JMS Swiftlet
JMS Implementation
The JMS Swiftlet implements the JMS 1.1 specification.
Queue Location Dependency
Queues are the base for the Point-To-Point message model. This model is
usually taken to implement server inbound queues. Queues are location
dependent. They reside on a specific router, usually for a long time.
Sending messages to a queue could be performed from every router in a
network that has a route to the router where the queue is hosted.
Receiving messages from a queue is limited to the queue's hosting
router. It is not possible to create a QueueReceiver for a queue on a
different router.
Multiple Queue Receivers
Usually a queue has one receiver that fetches and processes the messages. SwiftMQ permits to create multiple receivers per queue. With this approach a 'natural' round-robin scheduling takes place where each receiver fetches the next available message from the top of the queue. This means that a load balancing on the client side could be easily implemented by simply starting more client process instances to increase the message troughput.
Queue Names
Due to location dependency, a queue name must always be completely qualified to ensure correct message routing:
<queue>@<routername>
In exception to this rule, the initial definition of queues in the Queue Manager configuration must always be without the router name. This makes it easy to change it. For this reason it is suggested to define an JNDI alias for queues to avoid definitions of router names into JMS applications.
Predefined Queue unrouteable
There is one predefined queue on each router for messages that cannot be
routed to their destination queue because the queue is dropped while the
message is travelling the router network. These messages become
unrouteable and will be forwarded to the queue unrouteable on the
specific router. To get this messages, a JMS application can create a
QueueReceiver and send them again e. g. with a new destination.
Predefined Queue routerdlq
The predefined queue routerdlq is the router's deadletter queue and
serves as a destination for expired messages if the Queue Manager's job
Queue Cleanup DLQ is used. See the Queue Manager Swiftlet
documentation.
Predefined Topic swiftmq.jndi
There is one predefined topic that is shared between JMS clients and
internal SwiftMQ Swiftlets; the topic to broadcast JNDI lookups, the use
of which is restricted to SwiftMQ's JNDI implementation. The topic name
is swiftmq.jndi. To use this topic, a publish-grant is needed. This
could simply be done by defining this grant within the public group. For
details have a look at the Authentication Swiftlet configuration.
Topic Location Independency
In contrast to queues (PTP message model), topics are location independent. They are available on every router in a connected router network due to automatic broadcasts of local subscribers from every router to all connected routers in the network. In fact, one can publish or subscribe from any router in a router network if the authentication process on the specific local router was successful.
Topic Hierarchy
SwiftMQ provides the possibility to define topic hierarchies in the form <roottopic>.<subtopic>.<subsubtopic> etc.
Example:
iit.sales.EU
iit.sales.US
iit.projects.swiftmq.users
news.weather.forecasts
sports.formula1.MichaelSchumacher
Publishing and subscribing rules to nodes in a hierarchy:
- Selecting a specific node in a topic hierarchy publishes messages to
the addressed node and all concerning sub-nodes. Example: publishing
to node
iit.salessends the messages also toiit.sales,iit.sales.US,iit.sales.EU. - Subscribing to a specific node in a topic hierarchy means to receive
all messages addressed to this node and all parent and sub-nodes.
Example: subscribing to
iit.sales.USone receives all messages published in iit, iit.sales, and iit.sales.US; subscribing toiit.salesone receives all messages published iniit,iit.sales,iit.sales.US,iit.sales.EU, but you don't receive the messages published in theiit.projectshierarchy. - A subscriber receives a message only once, regardless of the number of topics his subscription matches.
SQL-Like Predicate Topic Addressing
As an extension to the normal topic node- and subnode-addressing scheme, SwiftMQ provides SQL-Like predicate topic addressing. So every specified subnode could be a SQL-Like predicate. A SQL-Like predicate could contain wildcards which match a single character (the underscore '_'), or any characters (the percent sign '%'). Escape character is '\'.
Example:
To address the topic iit.sales.US one can also write iit.s%s._S; to
address all subnodes within the same hierarchy level on hierarchy iit
concerning swiftmq the predicate is iit.%.swiftmq.
