STOMP Control

Properties   Methods   Events   Config Settings   Errors  

A simple but powerful STOMP client implementation.

Syntax

STOMP

Remarks

The STOMP control provides an easy-to-use STOMP client implementation that supports STOMP versions 1.1 and 1.2. The control supports both plaintext and TLS-enabled connections over TCP.

Connecting

Connecting to a STOMP server is easy; in the simplest case just call the ConnectTo method, passing the server's hostname and port number.

When connecting to a STOMP server, the control sends information from the following properties, if populated:

• IncomingHeartbeat
• OutgoingHeartbeat
• User
• Password

In addition to the above properties, the following configuration settings can be set before connecting (though in most cases this is not necessary):

• SupportedVersions: Controls which STOMP versions the control advertises support for.
• VirtualHost: Controls the virtual host to connect to. If left empty (default), the value from RemoteHost is used.

Subscriptions & Receiving Messages

When Subscribe is called, it will return a subscription Id. To unsubscribe, pass this subscription Id to the Unsubscribe method.

After subscribing to a message destination, any messages received will cause the MessageIn event to fire.

Basic Subscriptions Example stomp1.OnMessageIn += (s, e) => { Console.WriteLine("Received message from destination '" + e.Destination + "':"); Console.WriteLine(e.Data); }; string subId = stomp1.Subscribe("test/a/b", false); // Some time later... stomp1.Unsubscribe(subId);

Refer to Subscribe, Unsubscribe, and MessageIn for more information about subscriptions and receiving messages.

Sending Messages

To send messages, use the SendMessage and SendData methods. SendMessage is used to send messages with string payloads, while SendData is used to send messages with binary payloads.

Send String Message Example stomp1.SendMessage("test/a/b", "Hello, world!");

Send Binary Message Example byte[] fileContent = File.ReadAllBytes("C:\test\stuff.dat"); stomp1.SendData("test/a/b", fileContent);

Refer to SendMessage and SendData for more information about sending messages.

Using Transactions

STOMP transactions are used to group messages together for processing on the server. Messages sent as part of a transaction will not be delivered by the server until the transaction is committed. If the transaction is aborted, the server will discard the messages without attempting to deliver them.

Basic Transaction Example // Open a new transaction. stomp1.BeginTransaction("txn1"); // Set the Transaction property to make sure that messages are sent as part of the transaction. stomp1.Transaction = "txn1"; stomp1.SendMessage("test/a/b", "Hello, world!"); stomp1.SendMessage("test/a/b", "This is a test."); stomp1.SendMessage("test/a/b", "Another test!"); // At this point, none of the messages sent above would have been delivered to any clients // subscribed to the "test/a/b" destination yet, because the transaction is still open. // If we close and commit the transaction, the server will then deliver the messages to subscribers, // queue them, or process them in another manner; the behavior is server-dependent. stomp1.CommitTransaction("txn1"); // Or, the transaction can be aborted, in which case the server will discard the messages // without delivering them to the subscribers. //stomp1.AbortTransaction("txn1"); // Reset (or change) the Transaction property after committing or aborting a transaction // so that future messages are not associated with the previous transaction. stomp1.Transaction = "";

Refer to BeginTransaction for more information about using transactions.

Property List

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

Method List

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

Event List

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

Config Settings

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

Connected Property (STOMP Control)

Triggers a connection or disconnection.

Syntax

stompcontrol.Connected[=boolean]

Default Value

False

Remarks

This property triggers a connection or disconnection. Setting this property to True makes the control attempt to connect to the host identified by the RemoteHost property. If successful, after the connection is achieved the value of the property changes to True and the Connected event is fired.

Setting this property to False closes the connection.

When connecting to a STOMP server, the control sends information from the following properties, if populated:

• IncomingHeartbeat
• OutgoingHeartbeat
• User
• Password

In addition to the above properties, the following configuration settings can be set before connecting (though in most cases this is not necessary):

• SupportedVersions: Controls which STOMP versions the control advertises support for.
• VirtualHost: Controls the virtual host to connect to. If left empty (default), the value from RemoteHost is used.

This property is not available at design time.

Data Type

Boolean

ContentType Property (STOMP Control)

The content type of the outgoing message.

Syntax

stompcontrol.ContentType[=string]

Default Value

"text/plain"

Remarks

This property is used to specify the content type (MIME type) for outgoing messages sent using SendMessage. The default value is text/plain, which should be sufficient is most cases.

Note that this property is ignored for messages sent using SendData, as such messages do not have a content-type header added to them. The absence of a content-type header indicates to the server that the data should be treated as a binary blob.

This property is not available at design time.

