Security, Performance. Load Balancing and Failover for your web applications
SPLF stands for Security, Performance, Load Balancing and Failover.
This special server is used as a manager and application collaborator that provides services and resources to one or more DataFlex WebApp Servers executing web applications.
The SPLF Server is the HTTP interface for DataFlex web and mobile applications. It intercepts users HTTP requests and directs them to one or more connected application servers. The application server(s) return application pages and data through the SPLF server. 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 by internet users. With this configuration, applications and, just as importantly, application data, are never 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 computing capacity of the server is used by IIS the Microsoft HTTP server program. This can materially limit the computing capacity of the server available for applications (sometimes as little as 50% of the servers resources are available for application processing). By moving the overhead of IIS to a separate SPLF server, the majority of an application servers 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 DataFlex WebApp Servers for 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 Servers list of available servers.
- 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 assigning each server in the cluster with a load that it is capable of processing.
Failover - In addition to distributing load, in the event that an application server 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.