Chapter 9. Customizing Fuse Online

After you upload an OpenAPI schema to Fuse Online, a connector to the REST API becomes available. You can select the connector to create a REST API client connection. You can then create a new integration and add the REST API client connection, or you can edit an existing integration to add the REST API client connection.

Fuse Online connectors support OAuth 2.0, HTTP basic authorization, and API keys. If access to the REST API requires Transport Layer Security (TLS) then the API needs to use a valid certificate that is issued by a recognized Certificate Authority (CA).

A REST API that uses OAuth must have an authorization URL that takes a client callback URL as input. After Fuse Online creates the connector and before you use the connector to create a connection, you must visit that URL to register your Fuse Online environment as a client of the REST API. This authorizes your Fuse Online environment to access the REST API. As part of registration, you provide the Fuse Online callback URL. The details for doing this are described in Connecting Fuse Online to Applications and Services, Registering Fuse Online as a REST API client.

For a REST API that uses OAuth, Fuse Online supports only the Authorization Code grant flow for obtaining authorization. In the OpenAPI document that you upload to create the connector, in the OAuth securityDefinitions object, you must set the flow attribute to accessCode, for example:

securityDefinitions:
  OauthSecurity:
    type: oauth2
    flow: accessCode
    authorizationUrl: 'https://oauth.simple.api/authorization'
    tokenUrl: 'https://oauth.simple.api/token'

You must not set flow to implicit, password, or application.

The OpenAPI schema for a REST API client connector cannot have cyclic schema references. For example, a JSON schema that specifies a request or response body cannot reference itself as a whole nor reference any part of itself through any number of intermediate schemas.

Fuse Online cannot create connectors for REST APIs that support the HTTP 2.0 protocol.

When Fuse Online creates a REST API client connector, it maps each resource operation in the OpenAPI document to a connection action. The action name and action description come from documentation in the OpenAPI document.

The more detail that the OpenAPI document provides, the more support Fuse Online can offer when connecting to the API. For example, the API definition is not required to declare data types for requests and responses. Without type declarations, Fuse Online defines the corresponding connection action as typeless. However, in an integration, you cannot add a data mapping step immediately before or immediately after an API connection that performs a typeless action.

One remedy for this is to add more information to the OpenAPI document. Identify the OpenAPI resource operations that will map to the actions you want the API connection to perform. In the OpenAPI document, ensure that there is a YAML or JSON schema that specifies each operation’s request and response types.

After you upload the schema, Fuse Online gives you an opportunity to review and edit it in API Designer, which is a visual editor for designing APIs based on the OpenAPI document. You can add more detail, save your updates, and Fuse Online creates an API client connector that incorporates your updates. After Fuse Online creates the client connector, you can no longer edit the OpenAPI document. To implement a change, you must create a new client connector.

If the OpenAPI document for the API declares support for application/json content type and also application/xml content type then the connector uses the JSON format. If the OpenAPI document specifies consumes or produces parameters that define both application/json and application/xml, then the connector uses the JSON format.

When Fuse Online tries to obtain authorization to access an OAuth2 application, it uses HTTP basic authentication to provide client credentials. If you need to, you can change this default behavior so that Fuse Online passes client credentials to the provider as parameters instead of using HTTP basic authentication. This affects the use of the tokenUrl endpoint that is used to obtain an OAuth access token.

To specify that Fuse Online should pass client credentials as parameters, in the securityDefinitions section of the OpenAPI document, add the x-authorize-using-parameters vendor extension with a setting of true. In the example below, the last line specifies x-authorize-using-parameters:

securityDefinitions:
  concur_oauth2:
    type: 'oauth2'
    flow: 'accessCode'
    authorizationUrl: 'https://example.com/oauth/authorize'
    tokenUrl: 'https://example.com/oauth/token'
    scopes:
      LIST: Access List API
    x-authorize-using-parameters: true

The setting of the x-authorize-using-parameters vendor extension is true or false:

If an access token has an expiration date, then Fuse Online integrations that use that token to connect to an application stop running successfully when the token expires. To obtain a new access token, you must either reconnect to the application or re-register with the application.