Root nodes cannot be addressed as a predicate; i. e. it is not possible
to specify i%.%.swiftmq.
Predicate topics are normal topic destinations and are not available via
JNDI lookups. To create a predicate topic, one has to use the
createTopic() method from a TopicSession.
Example:
Topic allSwiftMQ = topicSession.createTopic("iit.%.swiftmq");
msg.setJMSDestination(allSwiftMQ);
publisher.publish(msg);
Access to predicate topics must be granted by the Authentication Swiftlet just like normal topics.
Durable Subscribers
Durable Subscribers (Programmatically)
The JMS specification may be unclear concerning creation, reconnection, change and deletion of durable subscribers. So let's have a look at how it works in reality:
Creating a durable subscriber:
- A valid client id must be set with
setClientID()as the first method call after creating a connection or the client id has to be preset within the connection factory. - A
TopicSessionmust be created. - Choose one of the
createDurableSubscriber()methods. - The durable subscriber is now in place and receives all the messages addressed to this topic.
Reconnect to an existing durable subscriber:
- Same procedure as above; supply the same parameters to
createDurableSubscriber().
Changing an existing durable subscriber:
- Same procedure as above, but supply different parameters on
createDurableSubriber()(except the durable subscriber name, that must match, otherwise a new one is created). - The durable subscriber will be dropped with all content and re-created with the new parameters.
Deleting an existing durable subscriber:
- A valid client id must be set with
setClientID()as the first method call after creating a connection or the client id has to be preset within the connection factory. - A
TopicSessionmust be created. - The
unsubscribe()method must be called with the name of the durable subscriber. - The durable subscriber will be dropped with all content.
Durable subscribers are location dependent. They reside on a specific router and can only be accessed from that router on which they have been created.
Durable Subscribers (Administratively)
Durable subscribers can be created and removed administratively via SwiftMQ Explorer or CLI.
To create a durable subscriber with SwiftMQ Explorer, select the node
Active Durable Topic Subscribers of the Topic Manager Swiftlet's
Usage folder. Right mouse click opens a popup menu:
Select Create a new Entity:
The Name has to of <clientid>$<durablename>. Bound To
will be set from SwiftMQ during the creation of the durable subscriber
and contains its queue name. After pushing the Create button, the
durable subscriber is created and can be used from JMS clients:
To remove an existing durable subscriber with SwiftMQ Explorer, select
its entry and do a right mouse click. This opens up a popup menu. Select
the only entry Delete Entity and the durable subscriber will be
removed:
Vendor Message Properties
JMS provides the possibility to specify vendor specific message properties. These properties have the prefix JMS_<vendor>. SwiftMQ defines the following vendor properties:
| Property Name | Type | Content |
|---|---|---|
| JMS_SWIFTMQ_CID | String | Contains the client id of the message producer. |
| JMS_SWIFTMQ_UR_REASON | String | Contains the reason for unroutable messages. |
JMS Examples
The SwiftMQ distribution contains a directory "samples" with various example programs. To use it, please consult the Readme.txt stored in the "samples" directory.
Thread Pools
The JMS Swiftlet uses the following thread pools:
- jms.connection
- jms.session
jms.connection
This thread pool is shared from all JMS connections at the router side and used for outbound writes from router to JMS clients. These outbound writes are actually very short running tasks and a single thread of thread pool jms.connection can handle hundreds of connections. However, if there are slow network connections (e.g. dial up) or if large messages are being transfered, the thread blocks until the outbound write has been completed and other writes are stacked up and have to wait. The default setting for this pool is min-threads=5, max-threads=5. It ensures that there is always a free threads, even when the above conditions occurs. The max-threads attribute should be increased when all threads of this pool are continuously busy. This can be observed with SwiftMQ Explorer, Threadpool Swiftlet/Usage.
jms.session
This thread pool is shared from all JMS session at the router side. In fact, all JMS work will be done from this pool. The work is scheduled as so-called async task that are dispatched into this pool. These tasks are actually short running so a thread from this pool will not block. The only exceptions are persistent operations, e.g. large messages stored via the JDBC Store Swiftlet. This can take time and a thread will block until the operation has been finished. The default setting for this pool is min-threads=5, max-threads=5. It ensures that there is always a free threads, even when the above conditions occurs. The max-threads attribute should be increased when all threads of this pool are continuously busy. This can be observed with SwiftMQ Explorer, Threadpool Swiftlet/Usage.
