Chapter 9. Developing extensions for Fuse Online integrations

Open the syndesis-extension-definition.json file in the Editor view and write the code that defines the global properties, the actions that the custom connector can perform, and each action’s properties.

Each global property corresponds to a connection configuration parameter in Fuse Online. Each action property corresponds to a Fuse Online connection action configuration parameter. In Fuse Online, when the user selects a custom connector, Fuse Online prompts for values for each connection configuration parameter. A custom connector can be for an application that uses the OAuth protocol. In this case, be sure to specify a global property for the OAuth client ID and another global property for the OAuth client secret. The Fuse Online user will need to specify values for these parameters for a connection created from this connector to work.

Each connector action declares a base Camel component scheme.

The example provided by the New Fuse Online Extension Project wizard uses the telegram Camel component scheme:

{
  "schemaVersion" : "v1",
  "name" : "Example Fuse Online Extension",
  "extensionId" : "fuse.online.extension.example",
  "version" : "1.0.0",
  "actions" : [ {
    "id" : "io.syndesis:telegram-chat-from-action",
    "name" : "Chat Messages",
    "description" : "Receive all messages sent to the chat bot",
    "descriptor" : {
      "componentScheme" : "telegram",
      "inputDataShape" : {
        "kind" : "none"
      },
      "outputDataShape" : {
        "kind" : "java",
        "type" : "org.apache.camel.component.telegram.model.IncomingMessage"
      },
      "configuredProperties" : {
        "type" : "bots"
      }
    },
    "actionType" : "connector",
    "pattern" : "From"
  }, {
    "id" : "io.syndesis:telegram-chat-to-action",
    "name" : "Send a chat Messages",
    "description" : "Send messages to the chat (through the bot).",
    "descriptor" : {
      "componentScheme" : "telegram",
      "inputDataShape" : {
        "kind" : "java",
        "type" : "java.lang.String"
      },
      "outputDataShape" : {
        "kind" : "none"
      },
      "propertyDefinitionSteps" : [ {
        "description" : "Chat id",
        "name" : "chatId",
        "properties" : {
          "chatId" : {
            "kind" : "parameter",
            "displayName" : "Chat Id",
            "type" : "string",
            "javaType" : "String",
            "description" : "The telegram's Chat Id, if not set will use CamelTelegramChatId from the incoming exchange."
          }
        }
      } ],
      "configuredProperties" : {
        "type" : "bots"
      }
    },
    "actionType" : "connector",
    "pattern" : "To"
  } ],
  "properties" : {
    "authorizationToken" : {
      "kind" : "property",
      "displayName" : "Authorization Token",
      "group" : "security",
      "label" : "security",
      "required" : true,
      "type" : "string",
      "javaType" : "java.lang.String",
      "secret" : true,
      "description" : "Telegram Bot Authorization Token"
    }
  }
}

If the custom connector requires additional dependencies, add them to the project’s pom.xml file. The default scope for dependencies is runtime. If you add a dependency that Red Hat ships, define its scope as provided, for example:

<dependencies>
    <dependency>
          <groupId>org.apache.camel</groupId>
          <artifactId>camel-telegram</artifactId>
          <scope>provided</scope>
    </dependency>
      </dependencies>

For a Camel route-based step, in the extension.xml file, create routes that address the purpose of the extension. The entrypoint of each route must match the entrypoint that you define in the syndesis-extension-definition.json file, as described in Step 2.

For a Java bean-based step, edit the java file.

In the syndesis-extension-definition.json file, write the code that defines the actions and their properties. You need a new action for each entrypoint.

Each action that you create corresponds to a custom step in Fuse Online. You can use different types of code for each action. That is, you can use a Camel route for one action and a Java bean for another action.

Each property corresponds to a Fuse Online step configuration parameter. In Fuse Online, when the user selects a custom step, Fuse Online prompts for values for configuration parameters. For example, a custom log step might have a level parameter that indicates how much information to send to the log.

Here is the template for the .json file that contains the extension metadata, including properties that will be filled in by the user in Fuse Online after uploading the extension and adding its custom step to an integration:

{
  "actions": [
    {
      "actionType": "extension",
      "id": "${actionId}",
      "name": "Action Name",
      "description": "Action Description",
      "tags": [
           "xml"
      ],
      "descriptor": {
        "kind": "ENDPOINT|BEAN|STEP",
        "entrypoint": "direct:${actionId}",
        "inputDataShape": {
          "kind": "any"
        },
        "outputDataShape": {
          "kind": "any"
        },
        "propertyDefinitionSteps": []
      }
    }
  ],
  "tags": [
    "feature",
    "experimental"
  ]
}