AMQP Class

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An easy-to-use AMQP 1.0 client implementation.

Syntax

ipworksiot.AMQP

Remarks

The AMQP class provides an easy-to-use AMQP 1.0 client implementation. The class supports both plaintext and TLS-enabled connections over TCP.

Connecting

The class implements all three layers of the AMQP 1.0 transport protocol, so the first step is to initiate the overall connection. Set the ContainerId property and call the ConnectTo method, passing it the server's hostname and port number.

Once connected, the next step is to create at least one session, which can be accomplished by using the CreateSession method. The class allows creating any number of sessions, up to the limit specified by the MaxSessionCount configuration setting.

Connecting and Creating a Session amqp1.ContainerId = "testClient"; amqp1.ConnectTo("amqp.test-server.com", 5672); amqp1.CreateSession("TestSession");

After creating a session, the next step is to create one or more links (which are created in the context of a session) so that messages can be sent and/or received. Links are unidirectional, so each one has a sender on one end and a receiver on the other.

The class can function both as a sender node (by opening sender links) and as a receiver node (by opening receiver links). But keep in mind that, since the class is implemented as an AMQP 1.0 client, it must be the one to open links (said another way, the class cannot accept any link requests made by other peers).

As with sessions, the class allows creating any number of links for each session, up to the limit specified by the MaxLinkCountPerSession configuration setting.

Creating Sender Links

The LinkReadyToSend event will fire when the newly created sender link is ready to send messages.

Creating a Sender Link amqp1.OnLinkReadyToSend += (s, e) => { Console.WriteLine("Link '" + e.LinkName + "' is ready to send messages!"); }; amqp1.CreateSenderLink("TestSession", "TestSenderLink", "TestTarget");

Sending Messages

At minimum, the Value and ValueType fields must be set. All other fields are optional, though specifying a unique value for MessageId is recommended. (If the GenerateMessageId configuration setting is enabled, the class will generate one automatically when the message is sent.)

Once the Message property's fields have be assigned as desired, call the SendMessage method, passing it the name of an existing sender link on which the message should be sent.

The MessageOut event will be fired when the message has been sent (and acknowledged, if Settled was set to false). The MessageOutcome event may also fire, if necessary, once the receiver reports the outcome of the message.

Refer to SendMessage, MessageOut, and MessageOutcome for more information.

Sending a Message amqp1.OnMessageOut += (s, e) => { Console.WriteLine("Message with Id '" + e.MessageId + "' has been sent on link '" + e.LinkName + "'."); }; amqp1.Message.MessageId = "TestMessageId"; amqp1.Message.Value = "Hello, world!"; amqp1.Message.ValueType = AMQPValueTypes.mvtString; amqp1.SendMessage("TestSenderLink");

The ResetMessage method can be used to reset the Message property's fields to their default values.

Sending Composite AMQP Data

The class supports sending composite AMQP data in a message through the use of JSON with a well-defined schema. Refer to the SendMessage method's documentation for more information and examples.

Creating Receiver Links

The ReceiveMode property controls which receive mode newly-created receiver links will use; refer to its documentation for more information.

After ensuring that ReceiveMode is set as desired, call CreateReceiverLink, passing it the name of an existing session, a unique name for the link, and (if necessary in your environment) the name of a source for the sender to route the link creation request to.

Creating a Receiver Link // Creating an automatic receiver link. amqp1.ReceiveMode = AmqpReceiveModes.rmAutomatic; amqp1.CreateReceiverLink("TestSession", "TestAutoReceiverLink", "TestSource1"); // Creating a retrieve-based receiver link. amqp1.ReceiveMode = AmqpReceiveModes.rmRetrieve; amqp1.CreateReceiverLink("TestSession", "TestRetrieveReceiverLink", "TestSource2");

Receiving Messages

For receiver links created in retrieve-based mode, the class will attempt to "retrieve" a message each time the RetrieveMessage method is called (optionally timing out after a time, if RetrieveTimeout is non-zero). When calling RetrieveMessage, pass it the name of a retrieve-based receiver link.

Regardless of whether a messages is received automatically or retrieved, any incoming message will cause the class to fire the MessageIn event and update the ReceivedMessage property's fields.

When the MessageIn event fires, its State event parameter can be used to specify the outcome of the message, which the class will then transmit back to the sender (as well as self-report by firing the MessageOutcome event). Refer to MessageIn for more information.

