If OGSA-DAI is deployed onto Tomcat then it supports a data source servlet. This allows the data exposed by an OGSA-DAI data source to be exposed via a servlet and so accessed by any HTTP client. Examples of the utility of the servlet are described in Chapter 103, Writing effective clients - using the data source servlet for delivery. This page outlines information from a server administrator's perspective.
The default name of the data source retrieval servlet is
DataSourceRetrievalServlet
. The URL
to access the servlet is defined, by default, to be this appended to
the prefix of all services on the OGSA-DAI server.
The prefix of all services is:
http://HOST:PORT/wsrf/services/dai
and the servlet has a default URL of:
http://HOST:PORT/wsrf/services/dai/DataSourceRetrievalServlet
For example:
http://coal.epcc.ed.ac.uk:8080/wsrf/services/dai/DataSourceRetrievalServlet
The servlet name and path, i.e.
/services/DataSourceRetrievalServlet
is defined in a web.xml
file in Tomcat.
This file is located in
$CATALINA_HOME/webapps/wsrf/WEB-INF/web.xml
and the servlet entry looks like:
<servlet> <servlet-name>DataSourceRetrievalServlet</servlet-name> <display-name>OGSA-DAI Servlet</display-name> <servlet-class>uk.org.ogsadai.servlets.DataSourceRetrievalServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>DataSourceRetrievalServlet</servlet-name> <url-pattern>/services/dai/DataSourceRetrievalServlet</url-pattern> </servlet-mapping>
You can change the name of the servlet by changing the value in the
url-pattern
field. For example,
changing the url-pattern
value to be
to be
servlets/DataSourceRetrievalServlet
would mean that the connection URL would be:
http://coal.epcc.ed.ac.uk:8080/wsrf/servlets/DataSourceRetrievalServlet