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Using the AMQ JavaScript Client

Red Hat AMQ 7.6

For Use with AMQ Clients 2.7

Abstract

This guide describes how to install and configure the client, run hands-on examples, and use your client with other AMQ components.

Chapter 1. Overview

AMQ JavaScript is a library for developing messaging applications. It enables you to write JavaScript applications that send and receive AMQP messages.

AMQ JavaScript is part of AMQ Clients, a suite of messaging libraries supporting multiple languages and platforms. For an overview of the clients, see AMQ Clients Overview. For information about this release, see AMQ Clients 2.7 Release Notes.

AMQ JavaScript is based on the Rhea messaging library. For detailed API documentation, see the AMQ JavaScript API reference.

1.1. Key features

  • An event-driven API that simplifies integration with existing applications
  • SSL/TLS for secure communication
  • Flexible SASL authentication
  • Automatic reconnect and failover
  • Seamless conversion between AMQP and language-native data types
  • Access to all the features and capabilities of AMQP 1.0

1.2. Supported standards and protocols

AMQ JavaScript supports the following industry-recognized standards and network protocols:

1.3. Supported configurations

AMQ JavaScript supports the OS and language versions listed below. For more information, see Red Hat AMQ 7 Supported Configurations.

  • Red Hat Enterprise Linux 6 (x86-64 only) and 7 with Node.js 6 and 8 from Software Collections
  • Red Hat Enterprise Linux 8 with Node.js 10
  • Microsoft Windows 10 Pro with Node.js 10
  • Microsoft Windows Server 2012 R2 and 2016 with Node.js 10

AMQ JavaScript is supported in combination with the following AMQ components and versions:

  • All versions of AMQ Broker
  • All versions of AMQ Interconnect
  • All versions of AMQ Online
  • A-MQ 6 versions 6.2.1 and newer

1.4. Terms and concepts

This section introduces the core API entities and describes how they operate together.

Table 1.1. API terms

EntityDescription

Container

A top-level container of connections.

Connection

A channel for communication between two peers on a network. It contains sessions.

Session

A context for sending and receiving messages. It contains senders and receivers.

Sender

A channel for sending messages to a target. It has a target.

Receiver

A channel for receiving messages from a source. It has a source.

Source

A named point of origin for messages.

Target

A named destination for messages.

Message

An application-specific piece of information.

Delivery

A message transfer.

AMQ JavaScript sends and receives messages. Messages are transferred between connected peers over senders and receivers. Senders and receivers are established over sessions. Sessions are established over connections. Connections are established between two uniquely identified containers. Though a connection can have multiple sessions, often this is not needed. The API allows you to ignore sessions unless you require them.

A sending peer creates a sender to send messages. The sender has a target that identifies a queue or topic at the remote peer. A receiving peer creates a receiver to receive messages. The receiver has a source that identifies a queue or topic at the remote peer.

The sending of a message is called a delivery. The message is the content sent, including all metadata such as headers and annotations. The delivery is the protocol exchange associated with the transfer of that content.

To indicate that a delivery is complete, either the sender or the receiver settles it. When the other side learns that it has been settled, it will no longer communicate about that delivery. The receiver can also indicate whether it accepts or rejects the message.

1.5. Document conventions

The sudo command

In this document, sudo is used for any command that requires root privileges. Exercise caution when using sudo because any changes can affect the entire system. For more information about sudo, see Using the sudo command.

File paths

In this document, all file paths are valid for Linux, UNIX, and similar operating systems (for example, /home/andrea). On Microsoft Windows, you must use the equivalent Windows paths (for example, C:\Users\andrea).

Variable text

This document contains code blocks with variables that you must replace with values specific to your environment. Variable text is enclosed in arrow braces and styled as italic monospace. For example, in the following command, replace <project-dir> with the value for your environment:

$ cd <project-dir>

Chapter 2. Installation

This chapter guides you through the steps to install AMQ JavaScript in your environment.

