Classmethod Tupl Storage Backend for Titan

Titan: Distributed Graph Database is a scalable graph database optimized for storing and querying graphs containing hundreds of billions of vertices and edges distributed across a multi-machine cluster. Titan is a transactional database that can support thousands of concurrent users executing complex graph traversals in real time. -- Titan Homepage

Tupl: The Unnamed Persistence Library is a high-performance, concurrent, transactional, scalable, low-level embedded database. Features include record-level locking, upgradable locks, deadlock detection, cursors, hot backups, striped files, encryption, pluggable replication, nested transaction scopes, and direct lock control. Although written in Java, Tupl doesn't suffer from garbage collection pauses when configured with a large cache. -- Tupl Homepage

Titan + Tupl = Embedded Graph Database - Storage Management

Features

The following is a list of features of the Classmethod Tupl Storage Backend for Titan.

• AWS managed authentication and authorization.
• Configurable storage directory allow multiple graphs to be stored in a single host in the same region.
• Integrated with Titan metrics.
• Titan 1.0.0 and Tinkerpop 3.0.1-incubating compatibility.
• All the store features titan-berkeleyje but with improved performance of Tupl across the board.
• Permissive Apache 2.0 license both for this Storage Backend and Tupl.

Getting Started

This example populates a Titan graph database backed by Tupl using the Marvel Universe Social Graph. The graph has a vertex per comic book character with an edge to each of the comic books in which they appeared.

Load a subset of the Marvel Universe Social Graph

1. Clone the repository in GitHub.

   git clone https://github.com/classmethod/tupl-titan-storage-backend.git
   

2. Run the install target to copy some dependencies to the target folder.

   mvn install
   

3. Clean up old ElasticSearch indexes.

   rm -rf /tmp/searchindex
   

4. Install Titan Server with the Classmethod Tupl Storage Backend for Titan, which includes Gremlin Server.

   src/test/resources/install-gremlin-server.sh
   

5. Change directories to the Gremlin Server home.

   cd server/tupl-titan100-storage-backend-1.0.0-hadoop1
   

6. Start Gremlin Server:

   bin/gremlin-server.sh ${PWD}/conf/gremlin-server/gremlin-server.yaml
   

7. Start a Gremlin shell with bin/gremlin.sh and connect to the Gremlin Server endpoint.

   :remote connect tinkerpop.server conf/remote.yaml
   

8. Load the first 100 lines of the Marvel graph using the Gremlin shell.

   :> jp.classmethod.titan.example.MarvelGraphFactory.load(graph, 100, false)
   

9. Print the characters and the comic-books they appeared in where the characters had a weapon that was a shield or claws.

   :> g.V().as('character').has('weapon', within('shield','claws')).out('appeared').as('comic-book').select('character','comic-book')
   

10. Print the characters and the comic-books they appeared in where the characters had a weapon that was not a shield or claws.

    :> g.V().as('character').has('weapon', without('shield','claws')).out('appeared').as('comic-book').select('character','comic-book')
    

11. Print a sorted list of the characters that appear in comic-book AVF 4.

    :> g.V().has('comic-book', 'AVF 4').in('appeared').values('character').order()
    

12. Print a sorted list of the characters that appear in comic-book AVF 4 that have a weapon that is not a shield or claws.

    :> g.V().has('comic-book', 'AVF 4').in('appeared').has('weapon', without('shield','claws')).values('character').order()
    

Complete the TinkerPop tutorial

1. Repeat steps 1 through 5, and step 7 of the Marvel graph section.
2. Now you can follow along the TinkerPop Tutorial. When the tutorial and documentation refer to the TinkerFactory.createModern(), you can create the graph with: jp.classmethod.titan.example.TuplTinkerFactory.createModern(). When the tutorial and documentation refer to the baby graph, you can create the graph with: jp.classmethod.titan.example.TuplTinkerFactory.creatBaby(). TuplTinkerFactory adds schema elements and makes adjustments to the original graph that are necessary for working through the tutorial with the Classmethod Tupl Storage Backend for Titan.

