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Apache Ratis Examples

Building and Running The Examples

The repository can be complied using mvn clean package -DskipTests under the project root directory; see also BUILDING.md.

For the Example 1 and 2, All the scripts for running the examples are located in the ratis-examples/src/main/bin directory; see below for the usage.

Example 3 does not contain any script to run it refer to Example 3 run section.

Example 1: FileStore

FileStore is a high performance file service supporting read, write and delete operations. The FileStoreStateMachine is implemented using the asynchronous event-driven model. The source code is located in

FileStore Server

To spawn a FileStore server, run

  • server.sh filestore server --id <SELF_ID> --storage <STORAGE_DIR> --peers <ID:IP_ADDRESS,...>

where

  • <SELF_ID>, which must be in the peer list, is the ID of the instance being spawned,
  • <STORAGE_DIR> is a local directory for storing Raft log and other data, and
  • <ID:IP_ADDRESS,...>, which is a comma separated list of ID and IP address pairs, specifies the list of server peers.

Note that when multiple servers running at the same host, they must use different <STORAGE_DIR>.

For example,

BIN=ratis-examples/src/main/bin
PEERS=n0:127.0.0.1:6000,n1:127.0.0.1:6001,n2:127.0.0.1:6002

ID=n0; ${BIN}/server.sh filestore server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}
ID=n1; ${BIN}/server.sh filestore server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}
ID=n2; ${BIN}/server.sh filestore server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}

FileStore Client

To spawn a FileStore load generation client, run

  • client.sh filestore loadgen --size <FILE_SIZE> --numFiles <NUM_FILES> --numClients <NUM_CLIENTS> --peers <ID:IP_ADDRESS,...>

where

  • <FILE_SIZE> is the size of the files to be generated in bytes, and
  • <NUM_FILES> is the number of files to be generated, and
  • <NUM_CLIENTS> is the number of clients.

Continue the server command example,

${BIN}/client.sh filestore loadgen --size 1048576 --numFiles 1000 --storage /tmp/ratis/loadgen --numClients 1 --peers ${PEERS}

Example 2: Arithmetic

Arithmetic is an implementation of a replicated state machine. A variable map is stored in the ArithmeticStateMachine which supports assign and get operations. Clients may assign a variable to a value by specifying either the value or a formula to compute the value.

In TestArithemetic, it uses Arithmetic to solve Pythagorean equation and compute π using Gauss–Legendre algorithm.

The source code is located in

Arithmetic Server

To spawn an Arithmetic server, run

  • server.sh arithmetic server --id <SELF_ID> --storage <STORAGE_DIR> --peers <ID:IP_ADDRESS,...>

where

  • <SELF_ID>, which must be in the peer list, is the ID of the instance being spawned,
  • <STORAGE_DIR> is a local directory for storing Raft log and other data, and
  • <ID:IP_ADDRESS,...>, which is a comma separated list of ID and IP address pairs, specifies the list of server peers.

Note that when multiple servers running at the same host, they must use different <STORAGE_DIR>.

For example,

BIN=ratis-examples/src/main/bin
PEERS=n0:127.0.0.1:6000,n1:127.0.0.1:6001,n2:127.0.0.1:6002

ID=n0; ${BIN}/server.sh arithmetic server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}
ID=n1; ${BIN}/server.sh arithmetic server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}
ID=n2; ${BIN}/server.sh arithmetic server --id ${ID} --storage /tmp/ratis/${ID} --peers ${PEERS}

Arithmetic Client

To run an Arithmetic client command, run

  • client.sh arithmetic get --name <VAR> --peers <ID:IP_ADDRESS,...>

or

  • client.sh arithmetic assign --name <VAR> --value <VALUE> --peers <ID:IP_ADDRESS,...>

where

  • <VAR> is the name of a variable, and
  • <VALUE> is the value (or a formula to compute the value) to be assigned.

Continue the server command example,

${BIN}/client.sh arithmetic assign --name a --value 3 --peers ${PEERS}
${BIN}/client.sh arithmetic assign --name b --value 4 --peers ${PEERS}
${BIN}/client.sh arithmetic assign --name c --value a+b --peers ${PEERS}
${BIN}/client.sh arithmetic get --name c --peers ${PEERS}

Example 3: Counter

This example designed to be the simplest possible example and because of that this example does not follow the scripts and command line parameters of previous examples. The Goal of this example is to maintain and replicate a counter value across a cluster. CounterServer class contains the main method to run the server and you can run it three times with three different parameters(1,2 and 3). all address and ports of the peers hardcoded in CounterCommon, so you don't need any extra configuration to run this example on your localhost. CounterClient class contains the main method to run the client,the client sends several INCREMENT command and after that, it sends a GET command and prints the result which should be the value of the counter. 'Counter State Machine' implemented in CounterStateMachine class. You can find more detail by reading these classes javaDocs.

Run Counter Server and Client

run the client and servers by these commands from ratis directory: for server: java -cp ./ratis-examples/target/*.jar org.apache.ratis.examples.counter.server.CounterServer {serverIndex} replace {serverIndex} with 0, 1, or 2 for client: java -cp ./ratis-examples/target/*.jar org.apache.ratis.examples.counter.client.CounterClient

Pre-Setup Vagrant Pseudo Cluster

Note: This option is only available to Example 1 and 2 One can see the interactions of a three server Ratis cluster with a load-generator running against it by using the run_all_tests.sh script found in dev-support/vagrant/. See the dev-support/vagrant/README.md for more on dependencies and what is setup. This will allow one to try a fully setup three server Ratis cluster on a single VM image, preventing resource contention with your development host and allowing failure injection too.