Receiving a Message // For automatic receiver links, only the event handler is necessary. amqp1.OnMessageIn += (s, e) => { Console.WriteLine("Message with Id '" + e.MessageId + "' has been received on link '" + e.LinkName + "'. Value:"); Console.WriteLine(amqp1.ReceivedMessage.Value); // The message state is already set to the "Accepted" outcome by default, but we'll set it again // for the purpose of this example. e.State = 0; // 0 = Accepted. }; // For retrieve-based links, it's also necessary to call RetrieveMessage(). It is recommended that the // RetrieveTimeout property be set to a non-zero value (60 seconds is the default) so that the retrieve // request will eventually time out if the sender doesn't have any messages available to deliver. amqp1.RetrieveTimeout = 60; amqp1.RetrieveMessage("TestRetrieveReceiverLink");

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.

AuthScheme Property (AMQP Class)

The authentication scheme to use when connecting.

Syntax

public int getAuthScheme();
public void setAuthScheme(int authScheme);

Enumerated values:
  public final static int smNone = 0;
  public final static int smSASLAnonymous = 1;
  public final static int smSASLPlain = 2;
  public final static int smSASLExternal = 3;

Default Value

2

Remarks

This property controls what authentication scheme the class should use when connecting to the remote host.

Valid values are:

• smNone (0)
• smSASLAnonymous (1)
• smSASLPlain (2) - Default
• smSASLExternal (3)

This property is not available at design time.

Connected Property (AMQP Class)

This property indicates whether the class is connected.

Syntax

public boolean isConnected();

Default Value

False

Remarks

This property indicates whether the class is connected to the remote host. Use the Connect and Disconnect methods to manage the connection.

This property is read-only and not available at design time.

ContainerId Property (AMQP Class)

The container Id the class should advertise when connecting.

Syntax

public String getContainerId();
public void setContainerId(String containerId);

Default Value

""

Remarks

This property specifies the container Id that the class should advertise when it's connecting to the remote host.

In AMQP, the top-level organizational grouping is called a "container", and each container can contain zero or more "nodes", which are the actual entities which send and receive messages over links.

Since this class handles multiple layers of the AMQP transport protocol (the overall connection, the sessions in that connection, and the links attached to those sessions), it must be given a unique container Id.

Note: The container Id cannot be changed while connected.

This property is not available at design time.

Firewall Property (AMQP Class)

A set of properties related to firewall access.

Syntax

public Firewall getFirewall();
public void setFirewall(Firewall firewall);

Remarks

This is a Firewall-type property, which contains fields describing the firewall through which the class will attempt to connect.

IdleTimeout Property (AMQP Class)

The maximum period of inactivity the class will allow before disconnecting.

Syntax

public int getIdleTimeout();
public void setIdleTimeout(int idleTimeout);

Default Value

0

Remarks

This property controls how long, in seconds, the class will allow the connection to sit idle before it disconnects from the remote host.

This property may be set to 0 to prevent the class from ever closing the connection due to inactivity.

Note: The idle timeout cannot be changed while connected.

This property is not available at design time.

IncomingMessages Property (AMQP Class)

Collection of incoming messages which have not been fully settled.

Syntax

public AMQPMessageList getIncomingMessages();

Remarks

This collection property holds a list of AMQPMessage items, one for each incoming message that has not been fully settled by the class (and, potentially, the remote host).

Refer to ReceiveMode for more information.

This property is read-only and not available at design time.

Links Property (AMQP Class)

Collection of active links.

Syntax

public AMQPLinkList getLinks();

Remarks

This collection property holds a list of AMQPLink items, one for each currently active link.

Refer to CreateReceiverLink, CreateSenderLink, and CloseLink for more information.

This property is read-only and not available at design time.

LocalHost Property (AMQP Class)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

public String getLocalHost();
public void setLocalHost(String localHost);

Default Value

""

Remarks

This property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalPort Property (AMQP Class)

The TCP port in the local host where the class binds.

Syntax

public int getLocalPort();
public void setLocalPort(int localPort);

Default Value

0

Remarks

This property must be set before a connection is attempted. It instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting this property to 0 (default) enables the system to choose an open port at random. The chosen port will be returned by the LocalPort property after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this property when a connection is active will generate an error.

This property is useful when trying to connect to services that require a trusted port on the client side.

Message Property (AMQP Class)

The message to send.

Syntax

public AMQPMessage getMessage();
public void setMessage(AMQPMessage message);

Remarks

This property holds an AMQPMessage object whose fields are used to construct a message to send when SendMessage is called.

Refer to SendMessage for more information. amqp.Message.ValueType = AMQPValueTypes.mvtString; amqp.Message.Value = "Hello World!"; amqp.SendMessage("SenderLinkName");

This property is not available at design time.