Configuration
The configuration of the JMS Swiftlet (XAASF) is defined within the element
<swiftlet name="sys$jms" .../>
of the router's configuration file. One can use the SwiftMQ Exlorer or CLI for configuration as well. They both save into that file.
Attributes of Element "swiftlet"
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| allow-same-clientid | java.lang.Boolean | No | Allows multiple connection with the same JMS Client Id if set to true |
| collect-interval | java.lang.Long | No | Collect Interval Messages/Sec |
| max-connections | java.lang.Integer | No | Maximum JMS Connections |
| consumer-cache-low-water-mark | java.lang.Integer | No | Consumer caches are refilled when reaching this mark |
| crfactory-class | java.lang.String | No | Challenge/Response Factory Class |
Values
| Attribute | Values |
|---|---|
| allow-same-clientid | Default: false |
| collect-interval | Default: 10000 |
| max-connections | Default: -1 |
| consumer-cache-low-water-mark | Min: 0 Default: 100 |
| crfactory-class | Default: com.swiftmq.auth.ChallengeResponseFactoryImpl |
Element List "intravm-connection-factories", Parent Element: "swiftlet"
IntraVM Connection Factories. This element list contains zero or more "intravm-connection-factory" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this IntraVM Connection Factory |
| smqp-producer-reply-interval | java.lang.Integer | Yes | Number of SMQP Requests after which a SMQP Reply is required |
| smqp-consumer-cache-size | java.lang.Integer | Yes | Cache Size per Consumer (Messages) |
| smqp-consumer-cache-size-kb | java.lang.Integer | Yes | Cache Size per Consumer (KB) |
| jms-client-id | java.lang.String | No | JMS Client Id for durable Subscribers |
| jms-default-delivery-mode | java.lang.String | Yes | JMS Default Delivery Mode |
| jms-default-message-ttl | java.lang.Long | Yes | JMS Default Message TTL |
| jms-default-message-priority | java.lang.Integer | Yes | JMS Default Message Priority |
| jms-default-message-id-enabled | java.lang.Boolean | No | JMS Default Message Id Enabled |
| jms-default-message-timestamp-enabled | java.lang.Boolean | No | JMS Default Message Timestamp Enabled |
| thread-context-classloader-for-getobject | java.lang.Boolean | No | Use the Thread Context Classloader for getObject() |
Values
| Attribute | Values |
|---|---|
| smqp-producer-reply-interval | Min: 1 Default: 20 |
| smqp-consumer-cache-size | Min: 1 Default: 500 |
| smqp-consumer-cache-size-kb | Default: 2048 |
| jms-client-id | |
| jms-default-delivery-mode | Choice: persistent non_persistent Default: persistent |
| jms-default-message-ttl | Min: 0 Default: 0 |
| jms-default-message-priority | Min: 0 Max: 9 Default: 4 |
| jms-default-message-id-enabled | Default: true |
| jms-default-message-timestamp-enabled | Default: true |
| thread-context-classloader-for-getobject | Default: false |
Element List "listeners", Parent Element: "swiftlet"
Listener Definitions. This element list contains zero or more "listener" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Listener |
| connectaddress | java.lang.String | No | Listener Connect IP Address for NAT |
| bindaddress | java.lang.String | No | Listener Bind IP Address |
| port | java.lang.Integer | Yes | Listener Port |
| hostname2 | java.lang.String | No | Hostname of the 2nd HA Instance |
| connectaddress2 | java.lang.String | No | Listener Connect IP Address for NAT of the 2nd HA Instance |
| bindaddress2 | java.lang.String | No | Listener Bind IP Address of the 2nd HA Instance |
| port2 | java.lang.Integer | No | Listener Port 2nd HA Instance of the 2nd HA Instance |
| use-tcp-no-delay | java.lang.Boolean | Yes | Use Tcp No Delay |
| socketfactory-class | java.lang.String | No | Listener Socketfactory Class |
| keepalive-interval | java.lang.Long | No | Interval for sending Keep Alive Messages |
| max-connections | java.lang.Integer | No | Maximum JMS Connections for this Listener |
