected robot.
Recursion detected: …	The invoked process is already running higher up in the same invocation chain. Reorganize the logic so it is not invoked again.
Maximum invocation depth reached (32 levels).	Too many processes or playbooks are invoking each other in a chain. Flatten the structure.
Output '…' was not assigned to '…': …	Warning: the variable that receives the output is not declared or its type is not compatible. Declare it with the right type.
The invoked process '…' failed.	The invoked process failed without a message of its own. When it has one, the activity fails with that same message and type (a business error is still a business error). Handle it with a Try / Catch.
'process' is required.	The process name is missing.

Related activities

• Invoke Playbook — run another playbook from the same project.
• Try / Catch — handle a failure of the invoked process.
• Publish a process — how the invoked version gets published.
• Variables — how inputs are passed and outputs received.