Data Type

String

FirewallAutoDetect Property (STOMP Control)

This property tells the control whether or not to automatically detect and use firewall system settings, if available.

Syntax

stompcontrol.FirewallAutoDetect[=boolean]

Default Value

False

Remarks

This property tells the control whether or not to automatically detect and use firewall system settings, if available.

Data Type

Boolean

FirewallType Property (STOMP Control)

This property determines the type of firewall to connect through.

Syntax

stompcontrol.FirewallType[=integer]

Possible Values

fwNone(0), 
fwTunnel(1), 
fwSOCKS4(2), 
fwSOCKS5(3), 
fwSOCKS4A(10)

Default Value

0

Remarks

This property determines the type of firewall to connect through. The applicable values are as follows:

Data Type

Integer

FirewallHost Property (STOMP Control)

This property contains the name or IP address of firewall (optional).

Syntax

stompcontrol.FirewallHost[=string]

Default Value

""

Remarks

This property contains the name or IP address of firewall (optional). If a FirewallHost is given, the requested connections will be authenticated through the specified firewall when connecting.

If this property is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, the control fails with an error.

Data Type

String

FirewallPassword Property (STOMP Control)

This property contains a password if authentication is to be used when connecting through the firewall.

Syntax

stompcontrol.FirewallPassword[=string]

Default Value

""

Remarks

This property contains a password if authentication is to be used when connecting through the firewall. If FirewallHost is specified, the FirewallUser and FirewallPassword properties are used to connect and authenticate to the given firewall. If the authentication fails, the control fails with an error.

Data Type

String

FirewallPort Property (STOMP Control)

This property contains the transmission control protocol (TCP) port for the firewall Host .

Syntax

stompcontrol.FirewallPort[=integer]

Default Value

0

Remarks

This property contains the transmission control protocol (TCP) port for the firewall FirewallHost. See the description of the FirewallHost property for details.

Note: This property is set automatically when FirewallType is set to a valid value. See the description of the FirewallType property for details.

Data Type

Integer

FirewallUser Property (STOMP Control)

This property contains a user name if authentication is to be used connecting through a firewall.

Syntax

stompcontrol.FirewallUser[=string]

Default Value

""

Remarks

This property contains a user name if authentication is to be used connecting through a firewall. If the FirewallHost is specified, this property and FirewallPassword properties are used to connect and authenticate to the given Firewall. If the authentication fails, the control fails with an error.

Data Type

String

HeaderCount Property (STOMP Control)

The number of records in the Header arrays.

Syntax

stompcontrol.HeaderCount[=integer]

Default Value

0

Remarks

This property controls the size of the following arrays:

• HeaderKey
• HeaderValue

The array indices start at 0 and end at HeaderCount - 1.

This property is not available at design time.

Data Type

Integer

HeaderKey Property (STOMP Control)

This header's key.

Syntax

stompcontrol.HeaderKey(HeaderIndex)[=string]

Default Value

""

Remarks

This header's key.

This property holds this header's key (or name).

The HeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the HeaderCount property.

This property is not available at design time.

Data Type

String

HeaderValue Property (STOMP Control)

This header's value.

Syntax

stompcontrol.HeaderValue(HeaderIndex)[=string]

Default Value

""

Remarks

This header's value.

This property holds this header's value.

The HeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the HeaderCount property.

This property is not available at design time.

Data Type

String

IncomingHeartbeat Property (STOMP Control)

Specifies the server-to-control heartbeat timing.

Syntax

stompcontrol.IncomingHeartbeat[=integer]

Default Value

0

Remarks

This property specifies the incoming heartbeat interval, which is the number of seconds without any server-to-control communication that the server will allow to elapse before sending the control a heartbeat (keepalive). If set to 0 (default), incoming heartbeats are disabled.

For information about outgoing (control-to-server) heartbeats; see the OutgoingHeartbeat property.

Before Connecting

Before connecting, this property is used to specify the desired incoming heartbeat interval (in seconds). By default, this property is set to 0 (no heartbeat).

During the connection process, the incoming heartbeat interval requested by the control is compared to the minimum interval supported by the server, and the larger of the two values is selected. If one or both sides supply 0 as their value, then no server-to-control heartbeats will be sent.

After Connecting

After connecting, this property cannot be set. Instead, it reflects the incoming heartbeat interval agreed upon by the control and the server during the connection process.

As the incoming heartbeat interval negotiation notes above imply, it is possible that the agreed-upon incoming heartbeat interval may either be larger than what the control requested, or may be 0 (i.e., incoming heartbeats are disabled).

This property is not available at design time.

Data Type

Integer

LocalHost Property (STOMP Control)

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

Syntax

stompcontrol.LocalHost[=string]

Default Value

""

Remarks

The LocalHost 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 multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the control initiate connections (or accept in the case of server controls) only through that interface.