OutgoingMessages Property (AMQP Class)

Collection of outgoing messages which have not been fully settled.

Syntax

public AMQPMessageList getOutgoingMessages();

Remarks

This collection property holds a list of AMQPMessage items, one for each outgoing message that has not been fully settled by the class (and, potentially, the remote host).

Refer to SendMessage for more information.

This property is read-only and not available at design time.

Password Property (AMQP Class)

A password to use for SASL authentication.

Syntax

public String getPassword();
public void setPassword(String password);

Default Value

""

Remarks

This property contains a password to use for SASL authentication.

This property is not available at design time.

ReadyToSend Property (AMQP Class)

Indicates whether the class is ready to send data.

Syntax

public boolean isReadyToSend();

Default Value

False

Remarks

This property indicates that the underlying TCP/IP subsystem is ready to accept data. This is True after connecting to the remote host, and will become False if a call to SendMessage fails due to a WOULDBLOCK condition.

Once data can be sent again, the ReadyToSend event will fire and this property will be True.

If a WOULDBLOCK error occurs while sending a message the class will automatically complete the transmission when sending is possible. No action needs to be taken to re-send the message. ReadyToSend will fire after the class completes any partially sent messages.

This property is read-only and not available at design time.

ReceivedMessage Property (AMQP Class)

The last message received.

Syntax

public AMQPMessage getReceivedMessage();

Remarks

This property is an AMQPMessage object which represents the last message received by the class. It is set by the class automatically each time the MessageIn event fires.

Refer to MessageIn for more information.

This property is read-only and not available at design time.

ReceiveMode Property (AMQP Class)

Controls what mode new receiver links are created with.

Syntax

public int getReceiveMode();
public void setReceiveMode(int receiveMode);

Enumerated values:
  public final static int rmAutomatic = 0;
  public final static int rmRetrieve = 1;

Default Value

0

Remarks

This property controls which receive mode newly created receiver links should use to receive messages from the sender. Valid values are:

• rmAutomatic (0 - default)
• rmRetrieve (1)

Receiving Messages Automatically

In this mode, receiver links will be created with the amount of credit, and the credit threshold, specified by the DefaultCredit and DefaultCreditThreshold configuration settings. Anytime the link's credit reaches the credit threshold, the class will automatically set it back to its initial value.

Retrieving Messages On-Demand

In this mode, receiver links will be created with no credit (regardless of what DefaultCredit is set to). When RetrieveMessage is called, the class will supply the sender with a single credit and then block until a message is received (if the RetrieveTimeout property is set to zero).

If RetrieveTimeout is non-zero, the class will only block for the specified number of seconds; once that time expires, it will instruct the sender to consume the credit. If the sender chooses to consume the credit by incrementing the value of the AMQPLink.DeliveryCount field rather than by sending a message, then the class will throw an error indicating a timeout.

Refer to RetrieveMessage and RetrieveTimeout for more information. amqp.ReceiveMode = AmqpReceiveModes.rmRetrieve; amqp.CreateReceiverLink("SessionID", "ReceiverLinkName", "SomeTarget");

This property is not available at design time.

RemoteHost Property (AMQP Class)

This property includes the address of the remote host. Domain names are resolved to IP addresses.

Syntax

public String getRemoteHost();
public void setRemoteHost(String remoteHost);

Default Value

""

Remarks

This property specifies the IP address (IP number in dotted internet format) or the domain name of the remote host. It is set before a connection is attempted and cannot be changed once a connection is established.

If this property is set to a domain name, a DNS request is initiated, and upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, an error is returned.

If the class is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

Example. Connecting:

TCPClientControl.RemoteHost = "MyHostNameOrIP" TCPClientControl.RemotePort = 777 TCPClientControl.Connected = true

RemotePort Property (AMQP Class)

The port of the AQMP server (default is 5672). The default port for SSL is 5671.

Syntax

public int getRemotePort();
public void setRemotePort(int remotePort);

Default Value

5672

Remarks

This property specifies a service port on the remote host to connect to.

A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

This property is not available at design time.

RetrieveTimeout Property (AMQP Class)

How long the class should wait for a message to be received after RetrieveMessage is called.

Syntax

public int getRetrieveTimeout();
public void setRetrieveTimeout(int retrieveTimeout);

Default Value

60

Remarks

This property controls how long, in seconds, the class will wait for a message to be received after RetrieveMessage is called before timing out the request. If set to zero, the class will wait indefinitely.

Refer to RetrieveMessage for more information.

This property is not available at design time.

Sessions Property (AMQP Class)

Collection of active sessions.

