Checking the Server

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Checking the Server
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Location of Server Files on the Virtual Machine

• On your virtual machine
• The Tomcat servlet engine is in
  /usr/local/javadev/apache/tomcat-5.5.12 (this is
  the value of CATALINA_HOME)
• The BES, data handlers and related source files
  are in /usr/local/src. The BES has been built and
  installed in /usr/local/ (prefix)
• The OLFS web archive file is CATALINA_HOME/webapp
  s/opendap.war
• BES bes.conf, found at prefix/etc/bes/bes.conf
• OLFS olfs.xml and catalog.xml, found at
  CATALINA_HOME/content/opendap

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Background Starting the Server

• Start the BES (back-end data processing
  component)
• Use bescmdln to verify its working
• Start Tomcat This automatically starts all
  installed servlets
• Servlets are installed by copying the .war file
  to the servlets webapps directory
• Verify its working using a web browser

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Start the BES
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Verify the BES is running
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Start Tomcat the OLFS

• Typical steps
• Unpack the olfs jar-file
• Copy the opendap.war file to Tomcats webapps
  directory
• Start Tomcat
• Since all but the last step has been done
  already, start Tomcat
• /usr/local/javadev/apache-tomcat-5.5.12/bin/startu
  p.sh

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terminal view
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Verify Tomcat is running
http//localhost8080
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and Hyrax
http//localhost8080/opendap
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Troubleshooting

• The getdap command line client
• Can request any of the DAP response objects
• Can act as a simple, generic web client
• When even getdap cannot diagnose a problem, use
  telnet!

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Troubleshooting with getdap

• Use getdap to get
• The DAS, DDS, Data, DDX
• Version information
• Use telnet to view the raw HTTP response
• If the server times out too quickly, use expect
  to control telnet

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Use the -a option to get a DAS response
Also provide a valid URL http//localhost8080/ope
ndap/data/nc/fnoc1.nc
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Use the -d option to get a DDS response
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or drop the -d option and append the .dds
suffix
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Use the -D (data) and -c (constraint)
options to get a data response.
A constraint expression with just one variable.
We got this from the DDS above
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This constraint is asking for the values of
time between indexes 2 and 6 (every second
value).
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Appending the string version to the server root
name requests version information. It comes back
in an XML document.
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Telnet reveals all

• Use telnet to pass HTTP commands directly to the
  opendap web application
• Open the connection using the host name and port
  number
• Use the GET command, the pathname part of the
  URL including the DAP request extension and
  HTTP/1.1 or HTTP/1.0
• Often you will need to supply a Host ltnamegt
  header
• A blank line.

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Connect to the Tomcat or Apache server
GET ltpathnamegt HTTP/1.1 (or 1.0) - hit return
quickly!
Host header is important for a virtual server
Heres the payoff - we can see all of the
headers set by both the web app and the server,
plus the response. Be cautious with data
responses because they are binary and will mess
up your terminal session. Note the HTTP 1.1
chunking counts (c5 and 0)