Skip to main content

Messing with the Engine

Don't ask me why -- well, ok, ask me and I'll tell you -- but I have been investigating lately how to create my own Engine instance (i.e. Tridion.ContentManager.Templating.Engine). Engine is an abstract class and as such cannot be instantiated directly. Time to get decompily...

I figured out there are a couple of implementations for Engine, but question is when is one used over the other. The simple solution was to log somehow the engine.GetType() method call in different contexts and see what comes back.

I ended up with a very simple C# Fragment:

    package.CreateStringItem(ContentType.Text, engine.GetType()));

And its DWT counterpart:

Engine type: @@TYPE@@

The result is the following:
  • executing the template in Template Builder displays:  Tridion.ContentManager.Templating.Debugging.DebuggingEngine
  • executing in CME Preview or doing an actual publish displays :  Tridion.ContentManager.Templating.TemplatingRenderer
Creating an instance of DebuggingEngine seems like black magic, so I didn't even try. TemplatingRenderer on the other hand is doable, although very laborious:

Session session = new Session();
Page page = new Page(new TcmUri("tcm:20-102-64"), session);
Template template = new PageTemplate(new TcmUri("tcm:20-715-128"), session);
ResolvedItem resolvedItem = new ResolvedItem(page, template);

PublishInstruction publishInstruction = new PublishInstruction(session);
PublicationTarget publicationTarget = new PublicationTarget(new TcmUri("tcm:0-1-65537"), session);

RenderInstruction renderInstruction = new RenderInstruction(session) { RenderMode = Tridion.ContentManager.Publishing.RenderMode.PreviewDynamic };
RenderedItem renderedItem = new RenderedItem(resolvedItem, renderInstruction);

RenderContext renderContext = new RenderContext();

IRenderer engine = new TemplatingRenderer();
engine.Render(resolvedItem, publishInstruction, publicationTarget, renderedItem, renderContext);

If you notice, engine is in fact initialized when the Render method is executed. Weirdly, Render is a method defined by IRenderer. That is pretty weird! TemplateRenderer extends/implements both Engine and IRenderer.

The code above will in fact start the publishing of the given Page with the given Page Template. That's a bit too much from what I was intending to do in the first place.

My goal is to simply have an Engine object so that I can instantiate a Package object. It seems like the following code is enough:

Engine engine = new TemplatingRenderer();
Package package = new Package(engine);

// test it 
package.PushItem("name", package.CreateHtmlItem("value"));

This will create a new item in the Package, so I can now use the object locally without having to perform an actual publish or preview in Template Builder.

What a hack!


Chris Summers said…
Please tell us why...
Mihai Cădariu said…
For short, I wanted to be able to run templates in a stand-alone application (e.g. Console app).

For long, I wanted to play with it in my Java Mediator quickly, without having to go load the TBB in Template Builder, execute it, stop TB because it locked all my JARs/DLLs, etc.

However, I also see a strong use-case for unit testing your templates! A continuous build environment (CM side). This can be fine grained (even at TBB level). Kinda: if that's the input package, that's the output. Is it the expected one?

Pretty cool :)

Popular posts from this blog

Running sp_updatestats on AWS RDS database

Part of the maintenance tasks that I perform on a MSSQL Content Manager database is to run stored procedure sp_updatestats . exec sp_updatestats However, that is not supported on an AWS RDS instance. The error message below indicates that only the sa  account can perform this: Msg 15247 , Level 16 , State 1 , Procedure sp_updatestats, Line 15 [Batch Start Line 0 ] User does not have permission to perform this action. Instead there are several posts that suggest using UPDATE STATISTICS instead: I stumbled upon the following post from 2008 (!!!), , which describes a way to wrap the call to sp_updatestats and execute it under a different user: create procedure dbo.sp_updstats with execute as 'dbo' as

Content Delivery Monitoring in AWS with CloudWatch

This post describes a way of monitoring a Tridion 9 combined Deployer by sending the health checks into a custom metric in CloudWatch in AWS. The same approach can also be used for other Content Delivery services. Once the metric is available in CloudWatch, we can create alarms in case the service errors out or becomes unresponsive. The overall architecture is as follows: Content Delivery service sends heartbeat (or exposes HTTP endpoint) for monitoring Monitoring Agent checks heartbeat (or HTTP health check) regularly and stores health state AWS lambda function: runs regularly reads the health state from Monitoring Agent pushes custom metrics into CloudWatch I am running the Deployer ( installation docs ) and Monitoring Agent ( installation docs ) on a t2.medium EC2 instance running CentOS on which I also installed the Systems Manager Agent (SSM Agent) ( installation docs ). In my case I have a combined Deployer that I want to monitor. This consists of an Endpoint and a

SDL Web 8 - Content Delivery Microservices

Among the new features in SDL Web 8 there are the Content Delivery Microservices, namely: Audience Manager Content Deployer Contextual Image Delivery Discovery Service Dynamic Content Dynamic Linking Profiling and Personalization Metadata Query Taxonomy User Generated Content These microservices make up the Content Interaction Services and they expose the existing Content Delivery in-process APIs as RESTful services. They provide the server-side component in a Services-Oriented Architecture and act as data layer between the the web client and the Content Delivery Storage Layer. According to the SDL marketing, these microservices: Simplify upgrades, thus offering shorter time to value Modernize architecture, offering better separation between the web application and Tridion APIs Offer more flexibility with less downtime and improved scalability Improve quality, being self-running, contained and having less dependencies In technical words, these microservices