Load the Graph of the Gods

1. Repeat steps 1 through 7 of the Marvel graph section.

2. Load the Graph of the Gods.

   :> com.thinkaurelius.titan.example.GraphOfTheGodsFactory.load(graph)
   

3. Now you can follow the rest of the Titan Getting Started documentation, starting from the Global Graph Indeces section. You need to prepend each command with :> for remotely executing the commands on the Gremlin Server endpoint. Also whenever you remotely execute traversals that include local variables in steps, those local variables need to be defined in the same line before the traversal. For example, to run the traversal g.V(hercules).out('father', 'mother').values('name') remotely, you would need to prepend it with the definition for Hercules:

   :> hercules = g.V(saturn).repeat(__.in('father')).times(2).next(); g.V(hercules).out('father', 'mother').values('name')
   

Note that the definition of Hercules depends on the definition of Saturn, so you would need to define Saturn first:

```
:> saturn = g.V().has('name', 'saturn').next(); hercules = g.V(saturn).repeat(__.in('father')).times(2).next(); g.V(hercules).out('father', 'mother').values('name')
```

The reason these need to be prepended is that local variable state is not carried over for each remote script execution, except for the variables defined in the scripts that run when Gremlin server is turned on. See the scriptEngines/gremlin-groovy/scripts list element in the Gremlin Server YAML file for more information. 4. Alternatively, repeat steps 1 through 8 of the Marvel graph section and follow the examples in the TinkerPop documentation, prepending each command with :> for remote execution. Skip the TinkerGraph.open() step as the remote execution environment already has a graph variable set up.

Run Gremlin on Gremlin Server in EC2 using a CloudFormation template

The Classmethod Tupl Storage Backend for Titan includes a CloudFormation template that creates a VPC, an EC2 instance in the VPC, installs Gremlin Server with the Classmethod Tupl Storage Backend for Titan installed, and starts the Gremlin Server websockets endpoint. The Network ACL of the VPC includes just enough access to allow:

• you to connect to the instance using SSH and create tunnels (SSH inbound)
• the EC2 instance to download yum updates from central repositories (HTTP outbound)
• the EC2 instance to download your tupl.properties file and the Gremlin Server package from S3 (HTTPS outbound)
• the ephemeral ports required to support the data flow above, in each direction

Requirements for running this CloudFormation template include two items.

• You require an SSH key for EC2 instances must exist in the region you plan to create the Gremlin Server stack.
• You need to have created an IAM role in the region that has S3 Read access, the very minimum policies required to run this CloudFormation stack. S3 read access is required to provide the tupl.properties file to the stack in cloud-init.

Note, this cloud formation template downloads repackaged versions of the Titan zip files available on the Titan downloads page. We repackaged these zip files in order to include the Classmethod Tupl Storage Backend for Titan and its dependencies. The repackaged version of the Titan zip's SHA-256 hash is 27915a82bac4d9bd1793efc4c7c98be68280be420a30f27994b9aea480c69e3b.

1. Click to launch the stack in Oregon (the usual Amazon EC2 and EBS charges will apply). The SHA-256 hash of the CloudFormation script is 27915a82bac4d9bd1793efc4c7c98be68280be420a30f27994b9aea480c69e3b.
2. On the Specify Parameters page, you need to specify the following:

• The size of the EBS volume used to store the graph
• EC2 Instance Type
• The network whitelist pattern for Gremlin Server Websockets port
• The Gremlin Server port, default 8182.
• The S3 URL to your tupl.properties configuration file
• The name of your pre-existing EC2 SSH key
• The network whitelist for the SSH protocol. You will need to allow incoming connections via SSH to enable the SSH tunnels that will secure Websockets connections to Gremlin Server.
• The path to an IAM role that has the minimum amount of privileges to run this CloudFormation script and run Gremlin Server with the Classmethod Tupl Storage Backend for Titan. This role will require S3 read access to get the tupl.properties file.

3. On the Options page, click Next.
4. On the Review page, select "I acknowledge that this template might cause AWS CloudFormation to create IAM resources." Then, click Create.
5. Create an SSH tunnel from your localhost port 8182 to the Gremlin Server port (8182) on the EC2 host after the stack deployment is complete. The SSH tunnel command is one of the outputs of the CloudFormation script so you can just copy-paste it.
6. Repeat steps 4, 5, and 7 of the Marvel graph section above.

Tupl Specific Configuration

Each configuration option has a certain mutability level that governs whether and how it can be modified after the database is opened for the first time. The following listing describes the mutability levels.

1. FIXED - Once the database has been opened, these configuration options cannot be changed for the entire life of the database
2. GLOBAL_OFFLINE - These options can only be changed for the entire database cluster at once when all instances are shut down
3. GLOBAL - These options can only be changed globally across the entire database cluster
4. MASKABLE - These options are global but can be overwritten by a local configuration file
5. LOCAL - These options can only be provided through a local configuration file

Leading namespace names are shortened and sometimes spaces were inserted in long strings to make sure the tables below are formatted correctly.