If the control 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 multi-homed 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.

Data Type

String

LocalPort Property (STOMP Control)

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

Syntax

stompcontrol.LocalPort[=integer]

Default Value

0

Remarks

This property must be set before a connection is attempted. It instructs the control 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 in the client side.

Data Type

Integer

OutgoingHeartbeat Property (STOMP Control)

Specifies the control-to-server heartbeat timing.

Syntax

stompcontrol.OutgoingHeartbeat[=integer]

Default Value

0

Remarks

This property specifies the outgoing heartbeat interval, which is the number of seconds without any control-to-server communication that the control will allow to elapse before sending the server a heartbeat (keepalive). If set to 0 (default), outgoing heartbeats are disabled.

For information about incoming (server-to-control) heartbeats; see the IncomingHeartbeat property.

Before Connecting

Before connecting, this property is used to specify the minimum supported outgoing heartbeat interval (in seconds). By default, this property is set to 0 (no heartbeat).

During the connection process, the minimum outgoing heartbeat interval supported by the control is compared to the interval requested by the server, and the larger of the two values is selected. If one or both sides supply 0 as their value, then no control-to-server heartbeats will be sent.

After Connecting

After connecting, this property cannot be set. Instead, it reflects the outgoing heartbeat interval agreed upon by the control and the server during the connection process.

As the outgoing heartbeat interval negotiation notes above imply, it is possible that the agreed-upon outgoing heartbeat interval may either be larger than the control's supported minimum, or may be 0 (i.e., outgoing heartbeats are disabled).

This property is not available at design time.

Data Type

Integer

ParsedHeaderCount Property (STOMP Control)

The number of records in the ParsedHeader arrays.

Syntax

stompcontrol.ParsedHeaderCount

Default Value

0

Remarks

This property controls the size of the following arrays:

• ParsedHeaderKey
• ParsedHeaderValue

The array indices start at 0 and end at ParsedHeaderCount - 1.

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

Data Type

Integer

ParsedHeaderKey Property (STOMP Control)

This header's key.

Syntax

stompcontrol.ParsedHeaderKey(ParsedHeaderIndex)

Default Value

""

Remarks

This header's key.

This property holds this header's key (or name).

The ParsedHeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ParsedHeaderCount property.

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

Data Type

String

ParsedHeaderValue Property (STOMP Control)

This header's value.

Syntax

stompcontrol.ParsedHeaderValue(ParsedHeaderIndex)

Default Value

""

Remarks

This header's value.

This property holds this header's value.

The ParsedHeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ParsedHeaderCount property.

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

Data Type

String

Password Property (STOMP Control)

A password if authentication is to be used.

Syntax

stompcontrol.Password[=string]

Default Value

""

Remarks

If this property is set when connecting, the control will send the password in the passcode header.

This property is not available at design time.

Data Type

String

ReadyToSend Property (STOMP Control)

Indicates whether the control is ready to send data.

Syntax

stompcontrol.ReadyToSend

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 SendData or 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 control 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 control completes any partially sent messages.

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

Data Type

Boolean

RemoteHost Property (STOMP Control)

The address of the remote host. Domain names are resolved to IP addresses.

Syntax

stompcontrol.RemoteHost[=string]

Default Value

""

Remarks

This property specifies the IP address (IP number in dotted internet format) or 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 control 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.

By default the control will connect in plaintext. To enable SSL set SSLEnabled to True.

Data Type

String

RemotePort Property (STOMP Control)

The port of the STOMP server (default is 61613). The default port for SSL is 61612.

Syntax

stompcontrol.RemotePort[=integer]

Default Value

61613

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.

Data Type

Integer

RequestReceipts Property (STOMP Control)

Whether the control should request that the server provide message receipts.

Syntax

stompcontrol.RequestReceipts[=boolean]

Default Value

False

Remarks

This property is used to specify whether the control should request that the server send back confirmations (known as a "receipts" in STOMP terminology) when it receives messages from the control. This is done by adding a receipt header to the outgoing frame.

When this property is set to True, and a message is sent, the ReceiptOut event will fire immediately after the MessageOut event fires.

Note that, while this property only controls receipt requests for outgoing messages, the control is capable of requesting receipts for any outgoing frame type. Use this table to determine which API members control receipt request for each outgoing frame type (all are False by default):

Received Receipt Notes

When a receipt is received, the ReceiptIn event fires.

Note that receipts are cumulative, and a STOMP server is not required to send back discrete receipts for each frame it receives that has a receipt header. For example, if the control has sent four message frames with the following receipt header values (in chronological order):

1. SEND-3
2. SEND-4
3. SEND-5
4. SEND-6

This property is not available at design time.

