9.3. 开发 Fuse 在线扩展

要开发自定义步骤，您可以将该操作作为 XML 片段实施，该片段是一个 Camel 路由，具有输入，如 direct。Syndesis 运行时调用此路由的方式与调用任何其他 Camel 路由的方式相同。

例如，假设您想创建一个步骤，该步骤使用可选前缀记录消息的正文。以下 XML 定义了执行此操作的 Camel 路由。

<?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>

在 XML 中开发扩展时，您必须自行创建扩展定义 JSON 文件。对于此 XML 片段，src/main/resources/META-INF/syndesis/syndesis-extension-definition.json 文件可定义操作，如下所示：

{
  "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"
      }
    }
  } ]
  }
}

您可以通过开发一个操作作为 Camel 路由来实现自定义步骤，并支持 RouteBuilder 类。此类路由具有一个输入，如 直接。Syndesis 以其调用任何其他 Camel 路由的方式调用此路由。

要实现示例，它会创建一个步骤，该步骤使用可选前缀记录消息的正文，您可以写类似如下的内容：

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();
    }
}

此 Java 代码使用 Syndesis 注解，这意味着 extension-maven-plugin 可以自动生成操作定义。在扩展定义 JSON 文件中，操作定义类似如下：

{
  "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"
}

您可以通过开发一个操作作为 Camel 路由来实现自定义步骤，并支持 RouteBuilder 类和 Spring Boot。在本例中，Spring Boot 是在 Camel 上下文中注册 RouteBuilder 对象的功能。Syndesis 以其调用任何其他 Camel 路由的方式调用此路由。

要实现示例，它会创建一个步骤，该步骤使用可选前缀记录消息的正文，您可以写类似如下的内容：

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();
             }
        };
    }
}

此 Java 代码使用 Syndesis 注解，这意味着 extension-maven-plugin 可以自动生成操作定义。在扩展定义 JSON 文件中，操作定义类似如下：

{
  "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"
}

使用 Spring Boot 时，您最终在配置类中注册的每个 bean 都可用于 Camel 上下文。详情请参阅 Spring Boot 文档来创建自己的自动配置。

您可以通过开发一个操作作为 Camel bean 处理器来实现自定义步骤。要实现示例，它会创建一个步骤，该步骤使用可选前缀记录消息的正文，您可以写类似如下的内容：

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);
        }
    }
}

此 Java 代码使用 Syndesis 注解，这意味着 extension-maven-plugin 可以自动生成操作定义。在扩展定义 JSON 文件中，操作定义类似如下：

{
  "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"
}

使用 Bean 时，您可能会发现将用户属性注入到 bean 中，而不是从交换标头中检索它们。为此，请实施您要注入的属性的 getter 和 setter 方法。操作实现类似如下：

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);
        }
    }
}

您可以使用 Syndesis Step API 实施自定义步骤。这提供了一种与运行时路由创建交互的方法。您可以使用 ProcessorDefinition 类提供的任何方法，您可以创建更复杂的路由。Syndesis API 的信息位于 http://javadoc.io/doc/io.syndesis.extension/extension-api。

以下是使用 Syndesis Step API 实现分割操作的步骤扩展示例：

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);
    }
}

此 Java 代码使用 Syndesis 注解，这意味着 extension-maven-plugin 可以自动生成操作定义。在扩展定义 JSON 文件中，操作定义类似如下：

{
  "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"
}