If you need to, you can change this default behavior so that Fuse Online automatically requests a new access token in the following situations:

To specify that Fuse Online should automatically try to obtain a new access token in the situations described, in the securityDefinitions section of the OpenAPI document, add the x-refresh-token-retry-statuses vendor extension. The setting of this extension is a comma separated list that specifies HTTP response status codes. When an access token’s expiration date is reached or when Fuse Online receives a message from an OAuth2 provider and the message has one of these response status codes, then Fuse Online automatically tries to obtain a new access token. In the example below, the last line specifies x-refresh-token-retry-statuses:

securityDefinitions:
  concur_oauth2:
    type: 'oauth2'
    flow: 'accessCode'
    authorizationUrl: 'https://example.com/oauth/authorize'
    tokenUrl: 'https://example.com/oauth/token'
    scopes:
      LIST: Access List API
    x-refresh-token-retry-statuses: 401,402,403

Upload an OpenAPI document to enable Fuse Online to create a REST API client connector.

Upload a WSDL file to enable Fuse Online to create a SOAP API client connector.

Both inline and external (WSDL URLs) support multiple schemas with unique namespaces.

When there is an update to an OpenAPI document or WSDL file from which you created an API client connector, and you want your API client connector to use those updates, you must create a new API client connector. You cannot directly update an API client connector. After you create the new API client connector, you use it to create a new connection and then you edit each integration that uses a connection that was created from the out-of-date connector.

You cannot delete a connector when there is a connection that was created from that connector and this connection is being used in an integration. After you delete an API client connector, you cannot use a connection that was created from that connector.

Before you start to develop an extension, become familiar with the tasks that you will need to accomplish.

An extension defines one of the following:

A business integrator shares requirements with a developer who codes the extension. The developer provides a .jar file that contains the extension. The business integrator uploads the .jar file in Fuse Online to make the custom connector, custom step(s), or library resource available for use within Fuse Online.

An extension .jar file that you upload to Fuse Online always contains exactly one extension.

For an example of uploading and using an extension that provides a step that operates on data between connections, see the AMQ to REST API sample integration tutorial.

An extension is a collection of classes, dependencies, and resources that are packaged in a .jar file.

Fuse Online uses Spring Boot to load an extension. Consequently, you must package an extension according to Spring Boot’s executable JAR format. For example, ensure that you use the ZipEntry.STORED() method to save a nested JAR file.

The structure of a .jar file that packages an extension is as follows:

extension.jar
|
+- META-INF
|  |
|  +- syndesis
|     |
|     +- syndesis-extension-definition.json 1
|
+- mycompany
|  |
|  +-project
|    |
|    +-YourClasses.class 2
|
+- lib 3
  |
  +-dependency1.jar
  |
  +-dependency2.jar

Each extension must have a .json file that defines the extension by specifying values for data structures such as name, description, supported actions, and dependencies. For each extension type, the following table indicates whether Maven can generate the extension definition JSON file and which data structures are required.

*While specification of dependencies is not strictly required, in practice, there are almost always dependencies that you need to specify.

Typically, an extension definition file has the following layout:

{
  "schemaVersion": "v1",
  "name": "",
  "description": "",
  "version": "",
  "extensionId": "",
  "extensionType": "",
  "properties": {
  },
  "actions": [
  ],
  "dependencies": [
  ],
}

In connector extensions and step extensions, specify user interface properties in the extension definition JSON file or in Java class files. The settings of these properties define the HTML form controls that Fuse Online displays when a Fuse Online user creates a connection, configures a connection action, or configures a step that is provided by the extension.

You must specify properties for each form control that you want to appear in the extension’s user interface in the Fuse Online console. For each form control, specify some or all properties in any order.