2.1. Prerequisites

  • You must have a subscription to access AMQ release files and repositories.
  • To use AMQ JavaScript, you must install Node.js in your environment. See the Node.js website for more information.
  • AMQ JavaScript depends on the Node.js debug module. See the npm page for installation instructions.

2.2. Installing on Red Hat Enterprise Linux

Procedure

  1. Open a browser and log in to the Red Hat Customer Portal Product Downloads page at access.redhat.com/downloads.
  2. Locate the Red Hat AMQ Clients entry in the INTEGRATION AND AUTOMATION category.
  3. Click Red Hat AMQ Clients. The Software Downloads page opens.
  4. Download the AMQ Clients 2.7.0 JavaScript .zip file.
  5. Use the unzip command to extract the file contents into a directory of your choosing.

    $ unzip amq-clients-2.7.0-javascript.zip

When you extract the contents of the .zip file, a directory named amq-clients-2.7.0-javascript is created. This is the top-level directory of the installation and is referred to as <install-dir> throughout this document.

To configure your environment to use the installed library, add the node_modules directory to the NODE_PATH environment variable.

$ cd amq-clients-2.7.0-javascript
$ export NODE_PATH=$PWD/node_modules:$NODE_PATH

To make this configuration take effect for all new console sessions, set NODE_PATH in your $HOME/.bashrc file.

To test your installation, use the following command. It prints OK to the console if it successfully imports the installed library.

$ node -e 'require("rhea")' && echo OK
OK

2.3. Installing on Microsoft Windows

Procedure

  1. Open a browser and log in to the Red Hat Customer Portal Product Downloads page at access.redhat.com/downloads.
  2. Locate the Red Hat AMQ Clients entry in the INTEGRATION AND AUTOMATION category.
  3. Click Red Hat AMQ Clients. The Software Downloads page opens.
  4. Download the AMQ Clients 2.7.0 JavaScript .zip file.
  5. Extract the file contents into a directory of your choosing by right-clicking on the zip file and selecting Extract All.

When you extract the contents of the .zip file, a directory named amq-clients-2.7.0-javascript is created. This is the top-level directory of the installation and is referred to as <install-dir> throughout this document.

To configure your environment to use the installed library, add the node_modules directory to the NODE_PATH environment variable.

$ cd amq-clients-2.7.0-javascript
$ set NODE_PATH=%cd%\node_modules;%NODE_PATH%

2.4. Preparing the library for use in browsers

AMQ JavaScript can run inside a web browser. To create a browser-compatible version of the library, use the npm run browserify command.

$ cd amq-clients-2.7.0-javascript/node_modules/rhea
$ npm install
$ npm run browserify

This produces a file named rhea.js that can be used in browser-based applications.

Chapter 3. Getting started

This chapter guides you through the steps to set up your environment and run a simple messaging program.

3.1. Prerequisites

  • You must complete the installation procedure for your environment.
  • You must have an AMQP 1.0 message broker listening for connections on interface localhost and port 5672. It must have anonymous access enabled. For more information, see Starting the broker.
  • You must have a queue named examples. For more information, see Creating a queue.

3.2. Running Hello World on Red Hat Enterprise Linux

The Hello World example creates a connection to the broker, sends a message containing a greeting to the examples queue, and receives it back. On success, it prints the received message to the console.

Change to the examples directory and run the helloworld.js example.

$ cd <install-dir>/node_modules/rhea/examples
$ node helloworld.js
Hello World!

3.3. Running Hello World on Microsoft Windows

The Hello World example creates a connection to the broker, sends a message containing a greeting to the examples queue, and receives it back. On success, it prints the received message to the console.

Change to the examples directory and run the helloworld.js example.

> cd <install-dir>/node_modules/rhea/examples
> node helloworld.js
Hello World!

Chapter 4. Examples

This chapter demonstrates the use of AMQ JavaScript through example programs.

