10.0

© 2011 ABBYY. All rights reserved.
104
The choice between the Unicast and Multicast methods depends on your network configuration. A detailed description of the two
methods can be found on the Microsoft website.
Balancing Workloads in the Cluste
r, Setting Up Hosts
You can set up cluster traffic to be balanced and filtered by ports.
ABBYY FlexiCapture 10 requires the TCP protocol for its operation. There are two filtering modes: Single Host and Multiple
Host.
• Single host
This mode provides fault tolerance, but does not allow load balancing. Only one cluster node is active at a time.
• Multiple host
Traffic from a predefined range of ports is handled by the node with the highest priority in the cluster. All cluster nodes function
simultaneously.
This mode provides both workload balancing and fault tolerance.
Traffic from a predefined range of ports is balanced among nodes. You can also set the Affinity parameter to:
• None (not recommended)
If this option is selected, multiple connections (TCP sessions) from a single client can be handled by different nodes.
• Single (recommended)
If this option is selected, all connections from a single client are handled by one node.
• Network (Class C) (recommended)
If this option is selected, all queries from the TCP/IP Class C address space are handled by one node. This may be nec-
essary if there is a proxy server between the client and the cluster.
Setting Up the Application Server
Com
plete the following steps to set up the Application Server:
1. Create a shared folder that can be accessed by all of the nodes in the cluster.
2. Install Microsoft SQL Server. Microsoft SQL Server must be available to all cluster nodes.
3. Install the Application Sever on all cluster nodes.
4. On the first cluster node, run the Administration and Monitoring Console and create a database and specify a shared
storage.
5. On each of the remaining cluster nodes, run the Administration and Monitoring Console and connect to the database
you created.
Important! For this operation, SQL authentication must be used.
6. On the SQL Server, give full access permissions for the database to all users on all cluster nodes under whose accounts
IIS is running (the World Wide Web Publishing Service must be running in the service list). Permissions for the first
node are given automatically when the database is created, other permissions must be given manually. By default, IIS
runs under the user Network Service. In this case, assuming IIS is running on computer NodeN, you must give full ac-
cess permissions to the user DomainName\NodeN$ on the SQL Server.
7. If the Application Server is not unavailable in the cluster, but PING requests still reach the cluster, check if IIS is avail-
able in the cluster. To do this check, place a static *.html file in the folder %systemdrive%\inetpub\wwwroot (usually
this folder already contains an iisstart.htm file) and open this file in a browser: \\ClusterAddress\iisstart.htm. Pay atten-
tion to the proxy server settings in your browser when opening the file.
Running Server Application Clients
W
e recommend that you place all cluster nodes in one domain and run Application Server clients under domain user accounts.
Running Application Server clients under local user accounts is not recommended for the following reason.
In the usual (i.e. non-clustered) configuration of the Application Server, the following authentication method may be used: on the
computer where the Application Server is installed, a local user is created, with its own user name and password; now any client
may connect to the Application Server under this user’s account.
In a clustered configuration, the Application Server that processes client requests may be placed on different computers, and the
actual user name will change accordingly: on the computer node1, the user name will be node1\User, while on the computer
node2, the user name will be node2\User. This may disrupt the operation of the system.
Running Application Server clients under domain users avoids this problem.
To connect clients on remote computers which are not in the domain, you can use basic authentication and a user account in the
domain to which the cluster belongs. Suppose the clustered Application Server is in the cluster domain and the computer of the
verification operator is not in this domain. All you need to do is create in the cluster domain an account for the user clus-
ter\VerificationOperator and communicate the account name and password to the verification operator. Now the verification op-
erator will be able to connect to the Application Server using this account and basic authentication on the Verification Station.
Note. To use basic authentication for clients, be sure to enable basic authentication for the folder FlexiCapture10\Server in IIS.
Otherwise, users will get HTTP 401 error when attempting to connect.