| router-input-buffer-size | java.lang.Integer | No | Router Network Input Buffer Size |
| router-input-extend-size | java.lang.Integer | No | Router Network Input Extend Size |
| router-output-buffer-size | java.lang.Integer | No | Router Network Output Buffer Size |
| router-output-extend-size | java.lang.Integer | No | Router Network Output Extend Size |
Values
| Attribute | Values |
|---|---|
| connectaddress | |
| bindaddress | |
| port | |
| hostname2 | |
| connectaddress2 | |
| bindaddress2 | |
| port2 | Default: -1 |
| use-tcp-no-delay | Default: true |
| socketfactory-class | Default: com.swiftmq.net.PlainSocketFactory |
| keepalive-interval | Default: 60000 |
| max-connections | Default: -1 |
| router-input-buffer-size | Min: 4096 Default: 131072 |
| router-input-extend-size | Min: 4096 Default: 65536 |
| router-output-buffer-size | Min: 4096 Default: 131072 |
| router-output-extend-size | Min: 4096 Default: 65536 |
Element List "host-access-list", Parent Element: "listener"
Host Access List. This element list contains zero or more "host-access-entry" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Host Access Entry |
Element List "connection-factories", Parent Element: "listener"
Connection Factories. This element list contains zero or more "connection-factory" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Connection Factory |
| reconnect-enabled | java.lang.Boolean | No | Reconnect Enabled |
| reconnect-max-retries | java.lang.Integer | No | Maximum Retries for Reconnect |
| reconnect-delay | java.lang.Long | No | Reconnect Delay in ms |
| duplicate-message-detection | java.lang.Boolean | No | Enables Duplicate Message Detection for Consumers |
| duplicate-backlog-size | java.lang.Integer | No | Max. Number of Entries of JMS Message IDs in the Duplicate Backlog |
| client-input-buffer-size | java.lang.Integer | No | Client Network Input Buffer Size |
| client-input-extend-size | java.lang.Integer | No | Client Network Input Extend Size |
| client-output-buffer-size | java.lang.Integer | No | Client Network Output Buffer Size |
| client-output-extend-size | java.lang.Integer | No | Client Network Output Extend Size |
| smqp-producer-reply-interval | java.lang.Integer | Yes | Number of SMQP Requests after which a SMQP Reply is required |
| smqp-consumer-cache-size | java.lang.Integer | Yes | Cache Size per Consumer (Messages) |
| smqp-consumer-cache-size-kb | java.lang.Integer | Yes | Cache Size per Consumer (KB) |
| jms-client-id | java.lang.String | No | JMS Client Id for durable Subscribers |
| jms-default-delivery-mode | java.lang.String | Yes | JMS Default Delivery Mode |
| jms-default-message-ttl | java.lang.Long | Yes | JMS Default Message TTL |
| jms-default-message-priority | java.lang.Integer | Yes | JMS Default Message Priority |
| jms-default-message-id-enabled | java.lang.Boolean | No | JMS Default Message Id Enabled |
| jms-default-message-timestamp-enabled | java.lang.Boolean | No | JMS Default Message Timestamp Enabled |
| thread-context-classloader-for-getobject | java.lang.Boolean | No | Use the Thread Context Classloader for getObject() |
Values
| Attribute | Values |
|---|---|
| reconnect-enabled | Default: true |
| reconnect-max-retries | Default: 10 |
| reconnect-delay | Default: 10000 |
| duplicate-message-detection | Default: true |
| duplicate-backlog-size | Default: 2000 |
| client-input-buffer-size | Min: 4096 Default: 131072 |
| client-input-extend-size | Min: 4096 Default: 65536 |
| client-output-buffer-size | Min: 4096 Default: 131072 |
| client-output-extend-size | Min: 4096 Default: 65536 |
| smqp-producer-reply-interval | Min: 1 Default: 20 |
| smqp-consumer-cache-size | Min: 1 Default: 500 |
| smqp-consumer-cache-size-kb | Default: 2048 |
| jms-client-id | |
| jms-default-delivery-mode | Choice: persistent non_persistent Default: persistent |
| jms-default-message-ttl | Min: 0 Default: 0 |