For more examples, see the AMQ JavaScript example suite.

4.1. Sending messages

This client program connects to a server using <connection-url>, creates a sender for target <address>, sends a message containing <message-body>, closes the connection, and exits.

Example: Sending messages

"use strict";

var rhea = require("rhea");
var url = require("url");

if (process.argv.length !== 5) {
    console.error("Usage: send.js <connection-url> <address> <message-body>");
    process.exit(1);
}

var conn_url = url.parse(process.argv[2]);
var address = process.argv[3];
var message_body = process.argv[4];

var container = rhea.create_container();

container.on("sender_open", function (event) {
    console.log("SEND: Opened sender for target address '" +
                event.sender.target.address + "'");
});

container.on("sendable", function (event) {
    var message = {
        body: message_body
    };

    event.sender.send(message);

    console.log("SEND: Sent message '" + message.body + "'");

    event.sender.close();
    event.connection.close();
});

var opts = {
    host: conn_url.hostname,
    port: conn_url.port || 5672,
    // To connect with a user and password:
    // username: "<username>",
    // password: "<password>",
};

var conn = container.connect(opts);
conn.open_sender(address);

Running the example

To run the example program, copy it to a local file and invoke it using the node command.

$ node send.js amqp://localhost queue1 hello

4.2. Receiving messages

This client program connects to a server using <connection-url>, creates a receiver for source <address>, and receives messages until it is terminated or it reaches <count> messages.

Example: Receiving messages

"use strict";

var rhea = require("rhea");
var url = require("url");

if (process.argv.length !== 4 && process.argv.length !== 5) {
    console.error("Usage: receive.js <connection-url> <address> [<message-count>]");
    process.exit(1);
}

var conn_url = url.parse(process.argv[2]);
var address = process.argv[3];
var desired = 0;
var received = 0;

if (process.argv.length === 5) {
    desired = parseInt(process.argv[4]);
}

var container = rhea.create_container();

container.on("receiver_open", function (event) {
    console.log("RECEIVE: Opened receiver for source address '" +
                event.receiver.source.address + "'");
});

container.on("message", function (event) {
    var message = event.message;

    console.log("RECEIVE: Received message '" + message.body + "'");

    received++;

    if (received == desired) {
        event.receiver.close();
        event.connection.close();
    }
});

var opts = {
    host: conn_url.hostname,
    port: conn_url.port || 5672,
    // To connect with a user and password:
    // username: "<username>",
    // password: "<password>",
};

var conn = container.connect(opts);
conn.open_receiver(address);

Running the example

To run the example program, copy it to a local file and invoke it using the python command.

$ node receive.js amqp://localhost queue1

Chapter 5. Using the API

For more information, see the AMQ JavaScript API reference and AMQ JavaScript example suite.

5.1. Handling messaging events

AMQ JavaScript is an asynchronous event-driven API. To define how the application handles events, the user registers event-handling functions on the container object. These functions are then called as network activity or timers trigger new events.

Example: Handling messaging events

var rhea = require("rhea");
var container = rhea.create_container();

container.on("sendable", function (event) {
    console.log("A message can be sent");
});

container.on("message", function (event) {
    console.log("A message is received");
});

These are only a few common-case events. The full set is documented in the {ClientAmqpJavaScriptApiLink}.

5.3. Creating a container

The container is the top-level API object. It is the entry point for creating connections, and it is responsible for running the main event loop. It is often constructed with a global event handler.

Example: Creating a container

var rhea = require("rhea");
var container = rhea.create_container();

5.4. Setting the container identity

Each container instance has a unique identity called the container ID. When AMQ JavaScript makes a network connection, it sends the container ID to the remote peer. To set the container ID, pass the id option to the create_container method.

Example: Setting the container identity

var container = rhea.create_container({id: "job-processor-3"});

If the user does not set the ID, the library will generate a UUID when the container is constucted.