Data Type

Boolean

SSLAcceptServerCertEncoded Property (STOMP Control)

This is the certificate (PEM/Base64 encoded).

Syntax

stompcontrol.SSLAcceptServerCertEncoded[=string]

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLAcceptServerCertStore and SSLAcceptServerCertSubject properties also may be used to specify a certificate.

When SSLAcceptServerCertEncoded is set, a search is initiated in the current SSLAcceptServerCertStore for the private key of the certificate. If the key is found, SSLAcceptServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLAcceptServerCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLAcceptServerCertEncodedB.

This property is not available at design time.

Data Type

Binary String

SSLCertEncoded Property (STOMP Control)

This is the certificate (PEM/Base64 encoded).

Syntax

stompcontrol.SSLCertEncoded[=string]

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLCertStore and SSLCertSubject properties also may be used to specify a certificate.

When SSLCertEncoded is set, a search is initiated in the current SSLCertStore for the private key of the certificate. If the key is found, SSLCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLCertEncodedB.

This property is not available at design time.

Data Type

Binary String

SSLCertStore Property (STOMP Control)

This is the name of the certificate store for the client certificate.

Syntax

stompcontrol.SSLCertStore[=string]

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The SSLCertStoreType property denotes the type of the certificate store specified by SSLCertStore. If the store is password protected, specify the password in SSLCertStorePassword.

SSLCertStore is used in conjunction with the SSLCertSubject property to specify client certificates. If SSLCertStore has a value, and SSLCertSubject or SSLCertEncoded is set, a search for a certificate is initiated. Please see the SSLCertSubject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLCertStoreB.

Data Type

Binary String

SSLCertStorePassword Property (STOMP Control)

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

stompcontrol.SSLCertStorePassword[=string]

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Data Type

String

SSLCertStoreType Property (STOMP Control)

This is the type of certificate store for this certificate.

Syntax

stompcontrol.SSLCertStoreType[=integer]

Possible Values

cstUser(0), 
cstMachine(1), 
cstPFXFile(2), 
cstPFXBlob(3), 
cstJKSFile(4), 
cstJKSBlob(5), 
cstPEMKeyFile(6), 
cstPEMKeyBlob(7), 
cstPublicKeyFile(8), 
cstPublicKeyBlob(9), 
cstSSHPublicKeyBlob(10), 
cstP7BFile(11), 
cstP7BBlob(12), 
cstSSHPublicKeyFile(13), 
cstPPKFile(14), 
cstPPKBlob(15), 
cstXMLFile(16), 
cstXMLBlob(17), 
cstJWKFile(18), 
cstJWKBlob(19), 
cstSecurityKey(20), 
cstBCFKSFile(21), 
cstBCFKSBlob(22), 
cstPKCS11(23), 
cstAuto(99)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The control supports both public and private keys in a variety of formats. When the cstAuto value is used, the control will automatically determine the type. This property can take one of the following values:

Data Type

Integer

SSLCertSubject Property (STOMP Control)

This is the subject of the certificate used for client authentication.

Syntax

stompcontrol.SSLCertSubject[=string]

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

Data Type

String

SSLEnabled Property (STOMP Control)

Whether TLS/SSL is enabled.

Syntax

stompcontrol.SSLEnabled[=boolean]

Default Value

False

Remarks

This setting specifies whether TLS/SSL is enabled in the control. When False (default) the control 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.

This property is not available at design time.

Data Type

Boolean

SSLProvider Property (STOMP Control)

This specifies the SSL/TLS implementation to use.

Syntax

stompcontrol.SSLProvider[=integer]

Possible Values

sslpAutomatic(0), 
sslpPlatform(1), 
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 control 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:

In most cases using the default value (Automatic) is recommended. The control 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.

Data Type

Integer

SSLServerCertEncoded Property (STOMP Control)

This is the certificate (PEM/Base64 encoded).

Syntax

stompcontrol.SSLServerCertEncoded

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLServerCertStore and SSLServerCertSubject properties also may be used to specify a certificate.

When SSLServerCertEncoded is set, a search is initiated in the current SSLServerCertStore for the private key of the certificate. If the key is found, SSLServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLServerCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLServerCertEncodedB.

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

Data Type

Binary String

SubscriptionCount Property (STOMP Control)

The number of records in the Subscription arrays.

Syntax

stompcontrol.SubscriptionCount

Default Value

0

Remarks

This property controls the size of the following arrays:

• SubscriptionDestination
• SubscriptionId

The array indices start at 0 and end at SubscriptionCount - 1.

