Create your own messages

Microsoft Dataverse exposes APIs using messages. There are many out-of-box messages available for you to use. Custom messages are typically used to add new domain specific functionality to combine multiple message requests into a single request. For example, in a support call center, you may want to combine the Create, Assign, and Update messages into a single new Escalate message.

There are now two ways to define custom messages:

Custom message method	Description
Custom Process Action	Also known as simply Custom Actions, these have been part of Dataverse for many years. Custom Process Actions provide a no-code way to define a custom message using the Workflow designer. The logic in these workflows can also be extended with code by using custom workflow activities. More information: Use Custom Process Actions with code
Custom API	Extends the concept of custom actions to provide developers with capabilities not limited by the workflow designer. More information: Create and use custom APIs

Many developers have been creating Custom Process Actions simply to create new messages without implementing any logic in the workflow designer. Instead, they register plug-ins for the message created by the custom action to implement all of their logic. The custom API feature makes this pattern a first class capability for developers to extend Dataverse with no dependency on the workflow designer or the technology it depends on.

Compare Custom Process Action and custom API

The following table describes some of the different capabilities.

Capability	Custom Process Action	Custom API	Description
Declarative logic with workflow	Yes	No	Workflow Actions can have logic defined without writing code using the Classic Workflow designer. Custom APIs require a plug-in written in .NET to implement logic that is applied on the server.
Require specific privilege	No	Yes	With custom API you can designate that a user must have a specific privilege to call the message. If the user doesn't have that privilege through their security roles or team membership, an error will be returned.
Define main operation logic with code	Yes	Yes	With Custom Process Actions the main operation processes the Workflow definition which may include custom workflow activities. The code in these custom workflow activities is processed in the main operation together with any other logic in the workflow. When the custom process action doesn't contain any custom workflow activities, developers frequently add logic to the Post-Operation stage in the event pipeline to define logic. With custom API the message creator simply associates their plug-in type with the custom API to provide the main operation logic. More information: Event execution pipeline
Block Extension by other plug-ins	Yes	Yes	With Custom Process actions set the IsCustomProcessingStepAllowedForOtherPublishers managed property to true if you wish to allow 3rd party plug-ins to run when registered on the message for your custom process action. When set to false, only plug-ins from the same solution publisher will run when a plug-in step is registered for the message. For custom API, set the AllowedCustomProcessingStepType to control whether any plug-ins steps may be registered, or if only asynchronous plug-ins may be registered. More information: Select a Custom Processing Step Type
Make message private	No	Yes	When you create a message using a Custom Process Action, it is exposed publicly in the endpoint for anyone else to discover and use. If someone else takes a dependency on the message you created, their code will be broken if you remove, rename, or change the input or output parameter signature in the future. If you do not intend for your message to be used by anyone else, you can mark it as a private message. This will indicate that you do not support others using the message you create, and it will not be included in definitions of available functions or actions exposed by the Web API $metadata service definition. Classes for calling these messages will not be generated using code generation tools, but you will still be able to use it. More information: When to make your custom API private
Localizable names and descriptions	No	Yes	While Custom Process Actions provide for a friendly name for the custom action and any input and output parameters it uses, these values are not localizable. With custom API you can provide localizable names and descriptions. These localized strings can then be bound to controls that provide a UI to use the message. More information: Localized Label values
Create OData Function	No	Yes	The Dataverse Web API is an OData web service. OData provides for two types of operations: Actions & Functions. An Action is an operation that makes changes to data in the system. It is invoked using the Http POST method and parameters are passed in the body of the request. A Function is an operation that makes no change to data, for example an operation that simply retrieves data. It is invoked using an Http GET method and the parameters are passed in the URL of the request Custom Process Actions are always Actions. Custom API provides the option to define custom Functions. More information: When to create a Function
Create a global operation not bound to a table	Yes	Yes	Both provide the ability to define a global message not bound to a table.
Bind an operation to a table	Yes	Yes	Both provide the ability to pass a reference to a specific table record by binding it to a table.
Bind an operation to a table collection	No	Yes	Binding an operation to a table collection allows for another way to define the signature for the custom API. While this does not pass a collection of entities as an input parameter, it restricts the context of the operation to that type of table collection. Use this when your operation works with a collection of a specific type of table or your operation will return a collection of that type.
Compose or modify a custom API by editing a solution	No	Yes	ISVs who build and maintain products that work with the Power Platform apply ALM practices that involve solutions. The data within a solution is commonly checked into a source code repository and checked out by a developer applying changes. A Custom Process Action is defined by a XAML Windows Workflow Foundation document which is transported as part of a solution. However, creating new or editing existing workflow definitions outside of the workflow designer is not supported. Custom API definitions are solution aware components included in a solution through a set of folders and XML documents. These files and the file structure enable transport the API from one environment to another. Because these are plain text files, changes can be made to them, or new APIs can be defined by working with these files. This method of defining custom APIs is supported. More information: Create a custom API with solution files.
Subject to 2 minute time limit	No	Yes	A plug-in that implements the main operation for a custom API is subject to the 2 minute time limit to complete execution. A Custom Process Action is not technically limited to two minutes. If a step in the Workflow logic contains a custom workflow activity, that part will be limited to two minutes. But the entire workflow cannot run indefinitely. There are other limitations that will cause long-running Custom Process Actions to fail. More information: Watch out for long running actions

Next Steps

Use Custom Process Actions with code
Create and use custom APIs