Syntax

public AMQPSessionList getSessions();

Remarks

This collection property holds a list of AMQPSession items, one for each currently active session.

Refer to CreateSession and CloseSession for more information.

This property is read-only and not available at design time.

SSLAcceptServerCert Property (AMQP Class)

Instructs the class to unconditionally accept the server certificate that matches the supplied certificate.

Syntax

public Certificate getSSLAcceptServerCert();
public void setSSLAcceptServerCert(Certificate SSLAcceptServerCert);

Remarks

If it finds any issues with the certificate presented by the server, the class will normally terminate the connection with an error.

You may override this behavior by supplying a value for SSLAcceptServerCert. If the certificate supplied in SSLAcceptServerCert is the same as the certificate presented by the server, then the server certificate is accepted unconditionally, and the connection will continue normally.

Note: This functionality is provided only for cases in which you otherwise know that you are communicating with the right server. If used improperly, this property may create a security breach. Use it at your own risk.

SSLCert Property (AMQP Class)

The certificate to be used during Secure Sockets Layer (SSL) negotiation.

Syntax

public Certificate getSSLCert();
public void setSSLCert(Certificate SSLCert);

Remarks

This property includes the digital certificate that the class will use during SSL negotiation. Set this property to a valid certificate before starting SSL negotiation. To set a certificate, you may set the Encoded field to the encoded certificate. To select a certificate, use the store and subject fields.

SSLEnabled Property (AMQP Class)

This property indicates whether Transport Layer Security/Secure Sockets Layer (TLS/SSL) is enabled.

Syntax

public boolean isSSLEnabled();
public void setSSLEnabled(boolean SSLEnabled);

Default Value

False

Remarks

This property specifies whether TLS/SSL is enabled in the class. When False (default), the class operates in plaintext mode. When True, TLS/SSL is enabled.

TLS/SSL may also be enabled by setting SSLStartMode. Setting SSLStartMode will automatically update this property value.

If the default port (5672) is selected when SSLEnabled is set to true, the port will automatically be changed to the default port for AMQP with SSL (5671). Likewise, if port 5671 is selected when SSLEnabled is set to false, the port will automatically be changed to the default port. If the port has been set to any value other than the default values, it will remain the same when the value of SSLEnabled changes.

This property is not available at design time.

SSLProvider Property (AMQP Class)

The Secure Sockets Layer/Transport Layer Security (SSL/TLS) implementation to use.

Syntax

public int getSSLProvider();
public void setSSLProvider(int SSLProvider);

Enumerated values:
  public final static int sslpAutomatic = 0;
  public final static int sslpPlatform = 1;
  public final static int sslpInternal = 2;

Default Value

0

Remarks

This property specifies the SSL/TLS implementation to use. In most cases the default value of 0 (Automatic) is recommended and should not be changed. When set to 0 (Automatic), the class will select whether to use the platform implementation or the internal implementation depending on the operating system as well as the TLS version being used.

Possible values are as follows:

In most cases using the default value (Automatic) is recommended. The class will select a provider depending on the current platform.

When Automatic is selected, the platform implementation is used by default. When TLS 1.3 is enabled via SSLEnabledProtocols, the internal implementation is used.

SSLServerCert Property (AMQP Class)

The server certificate for the last established connection.

Syntax

public Certificate getSSLServerCert();

Remarks

This property contains the server certificate for the last established connection.

SSLServerCert is reset every time a new connection is attempted.

This property is read-only.

Timeout Property (AMQP Class)

This property includes the timeout for the class.

Syntax

public int getTimeout();
public void setTimeout(int timeout);

Default Value

60

Remarks

This property defines the timeout when sending data. When SSLEnabled is False a value of 0 means data will be sent asynchronously and a positive value means data is sent synchronously. When SSLEnabled is True all data is sent synchronously regardless of the Timeout value. Please see the notes below for details.

Plaintext

If the Timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.

If Timeout is set to a positive value, data is sent in a blocking manner and the class will wait for the operation to complete before returning control. The class will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

SSL

If the Timeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the class will wait for the operation to complete before returning control.

Additional Notes

The class will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.

If Timeout expires, and the operation is not yet complete, the class throws an exception.

Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

User Property (AMQP Class)

A username to use for SASL authentication.

Syntax

public String getUser();
public void setUser(String user);

Default Value

""

Remarks

This property contains a username to use for SASL authentication.

This property is not available at design time.

CloseLink Method (AMQP Class)

Closes a link.

Syntax

public void closeLink(String name);

Remarks

This method closes the link named Name and removes it from the Links collection. If no link with the given Name exists, an error will be thrown.

CloseSession Method (AMQP Class)

Closes a session.