Chapter 6. Network connections

6.1. Creating outgoing connections

To connect to a remote server, pass connection options containing the host and port to the container.connect() method.

Example: Creating outgoing connections

container.on("connection_open", function (event) {
    console.log("Connection " + event.connection + " is open");
});

var opts = {
    host: "example.com",
    port: 5672
};

container.connect(opts);

The default host is localhost. The default port is 5672.

See the Chapter 7, Security section for information about creating secure connections.

6.2. Configuring reconnect

Reconnect allows a client to recover from lost connections. It is used to ensure that the components in a distributed system reestablish communication after temporary network or component failures.

AMQ JavaScript enables reconnect by default. If a connection attempt fails, the client will try again after a brief delay. The delay increases exponentially for each new attempt, up to a default maximum of 60 seconds.

To disable reconnect, set the reconnect connection option to false.

Example: Disabling reconnect

var opts = {
    host: "example.com",
    reconnect: false
};

container.connect(opts);

To control the delays between connection attempts, set the initial_reconnect_delay and max_reconnect_delay connection options. Delay options are specified in milliseconds.

To limit the number of reconnect attempts, set the reconnect_limit option.

Example: Configuring reconnect

var opts = {
    host: "example.com",
    initial_reconnect_delay: 100,
    max_reconnect_delay: 60 * 1000,
    reconnect_limit: 10
};

container.connect(opts);

6.3. Configuring failover

AMQ JavaScript allows you to configure alternate connection endpoints programatically.

To specify multiple connection endpoints, define a function that returns new connection options and pass the function in the connection_details option. The function is called once for each connection attempt.

Example: Configuring failover

var hosts = ["alpha.example.com", "beta.example.com"];
var index = -1;

function failover_fn() {
    index += 1;

    if (index == hosts.length) index = 0;

    return {host: hosts[index].hostname};
};

var opts = {
    host: "example.com",
    connection_details: failover_fn
}

container.connect(opts);

This example implements repeating round-robin failover for a list of hosts. You can use this interface to implement your own failover behavior.

6.4. Accepting incoming connections

AMQ JavaScript can accept inbound network connections, enabling you to build custom messaging servers.

To start listening for connections, use the container.listen() method with options containing the local host address and port to listen on.

Example: Accepting incoming connections

container.on("connection_open", function (event) {
    console.log("New incoming connection " + event.connection);
});

var opts = {
    host: "0.0.0.0",
    port: 5672
};

container.listen(opts);

The special IP address 0.0.0.0 listens on all available IPv4 interfaces. To listen on all IPv6 interfaces, use [::0].

For more information, see the server receive.js example.

Chapter 7. Security

7.1. Securing connections with SSL/TLS

AMQ JavaScript uses SSL/TLS to encrypt communication between clients and servers.

To connect to a remote server with SSL/TLS, set the transport connection option to tls.

Example: Enabling SSL/TLS

var opts = {
    host: "example.com",
    port: 5671,
    transport: "tls"
};

container.connect(opts);

Note

By default, the client will reject connections to servers with untrusted certificates. This is sometimes the case in test environments. To bypass certificate authorization, set the rejectUnauthorized connection option to false. Be aware that this compromises the security of your connection.

7.2. Connecting with a user and password

AMQ JavaScript can authenticate connections with a user and password.

To specify the credentials used for authentication, set the username and password connection options.

Example: Connecting with a user and password

var opts = {
    host: "example.com",
    username: "alice",
    password: "secret"
};

container.connect(opts);

7.3. Configuring SASL authentication

AMQ JavaScript uses the SASL protocol to perform authentication. SASL can use a number of different authentication mechanisms. When two network peers connect, they exchange their allowed mechanisms, and the strongest mechanism allowed by both is selected.

AMQ JavaScript enables SASL mechanisms based on the presence of user and password information. If the user and password are both specified, PLAIN is used. If only a user is specified, ANONYMOUS is used. If neither is specified, SASL is disabled.

