Call Workflow Service

Calls another workflow and obtains the results for further processing in this workflow. The workflow can receive inputs via Workflow Service Input nodes and return outputs using Workflow Service Output nodes.

Each Workflow Service Input node in the workflow to be called will create an input port on this node when finishing the configuration of the Call Workflow Service node. Similarly, each Workflow Service Output node will create an output port on the node.

The called workflow can be local or remote. If the workflow is remote, e.g., on the KNIME Hub, the execution will also be remote. When the workflow is local, the execution will be performed on the machine on which the Analytics Platform is running. In contrast to the Workflow Executor node, this node does not require the workflow to be read using a Workflow Reader node.

The difference between this node and the Call Workflow (Table Based) node is the set of supported workflow input and output nodes. This node supports the Workflow Service Input and Workflow Service Output nodes, which support arbitrary port types and are more efficient than the various Container Input and Container Output nodes. The container input and output nodes on the other hand expect and produce data in a format that can easily be produced by third-party software, whereas Workflow Service Input and Workflow Service Output nodes are designed exclusively to be used by other KNIME workflows.

To define which Workflow Service Input node receives data from which of this node's input ports, each input node defines a parameter identifier. The parameter identifier is supposed to be unique, but it might happen that a workflow has multiple input nodes defining the same parameter name. In this case, KNIME will make the parameter names unique by appending the input node's node ID to the parameter name, e.g., "input-table" becomes "input-table-7".

Options

Workflow

Remote execution address: Displays the address of the connected remote executor.
Short duration (only for remote execution): Choose this if the called workflow is expected to finish within ten seconds. When selected, the invocation of the workflow will not poll its status but wait until the job completes (or fails). This removes the polling overhead and makes this option quicker for short-running workflows. Choosing this option for long-running workflows (> a minute) will cause timeout problems.
Long duration (only for remote execution): Choose this if the called workflow is expected to run for more than ten seconds. When selected, the invocation of the workflow will poll its status repeatedly until the job completes (or fails). The polling is implemented so that for the first few seconds there will be frequent status checks (poll interval 100ms or 500ms), whereas jobs that run minutes or hours will be checked only every few seconds.
Retain job on failure (only for remote execution): When selected, failing jobs of the called workflow will be kept on the remote executor. This can be useful for debugging purposes. When not selected, the failing jobs will be discarded.
Discard job on successful execution (only for remote execution): When selected, successful jobs of the called workflow will be discarded from the remote executor. When not selected, successful jobs will be kept.
Workflow path: The path to the workflow you want to call. Use the "Browse..." button to select. The selected path can be set via a path flow variable or exported to a path flow variable.
Deployment: The deployed workflow to execute. Use the "Browse..." button to select. This option is only visible when the node is connected to a KNIME Hub Authenticator node.
Execution context: Only for workflows on a KNIME Hub. The workflow will be executed in the selected context. An execution context of a hub space defines for instance the installed extensions, available credentials, and the pool from which computation resources are used when the service is invoked.
Input Parameters: After you have specified a workflow path, you will see the input parameters of the workflow. Every input parameter corresponds to an input port of the node. This panel shows which input port's data is sent to which input parameter. By using the arrows, you can configure the binding of input ports to input parameters.
Output Parameters: Similar to the input parameters panel. Maps data sent back from the workflow to this node's output ports.
Adjust node ports: When the node ports differ from the workflow parameters, this button is used to confirm updating the node ports, which may remove connections to other nodes.

Advanced Settings

Workflow load timeout (only for remote execution): The maximum amount of time to wait for the remote executor when trying to initialize remote workflow execution. Specified in seconds. A value of 0 means that no timeout will be used.
Fetch workflow parameters timeout (only for remote execution): The maximum amount of time to wait for the remote executor when fetching the input and output parameters of the called workflow. Specified in seconds. A value of 0 means that no timeout will be used.
Job Status Polling (only for remote execution): During asynchronous invocation (option "Long Duration"), if a HTTP 5XX error occurs when polling for the job status, the node will retry the request. The node will wait a certain amount of time before each retry. The time to wait before the n-th attempt is determined by base * multiplier^n. Use a multiplier of 1 for a constant backoff, or a multiplier greater than 1 for an exponential backoff. Set the number of retries to 0 to disable retrying.

Input Ports

…: An optional connection to a file system that contains the callee workflow or a hub instance that provides deployed workflows. The callee workflow will be executed where it is located, e.g., on the KNIME Hub. If a Hub Authenticator is connected, only workflows that have previously been deployed can be executed. If a Space Connector or Mountpoint connector is connected, any workflow can be selected and executed.
…: One input port for each Workflow Service Input node in the workflow to be executed. The ports are automatically created when finishing the configuration of the node.

Output Ports

…: One output port for each Workflow Service Output node in the workflow to be executed. The ports are automatically created when finishing the configuration of the node.

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Installation

To use this node in KNIME, install the extension KNIME Personal Productivity Tools from the below update site following our NodePit Product and Node Installation Guide:

v5.2

A zipped version of the software site can be downloaded here.

Plugin provider: KNIME AG, Zurich, Switzerland

Plugin version: 5.2.0.v202311281916

On NodePit since: 2023-12-06

Last update: 2024-04-26

KNIME versions: Since v4.7

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