"properties": {
   "hostname": {
     "description": "IRC Server hostname",
     "displayName": "Hostname",
     "labelHint": "Hostname of the IRC server to connect to",
     "order": "1",
     "required": true,
     "secret": false,
     "type": "string"
   },
   "password": {
     "description": "IRC Server password",
     "displayName": "Password",
     "labelHint": "Required if IRC server requires it to join",
     "order": "3",
     "required": false,
     "secret": true,
     "type": "string"
   },
   "port": {
     "description": "IRC Server port",
     "displayName": "Port",
     "labelHint": "Port of the IRC server to connect to",
     "order": "2",
     "required": true,
     "secret": false,
     "tags": [],
     "type": "int"
   }
 },

Based on these property specifications, when a Fuse Online user selects the IRC connector, Fuse Online displays the following dialog. After the user enters values in the two required fields and clicks Next, Fuse Online creates an IRC connection that is configured with the values that the Fuse Online user enters.

In a step extension, the actions object contains a properties object. The properties object defines a set of properties for each form control for configuring the step. The JSON hierarchy looks like this:

"actions": [
   {
      ...

      "propertyDefinitionSteps": [
         {
            ...

            "properties":
               {
                  "control-ONE": {
                     "type": "string",
                     "displayName": "Topic Name",
                     "order": "2",
                     ...,
                     }

                  "control-TWO": {
                     "type": "boolean",
                     "displayName": "Urgent",
                     "order": "3",
                     ...
                     }

                  "control-THREE": {
                     "type": "textarea",
                     "displayName": "Comment",
                     "order": "1",
                     ...,
                     }
 } } ]

The following code shows property definitions for one form control. This code is in the example of developing a Camel route with RouteBuilder:

public class LogAction extends RouteBuilder {
    @ConfigurationProperty(
        name = "prefix",
        description = "The Log body prefix message",
        displayName = "Log Prefix",
        type = "string")

The following code shows property definitions for two controls. This code is from the example of using the Syndesis Step API:

@Action(id = "split", name = "Split", description = "Split your exchange")
public class SplitAction implements Step {

    @ConfigurationProperty(
        name = "language",
        displayName = "Language",
        description = "The language used for the expression")
    private String language;

    @ConfigurationProperty(
        name = "expression",
        displayName = "Expression",
        description = "The expression used to split the exchange
     private String language;

The following table lists the possible input types for Fuse Online form controls. In the set of properties for a control, if you specify a type value that is unknown, Fuse Online displays an input field that accepts one line of text. That is, the default is "type": "text".

The extension-maven-plugin supports extension development by packaging the extension as a valid Spring Boot module. For step extensions that you implement in Java, this plugin can generate the extension definition JSON file.

In your Maven project’s pom.xml file, add the following plugin declaration:

<plugin>
    <groupId>io.syndesis.extension</groupId>
    <artifactId>extension-maven-plugin</artifactId>
    <version>${syndesis.version}</version>
    <executions>
        <execution>
        <goals>
            <goal>generate-metadata</goal>
            <goal>repackage-extension</goal>
        </goals>
        </execution>
    </executions>
</plugin>

The extension-maven-plugin defines the following goals:

For example, suppose your Maven project has the following pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <groupId>com.company</groupId>
  <artifactId>my-extension</artifactId>
  <version>1.0.0</version>
  <name>MyExtension</name>
  <description>A Sample Extension</description>
  <packaging>jar</packaging>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.syndesis.extension</groupId>
        <artifactId>extension-bom</artifactId>
        <version>1.3.10</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>io.syndesis.extension</groupId>
      <artifactId>extension-api</artifactId>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>com.github.lalyos</groupId>
      <artifactId>jfiglet</artifactId>
      <version>0.0.8</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.7.0</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <groupId>io.syndesis.extension</groupId>
        <artifactId>extension-maven-plugin</artifactId>
        <version>1.3.10</version>
        <executions>
          <execution>
            <goals>
              <goal>generate-metadata</goal>
              <goal>repackage-extension</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

