|
We accept the following payment methods:
|
|
Tomcat Quick Start Guide
This guide offers a quick start guide to deploying and undeploying
web applications under the the shared Tomcat JVM account.
It assumes some knowledge of servlet and jsp technology as well as a
running nameonthe.net account.
Deploying your first application
The directory paths used during this guide differ dependent upon if
your account is SSH enabled (enabling you to obtain a Unix shell). If
the account is SSH enabled the web app base will be /web, if not then the
root application directory will be /.
By default a ROOT level context will be pre-configured as part of the
account creation process (this is optional). This allows you to start
development immediately by placing jsp files into the root level directory
(/) and placing servlets within the WEB-INF/classes/ directory (relative to either
/web or / - see above). If this is not what is required, such as if you intend to take advantage of the automatic
deployment of web applications please instruct support to remove the default Context.
Hot Deployment of web applications
Using the pre-configured root context is useful during incremental development, allowing
you to upload servlets and jsps which will be automatically reloaded when Tomcat
detects them. Tomcat (like other servlet containers) offers the option of
deploying web applications via alternative routes. Using .war files is perhaps
the best known, the application developer packages the web application within an
jar file which according to a structure defined by the servlet specification.
A minimal .war file would have the following entries
/WEB-INF/web.xml
/index.jsp
This is the bare minimum (in fact the web.xml is not actually required under Tomcat)
for Tomcat to detect and reload the war and subsequently be able to process requests
for the index.jsp page.
To deploy a war file while Tomcat is running copy a .war file into the root directory
of your web space (/ for non ssh users, /web for ssh users). Tomcat will detect this
and deploy it.
.war naming conventions and accessing your application
The name of the .war file determines where the the application will be visible
via the web (the path). The basic rule is: the name of the war file stripped of the .war extension
will be the name of the application. For example, if the war file is named catalog.war
then the root url of the application will be based at http://www.yourdomain.com/catalog.
The exception to this rule is war files with the name ROOT.war. When Tomcat deploys this
war file it will be accessible at the root level of your domain http://www.yourdomain.com/.
Deploying web application using directories
In addition to the standard .war deployment process, Tomcat is intelligent enough to
deploy applications on the basis of what looks like a valid web application. When Tomcat is
scanning the web application root it looks for directories beneath this directory
which adhere to the minimal .war file structure presented above, if it finds a suitable
directory it will create and deploy an application. It uses the same algorithm as that used during war file
deployment to determine what path the web application should be assigned.
Deployment using .xml files (Advanced)
When Tomcat scans the web application root directory it attempts to find files with a .xml
extension. If found, it attempts to locate a valid element which would normally
appear in Tomcat main configuration file (server.xml). If well formed and valid, it then deploys
a web application using this as it's source of configuration information. The benefits of this
approach are it offers the developer access to configuration options (such a JNDI) which are
unavailable when deploying web applications using the alternative approaches above.
Reloading web applications
By default Tomcat is configured to scan web applications for changes in jsps, classes within
/WEB-INF/classes and the timestamp on the web.xml. Dependent upon the event, modified Tomcat will:
- jsps - recompile
- classes - reload (creating a new ClassLoader)
- web.xml - reload the whole application
Destroying web application (hot deployment)
Unique to nameonthe.net is the process of hot undeployment. Under normal conditions, Tomcat may
mark an application as unavailable due to errors within the web.xml file. This can occur during
startup of Tomcat or during a reload triggered by the timestamp on the web.xml being updated.
To avoid this problem, which can be frustrating because a restart of Tomcat is required,
nameonthe.net have written a patch which will keep attempting to deploy a malformed web application.
An additional bonus is 'hot deployment', if a web application has been loaded and is no longer
required removing the source (.war, directory, .xml) file will cause Tomcat to undeploy this application.
Using the mysql command line client
The SSH enabled accounts come with the mysql client preinstalled which allows you to carry out database
maintenance tasks. In supplement to the database web interface the mysql command line client is used
to perform more complex tasks that cannot be made via the web interface. To connect to the client once logged
in (see above) use the following command:mysql
You should see the client introduce itself as shown below:
bash-2.05$ mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 7 to server version: 3.23.55-max
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql>
To carry out a task issue the sql statement (note the mysql client accepts non SQL command
for mysql specific purposes) followed by a ';'. Example:
mysql> select * from test;
+----------+
| test |
+----------+
| ttesting |
+----------+
1 row in set (0.00 sec)
To exit from the mysql client type issue the 'exit' command. Those familiar with mysql will
be aware that the client will normally require command line arguments to connect, for your
convenience a .my.cnf file has been created which mysql uses to find which parameters to use
when it connects to the database.
Using the psql command line client
If Postgres was chosen for the database and the account is ssh enabled, the psql client is
available for use. To connect to the database use the following command:
psql -U username -h 127.0.0.1 username
Using the Tomcat manager application
The Tomcat manager application is pre-installed and configured appropriately with all shared JVM accounts.
The manager application provides a web interface which can be used to manage the configuration of contexts
associated with your your domain (you cannot view other user's web applications), using this interface
you can start and stop contexts as well as perform other
routine tasks. This application can be accessed from http://yourdomain/manager/html, the username and password
will be the same as your ftp/ssh login credentials (you can modify this by editing /etc/tomcat-users.xml).
Viewing the Tomcat Logs
By default all the logging activity will be placed within the /logs/ directory of your application. If a
ssh shell is available (if not, speak to support and ask for one) then 'tailing' the logs can provide
a powerful tool in debugging your web application. Viewing the logs is recommended when you suspect that
errors are occurring during the loading/reloading of your web application.
Contact Support
If you require support please email support@nameonthe.net
|
|
|