Syntax

public void closeSession(String name);

Remarks

This method closes the session named Name and removes it from the Sessions collection. If no session with the given Name exists, an error will be thrown.

Any links open on the specified session when this method is called will be automatically closed and removed from the Links collection.

Config Method (AMQP Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Connect Method (AMQP Class)

This method connects to a remote host.

Syntax

public void connect();

Remarks

This method connects to the remote host specified by RemoteHost and RemotePort. For instance: component.RemoteHost = "MyHostNameOrIP"; component.RemotePort = 7777; component.Connect();

ConnectTo Method (AMQP Class)

This method connects to a remote host.

Syntax

public void connectTo(String host, int port);

Remarks

This method connects to the remote host specified by the Host and Port parameters. For instance: component.ConnectTo("MyHostNameOrIP", 777)

CreateReceiverLink Method (AMQP Class)

Creates a new receiver link with the given name on the specified session.

Syntax

public void createReceiverLink(String sessionName, String name, String source);

Remarks

This method creates a new receiver link with the given Name on the session specified by SessionName and adds it to the Links collection. If a link (sender or receiver) with the given Name already exists, or if no session with the given SessionName exists, an error will be thrown.

Source may be set to specify the address of the node at the remote host which should act as the sender. This may not be necessary in all environments, in which case an empty string will suffice.

Receiver links can operate in one of two receive modes: automatic, where the class will work to ensure that messages are received as soon as they are available; and retrieve-based, where the class will only "retrieve" a new message when explicitly instructed to.

The ReceiveMode property controls which receive mode newly-created receiver links will use; refer to its documentation for more information.

AMQP 1.0's transport protocol has three layers: an overarching connection between two containers, the sessions opened on that connection, and the links (between the containers' nodes) attached to those sessions. amqp.ReceiveMode = AmqpReceiveModes.rmRetrieve; amqp.CreateReceiverLink("SessionID", "ReceiverLinkName", "SomeTarget");

CreateSenderLink Method (AMQP Class)

Creates a new sender link with the given name on the specified session.

Syntax

public void createSenderLink(String sessionName, String name, String target);

Remarks

This method creates a new sender link with the given Name on the session specified by SessionName and adds it to the Links collection. If a link (sender or receiver) with the given Name already exists, or if no session with the given SessionName exists, an error will be thrown.

Target may be set to specify the address of the node at the remote host which should act as the receiver. This may not be necessary in all environments, in which case an empty string will suffice.

The LinkReadyToSend event will fire when a newly-created sender link is ready to send.

Sender links are created using the Mixed settle mode by default, letting the value of the Message.Settled field control whether each message is settled (the default) or unsettled when it is sent. The DefaultSenderSettleMode configuration setting can be used to control the settle mode that new sender links are created with. Refer to SendMessage for more information on message settlement in general.

AMQP 1.0's transport protocol has three layers: an overarching connection between two containers, the sessions opened on that connection, and the links (between the containers' nodes) attached to those sessions.

CreateSession Method (AMQP Class)

Creates a new session with the given name.

Syntax

public void createSession(String name);

Remarks

This method creates a new session with the given Name and adds it to the Sessions collection. If a session with the given Name already exists, an error will be thrown.

AMQP 1.0's transport protocol has three layers: an overarching connection between two containers, the sessions opened on that connection, and the links (between the containers' nodes) attached to those sessions.

Disconnect Method (AMQP Class)

This method disconnects from the remote host.

Syntax

public void disconnect();

Remarks

This method disconnects from the remote host. Calling this method is equivalent to setting the Connected property to False.

DoEvents Method (AMQP Class)

This method processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

Interrupt Method (AMQP Class)

This method interrupts the current action.

Syntax

public void interrupt();

Remarks

This method interrupts the current action. If you use SendFile to upload a file, the class will run synchronously until the upload is completed. This method will allow you to stop the file from uploading without disconnecting from the host.

Reset Method (AMQP Class)

This method will reset the class.

Syntax

public void reset();

Remarks

This method will reset the class's properties to their default values.

ResetMessage Method (AMQP Class)

Resets the Message properties.

Syntax

public void resetMessage();

Remarks

This method resets the Message property.

RetrieveMessage Method (AMQP Class)

Retrieves a single message over the specified receiver link.

Syntax

public void retrieveMessage(String linkName);

Remarks

When RetrieveMessage is called, the class will supply the sender with a single credit and then block until a message is received (if the RetrieveTimeout property is set to zero).