Chapter 8. Senders and receivers

The client uses sender and receiver links to represent channels for delivering messages. Senders and receivers are unidirectional, with a source end for the message origin, and a target end for the message destination.

Source and targets often point to queues or topics on a message broker. Sources are also used to represent subscriptions.

8.1. Creating queues and topics on demand

Some message servers support on-demand creation of queues and topics. When a sender or receiver is attached, the server uses the sender target address or the receiver source address to create a queue or topic with a name matching the address.

The message server typically defaults to creating either a queue (for one-to-one message delivery) or a topic (for one-to-many message delivery). The client can indicate which it prefers by setting the queue or topic capability on the source or target.

To select queue or topic semantics, follow these steps:

  1. Configure your message server for automatic creation of queues and topics. This is often the default configuration.
  2. Set either the queue or topic capability on your sender target or receiver source, as in the examples below.

Example: Sending to a queue created on demand

var conn = container.connect({host: "example.com"});

var sender_opts = {
    target: {
        address: "jobs",
        capabilities: ["queue"]
    }
}

conn.open_sender(sender_opts);

Example: Receiving from a topic created on demand

var conn = container.connect({host: "example.com"});

var receiver_opts = {
    source: {
        address: "notifications",
        capabilities: ["topic"]
    }
}

conn.open_receiver(receiver_opts);

For more details, see the following examples:

8.2. Creating durable subscriptions

A durable subscription is a piece of state on the remote server representing a message receiver. Ordinarily, message receivers are discarded when a client closes. However, because durable subscriptions are persistent, clients can detach from them and then re-attach later. Any messages received while detached are available when the client re-attaches.

Durable subscriptions are uniquely identified by combining the client container ID and receiver name to form a subscription ID. These must have stable values so that the subscription can be recovered.

  1. Set the connection container ID to a stable value, such as client-1:

    var container = rhea.create_container({id: "client-1"});
  2. Create a receiver with a stable name, such as sub-1, and configure the receiver source for durability by setting the durable and expiry_policy properties:

    var receiver_opts = {
        source: {
            address: "notifications",
            name: "sub-1",
            durable: 2,
            expiry_policy: "never"
        }
    }
    
    conn.open_receiver(receiver_opts);

To detach from a subscription, use the receiver.detach() method. To terminate the subscription, use the receiver.close() method.

For more information, see the durable-subscribe.js example.

8.3. Creating shared subscriptions

A shared subscription is a piece of state on the remote server representing one or more message receivers. Because it is shared, multiple clients can consume from the same stream of messages.

The client configures a shared subscription by setting the shared capability on the receiver source.

Shared subscriptions are uniquely identified by combining the client container ID and receiver name to form a subscription ID. These must have stable values so that multiple client processes can locate the same subscription. If the global capability is set in addition to shared, the receiver name alone is used to identify the subscription.

To create a durable subscription, follow these steps:

  1. Set the connection container ID to a stable value, such as client-1:

    var container = rhea.create_container({id: "client-1"});
  2. Create a receiver with a stable name, such as sub-1, and configure the receiver source for sharing by setting the shared capability:

    var receiver_opts = {
        source: {
            address: "notifications",
            name: "sub-1",
            capabilities: ["shared"]
        }
    }
    
    conn.open_receiver(receiver_opts);

To detach from a subscription, use the receiver.detach() method. To terminate the subscription, use the receiver.close() method.

For more information, see the shared-subscribe.js example.

Chapter 9. File-based configuration

AMQ JavaScript can read the configuration options used to establish connections from a local file named connect.json. This enables you to configure connections in your application at the time of deployment.

The library attempts to read the file when the application calls the container connect method without supplying any connection options.

9.1. File locations

If set, AMQ JavaScript uses the value of the MESSAGING_CONNECT_FILE environment variable to locate the configuration file.

If MESSAGING_CONNECT_FILE is not set, AMQ JavaScript searches for a file named connect.json at the following locations and in the order shown. It stops at the first match it encounters.

