# MINA Component

## Overview

The mina: component is a transport for working with Apache MINA

## URI format

    mina:tcp://hostname[:port][?options]
    mina:udp://hostname[:port][?options]
    mina:vm://hostname[:port][?options]

From Apache Camel 1.3 onwards you can specify a codec in the Registry using the codec option. If you are using TCP and no codec is specified then the `textline` flag is used to determine if text line based codec or object serialization should be used instead. By default the object serialization is used.

For UDP, if no codec is specified the default uses a basic `ByteBuffer` based codec.

The VM protocol is used as a direct forwarding mechanism in the same JVM. See the MINA VM-Pipe API documentation for details.

A Mina producer has a default timeout value of 30 seconds, while it waits for a response from the remote server.

In normal use, `camel-mina` only supports marshalling the body content—message headers and exchange properties are not sent. However, the option, transferExchange, does allow you to transfer the exchange itself over the wire. See options below.

You can append query options to the URI in the following format, `?option=value&option=value&...`

## Options

Table 60 lists the Mina uri options:

Table 60. URI options

Option | Default Value | Description
--- | --- | ---
`codec` | `null` | As of 1.3, you can refer to a named `ProtocolCodecFactory` instance in your Registry such as your Spring `ApplicationContext`, which is then used for the marshalling.
`codec` | `null` | Apache Camel 2.0: You must use the `#` notation to look up your codec in the Registry. For example, use `#myCodec` to look up a bean with the `id` value, `myCodec`.
`disconnect` | `false` | Apache Camel 2.3: Whether or not to disconnect(close) from Mina session right after use. Can be used for both consumer and producer.
`textline` | `false` | Only used for TCP. If no codec is specified, you can use this flag in 1.3 or later to indicate a text line based codec; if not specified or the value is `false`, then Object Serialization is assumed over TCP.
`textlineDelimiter` | `DEFAULT` | Apache Camel 1.6.0/2.0 Only used for TCP and if textline=true. Sets the text line delimiter to use. Possible values are: `DEFAULT`, `AUTO`, `WINDOWS`, `UNIX` or `MAC`. If none provided, Apache Camel will use `DEFAULT`. This delimiter is used to mark the end of text.
`sync` | `true` | As of Apache Camel 1.3, you can configure the exchange pattern to be either InOnly (default) or InOut. Setting `sync=true` means a synchronous exchange (InOut), where the client can read the response from MINA (the exchange Out message). The default value has changed in Apache Camel 1.5 to `true`. In older releases, the default value is `false`.
`lazySessionCreation` | See description | As of Apache Camel 1.3, sessions can be lazily created to avoid exceptions, if the remote server is not up and running when the Apache Camel producer is started. From Apache Camel 2.0 onwards, the default is `true`. In Apache Camel 1.x, the default is `false`.
`timeout` | `30000` | As of Apache Camel 1.3, you can configure the timeout that specifies how long to wait for a response from a remote server. The timeout unit is in milliseconds, so 60000 is 60 seconds. The timeout is only used for Mina producer.
`encoding` | JVM Default | As of Apache Camel 1.3, you can configure the encoding (a charset name) to use for the TCP textline codec and the UDP protocol. If not provided, Apache Camel will use the JVM default Charset.
`transferExchange` | `false` | Only used for TCP. As of 1.3, you can transfer the exchange over the wire instead of just the body. The following fields are transferred: In body, Out body, fault body, In headers, Out headers, fault headers, exchange properties, exchange exception. This requires that the objects are serializable. Apache Camel will exclude any non-serializable objects and log it at `WARN` level.
`minaLogger` | `false` | As of Apache Camel 1.3, you can enable the Apache MINA logging filter. Apache MINA uses `slf4j` logging at `INFO` level to log all input and output.
`filters` | `null` | As of 2.0, you can set a list of Mina IoFilters to register. The `filters` value must be one of the following: Apache Camel 2.2: comma-separated list of bean references (e.g. `#filterBean1,#filterBean2`) where each bean must be of type `org.apache.mina.common.IoFilter`. Apache Camel 2.0: a reference to a bean of type `List<org.apache.mina.common.IoFilter>`.
`encoderMaxLineLength` | `-1` | As of Apache Camel 2.1, you can set the textline protocol encoder max line length. By default the default value of Mina itself is used which are `Integer.MAX_VALUE`.
`decoderMaxLineLength` | `-1` | As of Apache Camel 2.1, you can set the textline protocol decoder max line length. By default the default value of Mina itself is used which are 1024.
`allowDefaultCodec` | `true` | The mina component installs a default codec if both, `codec` is `null` and `textline` is `false`. Setting `allowDefaultCodec` to `false` prevents the mina component from installing a default codec as the first element in the filter chain. This is useful in scenarios where another filter must be the first in the filter chain, like the SSL filter.
`disconnectOnNoReply` | `true` | Apache Camel 2.3: If sync is enabled then this option dictates MinaConsumer if it should disconnect where there is no reply to send back.
`noReplyLogLevel` | `WARN` | Apache Camel 2.3: If sync is enabled this option dictates MinaConsumer which logging level to use when logging a there is no reply to send back. Values are: `FATAL, ERROR, INFO, DEBUG, OFF`.