Based on this pom.xml file, the generated extension definition JSON file looks like this:

{
  "name": "MyExtension",
  "description": "A Sample Extension",
  "extensionId": "com.company:my-extension",
  "version": "1.0.0",
  "dependencies": [ {
    "type": "MAVEN",
    "id": "io.syndesis.extension:extension-api:jar:1.3.10"
  } ],
  "extensionType": "Libraries",
  "schemaVersion": "v1"
}

The generated archive has this structure and content:

my-extension-1.0.0.jar
|
+- lib
|  |
|  + jfiglet-0.0.8.jar
|
+- META-INF
  |
  +- MANIFEST.MF
     |
     +- syndesis
        |
        +- syndesis-extension-definition.json

A data shape holds data type metadata for use by the data mapper. The data mapper transforms this metadata into internal documents that it uses to display the source and target data fields in the data mapper user interface. In an extension definition JSON file for a connector or for a custom step, each action specification defines an input data shape (inputDataShape) and an output data shape (outputDataShape).

When you are developing an extension, it is important to specify data shape properties that allow the data mapper to correctly handle and display the source and target fields. The following data shape properties affect data mapper behavior:

"outputDataShape": {
     "kind": "java",
     "type": "org.apache.camel.component.telegram.model.IncomingMessage"
},

When the kind property is set to anything other than java then any setting for the type property is ignored.

This name also appears in data type indicators in the Fuse Online flow visualization.

A step extension implements one or more custom steps. Each custom step implements one action for processing integration data between connections. The following examples demonstrate the alternatives for developing step extensions:

Syndesis provides custom Java annotations that you can use in conjunction with the syndesis-extension-plugin. When you implement a step extension or a connector extension in Java, you can specify annotations that enable Maven to add action definitions to the extension definition JSON file. To enable annotation processing, add the following dependency to your Maven project:

<dependency>
  <groupId>io.syndesis.extension</groupId>
  <artifactId>extension-annotation-processor</artifactId>
  <optional>true</optional>
</dependency>

Because Spring Boot is the integration runtime, to inject beans into a Camel context, be sure to follow standard Spring Boot practices. For example, create an auto-configuration class and create beans there. However, the default behavior is that extension code is not subject to package scanning. Consequently, you must create and populate the META-INF/spring.factories file in a step extension.

<?xml version="1.0" encoding="UTF-8"?>
<routes xmlns="http://camel.apache.org/schema/spring"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
      http://camel.apache.org/schema/spring
      http://camel.apache.org/schema/spring/camel-spring.xsd">

  <route id="log-body-with-prefix">
    <from uri="direct:log"/>
    <choice>
      <when>
        <simple>${header.prefix} != ''</simple>
        <log message="${header.prefix} ${body}"/>
      </when>
      <otherwise>
        <log message="Output ${body}"/>
      </otherwise>
    </choice>
  </route>

</routes>

{
  "actionType": "step",
  "id": "log-body-with-prefix",
  "name": "Log body with prefix",
  "description": "A simple body log with a prefix",
  "descriptor": {
    "kind": "ENDPOINT", 1
    "entrypoint": "direct:log", 2
    "resource": "classpath:log-body-action.xml", 3
    "inputDataShape": {
      "kind": "none"
    },
    "outputDataShape": {
      "kind": "none"
    },
  "propertyDefinitionSteps": [ {
    "description": "extension-properties",
    "name": "extension-properties",
    "properties": { 4
      "prefix": {
        "componentProperty": false,
        "deprecated": false,
        "description": "The Log body prefix message",
        "displayName": "Log Prefix",
        "javaType": "String",
        "kind": "parameter",
        "required": false,
        "secret": false,
        "type": "string"
      }
    }
  } ]
  }
}

import org.apache.camel.builder.RouteBuilder;

import io.syndesis.extension.api.annotations.Action;
import io.syndesis.extension.api.annotations.ConfigurationProperty;