On Linux:

  1. $PWD/connect.json, where $PWD is the current working directory of the client process
  2. $HOME/.config/messaging/connect.json, where $HOME is the current user home directory
  3. /etc/messaging/connect.json

On Windows:

  1. %cd%/connect.json, where %cd% is the current working directory of the client process

If no connect.json file is found, the library uses default values for all options.

9.2. The file format

The connect.json file contains JSON data, with additional support for JavaScript comments.

All of the configuration attributes are optional or have default values, so a simple example need only provide a few details:

Example: A simple connect.json file

{
    "host": "example.com",
    "user": "alice",
    "password": "secret"
}

SASL and SSL/TLS options are nested under "sasl" and "tls" namespaces:

Example: A connect.json file with SASL and SSL/TLS options

{
    "host": "example.com",
    "user": "ortega",
    "password": "secret",
    "sasl": {
        "mechanisms": ["SCRAM-SHA-1", "SCRAM-SHA-256"]
    },
    "tls": {
        "cert": "/home/ortega/cert.pem",
        "key": "/home/ortega/key.pem"
    }
}

9.3. Configuration options

The option keys containing a dot (.) represent attributes nested inside a namespace.

Table 9.1. Configuration options in connect.json

KeyValue typeDefault valueDescription

scheme

string

"amqps"

"amqp" for cleartext or "amqps" for SSL/TLS

host

string

"localhost"

The hostname or IP address of the remote host

port

string or number

"amqps"

A port number or port literal

user

string

None

The user name for authentication

password

string

None

The password for authentication

sasl.mechanisms

list or string

None (system defaults)

A JSON list of enabled SASL mechanisms. A bare string represents one mechanism. If none are specified, the client uses the default mechanisms provided by the system.

sasl.allow_insecure

boolean

false

Enable mechanisms that send cleartext passwords

tls.cert

string

None

The filename or database ID of the client certificate

tls.key

string

None

The filename or database ID of the private key for the client certificate

tls.ca

string

None

The filename, directory, or database ID of the CA certificate

tls.verify

boolean

true

Require a valid server certificate with a matching hostname

Chapter 10. Interoperability

This chapter discusses how to use AMQ JavaScript in combination with other AMQ components. For an overview of the compatibility of AMQ components, see the product introduction.

10.1. Interoperating with other AMQP clients

AMQP messages are composed using the AMQP type system. This common format is one of the reasons AMQP clients in different languages are able to interoperate with each other.

When sending messages, AMQ JavaScript automatically converts language-native types to AMQP-encoded data. When receiving messages, the reverse conversion takes place.

Note

More information about AMQP types is available at the interactive type reference maintained by the Apache Qpid project.

Table 10.1. AMQP types

AMQP typeDescription

null

An empty value

boolean

A true or false value

char

A single Unicode character

string

A sequence of Unicode characters

binary

A sequence of bytes

byte

A signed 8-bit integer

short

A signed 16-bit integer

int

A signed 32-bit integer

long

A signed 64-bit integer

ubyte

An unsigned 8-bit integer

ushort

An unsigned 16-bit integer

uint

An unsigned 32-bit integer

ulong

An unsigned 64-bit integer

float

A 32-bit floating point number

double

A 64-bit floating point number

array

A sequence of values of a single type

list

A sequence of values of variable type

map

A mapping from distinct keys to values

uuid

A universally unique identifier

symbol

A 7-bit ASCII string from a constrained domain

timestamp

An absolute point in time

JavaScript has fewer native types than AMQP can encode. To send messages containing specific AMQP types, use the wrap_ functions from the rhea/types.js module.

