An Application Object Server (AOS) instance is a core component of your
Microsoft Dynamics AX installation and is installed by using Setup. An AOS
instance enforces security, manages connections between clients and the
database, and provides the foundation where Microsoft Dynamics AX business
logic runs. Thus, installtion of AOS becomes most vital.
Apart from topology as
shown in image 1, above, there are two more suportted topolgies for installation
of AOS. The topics in this section describe the various roles in which AOS
can function. i.e. AOS Installation topologies. The other two topoligies are as
under:
1)
AOS clusters
without a dedicated load balancer
2)
AOS clusters with
a dedicated load balancer
Lets talk about both of
these how these work, practically and benefit/ loss of each toplogy.
1)
AOS CLUSTERS WITHOUT A DEDICATED LOAD BALANCER:
In this topology each AOS in the cluster acts independently. Each AOS has
to be provided in the client configuration file for the client to connect.
Based on a list of provided AOS servers in the client configuration file, the
client will attempt to access each server in the order listed to find an
available server. If a server's workload has reached its maximum level, then
the client will simply attempt to connect to the next AOS.
· When a Microsoft
Dynamics AX client starts, the client reads the list of AOS instances that is
specified in the Microsoft Dynamics AX 2012 Configuration utility. The client
initiates a handshake with the first AOS instance in the list. If the first AOS
instance does not respond, the client initiates a handshake with the next AOS
instance in the list. The client continues in this manner until the handshake occurs.
·
The AOS instance
that received the client request queries the database and all active AOS
instances in the cluster. The AOS instance returns to the client a list of all
active AOS instances in the cluster, sorted by workload. The server that has the
smallest workload is at the top of the list. The workload is based on the
number of connected clients, divided by the maximum number of clients that are
allowed on the server.
·
The client
attempts to connect to each AOS instance in the sorted list until a successful
connection is established. The client then uses the AOS instance that it
connected to for the whole session.
1)
AOS CLUSTERS WITH A DEDICATED LOAD BALANCER:
Microsoft Dynamics AX provides the option to load balance two or more
AOS's together. This is similar to how a web farm works for a SharePoint site.
Alternatively, you may opt to use hardware or another software solution to load
balance AOS access. It is recommended to have one AOS for no more than 50-60
users. In a load balanced cluster, one AOS is a dedicated load balancer,
delegating client connections to the appropriate AOS. It is not directly used
either for interactive purposes or for processing application code. Once a
client is connected to the load balancer AOS, it will then determine which AOS
it should connect to. If an AOS goes down, the load balancer AOS will
automatically re-route clients to an active and available AOS without having to
make any modifications to client configurations. Also, as a company grows and
more users are needed, it is as simple as installing a new AOS and connecting
it to the load balancer.
As previously mentioned, to set up load balancing, we must set up one AOS
as the load balancer. Afterwards, each additional AOS in the load-balanced
cluster will automatically listen for client connection requests from the Load
Balancer AOS.
However, in order for an AOS to be a load balancer, it must first satisfy
the
following criteria:
• Cannot be a Batch Server
• Must be an AOS that is active
·
When a Microsoft Dynamics AX client starts, the
client reads the list of active AOS instances that is specified in the
Microsoft Dynamics AX 2012 Configuration utility. The client initiates a
handshake with the first AOS instance in the list. In this scenario, the administrator
has configured the first AOS instance as a dedicated load balancer.
·
The load balancing AOS instance that received
the client request queries the database and all active AOS instances in the
cluster. The AOS instance returns to the client a list of all active AOS
instances in the cluster, sorted by workload. The server that has the smallest
workload is at the top of the list. The workload is based on the number of
connected clients, divided by the maximum number of clients that are allowed on
the server.
·
The client attempts to connect to each AOS
instance in the sorted list until a successful connection is established. The
client then uses the AOS instance that it connected to for the whole session.
·
An AOS instance that is configured as a load
balancer does not accept any client connections as either an application server
or a batch server. This AOS instance functions only as a load balancer.
·
A dedicated load balancer can be used only for
remote procedure call (RPC) connections. To balance the load of connections for
Application Integration Framework (AIF) and services, you must use Microsoft
Network Load Balancing (NLB).
·
An AOS instance that is configured as a load
balancer does not require an AOS license, because the server does not provide
any application services to the clients.
·
If you configure an AOS instance as a dedicated
load balancer, you do not have to update client configurations when AOS
instances are added to or removed from the cluster.
·
A dedicated load balancer has lower hardware
requirements than an AOS instance that functions as an application server,
because the load balancer does not process application requests or business
logic.
·
You can configure multiple AOS instances to
function as dedicated load balancers. However, you must make sure that
dedicated load balancers appear first in the list of active servers in the
client configuration.
In order to configure any AOS as load balancing follow
following path in AX
Company-Legal Entity/System
administration/Setup/System/Cluster Configuration
