SAS/IntrNet 9.2: Application Dispatcher

Development vs. Production Environments

In most cases, you will need separate services for your development and production Application Dispatcher environments. Isolating your development environment from your production applications will help you provide application stability and security to your end users, while providing flexibility and freedom to your application developers.

Development Services

A development environment can typically be provided by a one-server socket service. A single server will generally simplify debugging and will allow testing of most application features (other than performance). The developer is free to start and stop the server as needed. You might want to create a separate service for each developer to allow independent updates to the application under development.

Note: Applications that are intended to run in multiple-server services must be written and tested with this in mind. Programs must allow for concurrent access to shared resources by multiple servers. Even if the development is performed on a single-server service, some testing should be done on a multiple-server service before deploying the application.

Launch services were recommended for development on previous releases of SAS/IntrNet software. This was because the Version 6 SCL based Application Server was not tolerant of some common development errors (such as mismatched quotes in SAS code). Later releases of the Application Server are much more tolerant of these types of errors. Most programming errors will cause the individual request to fail without affecting the server.

Production Services

Most production applications can be deployed on a socket service with one or more servers. Additional servers can be added as the total system load grows. Servers can easily be distributed across multiple server systems. Once your service uses more than one server, you should consider using the Application Load Manager. The Load Manager provides intelligent load balancing between multiple servers in a socket service.

Applications with widely varying user loads or special security requirements might benefit from pool services. Pool services enable servers to be started and stopped dynamically as the user load grows and shrinks.

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