Answers to Frequently Asked Questions

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• Why don't applets show up in my browser?

  Applets in general are very dependent on the specifics of the browser. The browser must have Java enabled. There are browser plugins that will run various versions of applets. Essentially one has to program applets for specific browsers and specific plugins-ins. If this sounds like it's difficult to make applets work, well it is.
  
  
  

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• How is a servlet processed?

  A client browser sends a request to a web server (Apache at HostSRV.com). The web server, by looking at what follows the ".com", recognizes it as a servlet. (It recognizes it because the particular directory was mapped to the Java server in the web server's configuration file (httpd.conf for Apache. See below for more information on this mapping.). The Java server (Tomcat at HostSRV.com) finds the servlet in the application's directory tree and sends it to the Java Runtime Engine (JRE) to process as a java program. When complete, the Tomcat server returns the data (which could be html text or some other mime type) to the web server. The web server returns the data to the client browser.
  
  MSP is a servlet and is run by the Tomcat server when MSP is requested by a client browser. MSP connects to a Mathematica® kernel via JLink. The Mathematica® kernel executes the instructions from the MSP servlet script. These instructions take the form of MSP tags within a servlet script file (Integrator is an example of an MSP script file). The kernel can make full use of the Mathematica® FrontEnd. The result of the Mathematica® calculation is returned to Tomcat and then ultimately back to the client browser.
  
  
  

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• Why can't I execute all types of processes?

  In all but the Commercial Pro Setup account, some of the Tomcat processes are turned off. These include jndi, jdbc, ejb, and mail. Also, files ending in the following are not recognized as JSP: *.shtml, *.thtml. The Personal, Parked, and Commercial accounts have a clear focus on Mathematica Server Pages.
  
  
  

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• What are the meanings of the parts of the URL?

  Use as an example the following URL:
  
  http://www.hostsrv.com/webmaa/app1/servlet/SnoopServlet
  
  The http: part gives the protocol. The www.hostsrv.com maps to the IP address of the server. The webmaa maps to a particular Tomcat server. The app1 is the particular application on the webmaa Tomcat server. There can be more than one application. For example an author could have two very different applications each initialized with a special package. Each would have its own application name. The servlet says that what follows is the name of a servlet in this application. The SnoopServlet is the name of the servlet.
  
  http://www.hostsrv.com/webmaa/app1/MSP/Integrate?expr=Sin[x]^2
  
  In the above URL, MSP is the name of the servlet. (MSP has been mapped in Tomcat's configuration files to be recognized as a servlet). Integrator is the name of the MSP script that MSP will process. The ?expr=Sin[x]^2 gives a parameter to the Integrator script. The format of this parameter is name=value with name/value pair separated by commas. Note that no quotes are required around the Sin[x]^2. the ? marks the start of name=value pairs. In the particular case of Integrator, it could run without supplying a name=value pair as part of the URL.
  
  
  

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• What is a KernelMonitor?

  An author can use the KernelMonitor to restart kernels in an author's kernel pool. The KernelMonitor gives statistics on how the kernels in the kernel pool are operating. The KernelMonitor gives a listing of the content of log files and displays the most recent commands given to the kernel for processing. See KernelMonitor. KernelMonitor control is available to Commercial Pro Setup authors.
  
  
  

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• What is a Tomcat Server?

  Tomcat manages Java processes on a server. It can run as a standalone application or under the direction of a web server. (Tomcat is under the direction of Apache web server at HostSRV.com)
  
  Each Tomcat server may have several applications under its control. These applications could all be configured for different purposes.
  
  
  

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• What is the difference between a Tomcat server and an application?

  A Tomcat server controls the Java processes in which MSP, JLink, Mathematica® kernels, and FrontEnds are imbedded. Applications are particular instances of one of these processes. One Tomcat server can control many applications. Each Tomcat server controls processes that are each separate from any other Tomcat processes on the server.
  
  
  

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• What is the difference between public and private areas of an application?

  The public areas contain applications served to any web browser. Private applications require a password before any browsers may connect. Licensing terms for non-commercial accounts require that your scripts be publicly accessible. The only exception is that an author my have private scripts for his own, exclusive use.
  
  
  

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• How does an author control the Kernel timeout value?

  Commercial Pro Setup authors may control kernel timeout values from the MSP.conf file that applies to the particular application. This should be set to something reasonable. If an author's application takes too much cpu time, we will need to open discussions regarding pricing. See Specific Service Offerings for details on time-out values for other types of accounts.
  
  
  

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• How many kernels does an author control?

  Separate kernel pools are setup for Personal, Parked, and Commercial accounts. The kernels in such pools are shared by all Personal, Parked, and Commercial authors. Commercial Pro Setup authors initially share the commercial kernel pool. This should be sufficient to meet the needs of most authors. Additional kernels or private kernels are available for an additional monthly fee.