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vFabric™ GemFire®
WAN
Java Caching API Programming Example
The WAN example is an application that simulates two WAN sites, namely a US site
and an EU site. The example is located in the GemFire installation under
examples/dist/wan.
The WAN example contains the following four components:
- A US WAN client that puts entries into a WAN-enabled region
- A US WAN hub that receives those entries and distributes them to the EU WAN hub
- An EU WAN hub that receives the distributed WAN events from the US hub and distributes them to its clients
- An EU WAN client that receives the WAN events from the EU hub and displays them
In every shell used to run this example application, configure your
environment according to the instructions provided in
examples/EnvSetup.html.
Once your environment is set, change to the
examples/dist/wan directory to run the
application.
To run the WAN example, perform the following steps:
- Launch a shell for the US gateway hub
The US WAN hub is a cache server gateway to the EU WAN. This gateway forwards any client updates
to entries in the trades region to the EU WAN. Entry updates received from the EU WAN hub are
distributed to its clients.
Change to the examples/dist/wan/us-hub directory and run the following command:
cacheserver start
This command logs output like shown below:
Starting CacheServer with pid: 18087
CacheServer pid: 18087 status: running
- Launch a shell for the EU gateway hub
The EU WAN hub is a cache server gateway to the US WAN. This gateway forwards any client updates
to entries in the trades region to the US WAN. Entry updates received from the US WAN hub will be
distributed to its clients.
Change to the examples/dist/wan/eu-hub directory and
run the following command:
cacheserver start
This command logs output like shown below:
Starting CacheServer with pid: 18686
CacheServer pid: 18686 status: running
- Launch a shell for the EU client
Change to the examples/dist/wan/eu-client directory and run the following command:.
The EU WAN client listens for updates to entries in trades region.
java wan.WANClient eu
The WANClient class has a main method
that creates either a US or EU WAN client using the 'us' or 'eu' parameters.
Shown below is the WANClient usage.
$ java wan.WANClient
** Missing site name
usage: java wan.WANClient
site The name of the WAN site (either 'us' or 'eu')
Launches a WAN client
This command logs output like shown below:
Created GemFire cache: eu-client
Retrieved region: com.gemstone.gemfire.internal.cache.LocalRegion[path='/trades';scope=LOCAL';data-type=NORMAL]
Registered interest in [] for region trades
- Launch a shell for the US client
The US WAN client launches mulitple threads, each putting entries into the trades region.
Change to the examples/dist/wan/us-client directory and run the following command:
java wan.WANClient us
This command logs output like shown below:
Created GemFire cache: us-client
Retrieved region: com.gemstone.gemfire.internal.cache.LocalRegion[path='/trades';scope=LOCAL';data-policy=NORMAL]
Thread-1: Putting key-704->704
Thread-3: Putting key-2663->2663
Thread-2: Putting key-2822->2822
Thread-4: Putting key-853->853
Thread-5: Putting key-3612->3612
Thread-6: Putting key-1668->1668
Thread-7: Putting key-1872->1872
Thread-8: Putting key-4540->4540
Thread-9: Putting key-442->442
Thread-10: Putting key-1494->1494
Thread-8: Putting key-2661->2661
.
.
.
In addition, output like shown below is displayed in the EU client window:
WANListener received afterCreate event (1) for region trades: key-853->853
WANListener received afterUpdate event (2) for region trades: key-1494->1494
WANListener received afterCreate event (3) for region trades: key-4540->4540
WANListener received afterCreate event (4) for region trades: key-704->704
WANListener received afterUpdate event (5) for region trades: key-2822->2822
WANListener received afterCreate event (6) for region trades: key-442->442
WANListener received afterCreate event (7) for region trades: key-1872->1872
WANListener received afterCreate event (8) for region trades: key-2663->2663
WANListener received afterUpdate event (9) for region trades: key-1668->1668
WANListener received afterUpdate event (10) for region trades: key-3612->3612
WANListener received afterCreate event (11) for region trades: key-1926->1926
WANListener received afterUpdate event (12) for region trades: key-2661->2661
WANListener received afterCreate event (13) for region trades: key-2372->2372
.
.
.
- Stop the us-client and eu-client client VMs by pressing
CTRL-C in both shells. Stop the us-hub and eu-hub cache server VMs
by entering cacheserver stop in their shells.
An example is shown below.
cacheserver stop
CacheServer stopped
Close the four open shells by entering exit in each.