The DataFlex WebApp Server is a high performance, fully integrated application server for deploying browser-based applications, Web Services and service oriented architecture (SOA) solutions.
Since WebApp Server is an integrated component of DataFlex, it utilizes and leverages the complete resources of the environment. DataFlex Studio is the integrated development environment for web applications building; Data Dictionary Objects and Business Process Objects can be shared among Windows client-server and web applications and web services.
A single development-deployment architcture that uses shared components and common code means faster development, less code, easier maintenance and, overall, less complexity to build and deploy solutions.
Technically, the DataFlex WebApp Server is a compact, highly-efficient, C++ based application and transaction processing engine that connects to users and/or services via Microsoft IIS and to a variety of database options using DataFlex’s standard connectivity architecture.
The WebApp Server’s design provides a fundamentally secure environment. An HTML interface defines visual properties for web pages and a messaging protocol for communication with the application server. Server-side applications are driven entirely by messages. Applications code and database access and manipulation code are compiled and run in the server.
DataFlex WebApp Standby Servers
Standby servers provide customers with the entitlement to have a pre-configured secondary server instance (all software installed, ready to activate for production use) in the event of the failure of a primary production server. As a discounted, special purpose server, the secondary standby and the primary server must never operate concurrently (production server stops; standby server automatically takes over)
Two types of Standby Server Licenses are available:
- Hot Standby Server –A Hot Standby Server is defined as an up-and-running secondary server instance that is automatically activated by third party software upon the failure of a primary server instance.
- Price: 50% of the price of the server license that the Hot Standby Server will replace.
- Cold Standby Server – A Cold Standby Server is defined as a configured but non-running secondary server instance that is manually started upon the failure of a primary server instance.
- Price: 25% of the price of the server license that the Cold Standby Server will replace.
“SPLF” stands for Security, Performance, Load Balancing and Failover. This special server is used as a collaborator that provides services and resources to one or more DataFlex WebApp Servers executing applications.
The SPLF Server is the HTTP interface for all application processing user requests. It intercepts user HTTP requests and directs them to one or more connected application servers. The application server(s) return processed requests through the SPLF server. Details of 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) connection 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 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 significantly limit the computing capacity of the server available to the Web 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 server instance.
- Load Balancing – An SPL server can also distribute or “balance” user requests among 2 to 255 clustered DataFlex WebApp Servers for application processing. Each DataFlex WebApp Server will have the security and performance benefits described above. Load balancing is accomplished using tables hosted on the SPLF server that define the processing capability of each individual application server in the cluster. The SPLF server then assigns requests to each application server according to its individual, administrator defined capacity to handle requests. As load grows, application processing capability can scale easily and transparently by simply adding another application server instance to the cluster and including it in the list of available servers. If application server maintenance is required, temporarily removing an application server from the cluster list stops incoming requests and distributes them to other available servers. This flexible cluster design allows for the use of servers of varying levels of capacity and only assigning a 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).An 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.