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

Data Type

Integer

SubscriptionDestination Property (STOMP Control)

The destination on the server that this subscription is associated with.

Syntax

stompcontrol.SubscriptionDestination(SubscriptionIndex)

Default Value

""

Remarks

The destination on the server that this subscription is associated with.

This property reflects the destination on the server that this subscription is associated with.

The SubscriptionIndex parameter specifies the index of the item in the array. The size of the array is controlled by the SubscriptionCount property.

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

Data Type

String

SubscriptionId Property (STOMP Control)

This subscription's unique Id.

Syntax

stompcontrol.SubscriptionId(SubscriptionIndex)

Default Value

""

Remarks

This subscription's unique Id.

This property reflects the unique Id of this subscription.

The SubscriptionIndex parameter specifies the index of the item in the array. The size of the array is controlled by the SubscriptionCount property.

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

Data Type

String

Timeout Property (STOMP Control)

A timeout for the control.

Syntax

stompcontrol.Timeout[=integer]

Default Value

60

Remarks

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 control will wait for the operation to complete before returning control. The control will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

The control 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 control fails with an error.

Please note that by default, all timeouts are inactivity timeouts, i.e. 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.

Data Type

Integer

TransactionId Property (STOMP Control)

Specifies the Id of the transaction that outgoing messages are associated with.

Syntax

stompcontrol.TransactionId[=string]

Default Value

""

Remarks

This property, if not empty, is used to specify which transaction outgoing messages sent using SendMessage or SendData are associated with.

This property must either be empty, or set to the Id of a currently open transaction. The OpenTransactions configuration setting can be queried at any time to retrieve a comma-separated list of currently open transactions' Ids.

Note that this property only affects outgoing messages. It is also possible to send a message acknowledgment as part of a transaction by setting the AckTransactionId configuration setting during the MessageIn event handler.

Refer to BeginTransaction for more information about transactions.

This property is not available at design time.

Data Type

String

User Property (STOMP Control)

A username if authentication is to be used.

Syntax

stompcontrol.User[=string]

Default Value

""

Remarks

If this property is set when connecting, the control will send the user in the login header.

This property is not available at design time.

Data Type

String

AbortTransaction Method (STOMP Control)

Aborts an existing transaction.

Syntax

stompcontrol.AbortTransaction Id

Remarks

This method aborts a transaction previously started with BeginTransaction. Id identifies the transaction to abort.

The OpenTransactions configuration setting can be queried to obtain a list of currently-open transactions.

Refer to BeginTransaction for more information about transactions.

AddHeader Method (STOMP Control)

Adds a custom header to send with outgoing messages.

Syntax

stompcontrol.AddHeader Key, Value

Remarks

This method is used to add user-defined headers to the list of headers held by the Header* properties.

When SendMessage or SendData is called, all headers in the Header* properties are added to the outgoing message.

Note that the STOMP specification defines a number of standard headers necessary for implementing the STOMP protocol. When constructing an outgoing message, the control silently ignores any user-defined headers that are already set by the control.

BeginTransaction Method (STOMP Control)

Begins a new transaction.

Syntax

stompcontrol.BeginTransaction Id

Remarks

This method begins a new transaction using the specified Id, which must be unique. There is no limit to how many transactions may be open at any given time.

A transaction is a group of messages and message acknowledgments which are all processed atomically when the transaction is committed or aborted.

Messages sent in a transaction will not be delivered to clients subscribed to the messages' destinations until the transaction is committed.

Since it is possible for multiple transactions to be open at any given time, the TransactionId property is used to specify which transaction (if any) messages should be sent in. Similarly, message acknowledgments can be sent in a transaction by setting the AckTransactionId configuration setting during the MessageIn event handler.

The OpenTransactions configuration setting can be queried at any time to retrieve a comma-separated list of currently open transactions' Ids.

Basic Transaction Example // Open a new transaction. stomp1.BeginTransaction("txn1"); // Set the Transaction property to make sure that messages are sent as part of the transaction. stomp1.Transaction = "txn1"; stomp1.SendMessage("test/a/b", "Hello, world!"); stomp1.SendMessage("test/a/b", "This is a test."); stomp1.SendMessage("test/a/b", "Another test!"); // At this point, none of the messages sent above would have been delivered to any clients // subscribed to the "test/a/b" destination yet, because the transaction is still open. // If we close and commit the transaction, the server will then deliver the messages to subscribers, // queue them, or process them in another manner; the behavior is server-dependent. stomp1.CommitTransaction("txn1"); // Or, the transaction can be aborted, in which case the server will discard the messages // without delivering them to the subscribers. //stomp1.AbortTransaction("txn1"); // Reset (or change) the Transaction property after committing or aborting a transaction // so that future messages are not associated with the previous transaction. stomp1.Transaction = "";

CommitTransaction Method (STOMP Control)

Commits an existing transaction.