@Action( 1
    id = "log-body-with-prefix",
    name = "Log body with prefix",
    description = "A simple body log with a prefix",
    entrypoint = "direct:log")
public class LogAction extends RouteBuilder {
    @ConfigurationProperty( 2
        name = "prefix",
        description = "The Log body prefix message",
        displayName = "Log Prefix",
        type = "string")
    private String prefix;

    @Override
    public void configure() throws Exception {
        from("direct::start") 3
            .choice()
                .when(simple("${header.prefix} != ''"))
                    .log("${header.prefix} ${body}")
                .otherwise()
                    .log("Output ${body}")
            .endChoice();
    }
}

{
  "id": "log-body-with-prefix",
  "name": "Log body with prefix",
  "description": "A simple body log with a prefix",
  "descriptor": {
    "kind": "ENDPOINT", 1
    "entrypoint": "direct:log", 2
    "resource": "class:io.syndesis.extension.log.LogAction", 3
    "inputDataShape": {
      "kind": "none"
    },
    "outputDataShape": {
      "kind": "none"
    },
    "propertyDefinitionSteps": [ {
      "description": "extension-properties",
      "name": "extension-properties",
      "properties": { 4
        "prefix": {
          "componentProperty": false,
          "deprecated": false,
          "description": "The Log body prefix message",
          "displayName": "Log Prefix",
          "javaType": "java.lang.String",
          "kind": "parameter",
          "required": false,
          "secret": false,
          "type": "string",
          "raw": false
        }
      }
    } ]
  },
  "actionType": "step"
}

import io.syndesis.extension.api.annotations.Action;
import io.syndesis.extension.api.annotations.ConfigurationProperty;
import org.apache.camel.builder.RouteBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ActionsConfiguration {

    @Action( 1
        id = "log-body-with-prefix",
        name = "Log body with prefix",
        description = "A simple body log with a prefix",
        entrypoint = "direct:log")
    @ConfigurationProperty( 2
        name = "prefix",
        description = "The Log body prefix message",
        displayName = "Log Prefix",
        type = "string")
    @Bean 3
    public RouteBuilder logBodyWithprefix() {
        return new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                from("direct::start") 4
                    .choice()
                        .when(simple("${header.prefix} != ''"))
                            .log("${header.prefix} ${body}")
                        .otherwise()
                            .log("Output ${body}")
                    .endChoice();
             }
        };
    }
}

{
  "id": "log-body-with-prefix",
  "name": "Log body with prefix",
  "description": "A simple body log with a prefix",
  "descriptor": {
    "kind": "ENDPOINT", 1
    "entrypoint": "direct:log", 2
    "inputDataShape": {
      "kind": "none"
    },
    "outputDataShape": {
      "kind": "none"
    },
    "propertyDefinitionSteps": [ {
      "description": "extension-properties",
      "name": "extension-properties",
      "properties": { 3
        "prefix": {
          "componentProperty": false,
          "deprecated": false,
          "description": "The Log body prefix message",
          "displayName": "Log Prefix",
          "javaType": "java.lang.String",
          "kind": "parameter",
          "required": false,
          "secret": false,
          "type": "string",
          "raw": false
        }
      }
    } ]
  },
  "actionType": "step"
}

import org.apache.camel.Body;
import org.apache.camel.Handler;
import org.apache.camel.Header;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.syndesis.extension.api.annotations.Action;
import io.syndesis.extension.api.annotations.ConfigurationProperty;

@Action(
    id = "log-body-with-prefix",
    name = "Log body with prefix",
    description = "A simple body log with a prefix")
public class LogAction  {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogAction.class);

    @ConfigurationProperty(
        name = "prefix",
        description = "The Log body prefix message",
        displayName = "Log Prefix",
        type = "string")
    private String prefix;

    @Handler 1
    public void process(@Header("prefix") String prefix, @Body Object body) {
        if (prefix == null) {
            LOGGER.info("Output {}", body);
        } else {
            LOGGER.info("{} {}", prefix, body);
        }
    }
}

