| [[Cassandra-CamelCassandraComponent]] |
| Camel Cassandra Component |
| ------------------------- |
| |
| *Available as of Camel 2.15* |
| |
| http://cassandra.apache.org[Apache Cassandra] is an open source NoSQL |
| database designed to handle large amounts on commodity hardware. Like |
| Amazon's DynamoDB, Cassandra has a peer-to-peer and master-less |
| architecture to avoid single point of failure and garanty high |
| availability. Like Google's BigTable, Cassandra data is structured using |
| column families which can be accessed through the Thrift RPC API or a |
| SQL-like API called CQL. |
| |
| This component aims at integrating Cassandra 2.0+ using the CQL3 API |
| (not the Thrift API). It's based on |
| https://github.com/datastax/java-driver[Cassandra Java Driver] provided |
| by DataStax. |
| |
| Maven users will need to add the following dependency to their |
| `pom.xml`: |
| |
| *pom.xml* |
| |
| [source,xml] |
| ------------------------------------------------------------ |
| <dependency> |
| <groupId>org.apache.camel</groupId> |
| <artifactId>camel-cassandraql</artifactId> |
| <version>x.y.z</version> |
| <!-- use the same version as your Camel core version --> |
| </dependency> |
| ------------------------------------------------------------ |
| |
| [[Cassandra-URIformat]] |
| URI format |
| ~~~~~~~~~~ |
| |
| The endpoint can initiate the Cassandra connection or use an existing |
| one. |
| |
| [cols="<,<",options="header",] |
| |====================================================================== |
| |URI |Description |
| |`cql:localhost/keyspace` |Single host, default port, usual for testing |
| |`cql:host1,host2/keyspace` |Multi host, default port |
| |`cql:host1,host2:9042/keyspace` |Multi host, custom port |
| |`cql:host1,host2` |Default port and keyspace |
| |`cql:bean:sessionRef` |Provided Session reference |
| |`cql:bean:clusterRef/keyspace` |Provided Cluster reference |
| |====================================================================== |
| |
| To fine tune the Cassandra connection (SSL options, pooling options, |
| load balancing policy, retry policy, reconnection policy...), create |
| your own Cluster instance and give it to the Camel endpoint. |
| |
| [[Cassandra-EndpointOptions]] |
| Endpoint Options |
| ~~~~~~~~~~~~~~~~ |
| |
| [width="100%",cols="<34%,<33%,<33%",options="header",] |
| |======================================================================= |
| |Option |Default |Description |
| |`clusterName` | |Cluster name |
| |
| |`username and password` | |Session authentication |
| |
| |`cql` | |CQL query. Can be overriden with a message header. |
| |
| |`consistencyLevel` | |`ANY`, `ONE`, `TWO`, `QUORUM`, `LOCAL_QUORUM`... |
| |
| |`prepareStatements` |`true` |Use prepared statement (default) or not |
| |
| |`resultSetConversionStrategy` |`ALL` |How is ResultSet converted |
| transformed into message body `ALL`, `ONE`, `LIMIT_10`, `LIMIT_100`... |
| |======================================================================= |
| |
| [[Cassandra-Messages]] |
| Messages |
| ~~~~~~~~ |
| |
| [[Cassandra-IncomingMessage]] |
| Incoming Message |
| ^^^^^^^^^^^^^^^^ |
| |
| The Camel Cassandra endpoint expects a bunch of simple objects (`Object` |
| or `Object[]` or `Collection<Object>`) which will be bound to the CQL |
| statement as query parameters. If message body is null or empty, then |
| CQL query will be executed without binding parameters. |
| |
| Headers: |
| |
| * `CamelCqlQuery` (optional, `String` or `RegularStatement`): CQL query |
| either as a plain String or built using the `QueryBuilder`. |
| |
| [[Cassandra-OutgoingMessage]] |
| Outgoing Message |
| ^^^^^^^^^^^^^^^^ |
| |
| The Camel Cassandra endpoint produces one or many a Cassandra Row |
| objects depending on the `resultSetConversionStrategy`: |
| |
| |
| |
| * `List<Row>` if `resultSetConversionStrategy` is `ALL` or |
| `LIMIT_[0-9]+` |
| * Single` Row` if `resultSetConversionStrategy` is `ONE` |