## Default behavior changed

In Apache Camel 2.0 the codec option must use `#` notation for lookup of the codec bean in the Registry. In Apache Camel 2.0 the lazySessionCreation option now defaults to `true`.

In Apache Camel 1.5 the `sync` option has changed its default value from `false` to `true`, as we felt it was confusing for end-users when they used Mina to call remote servers and Apache Camel wouldn't wait for the response.

In Apache Camel 1.4 or later `codec=textline` is no longer supported. Use the `textline=true` option instead.

## Using a custom codec

See the Mina documentation how to write your own codec. To use your custom codec with `camel-mina`, you should register your codec in the Registry; for example, by creating a bean in the Spring XML file. Then use the `codec` option to specify the bean ID of your codec.

## Sample with sync=false

In this sample, Apache Camel exposes a service that listens for TCP connections on port 6200. We use the textline codec. In our route, we create a Mina consumer endpoint that listens on port 6200:

    from("mina:tcp://localhost:6200?textline=true&sync=false").to("mock:result");

As the sample is part of a unit test, we test it by sending some data to it on port 6200.

    MockEndpoint mock = getMockEndpoint("mock:result");
    mock.expectedBodiesReceived("Hello World");

    template.sendBody("mina:tcp://localhost:6200?textline=true&sync=false", "Hello World");

    assertMockEndpointsSatisfied();

## Sample with sync=true

In the next sample, we have a more common use case where we expose a TCP service on port 6201 also use the textline codec. However, this time we want to return a response, so we set the `sync` option to `true` on the consumer.

    from("mina:tcp://localhost:6201?textline=true&sync=true").process(new Processor() {
        public void process(Exchange exchange) throws Exception {
            String body = exchange.getIn().getBody(String.class);
            exchange.getOut().setBody("Bye " + body);
        }
    });

Then we test the sample by sending some data and retrieving the response using the `template.requestBody()` method. As we know the response is a `String`, we cast it to `String` and can assert that the response is, in fact, something we have dynamically set in our processor code logic.

    String response = (String)template.requestBody("mina:tcp://localhost:6201?textline=true&sync=true", "World");
    assertEquals("Bye World", response);

## Sample with XML DSL

XML DSL can, of course, also be used for Mina. In the sample below we expose a TCP server on port 5555:

    <route>
         <from uri="mina:tcp://localhost:5555?textline=true"/>
         <to uri="bean:myTCPOrderHandler"/>
      </route>

In the route above, we expose a TCP server on port 5555 using the textline codec. We let the Spring bean with ID, `myTCPOrderHandler`, handle the request and return a reply. For instance, the handler bean could be implemented as follows:

    public String handleOrder(String payload) {
            ...
            return "Order: OK"
       }

## Configuring Mina endpoints using Spring bean style

Available as of Apache Camel 2.0

Configuration of Mina endpoints is now possible using regular Spring bean style configuration in the Spring DSL.

However, in the underlying Apache Mina toolkit, it is relatively difficult to set up the acceptor and the connector, because you can not use simple setters. To resolve this difficulty, we leverage the `MinaComponent` as a Spring factory bean to configure this for us. If you really need to configure this yourself, there are setters on the `MinaEndpoint` to set these when needed.

The sample below shows the factory approach:

    <!-- Creating mina endpoints is a bit complex so we reuse MinaComponnet
         as a factory bean to create our endpoint, this is the easiest to do -->
    <bean id="myMinaFactory" class="org.apache.camel.component.mina.MinaComponent">
        <!-- we must provide a camel context so we refer to it by its id -->
        <constructor-arg index="0" ref="myCamel"/>
    </bean>

    <!-- This is our mina endpoint configured with Spring, we will use the factory above
         to create it for us. The goal is to invoke the createEndpoint method with the
         mina configuration parameter we defined using the constructor-arg option -->
    <bean id="myMinaEndpoint"
          factory-bean="myMinaFactory"
          factory-method="createEndpoint">
        <!-- and here we can pass it our configuration -->
        <constructor-arg index="0" ref="myMinaConfig"/>
    </bean>

