DWA topology and minimum requirements
This topology diagram shows a typical installation of DOORS and DWA.
Minimum requirements for interoperation servers
An interoperation server is a modified DOORS client. It is a single-threaded application, which can process only one request at a time. Any concurrency leads to significant degradation of DWA performance unless the servers are clustered. Therefore, a single interoperation server is not sufficient for a production environment. A set of four interoperation servers can support approximately 100 concurrent users. You can install multiple interoperation servers on one or more physical servers, but each interoperation server requires one core processor.
Interoperation servers cache data to improve performance and retain that data for some time. The cache results in an increasing memory use that is limited only by the memory allocation for each process at the operating system level. You can set the upper limit for memory usage by an interoperation server when you start it by including the -maxMemory parameter. Use this parameter to set the cache limit for the interoperation server. To calculate this limit, divide the available memory on the server by the number of interoperation servers on that server. Multiply that result by 0.75 to account for spikes in memory usage. For example, if four interoperation servers are on one server that has 16 GB RAM, calculate the maximum memory for each interoperation server as follows: (16/4) x 0.75 = 3 GB. For more information about starting interoperation servers, see Starting DWA on Windows or Starting DWA on Linux.
DWA uses the Apache Tomcat web server. You must have a separate Tomcat instance for each set of four interoperation servers. You can run multiple Tomcat installations in a cluster. Each Tomcat installation can have its own broker and set of interoperation servers, which all access a single DOORS database. This configuration accommodates many more users and ensures redundancy and resilience in the system.
Allocating extra memory for the JVM
To improve performance, you can allocate more memory to DWA Java™ virtual machine (JVM). The batch file for starting DWA includes a memory allocation parameter for the JVM. Typically, the server.start.bat batch file is located here: <install_dir>\DOORS Web Access\[version]. To improve performance, increase the value of the -Xmx parameter in that batch file.