To insert, delete, update, and retrieve data from your
data grid, you must write a client application. The getting started
sample includes a Java client application
that you can use to learn about creating your own client application.
The Client.java file in the wxs_install_root/ObjectGrid/gettingstarted/client/src/ directory
is the client program that demonstrates how to connect to a catalog
server, obtain the ObjectGrid instance, and use the ObjectMap API.
The ObjectMap API stores data as key-value pairs
and is ideal for caching objects that have no relationships involved.
The following steps discuss the contents of the Client.java file.
If you need to cache objects that have relationships,
use the EntityManager API.
- Connect to the catalog service by obtaining a ClientClusterContext
instance.
To connect to the catalog server, use the connect method
of ObjectGridManager API. The following code snippet demonstrates how to connect
to a catalog server and obtain a ClientClusterContext instance:
ClientClusterContext ccc = ObjectGridManagerFactory.getObjectGridManager().connect(cep, null, null);
If the connections to the catalog servers succeed,
the connect method returns a ClientClusterContext
instance. The ClientClusterContext instance is required to obtain
the ObjectGrid from the ObjectGridManager API.
- Obtain an ObjectGrid instance.
To obtain
ObjectGrid instance, use the getObjectGrid method
of the ObjectGridManager API. The getObjectGrid method
requires both the ClientClusterContext instance and the name of the
data grid instance. The ClientClusterContext instance is obtained
during the connection to catalog server. The
name of ObjectGrid instance is Grid that is
specified in the objectgrid.xml file. The
following code snippet demonstrates how to obtain the data grid by
calling the getObjectGrid method of the ObjectGridManager API.
ObjectGrid grid = ObjectGridManagerFactory.getObjectGridManager().getObjectGrid(ccc, "Grid");
- Get a Session instance.
You can get a Session
from the obtained ObjectGrid instance. A Session instance is required
to get the ObjectMap instance, and perform transaction demarcation.
The following code snippet demonstrates how to get a Session instance
by calling the getSession method of the ObjectGrid API.
Session sess = grid.getSession();
- Get an ObjectMap instance.
After getting
a Session, you can get an ObjectMap instance from a Session instance
by calling getMap method of the Session API. You must pass the name of map as parameter to getMap method to get the ObjectMap instance. The
following code snippet demonstrates how to obtain ObjectMap by calling
the getMap method of the Session API.
ObjectMap map1 = sess.getMap(mapName);
- Use the ObjectMap methods.
After an ObjectMap
instance is obtained, you can use the ObjectMap API.
Remember that the ObjectMap interface is a transactional map and requires
transaction demarcation by using the begin and commit methods
of the Session API. If there is no explicit transaction
demarcation in the application, the ObjectMap operations run with
auto-commit transactions.
The following code snippet demonstrates how to use the ObjectMap API
with an auto-commit transaction.
map1.insert(key1, value1);
You can either run a transaction on one
partition at a time, or on multiple partitions. To run a transaction
on a single partition, use a one-phase commit transaction: sess.setTxCommitProtocol(TxCommitProtocol.ONEPHASE);
sess.begin();
map1.insert(k, v);
sess.commit();
To run a transaction across multiple partitions,
use a two-phase commit transaction: sess.setTxCommitProtocol(TxCommitProtocol.TWOPHASE);
sess.begin();
map1.insert(k, v);
sess.commit();
- Optional: Close the Session. After all of the Session and ObjectMap operations are complete,
close the session with the Session.close() method.
Running this method returns the resources that were being used by
the session.
sess.close();
As a result, subsequent getSession() method
calls return faster, and fewer Session objects are in the heap.