Table 10.2. AMQ JavaScript types before encoding and after decoding

AMQP typeAMQ JavaScript type before encodingAMQ JavaScript type after decoding

null

null

null

boolean

boolean

boolean

char

wrap_char(number)

number

string

string

string

binary

wrap_binary(string)

string

byte

wrap_byte(number)

number

short

wrap_short(number)

number

int

wrap_int(number)

number

long

wrap_long(number)

number

ubyte

wrap_ubyte(number)

number

ushort

wrap_ushort(number)

number

uint

wrap_uint(number)

number

ulong

wrap_ulong(number)

number

float

wrap_float(number)

number

double

wrap_double(number)

number

array

wrap_array(Array, code)

Array

list

wrap_list(Array)

Array

map

wrap_map(object)

object

uuid

wrap_uuid(number)

number

symbol

wrap_symbol(string)

string

timestamp

wrap_timestamp(number)

number

Table 10.3. AMQ JavaScript and other AMQ client types (1 of 2)

AMQ JavaScript type before encodingAMQ C++ typeAMQ .NET type

null

nullptr

null

boolean

bool

System.Boolean

wrap_char(number)

wchar_t

System.Char

string

std::string

System.String

wrap_binary(string)

proton::binary

System.Byte[]

wrap_byte(number)

int8_t

System.SByte

wrap_short(number)

int16_t

System.Int16

wrap_int(number)

int32_t

System.Int32

wrap_long(number)

int64_t

System.Int64

wrap_ubyte(number)

uint8_t

System.Byte

wrap_ushort(number)

uint16_t

System.UInt16

wrap_uint(number)

uint32_t

System.UInt32

wrap_ulong(number)

uint64_t

System.UInt64

wrap_float(number)

float

System.Single

wrap_double(number)

double

System.Double

wrap_array(Array, code)

-

-

wrap_list(Array)

std::vector

Amqp.List

wrap_map(object)

std::map

Amqp.Map

wrap_uuid(number)

proton::uuid

System.Guid

wrap_symbol(string)

proton::symbol

Amqp.Symbol

wrap_timestamp(number)

proton::timestamp

System.DateTime

Table 10.4. AMQ JavaScript and other AMQ client types (2 of 2)

AMQ JavaScript type before encodingAMQ Python typeAMQ Ruby type

null

None

nil

boolean

bool

true, false

wrap_char(number)

unicode

String

string

unicode

String

wrap_binary(string)

bytes

String

wrap_byte(number)

int

Integer

wrap_short(number)

int

Integer

wrap_int(number)

long

Integer

wrap_long(number)

long

Integer

wrap_ubyte(number)

long

Integer

wrap_ushort(number)

long

Integer

wrap_uint(number)

long

Integer

wrap_ulong(number)

long

Integer

wrap_float(number)

float

Float

wrap_double(number)

float

Float

wrap_array(Array, code)

proton.Array

Array

wrap_list(Array)

list

Array

wrap_map(object)

dict

Hash

wrap_uuid(number)

-

-

wrap_symbol(string)

str

Symbol

wrap_timestamp(number)

long

Time

10.2. Interoperating with AMQ JMS

AMQP defines a standard mapping to the JMS messaging model. This section discusses the various aspects of that mapping. For more information, see the AMQ JMS Interoperability chapter.

JMS message types

AMQ JavaScript provides a single message type whose body type can vary. By contrast, the JMS API uses different message types to represent different kinds of data. The table below indicates how particular body types map to JMS message types.

For more explicit control of the resulting JMS message type, you can set the x-opt-jms-msg-type message annotation. See the AMQ JMS Interoperability chapter for more information.

Table 10.5. AMQ JavaScript and JMS message types

AMQ JavaScript body typeJMS message type

string

TextMessage

null

TextMessage

wrap_binary(string)

BytesMessage

Any other type

ObjectMessage

10.3. Connecting to AMQ Broker

AMQ Broker is designed to interoperate with AMQP 1.0 clients. Check the following to ensure the broker is configured for AMQP messaging:

  • Port 5672 in the network firewall is open.
  • The AMQ Broker AMQP acceptor is enabled. See Default acceptor settings.
  • The necessary addresses are configured on the broker. See Addresses, Queues, and Topics.
  • The broker is configured to permit access from your client, and the client is configured to send the required credentials. See Broker Security.