Syntax

stompcontrol.CommitTransaction Id

Remarks

This method commits a transaction previously started with BeginTransaction. Id identifies the transaction to commit.

The OpenTransactions configuration setting can be queried to obtain a list of currently-open transactions.

Refer to BeginTransaction for more information about transactions.

Config Method (STOMP Control)

Sets or retrieves a configuration setting.

Syntax

stompcontrol.Config ConfigurationString

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the control, 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 (STOMP Control)

Connects to the remote host.

Syntax

stompcontrol.Connect 

Remarks

This method connects to the remote host, specified by RemoteHost and RemotePort. Calling this method is equivalent to setting the Connected property to True.

By default the control will connect in plaintext. To enable SSL set SSLEnabled to True.

When connecting to a STOMP server, the control sends information from the following properties, if populated:

• IncomingHeartbeat
• OutgoingHeartbeat
• User
• Password

In addition to the above properties, the following configuration settings can be set before connecting (though in most cases this is not necessary):

• SupportedVersions: Controls which STOMP versions the control advertises support for.
• VirtualHost: Controls the virtual host to connect to. If left empty (default), the value from RemoteHost is used.

ConnectTo Method (STOMP Control)

Connects to the remote host.

Syntax

stompcontrol.ConnectTo Host, Port

Remarks

This method connects to the remote host specified by the Host and Port parameters. Calling this method is equivalent to setting the RemoteHost property to Host, setting RemotePort to Port, and then setting the Connected property to True.

By default the control will connect in plaintext. To enable SSL set SSLEnabled to True.

When connecting to a STOMP server, the control sends information from the following properties, if populated:

• IncomingHeartbeat
• OutgoingHeartbeat
• User
• Password

In addition to the above properties, the following configuration settings can be set before connecting (though in most cases this is not necessary):

• SupportedVersions: Controls which STOMP versions the control advertises support for.
• VirtualHost: Controls the virtual host to connect to. If left empty (default), the value from RemoteHost is used.

Disconnect Method (STOMP Control)

This method disconnects from the remote host.

Syntax

stompcontrol.Disconnect 

Remarks

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

DoEvents Method (STOMP Control)

Processes events from the internal message queue.

Syntax

stompcontrol.DoEvents 

Remarks

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

Interrupt Method (STOMP Control)

Interrupt the current action and disconnects from the remote host.

Syntax

stompcontrol.Interrupt 

Remarks

This method will interrupt the current method (if applicable) and cause the control to disconnect from the remote host.

Reset Method (STOMP Control)

Reset the control.

Syntax

stompcontrol.Reset 

Remarks

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

ResetHeaders Method (STOMP Control)

Clear the user-defined headers collection.

Syntax

stompcontrol.ResetHeaders 

Remarks

This method clears the Header* properties.

SendData Method (STOMP Control)

Publishes a message with a raw data payload.

Syntax

stompcontrol.SendData Destination, Data

Remarks

This method publishes a STOMP message with a raw data payload to the specified Destination. The MessageOut event will fire after the message has been sent.

The STOMP specification does not place any restrictions on Destination names. Instead, each STOMP server is free to define its own requirements for, and/or interpretations of, a Destination name; for example, a server might prohibit certain characters, require a specific format, or interpret some patterns in a special manner. Be sure to consult the documentation for your STOMP server to determine how to build proper Destination names.

In addition to the payload, the outgoing messages will include:

• All user-defined headers held by the Header* properties.
• If the TransactionId property is populated, the transaction Id that it specifies (which associates the message with that transaction).

If RequestReceipts is enabled when this method is called, the control will request that the server send back a receipt to confirm it has received the message. Refer to RequestReceipts for more information.

Note that no content type is defined for raw data payload messages; so the ContentType property is ignored by this method.

Send String Message Example stomp1.SendMessage("test/a/b", "Hello, world!");

Send Binary Message Example byte[] fileContent = File.ReadAllBytes("C:\test\stuff.dat"); stomp1.SendData("test/a/b", fileContent);

SendMessage Method (STOMP Control)

Publishes a message with a string payload.

Syntax

stompcontrol.SendMessage Destination, Message

Remarks

This method publishes a STOMP message with a string payload to the specified Destination. The MessageOut event will fire after the message has been sent.

The ContentType property can be used to specify the content type of the payload. By default, ContentType is set to text/plain.

