This would be the first of the series of blogs regarding my learnings on Sitecore Update Packages.
We know that Sitecore ZIP package helps in moving items between different environments.
But what if we need to move only the changes instead of the moving the whole item.
In that case we have to use UPDATE Package instead of ZIP Package.
Before diving deeper, let us explore what is inside zip/update package.
When we open the package.zip inside ZIP Package, we can see the following folders,
Items -> sitecore items
Files -> file sytem files
Metadata -> Details of the package like Author, license, readme etc.
Installer -> Sitecore version and package project details
Properties -> Item Properties like language, version etc. & Field Properties like Shared, Versioned etc.
Blob -> Media Item’s blob values
When we open the package.zip inside UPDATE Package(after renaming .update as .zip), we can see the following folders instead of items (and files),
addeditems -> items to be added
deleteditems -> items to be deleted
changeditems -> items to be modified
Now we know that, using an Update Package we can add/delete/change an item. But we can only add/overwrite/merge item using Sitecore ZIP Package and cannot delete or change an item.
If we have updated a field value for an item in a specific language, we will have to take the entire item including different languages and versions, which is an expensive operation. This increases the size of the package and also the installation time. Whereas with the help of an update package we can take the changed field value alone and not the entire item.
Everything inside an update package will be command. And these commands will be executed over the existing version of sitecore item. For eg: a ChangeField Command will change only the field value without affecting other fields or version of the item. A DeleteField Command will only delete the field value.
While installing these commands through UpdateInstallationWizard, we can analyze and understand the conflicts, before installation, which is currently not possible with ZIP Package InstallationWizard.
Hope this gives you a brief idea on Update Package.
We can discuss more on how to create different commands & update package in the next series of blogs.
Originally Posted at: https://www.nttdatasitecore.com/Blog/2016/September/How-does-Sitecore-Update-Package-Work-Introduction