Overview

Processes orchestrate your workflows and are a key component of your Appian applications. As such, there are a variety of ways in which your processes can be started, depending on your application's needs. This page highlights all the available ways to initiate processes in your application and details when you should consider each approach.

Starting a process from Tempo or sites

To allow users to initiate different business processes, like creating a new service request or updating the status of a service request, a process model should be exposed as a record action or an application action.

Record actions allow users to take action on a specific record or a list of records. These actions are configured in the record type and can be displayed on record views, the record list, or in your reports and forms using the record action component.

Record actions can allow your users to start processes like:

• Updating the status of a service request to "Closed" when the ticket's issue is resolved
• Adding documents related to one of your customers
• Opening a new service request in your IT support application
• Adding a new customer to your organization in your Customer Onboarding app

In addition to record actions, you can also leverage application actions. These actions expose process models in end user interfaces. You can display these actions as a page on your Site or in the Actions tab in Tempo.

Learn more:

• Create Record Actions
• Application Actions
• Appian Sites
• Embedded Interfaces

Starting a process from an interface

There are several different ways to launch a process directly from an interface.

a!startProcess: A function that starts a process when triggering an interface reevaluation. Use this for unattended activities related to a specific piece of information on the interface.

a!startProcessLink: A link type that starts a process and navigates the user through any initial chained forms. Use this for taking the user to a process related to a specific piece of information on an interface.

Record Actions: A configuration on a record type that starts a process within the context of a record view or a record list. The process can also be started on a report or form using a record action component. Use this for updating or adding records to your record type.

Behavior	a!startProcess	a!startProcessLink	Record Action
Pass in data to process	Yes	Yes	Yes
Show start and chained forms	No	Yes	Yes
Configure in any interface	Yes	Yes	Yes
Maintain original interface state after process starts	Yes	No	Yes*
Use for file upload cases	No	Yes	Yes
Display custom banner on submit	No	Yes	No
Save URL as bookmark	No	No	Yes
Use in a Web API	Yes	No	No
Access process data on completion	Yes	No	No
Write custom error handling	Yes	No	No

*This is only true when a record action is opened and submitted in a Dialog Box. For more information, see the a!refreshVariable

Starting a process from a process

Appian offers several ways to start a new process from within a running process. The best choice will depend on your use case. The following article will detail the differences between these and provide common uses cases when each is appropriate.

The ways to start a new process from within a running process are:

• Subprocess: A smart service that is used to launch subprocesses from within your current process. It links the two published process models through a parent-child relationship and allows you to transfer data between them. The parent and child processes each contain references to the other. Subprocesses can be run either asynchronously or synchronously.

• Start Process Smart Service: A smart service that allows you to initiate another process from your current process. The new process is started asynchronously and the process flow of the current process continues after the new process starts.

• Process Messaging: The Send Event and End Event activities can trigger the starting of a new process if that process model's start node is configured to receive messages. Note in the table below that the Start Process smart service is equivalent or better than process messaging in every category.

Comparing ways to start a process from a process

Attributes	Subprocess (Synchronous)	Subprocess (Asynchronous)	Start Process Smart Service	Process Messaging
Synchronicity	Synchronous	Asynchronous	Asynchronous	Asynchronous
Parent-Child Relationship	Yes	Yes	No	No
Process Variables	Can be passed by reference	Can be passed by reference	Cannot be passed by reference	Cannot be passed by reference
Process Outputs	Available	Not available	Not available	Not available
Process Reports of Parent	Can access	Can access	Cannot access	Cannot access
Execution Engine Balancing	Same Engine	Same Engine	Balanced	Balanced
Model to Start	Defined statically	Defined statically	Defined dynamically	Defined statically
Activity Chaining	Followed	Not followed	Followed*	Not followed
Performance Under High Load	Medium	Medium	Good	Poor
Quick Tasks	Shared	Not shared	Not shared	Not shared

*Will follow chaining in the new process until chaining ends, then the parent process resumes (even if the new process has not finished)

Common use cases

Use Case	Best Way to Start Process	Why?
Using the Results of a Subprocess	Subprocess (Synchronous)	Subprocess (Synchronous) gives the designer an easy way to map process variables of the subprocess to ones in the current process.
Chaining to a User Input Task	Subprocess (Synchronous)	Subprocess (Synchronous) is the only method that can follow activity chaining into the subprocess. Following an activity chain into a subprocess will continue to add to the number of unattended nodes that exists between two (attended) activity-chained tasks. See Activity-Chaining into a Subprocess Activity for more information about activity chaining.
Reporting on Asynchronous Subprocesses	Subprocess (Asynchronous)	When you want to start subprocesses asynchronously and have the subprocesses show up in process reports for the current process you must use Subprocess (Asynchronous). This is because other asynchronous methods don't guarantee the subprocess will be on the same engine as the current process.
Starting Multiple Processes at Once	Start Process Smart Service	When you want to start multiple subprocesses at the same time you should use Multiple Node Instances (MNI) functionality on the Start Process smart service. The main reason for doing this is that the Start Process smart service will manage load on the system by spreading the newly started processes across all execution engines.

See also:

• Messaging Best Practices
• Send Message Event

Starting a process from outside Appian

Appian isn't the only system in your enterprise, and because of this, you might eventually need to initiate Appian processes from one of those other systems.

There are three different ways to initiate Appian processes from other systems:

• Using a Web API to call the Start Process smart service or initiate a process from Appian RPA.
• Starting a process by sending an email
• Exposing your process model as a webservice

When to use each of these methods is outlined in the Choosing the Right Type of Integration page.

Automatically starting a process

Processes don't always need an user interaction or another system to initiate them. You can also configure process models to automatically start on a particular date and time or a scheduled interval.

Some examples of this include:

• If you had an Appian application for managing employee timesheets, you might want to run a process every Friday morning that found who hasn't submitted their timesheet yet and send those employees a reminder email.
• If all of your Appian user accounts are based on your company's company-wide Active Directory or LDAP system, you might need to periodically sync the information between that system and Appian.

Learn more about configuring scheduled processes on the process Start Event page.