General Tupl Configuration Parameters

All of the following parameters are in the storage (s) namespace, and most are in the storage.tupl (s.t) namespace subset.

Name	Description	Datatype	Default Value	Mutability
s.backend	The primary persistence provider used by Titan. To use Tupl you must set this to jp.classmethod.titan.diskstorage. tupl.TuplStoreManager	String		MASKABLE
s.directory	The storage directory for tupl. If not set, Tupl will run as a volatile, in-memory store that is not persisted to disk.	String		LOCAL
s.t.prefix	A file prefix to include in the database files Tupl creates for this graph.	String	tupldb	FIXED
s.t.map-data-files	Enable memory mapping of the data files. Entire graph needs to fit in memory.	Boolean	false	MASKABLE
s.t.min-cache-size	The tupl minimum cache size (bytes). Must be at least 5 pages long.	Long	100000000	MASKABLE
s.t.secondary-cache-size	The tupl secondary cache size (bytes). Off by default.	Long	0	MASKABLE
s.t.durability-mode	Default transaction durability mode.	String	SYNC	MASKABLE
s.t.sync-writes	Set true to ensure all writes to the main database file are immediately durable, although not checkpointed. This option typically reduces overall performance, but checkpoints complete more quickly. As a result, the main database file requires less pre-allocated pages and is smaller.	Boolean	false	MASKABLE
s.t.page-size	The page size in bytes.	Integer	4096	MASKABLE
s.t.direct-page-access	Set true to allocate all pages off the Java heap, offering increased performance and reduced garbage collection activity.	Boolean	true	MASKABLE

Tupl Locking Configuration Parameters

All of the following parameters are in the storage.tupl.lock (s.t.l) namespace.

Name	Description	Datatype	Default Value	Mutability
s.t.l.mode	Default lock mode. READ_UNCOMMITTED is needed to pass most Titan KV and KCV tests.	String	READ_UNCOMMITTED	MASKABLE
s.t.l.upgrade-rule	Default lock upgrade rule.	String	STRICT	MASKABLE
s.t.l.timeout	The lock timeout (milliseconds).	Long	60000	MASKABLE

Tupl Checkpointing Configuration Parameters

All of the following parameters are in the storage.tupl.checkpoint (s.t.c) namespace.

Name	Description	Datatype	Default Value	Mutability
s.t.c.rate	The checkpoint rate in milliseconds. Set to a negative number to disable automatic checkpoints.	String	1000	MASKABLE
s.t.c.delay-threshold	The checkpoint delay threshold in milliseconds (infinite if negative). This delay takes precedence over the size threshold. Set to zero for non-transactional operations.	String	60000	MASKABLE
s.t.c.size-threshold	The checkpoint size threshold in bytes. Set to zero for non-transactional operations.	Long	1073741824	MASKABLE

Run all tests against Tupl on an EC2 Amazon Linux AMI

1. Install dependencies. For Amazon Linux:

   sudo wget http://repos.fedorapeople.org/repos/dchen/apache-maven/epel-apache-maven.repo -O /etc/yum.repos.d/epel-apache-maven.repo
   sudo sed -i s/\$releasever/6/g /etc/yum.repos.d/epel-apache-maven.repo
   sudo yum update -y && sudo yum upgrade -y
   sudo yum install -y apache-maven git java-1.8.0-openjdk-devel
   sudo alternatives --set java /usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
   sudo alternatives --set javac /usr/lib/jvm/java-1.8.0-openjdk.x86_64/bin/javac
   git clone https://github.com/classmethod/tupl-titan-storage-backend.git
   sudo mkdir -p /usr/local/packages/tupl-titan100-storage-backend-1.0.0-hadoop1/data
   sudo chown -r ec2-user:ec2-user /usr/local/packages/tupl-titan100-storage-backend-1.0.0-hadoop1/data
   

2. Open a screen so that you can log out of the EC2 instance while running tests with screen.

3. Run the tests.

   mvn test -Pintegration-tests -Dproperties-file=src/test/resources/tupl.properties > o 2>&1
   

4. Exit the screen with CTRL-A D and logout of the EC2 instance.

5. Monitor the CPU usage of your EC2 instance in the EC2 console. When CPU usage goes to zero, that means the tests are done.

6. Log back into the EC2 instance and resume the screen with screen -r to review the test results.

   cd target/surefire-reports && grep testcase *.xml | grep -v "\/"
   

7. Terminate the instance when done.