If RetrieveTimeout is non-zero, the class will only block for the specified number of seconds; once that time expires, it will instruct the sender to consume the credit. If the sender chooses to consume the credit by incrementing the value of the AMQPLink.DeliveryCount field rather than by sending a message, then the class will throw an error indicating a timeout.

LinkName specifies the receiver link which should retrieve a message; if there is no such link, if the specified link is not a receiver link, or if the specified receiver link is not operating in rmSyncGet (1) mode, an error is thrown.

Refer to ReceiveMode and RetrieveTimeout for more information.

SendMessage Method (AMQP Class)

Sends a message on the specified link.

Syntax

public void sendMessage(String linkName);

Remarks

This method sends a message on the link specified by LinkName.

The Message property holds an AMQPMessage object whose fields are used to construct the message to send. At minimum, specify a Value and a ValueType. amqp.Message.ValueType = AMQPValueTypes.mvtString; amqp.Message.Value = "Hello World!"; amqp.SendMessage("SenderLinkName");

Message Settlement

• Settled - All messages will be sent in a settled state.
• Unsettled - All messages will be sent in an unsettled state.
• Mixed - Messages may be sent either settled or unsettled.

• First - Incoming messages will be settled immediately (and the sender will be notified that the message has been received, if the message was not already settled when sent).
• Second - Incoming messages will be settled after the sender has settled them (and the sender will be notified when a message has been received, if the message was not already settled when sent).

Together, the sender's and receiver's settle modes can form the following delivery guarantees:

It is important to note that the message settlement system has a big caveat: Whichever party opens the link can only request that the other end use a specific settle mode. For example, if the class opens a sender link, it has control over the sender settle mode it will use, but it can only request that the remote host use a specific receiver settle mode; so if the class requests that the receiver use Second, the receiver can instead choose to use First (if, e.g., it doesn't support Second).

The class currently only ever requests (and itself only supports) the First receiver settle mode since no other AMQP implementations appear to support the Second receiver settle mode at this time.

The class requests (and uses) the Mixed sender settle mode by default, but supports all of the sender settle modes (the default can be changed using the DefaultSenderSettleMode configuration setting). Sender links created with the Mixed sender use the value of the Message.Settled field to determine whether to send messages as settled or unsettled.

Sending Composite Data

Composite Data JSON Schema

The class uses JSON with a well-defined schema to represent composite data. The composite data JSON schema consists almost entirely of "type-value" objects, which hold an AMQP typename and a value. The syntax for a type-value object is:

{
  "type": "typename",
  "value": value
}

The following table provides a complete list of valid typenames, and describes how the associated values should be represented:

Arrays, Lists, and Maps

The AMQP data model defines three data structure types: array, list, and map. In the composite data JSON schema, their value is always a JSON array that contains zero or more type-value objects. Data structure types may be nested arbitrarily to any depth.

Note that the array and map data structures each have restrictions on their content:

• The elements in an array must all be of the same type (e.g., their typenames must match).
• The elements in a map represent keys (odd-numbered elements) and values (even-numbered elements). There must be an even number of elements (or none), and the values of the "key" elements must be unique.

{
  "type": "map",
  "value": [
    { "type": "symbol", "value": "key1" },
    { "type": "string", "value": "value1" },
    { "type": "symbol", "value": "key2" },
    { "type": "int", "value": 100 }
  ]
}

Described Types

As noted above, AMQP's data model includes the idea of "described types", which is simply a normal AMQP type annotated by a descriptor. The descriptor defines what the data it is associated with represents as a whole.

In the composite data JSON schema, a described type object is just a normal type-value object with an extra "descriptor" property on it (and the "descriptor" property's value is itself a normal type-value object). The syntax for a described type object is:

{
  "descriptor": { "type": "typename", "value": value },
  "type": "typename",
  "value": value
}

Described type objects can be used anywhere that normal type-value objects can be, except as the value of the "descriptor" property for another described type object, which must be a normal type-value object.

Note that, according to the AMQP specification, the type of the descriptor itself ulong or symbol, but the class does not enforce this.

Abbreviated Value Syntax

For brevity, it is possible to abbreviate both normal type-value objects and described type objects when their value type is null, boolean, or string.

For normal type-value objects, instead of using the standard syntax (e.g., { "type": "string", "value": "Hello, world!" }), just use the raw value itself (e.g., "Hello, world!"). Keep in mind that the abbreviated value must still be valid JSON; notably, strings must still be surrounded by quotes (e.g., "value", not value).

The abbreviated syntax for a described type object is a bit different; the "descriptor" property still needs to be associated with the value using a JSON object. To abbreviate a described type object, just exclude the "type" property, like so:

{
  "descriptor": { "type": "typename", "value": value },
  "value": value
}

The abbreviated value syntax can be used anywhere that an unabbreviated type-value object or described type object would normally be used.