    <!-- this is our mina configuration with plain properties -->
    <bean id="myMinaConfig" class="org.apache.camel.component.mina.MinaConfiguration">
        <property name="protocol" value="tcp"/>
        <property name="host" value="localhost"/>
        <property name="port" value="1234"/>
        <property name="sync" value="false"/>
    </bean>

And then we can refer to our endpoint directly in the route, as follows:

    <route>
        <!-- here we route from or mina endpoint we have defined above -->
        <from ref="myMinaEndpoint"/>
        <to uri="mock:result"/>
    </route>

## Closing Session When Complete

Available as of Apache Camel 1.6.1

When acting as a server you sometimes want to close the session when, for example, a client conversion is finished. To instruct Apache Camel to close the session, you should add a header with the key `CamelMinaCloseSessionWhenComplete` set to a boolean `true` value.

For instance, the example below will close the session after it has written the `bye` message back to the client:

            from("mina:tcp://localhost:8080?sync=true&textline=true").process(new Processor() {
                public void process(Exchange exchange) throws Exception {
                    String body = exchange.getIn().getBody(String.class);
                    exchange.getOut().setBody("Bye " + body);
                    exchange.getOut().setHeader(MinaConsumer.HEADER_CLOSE_SESSION_WHEN_COMPLETE, true);
                }
            });

## Get the IoSession for message

Available since Apache Camel 2.1 You can get the IoSession from the message header with this key `MinaEndpoint.HEADER_MINA_IOSESSION`, and also get the local host address with the key `MinaEndpoint.HEADER_LOCAL_ADDRESS` and remote host address with the key `MinaEndpoint.HEADER_REMOTE_ADDRESS`.

## Configuring Mina filters

Available since Apache Camel 2.0

Filters permit you to use some Mina Filters, such as `SslFilter`. You can also implement some customized filters. Please note that `codec` and `logger` are also implemented as Mina filters of type, `IoFilter`. Any filters you may define are appended to the end of the filter chain; that is, after `codec` and `logger`.

For instance, the example below will send a keep-alive message after 10 seconds of inactivity:

    public class KeepAliveFilter extends IoFilterAdapter {
        @Override
        public void sessionCreated(NextFilter nextFilter, IoSession session)
                throws Exception {
            session.setIdleTime(IdleStatus.BOTH_IDLE, 10);

            nextFilter.sessionCreated(session);
        }

        @Override
        public void sessionIdle(NextFilter nextFilter, IoSession session,
                IdleStatus status) throws Exception {
            session.write("NOOP"); // NOOP is a FTP command for keep alive
            nextFilter.sessionIdle(session, status);
        }
    }

As Apache Camel may use a request-reply scheme, the endpoint as a client would like to drop some message, such as a greeting, when the connection is established. For example, when you connect to an FTP server, you will get a `220` message with a greeting (`220 Welcome to Pure-FTPd`). If you don't drop the message, your request-reply scheme will be broken.

    public class DropGreetingFilter extends IoFilterAdapter {

        @Override
        public void messageReceived(NextFilter nextFilter, IoSession session,
                Object message) throws Exception {
            if (message instanceof String) {
                String ftpMessage = (String) message;
                // "220" is given as greeting. "200 Zzz" is given as a response to "NOOP" (keep alive)
                if (ftpMessage.startsWith("220") || or ftpMessage.startsWith("200 Zzz")) {
                    // Dropping greeting
                    return;
                }
            }
            nextFilter.messageReceived(session, message);
        }
    }

Then, you can configure your endpoint using XML DSL:

    <bean id="myMinaFactory" class="org.apache.camel.component.mina.MinaComponent">
        <constructor-arg index="0" ref="camelContext" />
    </bean>

    <bean id="myMinaEndpoint"
          factory-bean="myMinaFactory"
          factory-method="createEndpoint">
        <constructor-arg index="0" ref="myMinaConfig"/>
    </bean>

    <bean id="myMinaConfig" class="org.apache.camel.component.mina.MinaConfiguration">
        <property name="protocol" value="tcp" />
        <property name="host" value="localhost" />
        <property name="port" value="2121" />
        <property name="sync" value="true" />
        <property name="minaLogger" value="true" />
        <property name="filters" ref="listFilters"/>
    </bean>

    <bean id="listFilters" class="java.util.ArrayList" >
        <constructor-arg>
            <list value-type="org.apache.mina.common.IoFilter">
                <bean class="com.example.KeepAliveFilter"/>
                <bean class="com.example.DropGreetingFilter"/>
            </list>
        </constructor-arg>
    </bean>