Integration and Communication
A Blue Prism environment should be carefully configured to ensure that the communication between Blue Prism components uses the correct protocols with the desired levels of Security, is within given latency guidelines, guarantees High Availability and allows scalability. The topics covered here give an insight into the recommend configuration.
The Connection Mode defines the protocols that are used when communication takes place between the Application Server(s) and Digital Workers \ Interactive Clients. They are configured in two places, firstly in the Application Server service configuration, then in the connection configuration of a Digital Workers \ Interactive Clients.
There are numerous choices for the Blue Prism Connection Mode They are:
- WCF with Message Encryption and Windows Authentication. This is the default method and is the easiest to configure.
- WCF with Transport Encryption and Windows Authentication. Requires certificates, so more difficult to setup, but has better performance than Message Encryption.
- WCF with Transport Encryption. Same as above, but only supports Blue Prism Native Authentication.
- .Net Remoting: Secure. Now deprecated by WCF modes. Only included for backwards compatibility for customer upgrading from Version 5.
- .Net Remoting: InSecure. Same as above, but not a secured connection. Should be used only for debugging.
- WCF: Insecure. Not a secured connection. Should be used only for debugging.
Load Balancers can be placed between Application Servers and Digital Workers to provide High Availability in your Blue Prism environment.
There are numerous considerations when employing Load Balancers:
- Layer 4 or 7 Load Balancing is supported.
- Commonly used examples of Load Balancers are F5 or Citrix ADC \ NetScaler.
- Active health monitoring is highly recommended. The Application Server http Endpoint is ideal for monitoring (http://bpappserver001:8199/bpserver)
- The Least Connection or Round Robin algorithms are recommended.
- Any standard affinity patterns are supported.
- NAT is supported only with WCF based Connection Modes.
- Session persistence (stickiness) must be configured.
Guidelines for the recommended latency between components are as follows:
- Database to Application Server(s). Less than 5ms. Ideally, latency between these two components should always be minimized.
- Application Server to Digital Workers. This is the most resilient connection in the Blue Prism environment and Digital Workers can still operate under high latency. Ideally though, the connection should be less than 100ms.
- Application Server to Interactive Clients. When creating Processes and Objects in the Studio component of the Blue Prism Client ideally the latency should be less than 10ms.