A CTO file is composed of the following elements:

The composer model language, like other programming languages, has data types including String, Double, Integer, and so on.

Let's see some samples of assets, participants, transactions, and events.

IBM Bluemix provides a browser version playground without installation; we can use this tool to do a quick prototype. Here is the link: https://composer-playground.mybluemix.net/.

Connect to basic-sample-network. Playground will generate some default sample assets, participants, transactions, and events for you, for example:

sample.cto
/**
* Sample business network definition.
 */
namespace org.example.basic
asset SampleAsset identified by assetId {
  o String assetId
  --> SampleParticipant owner
  o String value
}
participant SampleParticipant identified by participantId {
  o String participantId
  o String firstName
  o String lastName
}
transaction SampleTransaction {
  --> SampleAsset asset
  o String newValue
}
event SampleEvent {
  --> SampleAsset asset
  o String oldValue
  o String newValue
}

A namespace org.example.basic was defined in sample.cto.SampleAsset and is an example of an Asset class. It defines an asset whose name is followed by an identifying field.o String assetId: a field of the SampleAsset.--> SampleParticipant owner:  field point to SampleParticipant instance.SampleParticipant is an example of a Participant class, the syntax is similar to SampleAsset.SampleTransaction is an example of a transaction class.SampleEvent is an example of an event class.