Samples in Globus Toolkit 3.0

A number of grid services are provided samples in the Globus Toolkit 3.0 (GTK3.0). This webpage provides details about setting up and running these samples.

The GTK3.0 must be installed on your system. In all the illustrations that are provided along with the guidelines, the GTK3.0 directory is test_install_dir and its location is /home/purshah/test_install_dir.

Building the Samples

In order to build the samples, use the following command from your GTK3.0 directory: ant samples. For example,
[purshah@danube test_install_dir]$ ant samples
generates the output that is provided in the file samples_build_output.txt.

If the samples are built successfully, then all the sample grid services have been deployed in the container provided in GTK3.0. In order to check what services have been deployed start the container in GTK3.0 by using the command ant startContainer from the GTK3.0 directory. This displays all the services that are presently deployed in the container in your GTK3.0. For example,
[purshah@danube test_install_dir]$ ant startContainer
generates the output that is provided in the file container_output.txt.

Using a Sample Grid Service

In order to use a Grid Service, the following steps must be taken:

Start the Container using ant startContainer.
Then in another window, create an instance of the Grid Service using java org.globus.ogsa.client.CreateService <service-url> <id>. In this command, <service-url> is the Grid Service Handle (GSH) of the Grid Service Factory that must produce an instance of the Grid Service called <id>.
Run the command-line client that interacts with the Grid Service instance.

For example, we shall have a look at a sample Basic Counter Service that is provided in GTK3.0. It is a simple counter maintaining the calculated value as state. Three operations can be performed:

GetValue - returns present value of the counter
Add - adds to the counter value
Subtract - subtracts from the counter value

The source code for the service is available in <gtk3.0>/samples/org/globus/ogsa/impl/samples/counter/basic and for the clients is available in <gtk3.0>/samples/org/globus/ogsa/impl/samples/counter/client. Steps 2 and 3 for this service are shown in counter.txt.

Creating a Client for a Sample Grid Service

In order to interact with a Grid Service, a client must be created that initiates some operation performed by the Grid Service. For this purpose, a client must use the Service Locator and Port Type classes defined for the Grid Service. Using these classes a new instance of the Grid Service's Port Type is created and a call is made to an operation (i.e. method) of the Grid Service by supplying the URL for the instance of the Grid Service and any other arguments as needed by the operation. Details about these classes and methods can be obtained from the APIs provided in GTK3.0 at <gtk3.0>/docs/api.

For example, a client for the sample Google Search Service is defined in DoSpellingSuggestion.java.