{
  "id": "log-body-with-prefix",
  "name": "Log body with prefix",
  "description": "A simple body log with a prefix",
  "descriptor": {
    "kind": "BEAN", 1
    "entrypoint": "io.syndesis.extension.log.LogAction::process", 2
    "inputDataShape": {
      "kind": "none"
    },
    "outputDataShape": {
      "kind": "none"
    },
    "propertyDefinitionSteps": [ {
      "description": "extension-properties",
      "name": "extension-properties",
      "properties": {
        "prefix": { 3
          "componentProperty": false,
          "deprecated": false,
          "description": "The Log body prefix message",
          "displayName": "Log Prefix",
          "javaType": "java.lang.String",
          "kind": "parameter",
          "required": false,
          "secret": false,
          "type": "string",
          "raw": false
        }
      }
    } ]
  },
  "actionType": "step"
}

import org.apache.camel.Body;
import org.apache.camel.Handler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.syndesis.extension.api.annotations.Action;
import io.syndesis.extension.api.annotations.ConfigurationProperty;

@Action(
    id = "log-body-with-prefix",
    name = "Log body with prefix",
    description = "A simple body log with a prefix")
public class LogAction  {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogAction.class);

    @ConfigurationProperty(
        name = "prefix",
        description = "The Log body prefix message",
        displayName = "Log Prefix",
        type = "string")
    private String prefix;

    public void setPrefix(String prefix) { 1
        this.prefix = prefix;
    }

    public String getPrefix() { 2
        return prefix;
    }

    @Handler
    public void process(@Body Object body) {
        if (this.prefix == null) {
            LOGGER.info("Output {}", body);
        } else {
            LOGGER.info("{} {}", this.prefix, body);
        }
    }
}

import java.util.Map;
import java.util.Optional;

import io.syndesis.extension.api.Step;
import io.syndesis.extension.api.annotations.Action;
import io.syndesis.extension.api.annotations.ConfigurationProperty;
import org.apache.camel.CamelContext;
import org.apache.camel.model.ProcessorDefinition;
import org.apache.camel.util.ObjectHelper;
import org.apache.camel.Expression;
import org.apache.camel.builder.Builder;
import org.apache.camel.processor.aggregate.AggregationStrategy;
import org.apache.camel.processor.aggregate.UseOriginalAggregationStrategy;
import org.apache.camel.spi.Language;

@Action(id = "split", name = "Split", description = "Split your exchange")
public class SplitAction implements Step {

    @ConfigurationProperty(
        name = "language",
        displayName = "Language",
        description = "The language used for the expression")
    private String language;

    @ConfigurationProperty(
        name = "expression",
        displayName = "Expression",
        description = "The expression used to split the exchange")
    private String expression;

    public String getLanguage() {
        return language;
    }

    public void setLanguage(String language) {
        this.language = language;
    }

    public String getExpression() {
        return expression;
    }

    public void setExpression(String expression) {
        this.expression = expression;
    }

    @Override
    public Optional<ProcessorDefinition> configure(
            CamelContext context,
            ProcessorDefinition route,
            Map<String, Object> parameters) { 1

        String languageName = language;
        String expressionDefinition = expression;

        if (ObjectHelper.isEmpty(languageName) && ObjectHelper.isEmpty(expressionDefinition)) {
            route = route.split(Builder.body());
        } else if (ObjectHelper.isNotEmpty(expressionDefinition)) {

            if (ObjectHelper.isEmpty(languageName)) {
                languageName = "simple";
            }

            final Language splitLanguage = context.resolveLanguage(languageName);
            final Expression splitExpression = splitLanguage.createExpression(expressionDefinition);
            final AggregationStrategy aggreationStrategy = new UseOriginalAggregationStrategy(null, false);

            route = route.split(splitExpression).aggregationStrategy(aggreationStrategy);
        }

