AX Databases include
- The Microsoft Dynamics AX database,
- The Model Store, and
- The Baseline database.
The AOS connects to the Microsoft Dynamics AX database to process transactions.
The AOS connects to the Model store to display application elements such as forms and reports.
Baseline Database:- The baseline database contains a model store that is used to upgrade X++ code to Microsoft Dynamics AX 2012. The baseline database is used to analyze application updates before they are applied.
A model is a set of elements in a given layer. Each layer consists of one or more models. Each layer contains one system-generated model that is specific to that layer. Every element in a layer belongs to only one model. In other words, no element can belong to two models in the same layer, and every element must belong to a model.
A model is permanently associated with the layer that is created in. If you need to move one of your models from one layer to another, you must create a project from the model in the AOT, export the project as an xpo file, create a target model in the desired layer, delete the original model to avoid having to resolve layer conflicts, and import the xpo file to the target model. If you are moving elements between models in the same layer, you can use the Move to model command in the AOT.
Models are stored in Model Store.
Model Store :-
The model store is the database where all application elements for Microsoft Dynamics AX are stored. Customizations are also stored in the model store. The model store replaces the Application Object Data (AOD) files that were used in earlier versions of Microsoft Dynamics AX.
Models that have been installed in the model store are used at run time.
Note: Models can be exported to files that have the .axmodel extension. These files are called model files. Model files are deployment artifacts. Model files can be signed with strong name signing and Microsoft Authenticode signing.
In Microsoft Dynamics AX 2012 R2, the model store was moved into a database that is separate from the business database. The name of the model store consists of the name of the business database plus _model.
Layer information and model information are integral parts of the model store. The Application Object Server (AOS) has access to the model store. The AOS manages layer flattening or overshadowing at runtime. That is, when you make an object modification in one layer, the modification overshadows the object on a lower layer at runtime. You could, for example, decide to change a caption on a standard form. The change is saved on your layer only, and the revised—or flattened—form replaces the standard form at runtime. The AOS also provides all the Microsoft Dynamics AX subsystems with model data, such as form rendering, report rendering, and X++ code.
Microsoft Dynamics AX contains sixteen layers. Each layer consists of one or more logical parts called models. A model is generated for each layer. For example, VAR Model is the model that the system generates for the VAR layer. The system-generated models let you install and work with the base Microsoft Dynamics AX system. When you customize the Microsoft Dynamics AX program, you can take advantage of the capabilities of models.
The model store is used in the following ways in Microsoft Dynamics AX:
Installation – During installation, the Setup program uses axutillib.dll to import the .axmodel files from the installation path into the model store.
Upgrade – During an upgrade, the application files, or AOD files, from the earlier version are imported into the model store, which is the new model. The application files are also imported into the baseline model store, or the model store for the earlier version of the metadata. The baseline model store is similar to the old folder in earlier versions of Microsoft Dynamics AX.
Development environment – In the development environment, developers can continue to use .xpo files to export and import code. Use .axmodel files to migrate application elements from one environment to another, such as from a development environment to a test environment. Export models from the source system to .axmodel files, and then import .axmodel files into the target system.
Run time – At run time, an Application Object Server (AOS) instance retrieves the application elements, such as forms, reports, and classes, from the model store to respond to client requests.
The following diagram provides an overview of the model store architecture.