public Workflow(Model.WorkflowDefinition workflowDefinition, params Assembly[] frameworkExtensionsAssemblies)
{
this.WorkflowDefinition = workflowDefinition;
//Validate and build worfklow steps
foreach (Model.StepDefinition step in workflowDefinition.Steps)
{
//Find concrete step class decorated by "StepAttribute" with the step type commming from workflow definition
Type stepType = frameworkExtensionsAssemblies
.ScanTypesForCustomAttributes((StepAttribute attribute) => attribute.Type == step.Type)
.SingleOrDefault();
if (stepType == null)
{
throw new InvalidOperationException($@"The worfklow step type ""{step.Type}"" was not found in registered framework extensions");
}
Type stepInterfaceType = stepType.GetInterfaces().Where(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IStep <>)).FirstOrDefault();
//Create a concrete step instance
if (stepInterfaceType != null)
{
Type paramType = stepInterfaceType.GetGenericArguments().Single();
object paramValue;
if (step.Param.GetType() == paramType)
{
paramValue = step.Param;
}
else if (step.Param is JToken jtoken)
{
paramValue = jtoken.ToObject(paramType);
}
else
{
throw new NotSupportedException($@"Step ""{step.Type}"" has invalid ""Param"" property type ""{step.Param.GetType()}""");
}
IStep stepInstance = (IStep)stepType.GetConstructor(new Type[] { paramType }).Invoke(new object[] { paramValue });
this.Steps.Add(new Step(step, stepInstance));
}
else
{
throw new NotSupportedException($@"The step type ""{stepType}"" doesn't implement ""{typeof(IStep<>)}"" interface");
}
}
}
public static async Task Main(string[] args)
{
if (args.Count() < 1)
{
Console.WriteLine(@"Missing argument.
Syntax: ""Workflow.ConsoleApp <workflow-definition-filename.json>""");
return;
}
string workflowFileName = args[0];
string workflowJson = File.ReadAllText(workflowFileName);
Model.WorkflowDefinition workflowDefinition = JsonConvert.DeserializeObject <Model.WorkflowDefinition>(workflowJson);
workflowDefinition.FileName = workflowFileName;
//create and validate workflow
Workflow.Framework.Workflow workflow = new Workflow.Framework.Workflow(workflowDefinition, Assembly.Load("Workflow.Extensions"));
//execute workflow
await workflow.ExecuteAsync();
}