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Understanding BizTalk operational architecture

We have already explored the core conceptual architecture of BizTalk Server 2010, but now we will delve more deeply into how this architecture fits into the real world of Windows Servers and applications.

At its core, BizTalk is a .NET application built on top of SQL Server. This already tells us that we have two definite dependencies: SQL Server and Windows Server. We also have a core dependency on Active Directory to provide a service account and user access and control; that said, in smaller environments, BizTalk can use local groups, but this does not scale well. The core set of servers involved in a BizTalk environment are shown in the following diagram:

These three servers are the core moving parts in any BizTalk environment. SQL Server hosts the message box and all the other databases. BizTalk provides most of the processing and Active Directory provides authentication. This book does not cover Active Directory as that is already expected to be running in your enterprise, but the other two will be explored in detail.

Administering BizTalk Server

Most administration and operation tasks for BizTalk Server are performed in the BizTalk Administration console; an MMC Snap-In designed to provide access to all the settings in a BizTalk group through a single interface. MMC provides a common user interface approach for Windows administration tasks and the use of an MMC Snap-In makes BizTalk very familiar to most administrators. Like most MMC Snap-Ins (IIS, Active Directory, and so on), there are three panes in the BizTalk Administration console Snap-In from left to right: navigation, information, and actions.

As you click on different nodes in the left navigation pane, different context comes up in the center and right panes. The right Actions pane changes further when different objects are selected in the center information pane. This context allows us to change specific settings more easily depending on where we have set our focus in the console.

The root node in the navigation pane displays a Console Root folder with the BizTalk Server Administration and Event Viewer (Local) nodes beneath it. By default, the first node will have the BizTalk group of the local machine listed within, but by right-clicking the BizTalk Server Administration node, we can connect to other BizTalk groups. This allows us to remotely administer multiple BizTalk groups from a single workstation. It also allows us to perform most administration tasks without logging into the BizTalk Servers directly. When connecting to a BizTalk group, we actually provide the connection information for the management database, which is the brain of BizTalk.

Within the BizTalk group, there are three primary areas of the console that we use to manage our solutions; each is represented by a node. They are introduced as follows and can be seen in the previous screenshot:

  • Applications: This node houses all the applications deployed to a BizTalk Server group. It is from here that we can configure and control specific applications in BizTalk. An application in BizTalk is the logical grouping for a set of related artifacts that normally form a solution. Within each application, the artifacts are categorized in the nodes, as shown in the following screenshot:

    These nodes largely correspond to concepts that we covered in the previous chapters. When our BizTalk application deploys locally from Visual Studio, all the assemblies should deploy to the same Application, and thus be part of the same “solution”. This view will list all artifacts from any assembly deployed to this application. Policies are BRE rule sets; this is their formal name. Send Port Groups are simple grouping mechanisms for the Send Ports. Role Links tie parties to ports and orchestrations.

  • Parties: These are mechanisms for working with trade partners and are particularly suited to solutions that require the same general processing for messages, but may need to send the results or intermediary requests to different end points. Parties are heavily utilized in B2B scenarios to create easily extensible solutions. A party can represent a trade partner or another system or division within the enterprise and are a key factor to EDI.
  • Platform Settings: This is the place where the settings for a BizTalk group and all its subordinate objects reside. Hosts, host instances, servers, message boxes, and adapters are all configured here. As the name implies, this is where we work with settings that affect the core BizTalk platform.

Scalability in BizTalk Server

According to Wikipedia, “scalability is the ability of a system, network, or process to handle growing amounts of work in a graceful manner, or its ability to be enlarged to accommodate that growth”. There are generally two types of scalabilities in the computer world: scale up, which means moving to a larger and more powerful server, and scaling out; which means adding more servers. For most software, scaling up is the simpler or even the only path. BizTalk is fundamentally designed to scale out with no changes needed to be made for the software running a solution. As we move further into the era of multicore processors, we are actually blurring this distinction and shifting more to the scale out model even when we choose to scale up. Only software and platforms that are made to be parallel can take full advantage of the multicore architectures now prominent in the industry.

Scaling SQL Server

There are two specific areas where BizTalk can scale out. The first and generally most important is the SQL Server area. SQL Server is frequently a bottleneck for BizTalk solutions. Often, this confuses administrators, even ones who know SQL Server, because they see low utilization on BizTalk Servers and don’t see high utilization on SQL Servers. Most often, this is because SQL Server tends to be a disk bound application; meaning that the real bottlenecks tend to be the disk queues of SQL operations waiting to take place.

BizTalk Server has been carefully designed to fully exploit SQL Server in an extremely optimized manner, and subsequently exploit the BizTalk databases, specifically the message box, which should not be on a shared SQL instance used by other applications. In fact, the message box should have its own instance separated even from the other BizTalk databases.