The class defaults to using the abbreviated syntax when returning composite data JSON. This can be configured using the SimplifiedJSONFormat configuration setting.

Composite Data JSON Example

{
  "descriptor": { "type": "symbol", "value": "nsoftware:compositeDataExample" },
  "type": "list",
  "value": [
    "Shorthand string value",
    null,
    true,
    { "type": "uuid", "value": "12345678-0000-1000-8000-00805F9B34FB" },
    {
      "type": "array",
      "value": [
        { "type": "uint", "value": 23 },
        { "type": "uint", "value": 52 },
        { "type": "uint", "value": 153325 }
      ]
    },
    {
      "type": "map",
      "value": [
        { "type": "symbol", "value": "name" },
        "Freezer temperature",
        { "type": "symbol", "value": "unit" },
        "Fahrenheit",
        { "type": "symbol", "value": "value" },
        { "type": "int", "value": -2 }
      ]
    },
    {
      "descriptor": { "type": "symbol", "value": "nsoftware:utf8Bytes" },
      "type": "binary",
      "value": "48656C6C6F2C20776F726C6421"
    }
  ]
}

Connected Event (AMQP Class)

Fired immediately after a connection completes (or fails).

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void connected(AMQPConnectedEvent e) {}
  ...
}

public class AMQPConnectedEvent {
  public int statusCode;
  public String description;
}

Remarks

If the connection is made normally, StatusCode is 0 and Description is "OK".

If the connection fails, StatusCode has the error code returned by the Transmission Control Protocol (TCP)/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Please refer to the Error Codes section for more information.

ConnectionStatus Event (AMQP Class)

Fired to indicate changes in the connection state.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void connectionStatus(AMQPConnectionStatusEvent e) {}
  ...
}

public class AMQPConnectionStatusEvent {
  public String connectionEvent;
  public int statusCode;
  public String description;
}

Remarks

This event is fired when the connection state changes: for example, completion of a firewall or proxy connection or completion of a security handshake.

The ConnectionEvent parameter indicates the type of connection event. Values may include the following:

Disconnected Event (AMQP Class)

Fired when a connection is closed.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void disconnected(AMQPDisconnectedEvent e) {}
  ...
}

public class AMQPDisconnectedEvent {
  public int statusCode;
  public String description;
}

Remarks

If the connection is broken normally, StatusCode is 0 and Description is "OK".

If the connection is broken for any other reason, StatusCode has the error code returned by the Transmission Control Protocol (TCP/IP) subsystem. Description contains a description of this code. The value of StatusCode is equal to the value of the TCP/IP error.

Please refer to the Error Codes section for more information.

Error Event (AMQP Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void error(AMQPErrorEvent e) {}
  ...
}

public class AMQPErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

LinkReadyToSend Event (AMQP Class)

Fires when a sender link is ready to send messages.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void linkReadyToSend(AMQPLinkReadyToSendEvent e) {}
  ...
}

public class AMQPLinkReadyToSendEvent {
  public String linkName;
  public int linkIndex;
}

Remarks

This event fires when a sender link is ready to send messages.

LinkName is the name of the sender link.

LinkIndex is the index of the sender link in the Links collection.

Log Event (AMQP Class)

Fires once for each log message.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void log(AMQPLogEvent e) {}
  ...
}

public class AMQPLogEvent {
  public int logLevel;
  public String message;
  public String logType;
}

Remarks

This event fires once for each log message generated by the class. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of the Message. Possible values are:

LogType identifies the type of log entry. Possible values are:

• Info: General information about the class.
• Session: Session status messages.
• Frame: Frame status messages.

MessageIn Event (AMQP Class)

Fires when the class receives a message.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void messageIn(AMQPMessageInEvent e) {}
  ...
}

public class AMQPMessageInEvent {
  public String sessionName;
  public int sessionIndex;
  public String linkName;
  public int linkIndex;
  public String messageId;
  public int state; //read-write
}

Remarks

This event fires whenever the class receives a message. The message itself is automatically stored as an AMQPMessage object in the ReceivedMessage property.

Specifying a Delivery Outcome

• 0: Accepted - The message has been processed successfully.
• 1: Rejected - The message failed to process successfully. Includes an error describing why.
• 2: Released - The message has not been (and will not be) processed.
• 3: Modified - Same as "Released", but with additional metadata for the sender.

When State is set to Rejected (1), the class will include error metadata when it informs the sender of the outcome. Set the RejectErrorCondition and RejectErrorDescription configuration settings before the event handler finishes to specify this error information.

