Workflow Assemblies - Rishan Solutions

In the evolving landscape of business applications and automation platforms, workflows are key to managing structured processes. They help automate sequences of tasks, integrate systems, and reduce manual operations. One of the most powerful and flexible ways to extend workflows is through the use of Workflow Assemblies. These components allow developers to introduce custom logic into workflow-driven environments.

In this article, we’ll explore what Workflow Assemblies are, how they function, why they’re used, and how to develop and deploy them. Whether you’re working in a CRM system like Microsoft Dynamics 365 or any platform that supports workflow extensibility, this guide will give you a solid foundation.

What Are Workflow Assemblies?

A Workflow Assembly is a compiled code library (usually a .NET assembly, i.e., a .dll file) that contains custom code which can be invoked from within a workflow. These are typically used to create custom workflow activities—components that go beyond the built-in functionality of a platform’s native workflow engine.

Key Characteristics

Reusable: Workflow assemblies can encapsulate logic that can be reused across multiple workflows.
Extensible: They allow for the extension of workflow engines beyond predefined activities.
Compiled Code: Written in languages like C# or VB.NET, then compiled into a DLL.
Registrable: Registered with the host platform (e.g., Dynamics 365, K2, or Nintex).

Common Use Cases

Workflow Assemblies are ideal in scenarios where native workflow actions are insufficient. Examples include:

Performing complex calculations or data transformations
Integrating with external systems via APIs
Triggering business logic like inventory updates or invoice generation
Executing conditional logic or advanced validations

Workflow Assemblies in Microsoft Dynamics 365

Microsoft Dynamics 365 is one of the most prominent platforms supporting Workflow Assemblies. In Dynamics, workflows are often used to automate business processes like sending emails, updating records, or managing approvals. But sometimes, the out-of-the-box actions are not enough.

This is where Custom Workflow Activities come in.

Structure

In Dynamics 365, a Workflow Assembly typically:

Is a class that inherits from CodeActivity
Implements an Execute method
Uses input and output arguments through the InArgument<T> and OutArgument<T> types

Sample Code

public class CalculateDiscount : CodeActivity
{
    [Input("Total Amount")]
    public InArgument<decimal> TotalAmount { get; set; }

    [Output("Discounted Amount")]
    public OutArgument<decimal> DiscountedAmount { get; set; }

    protected override void Execute(CodeActivityContext context)
    {
        decimal total = TotalAmount.Get(context);
        decimal discount = total * 0.10M; // 10% discount
        DiscountedAmount.Set(context, total - discount);
    }
}

This custom workflow activity can then be compiled into a DLL and registered in Dynamics 365.

Development Process

Creating Workflow Assemblies involves a systematic approach similar to developing any .NET class library. Here’s a step-by-step overview:

1. Set Up Your Development Environment

Use Visual Studio (or any .NET-compatible IDE)
Target .NET Framework 4.6.2 or as required by the host system
Add references to required assemblies (like System.Activities for Windows Workflow Foundation or CRM SDK libraries for Dynamics)

2. Create a Class Library Project

Start a new Class Library project
Name it something relevant, like MyCompany.Workflows

3. Define Workflow Activities

Each custom activity must inherit from CodeActivity and implement the Execute method. This method contains the logic that the workflow will perform.

4. Add Input and Output Arguments

Arguments allow data to flow between the workflow and the assembly.

[Input("Customer ID")]
public InArgument<string> CustomerId { get; set; }

[Output("Customer Score")]
public OutArgument<int> Score { get; set; }

5. Compile the Assembly

Build the project to generate the .dll file.

Registration and Deployment

Once the DLL is built, it must be registered with the workflow engine. The process depends on the host system.

In Dynamics 365:

Use the Plugin Registration Tool (part of the XRMToolBox or Dynamics SDK).
Register New Assembly
- Browse and select your compiled DLL
- Choose location (Database or Disk)
- Register each activity within the assembly
Add the activity to workflows
- Go to the workflow designer
- Look for your custom activity in the available steps

Debugging and Testing

Testing custom workflow activities is crucial for reliability. Since workflow logic is usually invoked by the platform, you might not be able to debug it directly with breakpoints.

Tips for Testing

Unit Testing: Create test projects to test the logic outside the host system.
Logging: Add logging or trace output to your code.
Workflow Logs: Use the platform’s workflow history or log tracing to analyze results.
Emulators/Mocks: In Dynamics, use mock services like FakeXrmEasy to simulate CRM behavior.

Best Practices

Keep It Simple: Workflow Assemblies should perform a single, focused task.
Validate Input: Always check for nulls or invalid data before processing.
Avoid Long-Running Tasks: Workflows are not ideal for time-intensive operations. Offload such work to background services.
Use Logging: Add sufficient logging to understand failures or unexpected behavior.
Follow Naming Conventions: Use clear and descriptive class and argument names.

Versioning and Maintenance

When you update a workflow assembly:

Increment the version number.
Update the registration in the host platform.
Test compatibility with existing workflows.

Some platforms allow multiple versions of an assembly to coexist, while others require re-deployment of dependent workflows.

Security Considerations

Workflow Assemblies run in the context of the application and can access sensitive data. Consider the following:

Limit Permissions: Access only the data and APIs you need.
Avoid Hardcoding: Don’t hardcode credentials or environment-specific details.
Input Validation: Prevent injection or malformed input from breaking the process.
Isolation: If possible, use sandboxed environments or context-specific permissions.

Performance Considerations

Since workflows may be triggered automatically and frequently, poor performance in a custom assembly can impact the whole system.

Optimize Logic: Avoid unnecessary database calls or loops.
Use Caching: Cache configuration or metadata if used repeatedly.
Asynchronous Operations: Use async patterns or background services where needed.

Workflow Assemblies Beyond Dynamics

Although Dynamics 365 is a popular context for Workflow Assemblies, the concept exists across other platforms:

1. Windows Workflow Foundation (WF)

WF allows the building of complex workflows with both XAML and code. Custom activities in WF are written much like Dynamics’ Workflow Assemblies.

2. K2 Workflows

K2 allows for custom workflow steps using SmartObjects or custom assemblies.

3. Nintex

Nintex workflows can be extended via web services or external code, somewhat akin to workflow assemblies.

Real-World Example: Order Approval System

Imagine a scenario where a company has an automated order approval workflow. The built-in conditions in the CRM only allow checking fixed thresholds. A Workflow Assembly could:

Look up a customer’s credit rating from an external API
Evaluate total outstanding invoices
Apply a custom rule like “Approve orders under $5,000 if credit rating > 700”

Such logic, encapsulated in a Workflow Assembly, enhances flexibility and decision-making accuracy.

Advantages of Using Workflow Assemblies

Powerful Customization: Enables logic not possible with built-in steps
Reusability: Write once, use in many workflows
Integration: Easily tie workflows into external systems
Separation of Concerns: Keep business logic out of the workflow definitions

Drawbacks

Complexity: Requires knowledge of development tools and deployment processes
Maintenance Overhead: Changes require re-deployment
Debugging Difficulty: Harder to troubleshoot than visual workflows
Version Management: Care needed to avoid breaking existing workflows