While we’re on the subject, now is probably a good time to raise a very important caveat about the message box. During configuration of BizTalk, the Max DOP setting on your SQL Server will be changed to one (1). This is because the message box is a highly tuned database that works very differently from most databases. The job of most databases is to hold data that will be returned as record sets. The Maximum Degree of Parallelism (Max DOP) setting, controls how SQL Server will try to run queries in parallel to each other to speed up their results. It is an instance-wide setting in SQL Server and defaults to zero (0), which allows SQL Server to use all available processors. For nearly all databases, the default Max DOP setting allows SQL Server to perform the query and return the data faster by breaking the query up amongst the processors on the server. This is sort of a divide and conquer approach if you will. This optimization in SQL Server will actually harm the performance of the message box database. The message box is structured in such a way that setting the Max DOP to any value other than one will cause the message box operations to slow down. This is because the operations performed on the message box are generally single record (and small record at that) operations. The overhead to parallelize them turns out to be more than beneficial from executing them in parallel. This will cause BizTalk to slow down if the SQL instance hosting the message box has the Max DOP set to any value besides one.

Having said all this, the other databases that make up BizTalk actually benefit from not setting the Max DOP to one. This is a great demonstration of why you may want to consider multiple SQL Servers or at least multiple instances for your BizTalk installation. Generally, SQL Server should be configured into two instances: one for the message box and one for all other databases. These can all be on the same physical server, but they should be separated from other databases and from each other. Newer versions of SQL Server do allow tighter resource control over databases, but this is still good advice for SQL 2008 R2. Within these databases, it is also a good idea to separate indexes from data storage to improve performance.

Adding more SQL Servers, or even just instances, to your BizTalk installation is a way to scale out the SQL Tier of your environment, but BizTalk also provides another way to scale out SQL Server by creating multiple message boxes. The idea is that one message box functions as the master message box, managing subscriptions and the other functions as runtime message boxes for delivering matched subscriptions (that is, starting orchestrations and send ports). This allows the master message box to focus only on subscription matching and thus it performs even better. It is suggested that if you create separate message boxes, so that you have at least three messages boxes in total, then one should master and the other two should be publishing, due to the extra overhead involved in using multiple message boxes. The intention is that these message boxes can each exist on different servers or at least on different SQL instances.

This is a very sophisticated technique and approach to addressing scalability, but like many tasks in BizTalk, this turns out to be surprisingly easy to accomplish. Simply right-click the Message Boxes node in the BizTalk Administration console (under Platform Settings), select New, and then select Message Box….

This will bring up a configuration dialog allowing you to specify the server and database name for this new message box. After you have created your new message boxes, you can go back to the master message box and disable new message publication, which will instruct the master message box to only perform routing and subscription matching. This entire operation can be performed while the platform is running.

If you ever need to remove a message box, you simply disable new message publication and let it continue running, then delete that message box.

Please note that you cannot delete the master message box without designating a new one.

Scaling BizTalk Server

After sorting out any SQL Server issues and scaling challenges, the next place to consider is the BizTalk tier. There are two ways to scale out the BizTalk tier: one is to add more hosts and host instances to the group, the other is to add more servers. Both turn out to be quite easy in BizTalk.

Adding more hosts and host instances

To add more hosts, you simply right-click the Hosts node in Platform Settings and select New | Host… from the context menu. The dialog that will appear is shown in the following screenshot:

In this dialog, you can specify the name and the Windows group that the host users will need to be a part of. You can also choose to mark a host as 32 bit in case you’re working with components that do not support 64 bit runtime. Allowing different Windows groups for hosts, enables us to strictly control security permissions. If we have a location that receives (or sends) messages to a non-secure endpoint, we can isolate the execution of that port or location by using a less privileged account; this will help enforce security within our application. Once you create the host, you perform a similar operation to create a new host instance for that host. If you now left-click the Host instances node, you will notice that the Actions pane, on the far right, provides an alternative to right-clicking for a context menu.

Clicking New here is the same as right-clicking and selecting New | Host Instance from the context menu. Again, this is common in all MMC Snap-Ins. From this dialog we configure the settings for a specific host instance shown as follows:

These settings consist of Host name:, which would be the host we created before, and the server within the group on which to configure this host instance. We must also provide Logon: credentials for the Windows service that will be automatically created on this server for us. We can optionally decide to make sure this host instance is not capable of starting. This can be useful if we’re setting up new hosts and instances on many servers, but are not yet ready to start them. We will see this presented more thoroughly later in this , in the section, Presenting the best practices for BizTalk configuration.

Adding more servers to the group

This step is a little more complicated, but only a little. All you have to do is install BizTalk on the new server and then run the BizTalk Server Configuration tool on the new server. When the wizard opens, click on Advanced Configuration and under Enterprise SSO, select Join and Existing SSO System, and under Group, select Join an existing BizTalk Group. Once this is done, the last task is to create host instances on the new server for all existing hosts; the same process we just did. As soon as we start the new host instances through the BizTalk Administration console, the new server will immediately begin processing the transactions. Adding new servers to the BizTalk group turns out to be very simple and enables us to quickly stand up with more capacity as needed.

As more servers are added to the group, they simply continue to pull work items off the queues independently. The more servers in the group, the more work it is able to perform. There is no practical limit to the number of servers that can be added to a BizTalk enterprise installation.

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