Chapter 69. CouchDB Component
Available as of Camel version 2.11
The couchdb: component allows you to treat CouchDB instances as a producer or consumer of messages. Using the lightweight LightCouch API, this camel component has the following features:
- As a consumer, monitors couch changesets for inserts, updates and deletes and publishes these as messages into camel routes.
- As a producer, can save, update and from Camel 2.18 delete (by using CouchDbMethod with DELETE value) documents into couch.
- Can support as many endpoints as required, eg for multiple databases across multiple instances.
- Ability to have events trigger for only deletes, only inserts/updates or all (default).
- Headers set for sequenceId, document revision, document id, and HTTP method type.
Maven users will need to add the following dependency to their pom.xml for this component:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-couchdb</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>69.1. URI format
couchdb:http://hostname[:port]/database?[options]
Where hostname is the hostname of the running couchdb instance. Port is optional and if not specified then defaults to 5984.
69.2. Options
The CouchDB component has no options.
The CouchDB endpoint is configured using URI syntax:
couchdb:protocol:hostname:port/database
with the following path and query parameters:
69.2.1. Path Parameters (4 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| protocol | Required The protocol to use for communicating with the database. | String | |
| hostname | Required Hostname of the running couchdb instance | String | |
| port | Port number for the running couchdb instance | 5984 | int |
| database | Required Name of the database to use | String |
69.2.2. Query Parameters (12 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| createDatabase (common) | Creates the database if it does not already exist | false | boolean |
| bridgeErrorHandler (consumer) | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | boolean |
| deletes (consumer) | Document deletes are published as events | true | boolean |
| heartbeat (consumer) | How often to send an empty message to keep socket alive in millis | 30000 | long |
| since (consumer) | Start tracking changes immediately after the given update sequence. The default, null, will start monitoring from the latest sequence. | String | |
| style (consumer) | Specifies how many revisions are returned in the changes array. The default, main_only, will only return the current winning revision; all_docs will return all leaf revisions (including conflicts and deleted former conflicts.) | main_only | String |
| updates (consumer) | Document inserts/updates are published as events | true | boolean |
| exceptionHandler (consumer) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. | ExceptionHandler | |
| exchangePattern (consumer) | Sets the exchange pattern when the consumer creates an exchange. | ExchangePattern | |
| synchronous (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean |
| password (security) | Password for authenticated databases | String | |
| username (security) | Username in case of authenticated databases | String |
69.3. Headers
The following headers are set on exchanges during message transport.
| Property | Value |
|---|---|
|
| the database the message came from |
|
| the couchdb changeset sequence number of the update / delete message |
|
| the couchdb document id |
|
| the couchdb document revision |
|
| the method (delete / update) |
Headers are set by the consumer once the message is received. The producer will also set the headers for downstream processors once the insert/update has taken place. Any headers set prior to the producer are ignored. That means for example, if you set CouchDbId as a header, it will not be used as the id for insertion, the id of the document will still be used.
69.4. Message Body
The component will use the message body as the document to be inserted. If the body is an instance of String, then it will be marshalled into a GSON object before insert. This means that the string must be valid JSON or the insert / update will fail. If the body is an instance of a com.google.gson.JsonElement then it will be inserted as is. Otherwise the producer will throw an exception of unsupported body type.
69.5. Samples
For example if you wish to consume all inserts, updates and deletes from a CouchDB instance running locally, on port 9999 then you could use the following:
from("couchdb:http://localhost:9999").process(someProcessor);If you were only interested in deletes, then you could use the following
from("couchdb:http://localhost:9999?updates=false").process(someProcessor);If you wanted to insert a message as a document, then the body of the exchange is used
from("someProducingEndpoint").process(someProcessor).to("couchdb:http://localhost:9999")