        return Optional.of(route);
    }
}

{
  "id": "split",
  "name": "Split",
  "description": "Split your exchange",
  "descriptor": {
    "kind": "STEP", 1
    "entrypoint": "io.syndesis.extension.split.SplitAction", 2
    "inputDataShape": {
      "kind": "none"
    },
    "outputDataShape": {
      "kind": "none"
    },
    "propertyDefinitionSteps": [ {
      "description": "extension-properties",
      "name": "extension-properties",
      "properties": {
        "language": {
          "componentProperty": false,
          "deprecated": false,
          "description": "The language used for the expression",
          "displayName": "Language",
          "javaType": "java.lang.String",
          "kind": "parameter",
          "required": false,
          "secret": false,
          "type": "string",
          "raw": false
        },
        "expression": {
          "componentProperty": false,
          "deprecated": false,
          "description": "The expression used to split the exchange",
          "displayName": "Expression",
          "javaType": "java.lang.String",
          "kind": "parameter",
          "required": false,
          "secret": false,
          "type": "string",
          "raw": false
        }
      }
    } ]
  },
  "tags": [],
  "actionType": "step"
}

If Fuse Online does not provide a connector for the application or service that you want to connect to in an integration, an experienced developer can code an extension that contributes a new connector to Fuse Online. This documentation provides an introduction to developing a connector extension. For details about developing a connector, see Developing Syndesis connectors on the Syndesis community site.

A connector is essentially a proxy for a Camel component. A connector configures the underlying component and creates endpoints according to options that are defined in the extension definition and in user-supplied options that the Fuse Online web interface collects.

The connector extension definition extends the extension definition that is required for step extensions with the following additional data structures:

public class DataSourceCustomizer implements ComponentProxyCustomizer, CamelContextAware {
    private final static Logger LOGGER = LoggerFactory.getLogger(DataSourceCustomizer.class);

    private CamelContext camelContext;

    @Override
    public void setCamelContext(CamelContext camelContext) { 1
        this.camelContext = camelContext;
    }

    @Override
    public CamelContext getCamelContext() { 2
        return this.camelContext;
    }

    @Override
    public void customize(ComponentProxyComponent component, Map<String, Object> options) {
        if (!options.containsKey("dataSource")) {
            if (options.containsKey("user") && options.containsKey("password") && options.containsKey("url")) {
                try {
                    BasicDataSource ds = new BasicDataSource();

                    consumeOption(camelContext, options, "user", String.class, ds::setUsername); 3
                    consumeOption(camelContext, options, "password", String.class, ds::setPassword); 4
                    consumeOption(camelContext, options, "url", String.class, ds::setUrl); 5

                    options.put("dataSource", ds);
                } catch (@SuppressWarnings("PMD.AvoidCatchingGenericException") Exception e) {
                    throw new IllegalArgumentException(e);
                }
            } else {
                LOGGER.debug("Not enough information provided to set-up the DataSource");
            }
        }
    }
}

public class DataSourceCustomizer implements ComponentProxyCustomizer, CamelContextAware {
    private final static Logger LOGGER = LoggerFactory.getLogger(DataSourceCustomizer.class);

    private CamelContext camelContext;
    private String userName;
    private String password;
    private String url;

    @Override
    public void setCamelContext(CamelContext camelContext) { 1
        this.camelContext = camelContext;
    }