The STOMP specification does not place any restrictions on Destination names. Instead, each STOMP server is free to define its own requirements for, and/or interpretations of, a Destination name; for example, a server might prohibit certain characters, require a specific format, or interpret some patterns in a special manner. Be sure to consult the documentation for your STOMP server to determine how to build proper Destination names.

In addition to the payload, the outgoing messages will include:

• All user-defined headers held by the Header* properties.
• If the TransactionId property is populated, the transaction Id that it specifies (which associates the message with that transaction).

If RequestReceipts is enabled when this method is called, the control will request that the server send back a receipt to confirm it has received the message. Refer to RequestReceipts for more information.

Send String Message Example stomp1.SendMessage("test/a/b", "Hello, world!");

Send Binary Message Example byte[] fileContent = File.ReadAllBytes("C:\test\stuff.dat"); stomp1.SendData("test/a/b", fileContent);

Subscribe Method (STOMP Control)

Subscribes to a message destination on the server.

Syntax

stompcontrol.Subscribe Destination, RequireAcks

Remarks

This method is used to subscribe to the specified message Destination on the server. The Id of the subscription is returned.

Once subscribed, the Subscribed event will fire and an item will be added to the Subscription* properties. The MessageIn event will fire anytime a message is received for any subscription.

The STOMP specification does not place any restrictions on Destination names. Instead, each STOMP server is free to define its own requirements for, and/or interpretations of, a Destination name; for example, a server might prohibit certain characters, require a specific format, or interpret some patterns in a special manner. Be sure to consult the documentation for your STOMP server to determine how to build proper Destination names.

If the RequireAcks parameter is set to True, the server will expect the control to send it a message acknowledgment for each message it delivers as part of this subscription. (Refer to the MessageIn event for more information about sending message acknowledgments).

Basic Subscriptions Example stomp1.OnMessageIn += (s, e) => { Console.WriteLine("Received message from destination '" + e.Destination + "':"); Console.WriteLine(e.Data); }; string subId = stomp1.Subscribe("test/a/b", false); // Some time later... stomp1.Unsubscribe(subId);

Unsubscribe Method (STOMP Control)

Removes an existing subscription.

Syntax

stompcontrol.Unsubscribe Id

Remarks

This method removes an existing subscription identified by the given Id, unsubscribing the control from the destination associated with the subscription.

Once unsubscribed, the relevant item will be removed from the Subscription* properties and the Unsubscribed event will fire.

Basic Subscriptions Example stomp1.OnMessageIn += (s, e) => { Console.WriteLine("Received message from destination '" + e.Destination + "':"); Console.WriteLine(e.Data); }; string subId = stomp1.Subscribe("test/a/b", false); // Some time later... stomp1.Unsubscribe(subId);

Connected Event (STOMP Control)

This event is fired immediately after a connection completes (or fails).

Syntax

Sub stompcontrol_Connected(StatusCode As Integer, Description As String)

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. The corresponding Visual Basic error code can be obtained by adding 15001 to this value.

Please refer to the Error Codes section for more information.

ConnectionStatus Event (STOMP Control)

This event is fired to indicate changes in the connection state.

Syntax

Sub stompcontrol_ConnectionStatus(ConnectionEvent As String, StatusCode As Integer, Description As String)

Remarks

The ConnectionStatus 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 (STOMP Control)

This event is fired when a connection is closed.

Syntax

Sub stompcontrol_Disconnected(StatusCode As Integer, Description As String)

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. The corresponding Visual Basic error code can be obtained by adding 15001 to this value.

Please refer to the Error Codes section for more information.

Error Event (STOMP Control)

Fired when a control or protocol error occurs.

Syntax

Sub stompcontrol_Error(ErrorCode As Integer, Description As String, Data As String)

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the control fails with an error.

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

STOMP Protocol Errors

When this occurs, ErrorCode will be 600, Description will reflect the value of the ERROR frame's message header, and Data will contain the body of the ERROR frame (if one is present).

The ErrorHeaders configuration setting will also be populated with the raw headers from the ERROR frame for the duration of the Error event handler.

Log Event (STOMP Control)

Fired once for each log message.

Syntax

Sub stompcontrol_Log(LogLevel As Integer, Message As String, LogType As String)

Remarks

This event fires once for each log message generated by the control. 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 control.
• Acknowledgment: Information about outgoing message acknowledgments.
• Frame: Frame content logging.

MessageIn Event (STOMP Control)

Fired when a message has been received.

Syntax

Sub stompcontrol_MessageIn(MessageId As String, SubscriptionId As String, Destination As String, Data As String, ContentType As String, Ack As Boolean)

Remarks

This events fires whenever the control has received a message.

