Which to chose On Publish Event, Storage or Deployer extension in given scenario?

Question

I have a scenario where I have to check if there is any change in a particular field of a Component, then I have to call some shell scripts and then move some files from one location to another.

The Publish status of the Component should be marked successful in CMS, only if the operation performed by scripts and file copy operation is successful.

My question is, where exactly should I implement this?

1. On Publish event of Component
2. Storage extension
3. Deployer extension

I want to add some more to my question:- The scripts may take time more than hours. In that case will it be good to use Storage extension.

Answer 1

I tried to figured out the difference between Deployer Extension and Storage Extension and the various scenario specifying which one to use - may be you want to follow this blog

Considering this specific requirement from your question - The Publish status of the Component should be marked successful in CMS, only if the operation performed by scripts and file copy operation is successful.

I would suggest using the Storage Extension, you will get complete control on the Publishing Transaction and can even send meaningful message to the CME in case of failure. And this particular extension would fulfill all your requirements. However, from Architecture perspective, this might sounds a bit vague to many people as you are not dealing with the Tridion Storage Layer - but with the Deployer Module. However, using Deployer Extension, as you are seeking a lots of control on the Publishing Transaction process, I am not sure how much you will be able to achieve.

Answer 2

If you want to check a component field value, then it will be easier to do this on the CM side, however if the files that you want to move around are in your web layer, then its probably not practical to run the scripts and move them from a CM-based application.

In order to determine where you should extend, its also important to understand a bit more about what should happen if the shell scripts fail. Should the items that were published then not be stored on the FS/DB, or do we simply want to notify the editor that something went wrong?

Storage extensions give you access to the moment an item is stored to FS/DB, so are a good extension point if you want to do stuff on an item by item basis, and have the ability to interrupt the transaction of storing the content. Deployer extensions operate in a pipeline, so are less integrated with the deployment of individual items, and have no control over the transaction of storing the published items (except if you put your extension first in the pipeline, and throw an error; subsequent deployment processes in the pipeline will not be executed).

For the event system you could look at the SaveEventArgs for PublishTransaction subject- this gives you access to the moments when the status in the Publish Queue is updated.

It might help if you gave a less abstract summary of your requirements.