10.4. Connecting to AMQ Interconnect

AMQ Interconnect works with any AMQP 1.0 client. Check the following to ensure the components are configured correctly:

  • Port 5672 in the network firewall is open.
  • The router is configured to permit access from your client, and the client is configured to send the required credentials. See Securing network connections.

Appendix A. Using your subscription

AMQ is provided through a software subscription. To manage your subscriptions, access your account at the Red Hat Customer Portal.

A.1. Accessing your account

Procedure

  1. Go to access.redhat.com.
  2. If you do not already have an account, create one.
  3. Log in to your account.

A.2. Activating a subscription

Procedure

  1. Go to access.redhat.com.
  2. Navigate to My Subscriptions.
  3. Navigate to Activate a subscription and enter your 16-digit activation number.

A.3. Downloading release files

To access .zip, .tar.gz, and other release files, use the customer portal to find the relevant files for download. If you are using RPM packages or the Red Hat Maven repository, this step is not required.

Procedure

  1. Open a browser and log in to the Red Hat Customer Portal Product Downloads page at access.redhat.com/downloads.
  2. Locate the Red Hat AMQ entries in the INTEGRATION AND AUTOMATION category.
  3. Select the desired AMQ product. The Software Downloads page opens.
  4. Click the Download link for your component.

A.4. Registering your system for packages

To install RPM packages on Red Hat Enterprise Linux, your system must be registered. If you are using downloaded release files, this step is not required.

Procedure

  1. Go to access.redhat.com.
  2. Navigate to Registration Assistant.
  3. Select your OS version and continue to the next page.
  4. Use the listed command in your system terminal to complete the registration.

For more information, see How to Register and Subscribe a System to the Red Hat Customer Portal.

Appendix B. Using AMQ Broker with the examples

The AMQ JavaScript examples require a running message broker with a queue named examples. Use the procedures below to install and start the broker and define the queue.

B.1. Installing the broker

Follow the instructions in Getting Started with AMQ Broker to install the broker and create a broker instance. Enable anonymous access.

The following procedures refer to the location of the broker instance as <broker-instance-dir>.

B.2. Starting the broker

Procedure

  1. Use the artemis run command to start the broker.

    $ <broker-instance-dir>/bin/artemis run
  2. Check the console output for any critical errors logged during startup. The broker logs Server is now live when it is ready.

    $ example-broker/bin/artemis run
               __  __  ____    ____            _
         /\   |  \/  |/ __ \  |  _ \          | |
        /  \  | \  / | |  | | | |_) |_ __ ___ | | _____ _ __
       / /\ \ | |\/| | |  | | |  _ <| '__/ _ \| |/ / _ \ '__|
      / ____ \| |  | | |__| | | |_) | | | (_) |   <  __/ |
     /_/    \_\_|  |_|\___\_\ |____/|_|  \___/|_|\_\___|_|
    
     Red Hat AMQ <version>
    
    2020-06-03 12:12:11,807 INFO  [org.apache.activemq.artemis.integration.bootstrap] AMQ101000: Starting ActiveMQ Artemis Server
    ...
    2020-06-03 12:12:12,336 INFO  [org.apache.activemq.artemis.core.server] AMQ221007: Server is now live
    ...

B.3. Creating a queue

In a new terminal, use the artemis queue command to create a queue named examples.

$ <broker-instance-dir>/bin/artemis queue create --name examples --address examples --auto-create-address --anycast

You are prompted to answer a series of yes or no questions. Answer N for no to all of them.

Once the queue is created, the broker is ready for use with the example programs.

B.4. Stopping the broker

When you are done running the examples, use the artemis stop command to stop the broker.

$ <broker-instance-dir>/bin/artemis stop

Revised on 2020-06-16 17:51:58 UTC

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