People familiar with the earlier versions of Dynamics AX may already know about the layer system. The layer system, in essence, is used to manage the application elements in a predefined order. The USR layer is the highest layer and the SYS is the lowest layer. The following table shows all the layers and the corresponding use:
|
Layer |
Used by |
Description |
|
USR |
Customer/partner |
The user layer is for user modifications, such as reports. |
|
CUS |
Customer/partner |
The customer layer is for modifications that are specific to a company. |
|
VAR |
Partner |
Value Added Resellers (VAR) can make modifications or new developments to the VAR layer, as specified by the customers or as a strategy of creating an industry-specific solution. |
|
ISV |
ISV solution |
When an Independent Software Vendor (ISV) creates his/her own solution, their modifications are saved in the ISV layer. |
|
SLN |
ISV |
The solution layer is used by distributors to implement vertical partner solutions. |
|
GLS |
Microsoft |
Country-specific localization layer. |
|
FPK |
Microsoft |
The FPK layer is an application object patch layer reserved by Microsoft for future patching or other updates. Note: The FPK layer is no longer used in operations, as Microsoft directly ships patches in the SYS layer. |
|
SYS |
Microsoft |
The standard application is implemented at the lowest level, the SYS layer. The application objects in the standard application can never be deleted. |
As shown in the preceding table, Microsoft ships code in the lower layers. Technically, when an element is overlayered in a higher layer, the higher layer makes a copy of the lower layer and then you can modify or add additional code in the higher layer. When the application is compiled, only the top-most layer of an application element is used.
The layer system will probably become less relevant, specially when all the source code delivered by Microsoft is hard sealed for overlayering. The concept may still be relevant for ISV solutions if they wish to support the overlayering concept. Later in this chapter, we have more details about the overlayering and extension programing model and Microsoft roadmap around eliminating overlayering.