| * Anything else, if `resultSetConversionStrategy` is a custom |
| implementation of the `ResultSetConversionStrategy` |
| |
| [[Cassandra-Repositories]] |
| Repositories |
| ~~~~~~~~~~~~ |
| |
| Cassandra can be used to store message keys or messages for the |
| idempotent and aggregation EIP. |
| |
| Cassandra might not be the best tool for queuing use cases yet, read |
| http://www.datastax.com/dev/blog/cassandra-anti-patterns-queues-and-queue-like-datasets[Cassandra |
| anti-patterns queues and queue like datasets]. It's advised to use |
| LeveledCompaction and a small GC grace setting for these tables to allow |
| tombstoned rows to be removed quickly. |
| |
| [[Cassandra-Idempotentrepository]] |
| Idempotent repository |
| ^^^^^^^^^^^^^^^^^^^^^ |
| |
| The `NamedCassandraIdempotentRepository` stores messages keys in a |
| Cassandra table like this: |
| |
| *CAMEL_IDEMPOTENT.cql* |
| |
| [source,sql] |
| --------------------------------------------------------- |
| CREATE TABLE CAMEL_IDEMPOTENT ( |
| NAME varchar, -- Repository name |
| KEY varchar, -- Message key |
| PRIMARY KEY (NAME, KEY) |
| ) WITH compaction = {'class':'LeveledCompactionStrategy'} |
| AND gc_grace_seconds = 86400; |
| --------------------------------------------------------- |
| |
| This repository implementation uses lightweight transactions (also known |
| as Compare and Set) and requires Cassandra 2.0.7+. |
| |
| Alternatively, the `CassandraIdempotentRepository` does not have a |
| `NAME` column and can be extended to use a different data model. |
| |
| [width="100%",cols="<34%,<33%,<33%",options="header",] |
| |======================================================================= |
| |Option |Default |Description |
| |
| |`table` |`CAMEL_IDEMPOTENT` |Table name |
| |
| |`pkColumns` |`NAME`,` KEY` |Primary key columns |
| |
| |`name` | | Repository name, value used for `NAME` column |
| |
| |`ttl` | | Key time to live |
| |
| |`writeConsistencyLevel` | | Consistency level used to insert/delete key: `ANY`, `ONE`, `TWO`, |
| `QUORUM`, `LOCAL_QUORUM`… |
| |
| |`readConsistencyLevel` | | Consistency level used to read/check key: `ONE`, `TWO`, `QUORUM`, |
| `LOCAL_QUORUM`… |
| |======================================================================= |
| |
| [[Cassandra-Aggregationrepository]] |
| Aggregation repository |
| ^^^^^^^^^^^^^^^^^^^^^^ |
| |
| The `NamedCassandraAggregationRepository` stores exchanges by |
| correlation key in a Cassandra table like this: |
| |
| *CAMEL_AGGREGATION.cql* |
| |
| [source,sql] |
| --------------------------------------------------------- |
| CREATE TABLE CAMEL_AGGREGATION ( |
| NAME varchar, -- Repository name |
| KEY varchar, -- Correlation id |
| EXCHANGE_ID varchar, -- Exchange id |
| EXCHANGE blob, -- Serialized exchange |
| PRIMARY KEY (NAME, KEY) |
| ) WITH compaction = {'class':'LeveledCompactionStrategy'} |
| AND gc_grace_seconds = 86400; |
| --------------------------------------------------------- |
| |
| Alternatively, the `CassandraAggregationRepository` does not have a |
| `NAME` column and can be extended to use a different data model. |
| |
| [width="100%",cols="<34%,<33%,<33%",options="header",] |
| |======================================================================= |
| |Option |Default |Description |
| |
| |`table` |`CAMEL_AGGREGATION` |Table name |
| |
| |`pkColumns` |`NAME`,`KEY` |Primary key columns |
| |
| |`exchangeIdColumn` |`EXCHANGE_ID` |Exchange Id column |
| |
| |`exchangeColumn` |`EXCHANGE` |Exchange content column |
| |
| |`name` | | Repository name, value used for `NAME` column |
| |
| |`ttl` | | Exchange time to live |
| |
| |`writeConsistencyLevel` | | Consistency level used to insert/delete exchange: `ANY`, `ONE`, `TWO`, |
| `QUORUM`, `LOCAL_QUORUM`… |
| |
| |`readConsistencyLevel` | | Consistency level used to read/check exchange: `ONE`, `TWO`, `QUORUM`, |
| `LOCAL_QUORUM`… |
| |======================================================================= |