In addition to the message details exposed by the event parameters, the ParsedHeader* properties are populated with the headers parsed from the message. When the MessageIn event handler exits, the parsed headers are cleared. The following parameters are available within this event:

• MessageId: The unique Id of the message.
• SubscriptionId: The subscription Id the message is associated with.
• Destination: The message destination on the server which the message originated from.
• Data: The message's payload.
• ContentType: The content type of the message (may be empty).
• Ack: Set to True or False to control whether the control should send back a positive (True, default) or negative (False) message acknowledgment.

Message acknowledgments are only sent back to the server for messages which require them. A positive acknowledgment indicates that the message has been accepted, while a negative acknowledgment represents that the message has been rejected.

The following two configuration settings are also relevant in the context of sending back message acknowledgments for incoming messages:

• The AckTransactionId configuration setting, if not empty, specifies a transaction Id to associate the message acknowledgment with. It can only be set during the MessageIn event handler, and will be reset when the event handler ends.
• The RequestAckReceipts configuration setting controls whether the control will request that the server confirm receipt of the message acknowledgment. It is False by default, and can be set at any time.

MessageOut Event (STOMP Control)

Fired after a message has been sent.

Syntax

Sub stompcontrol_MessageOut(Destination As String, Data As String, ContentType As String)

Remarks

This event fires after a message has been sent using either SendMessage or SendData. The following parameters are available within this event:

• Destination: The destination the message was sent to.
• Data: The message's payload.
• ContentType: The content type of the message (always empty for messages sent with SendData).

ReadyToSend Event (STOMP Control)

Fired when the control is ready to send data.

Syntax

Sub stompcontrol_ReadyToSend()

Remarks

The ReadyToSend event indicates that the underlying TCP/IP subsystem is ready to accept data after a call to SendData or SendMessage fails due to a WOULDBLOCK condition. The event is also fired immediately after a connection to the remote host is established.

ReceiptIn Event (STOMP Control)

Fires when the control receives a receipt from the server.

Syntax

Sub stompcontrol_ReceiptIn(ReceiptId As String)

Remarks

This event fires anytime the control receives a receipt (that is, a confirmation that the server has received one or more frames) from the server. The ReceiptId parameter reflects the value of the receipt-id header in the incoming RECEIPT frame.

Note that receipts are cumulative, and a STOMP server is not required to send back discrete receipts for each frame it receives that has a receipt header. For example, if the control has sent four message frames with the following receipt header values (in chronological order):

1. SEND-3
2. SEND-4
3. SEND-5
4. SEND-6

Refer to RequestReceipts for more information about receipts.

ReceiptOut Event (STOMP Control)

Fires when the control sends a STOMP frame that includes a 'receipt' header.

Syntax

Sub stompcontrol_ReceiptOut(ReceiptId As String)

Remarks

This event fires anytime the control sends any STOMP frame that includes a receipt header on it. The ReceiptId parameter reflects the value of the receipt header.

Having a receipt header on an outgoing frame indicates to the server that it should send back a receipt to confirm that it has received the frame (though it is not required to do so immediately; see ReceiptIn for details). Anytime the server sends back a receipt, the ReceiptIn event will fire.

Refer to RequestReceipts for more information about receipts.

SSLServerAuthentication Event (STOMP Control)

Fired after the server presents its certificate to the client.

Syntax

Sub stompcontrol_SSLServerAuthentication(CertEncoded As String, CertSubject As String, CertIssuer As String, Status As String, Accept As Boolean)

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 (STOMP Control)

Fired when secure connection progress messages are available.

Syntax

Sub stompcontrol_SSLStatus(Message As String)

Remarks

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

Subscribed Event (STOMP Control)

Fired when the control has subscribed to a message destination on the server.

Syntax

Sub stompcontrol_Subscribed(Id As String, Destination As String, RequireAcks As Boolean)

Remarks

This event fires each time the control has subscribed to a message destination on the server. The following parameters are available within this event:

• Id: The Id used to identify the subscription.
• Destination: The message destination on the server which the subscription is associated with.
• RequireAcks: Whether messages the control receives as a result of the subscription will require acknowledgments to be sent back to the server.

Unsubscribed Event (STOMP Control)

Fired when the control has unsubscribed from a message destination on the server.

Syntax

Sub stompcontrol_Unsubscribed(Id As String, Destination As String)

Remarks

This event fires each time the control has unsubscribed from a message destination on the server. The following parameters are available within this event:

• Id: The Id that was used to identify the subscription.
• Destination: The message destination on the server which the subscription was associated with.

Config Settings (STOMP Control)

STOMP Config Settings

TCPClient Config Settings

SSL Config Settings

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

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

Socket Config Settings

Trappable Errors (STOMP Control)

STOMP Errors

TCPClient Errors

SSL Errors

TCP/IP Errors