DataFlex WebApp SPLF Server

Security, Performance, Load Balancing and Failover for your web applications and services

“SPLF” stands for Security, Performance, Load Balancing and Failover.

This special server is used as a manager and re-director that provides services and resources to one or more physical, virtual or cloud server instances that are executing DataFlex WebApp Server applications. Read the DataFlex WebApp SPLF Server Ensures 24/7 Availability blog, which directly discusses how the DataFlex SPLF server was found to be the most cost effective load balancing, fail-over and release management solution for a large financial services institution in the Australasian region.

A feature summary is below and you can watch a DataFlex Learning Center video that describes SPLF Server use cases, configurtion and licensing.

The SPLF Server is the exposed HTTP interface for DataFlex web and mobile applications. The SPLF Server typically runs on a dedicated hardware, virtual or cloud server instance. It intercepts users’ HTTP requests and re-directs them to one or more securely connected server instances each running DataFlex WebApp applications. The application server(s) return requested application pages and data through the SPLF server to users’ devices. The four valuable functions provided by an SPLF server are:

• Security – The network connection between the SPLF server and the application servers attached to it can be configured using non-internet, Network Address Translation (NAT) addresses and other firewall mechanisms. In such a configuration, the SPLF server is internet connected – it has a public IP address. The application server(s) connected to the SPLF server will have internal, non-internet-exposed, NAT addresses that preclude direct access from the internet. With this configuration, applications and, just as importantly, application data, are never directly accessible from the internet thereby providing a highly secure environment.
• Performance – When IIS and DataFlex Web Framework applications are run on the same server instance, a significant portion of the capacity of that server is used by IIS – the Microsoft HTTP server program. This can materially limit the capacity of the server available for executing applications - sometimes as little as 50% of the server’s resources are available for application processing. By moving the overhead of IIS to a separate SPLF server, the majority of an application server’s resources can be devoted to processing user requests. More server capacity = more performance and more application processing power per application server instance.
• Load Balancing – An SPLF server can distribute or “balance” user requests among 2 to 255 clustered server instances running the DataFlex WebApp Servers software for scalable, high-capacity application processing. Each DataFlex WebApp Server will have the security and performance benefits described above so the effect of multiple application servers is cumulative.
  • As load grows, overall application processing capacity can scale easily and transparently by simply adding another application server instance to the cluster and including it in the SPLF Server’s list of available server instances.
  • If application server maintenance or upgrades are required, temporarily removing an application server from the cluster stops incoming requests to it and distributes the requests to other available servers so offline operations can been performed.
  • This flexible cluster design allows for the use of application servers of varying capacities, for example older and newer systems, and the assignment to each server in the cluster a load that it is capable of processing.

• Failover - In addition to distributing load, in the event that an application server instance in the cluster fails, the SPLF server will automatically sense the failure, remove the failed server from the cluster and distribute incoming requests to or among the remaining active server(s).

A DataFlex SPLF server runs on its own dedicated server instance. To keep licensing simple, the entitlement to connect to an SPLF server is licensed as a low-cost add-on fee to the application server license price. SPLF Servers can be connected to DataFlex WebApp Servers using either Web Client or Web Application licensing.