High Availability Sample

Open five terminal windows on UNIX, or five StreamBase Command Prompts on Windows.

In each window, navigate to your workspace copy of the sample.

For the basic sample, navigate to the basic-scripts folder; for the custom sample, navigate to the custom-scripts folder.

In window 1, start the first server with this command: startprimary.

This script sets environment variables, starts a server listening on port 9900, and loads the high availability application (ha) in a container, ha, on that server. The high availability application designates this server as the leader and starts app.ssql.

In window 5, run the following command to observe this outcome:

sbc -u :9900 list containers

This command generates the following output:

container   _SB_ha
container   app
container   ha_control_app
container   system

In window 2, run startsecondary.

This script performs the same actions as startprimary, except it starts its server on port 9901 and sets its leadership status as nonleader.

In window 3, run startfeedsim.

A feed simulation starts sending input data to both servers. Window 3 shows input, such as the following:

in (a=871)
in (a=6419)
in (a=2348)
in (a=8339)
in (a=5707)
in (a=909)
in (a=8756)
in (a=3983)
in (a=8748)
...

In window 4, run startdequeue.

The command sent by the startdequeue script is a comma-separated list of URIs to address both servers at the same time. After resolving the variables for port number, the command sent by startdequeue resolves to the following:

sbc -u sb://localhost:9900/app,sb://localhost:9901/app dequeue

Notice the hostname (myhostname) and the StreamBase URI of the responding server is shown for each line, and only one server is responding, namely the server designated as the leader.

out,2555,myhostname,sb://localhost:9900/
out,3091,myhostname,sb://localhost:9900/
out,8482,myhostname,sb://localhost:9900/
out,520,myhostname,sb://localhost:9900/
out,101,myhostname,sb://localhost:9900/
out,3538,myhostname,sb://localhost:9900/
out,867,myhostname,sb://localhost:9900/
out,8503,myhostname,sb://localhost:9900/
out,36,myhostname,sb://localhost:9900/
...

In window 5, run the following command to determine the status of both servers:

sbc -u :9900,:9901 status --verbose 

This command generates a status report line for each server. Notice that the server on port 9900, which is running in window 1, is designated as the leader.

In window 5, run the following command to shut down the primary server, the one that is now the leader:

sbadmin -p 9900 shutdown

Notice that the dequeued output stream in window 4 has switched to showing tuples from the server on port 9901:

out,6700,myhostname,sb://localhost:9901/
out,7156,myhostname,sb://localhost:9901/
out,1303,myhostname,sb://localhost:9901/
out,4798,myhostname,sb://localhost:9901/
out,2305,myhostname,sb://localhost:9901/
out,9540,myhostname,sb://localhost:9901/
...

In window 5, run the following command to determine the status of both servers:

sbc -u :9900,:9901 status --verbose 

Notice that the server on port 9901, which is running in window 2, is designated as the leader.

In window 1, restart the primary server by running the startprimaryasnonleader command. Notice that this server is the nonleader.

Shut down the secondary server, the one that is now the leader:

sbadmin -p 9901 shutdown

Notice the output stream in window 4 switches back to the server on port 9900.

Check the status again by running the same command as before:

sbc -u :9900,:9901 status --verbose 

Now, only one server is running, namely the server on port 9900, and it is the leader.

Open six terminal windows on UNIX, or six StreamBase Command Prompts on Windows.

In each window, navigate to your workspace copy of the sample.

In windows 5 and 6, type Ctrl+C to exit both sbc enq sessions.

In another terminal window or StreamBase Command Prompt, type:

sbadmin -p 9000 shutdown
sbadmin -p 9010 shutdown

This terminates both servers and both dequeuers, and closes windows 1 through 4.