Order in which resolved- and processed items are populated in PublishTransaction save event

Question

I am working on the following event system:

EventSystem.Subscribe<PublishTransaction, SaveEventArgs>(MyEventHandler, EventPhases.Initiated);

void MyEventHandler(PublishTransaction publishTransaction, SaveEventArgs saveEventArgs, EventPhases eventPhases)
{
    IdentifiableObject identifiableObject = publishTransaction.Items[0];
    if (identifiableObject.Id == "tcm:40-81620") //the test component
    {
        PublishContext publishContext = publishTransaction.PublishContexts[0];

        log.DebugFormat(
            "{0} - publishContext[0].ResolvedItems.Count = {1}; publishContext[0].ProcessedItems.Count = {2}",
            publishTransaction.State.ToString(),
            publishContext.ResolvedItems.Count,
            publishContext.ProcessedItems.Count);
    }
}

I need to do something with the resolved items, but I wasn't getting the behaviour I was expecting, so I decided to log the PublishTransactionState, ResolvedItems and ProcessedItems. In the handler I have set the code to run just for a single test component in order not to get logs for other transactions. The test component is being rendered with two templates.

Here is the log I get(using log4net):

WaitingForPublish - publishContext[0].ResolvedItems.Count = 0; publishContext[0].ProcessedItems.Count = 0
InProgress -  publishContext[0].ResolvedItems.Count = 0; publishContext[0].ProcessedItems.Count = 0
Resolving - publishContext[0].ResolvedItems.Count = 0; publishContext[0].ProcessedItems.Count = 0
Rendering - publishContext[0].ResolvedItems.Count = 0; publishContext[0].ProcessedItems.Count = 0
Rendering - publishContext[0].ResolvedItems.Count = 0; publishContext[0].ProcessedItems.Count = 2
ReadyForTransport - publishContext[0].ResolvedItems.Count = 2; publishContext[0].ProcessedItems.Count = 2
ReadyForTransport - publishContext[0].ResolvedItems.Count = 2; publishContext[0].ProcessedItems.Count = 2
WaitingForDeployment - publishContext[0].ResolvedItems.Count = 2; publishContext[0].ProcessedItems.Count = 2
Success - publishContext[0].ResolvedItems.Count = 2; publishContext[0].ProcessedItems.Count = 2

Can someone please explain the following:

• Why is the 'PublishContext[0].ProcessedItems' populated prior to 'PublishContext[0].ResolvedItems?
• Why are there two 'Rendering' states? In question PublishTransaction save event triggered multiple times Rick Pannekoek states that "In general, the Save event is called for any save (change) of the PublishTransaction, not only for state changes" which is clear, however I can't seem to find out which property change is causing this. Is there an easy way to find out what is causing this save?

Thank you in advance

Answer 1

Regarding the "Why are there two 'Rendering' states?", or more accurately "Why are there two Save events with State 'Rendering'?": you already more or less answered the question yourself -- the first one is for the State change to 'Rendering', the second one for changing the ProcessedItems.

IIRC, the ResolvedItems property is derived from ProcessedItems. I think this derivation happens when loading the item. That would explain why you don't see them yet in the Save event that happens when ProcessedItems are set. It also matters to which Event Phase ypu subscribed.