Lab 4 - Hazelcast

Hazelcast

In this lab and homework, we will use the Hazelcast In-memory data grid, version 4.2.

Manual https://docs.hazelcast.com/imdg/4.2/

Javadoc https://docs.hazelcast.org/docs/4.2.4/javadoc/

Download https://hazelcast.com/open-source-projects/downloads/#hazelcast-imdg

Alternatively, you can also use the newer Hazelcast Platform version 5.1.1. There should not be major differences for the purpose of this task.

Download https://hazelcast.com/open-source-projects/downloads/ - the smaller "slim" version is sufficient.

Manual https://docs.hazelcast.com/hazelcast/5.1/

Javadoc https://docs.hazelcast.org/docs/5.1.1/javadoc/

Download source code

https://d3s.mff.cuni.cz/files/teaching/nswi080/labs/Files/sources-4.zip

• Example - example and lab task
• Input - base for homework task

You can also look at the example from the lectures: https://github.com/D-iii-S/teaching-middleware/tree/master/src/hazelcast-basic-peer/java

Explore example source

Hazelcast configuration (hazelcast.yaml):

• contains configuration of Hazelcast cluster members
• the members listen on 127.0.0.1, ports assigned sequentially starting from 5701
• join section tells how members should join an existing cluster
• tells to join localhost:5701, that means the after starting the first member, which will get localhost:5701, all the subsequent members will join the same cluster (but only as long as the first member is still running)

ExampleMember.java:

• uses the hazelcast.yaml config file
• joins the Hazelcast cluster
• inserts a few entries into the Example distributed map
• if the map does not exist, it is created
• the keys start with the string specified as the command-line argument
• the value is the (auto-generated) name of the cluster member
• runs until enter is pressed

ExampleClient.java:

• connects to the cluster but does not join as a member
• executes an action on the members
• for each entry in the Example map, the code is executed at the member where the entry is located

Scripts:

• for compiling and running the examples
• puts hazelcast-4.2.jar on the classpath

Run the example

Download Hazelcast IMDG Server from https://hazelcast.org/imdg/download/. Extract hazelcast-4.2.tar.gz.

Configure the path to hazelcast in setenv.sh.

Compile source codes: bash make.sh

Run members: bash run-member.sh A bash run-member.sh B bash run-member.sh C

Run a client: bash run-client.sh

Note about security

Note that running the cluster on a publicly accessible machine is not completely safe, because other users could be able to join your cluster. In Hazelcast 4.2, security features are available only in the commercial enterprise edition.

If running hazelcast on the lab computers:

• Do not accept connection from outside (listen on 127.0.0.1).
• Do not leave your cluster running for long times.

If you want to be completely safe, you could run in a virtual machine. We can provide an installed image that can be used in Qemu on the lab computers. For more information, e-mail the teaching assistant.

Lab activity task

Run the example as described below and send the output by e-mail to the teaching assistant.

Run the following scenario:

• Launch 3 members, A, B, C as shown above.
• Run the client.
• Terminate the member B.
• Run the client again.

Save the output of these programs (3 members and 2 clients) and send them by e-mail.

Note: after lauching or the members, wait until the cluster re-adjusts before running the client.

Read the homework assignment

https://d3s.mff.cuni.cz/files/teaching/nswi080/labs/Files/task-4-en.html

Explore assignment source code

Client.java

• skeleton for the client application.
• implements command loop, reading input
• generating documents
  • simulates long running computation by sleeping
  • now runs on the client, but should run on the servers
• implement all TODO comments