    @Override
    public CamelContext getCamelContext() { 2
        return this.camelContext;
    }

    public void setUserName(String userName) { 3
      this.userName = userName;
    }

    public String getUserName() { 4
      return this.userName;
    }

    public void setPassword(String password) { 5
      this.password = password;
    }

    public String getPassword() { 6
      return this.password;
    }

    public void setUrl(String url) { 7
      this.url = url;
    }

    public String getUrl() { 8
      return this.url;
    }

    @Override
    public void customize(ComponentProxyComponent component, Map<String, Object> options) {
        if (!options.containsKey("dataSource")) {
            if (userName != null && password != null && url != null) {
                try {
                    BasicDataSource ds = new BasicDataSource();
                    ds.setUserName(userName);
                    ds.setPassword(password);
                    ds.setUrl(url);

                    options.put("dataSource", ds);
                } catch (@SuppressWarnings("PMD.AvoidCatchingGenericException") Exception e) {
                    throw new IllegalArgumentException(e);
                }
            } else {
                LOGGER.debug("Not enough information provided to set-up the DataSource");
            }
        }
    }
}

public class AWSS3DeleteObjectCustomizer implements ComponentProxyCustomizer {
  	private String filenameKey;

    public void setFilenameKey(String filenameKey) {
      this.filenameKey = filenameKey;
    }

    public String getFilenameKey() {
        return this.filenameKey;
    }

    @Override
    public void customize(ComponentProxyComponent component, Map<String, Object> options) {
      	component.setBeforeProducer(this::beforeProducer);
    }

    public void beforeProducer(final Exchange exchange) throws IOException {
      	exchange.getIn().setHeader(S3Constants.S3_OPERATION, S3Operations.deleteObject);

    	  if (filenameKey != null) {
    		    exchange.getIn().setHeader(S3Constants.KEY, filenameKey);
    	  }
    }
}

A library extension provides a resource that an integration requires at runtime. A library extension does not contribute steps or connectors to Fuse Online.

When you save an integration, you can optionally select one or more imported library extensions that you want to include with the integration.

A library extension does not define any actions. Here is a sample definition for a library extension:

{
  "schemaVersion" : "v1",
  "name" : "Example Library Extension",
  "description" : "Syndesis Extension for adding a runtime library",
  "extensionId" : "io.syndesis.extensions:syndesis-library",
  "version" : "1.0.0",
  "tags" : [ "my-libraries-extension" ],
  "extensionType" : "Libraries"
}

See also the sample library extension here: https://github.com/syndesisio/syndesis-extensions

Other than the lack of actions, the structure of a library extension is the same as the structure of a step or connector extension.

In a Maven project that creates a library extension, to add dependencies that are not available from a Maven repository, specify a system dependency, for example:

<dependency>
    <groupId>com.company</groupId>
    <artifactId>my-library-extension</artifactId>
    <version>1.0</version>
    <scope>system</scope>
    <systemPath>${project.basedir}/lib/my-library-extension.jar</systemPath>
</dependency>

To connect to a SQL database other than Apache Derby, MySQL, and PostgreSQL, you can create a library extension that wraps a JDBC driver for the database you want to connect to. After uploading this extension to Fuse Online, the Fuse Online-provided Database connector can access the driver to validate and create connections to the proprietary database. You do not create a new connector for your particular database.

The Syndesis open source community provides a project for creating an extension that wraps a JDBC driver.

Package one driver only in an extension. This makes it easier to manage the extension as part of managing your particular database. However, it is possible to create a library extension that wraps more than one driver.

The generated .jar file is in the syndesis-library-jdbc-driver/target folder. Import this .jar file as an extension in Fuse Online.

After you import a library extension, when you save an integration in Fuse Online you can optionally select the imported library extension and associate it with the integration.

To make a custom feature available for use in an integration, upload the extension to Fuse Online.

Before you update or delete an extension, you should identify the integrations that use customizations that are provided by that extension.

When a developer updates an extension, you can upload the updated .jar file to implement the updates in your integrations.

It is up to you to know exactly what is required to update each integration that uses a custom connector or a custom step from the updated extension. At the very least, you must republish each integration that uses a customization defined in the updated extension.

In some cases, you might need to edit the integration to change or add configuration details for a customization. You must communicate with the extension developer to understand how to update integrations.

You can delete an extension even if a running integration uses a step that is provided by that extension or uses a connection that was created from a connector that was provided by that extension. After you delete an extension, you cannot start an integration that uses a customization that was provided by that extension.