Just Sitecore Things

Last time I was involved into project because of some strange issue. Guys had environments divided on CM and CD, there were a few of them, and on each was problem with propagating content.

Let's start with details, well, imagine situation when you change something using content editor on  CM server. Then publish that changes and go to CD server. Now you notice that there are no changes here. Strange, right? 

Ok, then imagine situation when things mentioned before happened, but sometimes,nobody knows why, it's working. Yeap, in some situation your changes, like new field values or new items, appear on CD. 

Nice? 

Than imagine situation when things mentioned before happened and additionally you have an access from CD to Sitecore dashboard. We assume some intern didn't know to cut off access from there. To clarify both CD and CM use the same set of databases. To check master database we are making some changes in Content Editor and save it, than without publish we go to CD, go to Sitecore dashboard and open Content Editor. What we see ? There is no our changes. What more? sometimes it works, like on Web database.

To summarize:

- we have separation on CM and CD

- both use the same DBs set

- sometimes we see changes on each DB

Strange ? Strange is an euphemism.

via GIPHY

What we think firstly? Come on guys, there should be some other DB or some corrupted connection strings. Some other ideas, maybe some Load Balancer switch sometimes to other app version? Or maybe there is an issue with EventQueue, it's overloaded and doesn't refresh remote server so often as it should. Other ideas? 

After passing above points we also figure out a few more and our list after some time looked like:

After went through whole list, everybody can feel disappointed. So, the best assumption was check data propagation one more time, hence we came back to EventQueue. As before, it wasn't blocked, overflowed or something, so looked nice. I got instance name from InstanceName column and check with machines and what discovered, both had the same name !

What it means ?

It means there was sort of race between servers during reading EventQueue. Who read first EventQueue, then it has the newest value, second server in reading saw it has been read already by itself (the same instance name) and didn't invoke any event to refresh.

It was probably occurred by devops server creation, who just clone previous server :)

To ad hoc fix I've setup InstanceName settings in config. for each application instance on servers.

I hope it will help someone, because sometimes so small things can be imperceptible.

Mystery solved !

Story: 

During work with EXM I had very interesting story last time. I've installed EXM in correct way, according to guide standards. I was happy that any problems didn't happen and then I realized I have one :)

During EXM tests I've created One column Message, firstly new item was created (cool!). But after that I saw new item has one issue, message tab can't load.

Later I've figured out that it has empty Body field, although branch template has definition for that by default, so that what probably the issue of incomplete loading the message tab.

Since that point I've started looking for problem which cases breaking of creation an email in EXM. Because email message creation is based on branch, it's connected with branching I assumed. After a lot of searching I've noticed that when I comment out my "item:created" event declaration, EXM issue disappears. I've found it already ! I thought :)

I was digging more and what I saw was really interesting. mentioned "item:created" event has issue on method "DisplayNameSetup", because I had method like that.

Conclusions? Well, I can't setup the display name on item created because it will broke branching engines ! (important, not only EXM branches, but all of them) Yey ! But still, why ? :) Because that question was still in my head I've talked to Sitecore support and what is established is below.

Solution:

Firstly we have to establish one thing, maybe it's not obvious, but "item:created" event doesn't say that process of creation has been finished. Even more, there is at least 4 event handlers that occurs after our item created event. According to my issue with EXM, it consist also method which sets 'body' to item.

After each mentioned event handler there is also saving handler, which occurs when item will be changed during creation process. Hence, when we are changing item during creation, it blocks next event handlers to be called.

If you want to change items, it's better to use:

That events occurs after item has been created, so we have sure we don't interrupt process of creation and filling item fields.

Explanation:

Accessing an item from the ItemProvider in the CreateItem() method or in the 'item:created' event handler has no versions. The version is added later inside the Sitecore.Nexus assembly command.

When the version has been added, the Sitecore.Nexus command also copies field values from the branch template to the item and only after that the item gets saved. So mentioned action SaveItem() of the ItemProvider ensures that the item has at least 1 version and other case it will add one.

Our problem form the story starts when an item is edited inside the CreateItem() method of the ItemProvider or in the 'item:created' event.
Let's go through the path. After editing our item.Editing.EndEdit() method saves the item, but it doesn't have any version, hence version will be added in SaveItem().

Afterwards, when we go to the Sitecore.Nexus command some of the branch template field values will not be copied to the new item, because it already has a version (from SaveItem()).
In our story, result will be that 'body' field of the branch template will be not added to the item.

Hope it will help some of you :)