When State is set to Modified (3), the class can include additional metadata when it informs the sender of the outcome. Set zero or more of the ModifiedDeliveryFailed, ModifiedMessageAnnotations, and ModifiedUndeliverableHere configuration settings before the event handler finishes to specify this additional metadata.

Other Parameters

SessionIndex is the index of the session in the Sessions collection property.

LinkName is the name of the link the message was transmitted on.

LinkIndex is the index of the link in the Links collection property.

MessageId is the Id of the message; it may be empty if a message Id was not set.

MessageOut Event (AMQP Class)

Fires when the class sends a message.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void messageOut(AMQPMessageOutEvent e) {}
  ...
}

public class AMQPMessageOutEvent {
  public String sessionName;
  public int sessionIndex;
  public String linkName;
  public int linkIndex;
  public String messageId;
}

Remarks

This event fires whenever the class sends a message.

SessionName is the name of the session the message was transmitted on.

SessionIndex is the index of the session in the Sessions collection property.

LinkName is the name of the link the message was transmitted on.

LinkIndex is the index of the link in the Links collection property.

MessageId is the Id of the message; it may be empty if a message Id was not set.

MessageOutcome Event (AMQP Class)

Fires when a message's outcome is available.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void messageOutcome(AMQPMessageOutcomeEvent e) {}
  ...
}

public class AMQPMessageOutcomeEvent {
  public String sessionName;
  public int sessionIndex;
  public String linkName;
  public int linkIndex;
  public String messageId;
  public int direction;
  public int state;
}

Remarks

This event fires whenever the outcome for a message (incoming or outgoing) is available.

SessionName is the name of the session the message was transmitted on.

SessionIndex is the index of the session in the Sessions collection property.

LinkName is the name of the link the message was transmitted on.

LinkIndex is the index of the link in the Links collection property.

MessageId is the Id of the message; it may be empty if a message Id was not set.

Direction indicates whether this outcome was sent (0) or received (1).

State indicates the actual message outcome. Possible values are:

• 0: Accepted - The message has been processed successfully.
• 1: Rejected - The message failed to process successfully. Includes an error describing why.
• 2: Released - The message has not been (and will not be) processed.
• 3: Modified - Same as "Released", but with additional metadata for the sender.

When State is Rejected (1), the RejectErrorCondition and RejectErrorDescription configuration settings can be queried before the event handler finishes to retrieve the error information.

When State is Modified (3), the ModifiedDeliveryFailed, ModifiedMessageAnnotations, and ModifiedUndeliverableHere configuration settings can be queried before the event handler finishes to retrieve the additional metadata.

SSLServerAuthentication Event (AMQP Class)

Fired after the server presents its certificate to the client.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void SSLServerAuthentication(AMQPSSLServerAuthenticationEvent e) {}
  ...
}

public class AMQPSSLServerAuthenticationEvent {
  public byte[] certEncoded;
  public String certSubject;
  public String certIssuer;
  public String status;
  public boolean accept; //read-write
}

Remarks

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

SSLStatus Event (AMQP Class)

Fired when secure connection progress messages are available.

Syntax

public class DefaultAMQPEventListener implements AMQPEventListener {
  ...
  public void SSLStatus(AMQPSSLStatusEvent e) {}
  ...
}

public class AMQPSSLStatusEvent {
  public String message;
}

Remarks

The event is fired for informational and logging purposes only. This event tracks the progress of the connection.

AMQPLink Type

Represents an AMQP link.

Remarks

This type represents an AMQP link.

Fields

Constructors

public AMQPLink();

AMQPMessage Type

Represents an AMQP message.

Remarks

This type represents an AMQP message.

Fields

Constructors

public AMQPMessage();

AMQPSession Type

Represents an AMQP session.

Remarks

This type represents an AMQP session.

Fields

Constructors

public AMQPSession();

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

Firewall Type

The firewall the class will connect through.

Remarks

When connecting through a firewall, this type is used to specify different properties of the firewall, such as the firewall Host and the FirewallType.

Fields

Constructors

public Firewall();

Config Settings (AMQP Class)

AMQP Config Settings

{
  "type": "map",
  "value": [
    { "type": "symbol", "value": "key1" },
    { "type": "string", "value": "test" },
    { "type": "symbol", "value": "key2" },
    { "type": "int", "value": 100 }
  ]
}

TCPClient Config Settings

SSL Config Settings

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

Socket Config Settings

Base Config Settings

Trappable Errors (AMQP Class)

AMQP Errors

TCPClient Errors

SSL Errors

TCP/IP Errors