| jms-default-message-priority | Min: 0 Max: 9 Default: 4 |
| jms-default-message-id-enabled | Default: true |
| jms-default-message-timestamp-enabled | Default: true |
| thread-context-classloader-for-getobject | Default: false |
Element List "usage", Parent Element: "swiftlet"
Active JMS Connections. This element list contains zero or more "usage" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Active JMS Connection |
| version | java.lang.Integer | No | Version |
| clientid | java.lang.String | No | Client Id |
| username | java.lang.String | No | User Name |
| logintime | java.lang.String | No | Login Time |
| msgs-received | java.lang.Integer | No | Messages/Sec received from Client |
| msgs-sent | java.lang.Integer | No | Messages/Sec sent from Client |
| total-received | java.lang.Integer | No | Total Number of Messages received from Connection |
| total-sent | java.lang.Integer | No | Total Number of Messages sent from Connection |
Values
| Attribute | Values |
|---|---|
| version | |
| clientid | |
| username | |
| logintime | |
| msgs-received | Default: 0 |
| msgs-sent | Default: 0 |
| total-received | Default: 0 |
| total-sent | Default: 0 |
Element List "tempqueues", Parent Element: "usage"
Temporary Queues created by this Connection. This element list contains zero or more "tempqueue" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Temporary Queue |
Element List "sessions", Parent Element: "usage"
JMS Sessions created by this Connection. This element list contains zero or more "tempqueue" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this JMS Session |
| transacted | java.lang.Boolean | No | Transacted JMS Session |
| acknowledgemode | java.lang.String | No | Acknowledge Mode |
Values
| Attribute | Values |
|---|---|
| transacted | Default: false |
| acknowledgemode | Choice: AUTO_ACKNOWLEDGE CLIENT_ACKNOWLEDGE DUPS_OK_ACKNOWLEDGE |
Element List "receiver", Parent Element: "tempqueue"
Queue Receivers created by this Session. This element list contains zero or more "receiver" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Queue Receiver |
| queue | java.lang.String | No | Queue Name |
| selector | java.lang.String | No | Message Selector |
Values
| Attribute | Values |
|---|---|
| queue | |
| selector |
Element List "browser", Parent Element: "tempqueue"
Queue Browsers created by this Session. This element list contains zero or more "browser" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Queue Browser |
| queue | java.lang.String | No | Queue Name |
| selector | java.lang.String | No | Message Selector |
Values
| Attribute | Values |
|---|---|
| queue | |
| selector |
Element List "sender", Parent Element: "tempqueue"
Queue Senders created by this Session. This element list contains zero or more "sender" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Queue Sender |
| queue | java.lang.String | No | Queue Name |
Values
| Attribute | Values |
|---|---|
| queue |
Element List "publisher", Parent Element: "tempqueue"
Topic Publishers created by this Session. This element list contains zero or more "publisher" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Topic Publisher |
| topic | java.lang.String | No | Topic Name |
Values
| Attribute | Values |
|---|---|
| topic |
Element List "durables", Parent Element: "tempqueue"
Durable Topic Subscriber created by this Session. This element list contains zero or more "durables" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Durable Topic Subscriber |
| durablename | java.lang.String | No | Name of the durable Subscriber |
| clientid | java.lang.String | No | Client Id |
| topic | java.lang.String | No | Topic Name |
| selector | java.lang.String | No | Message Selector |
| nolocal | java.lang.Boolean | No | Receives no local published Messages |
| boundto | java.lang.String | No | Is bound to Queue |
Values
| Attribute | Values |
|---|---|
| durablename | |
| clientid | |
| topic | |
| selector | |
| nolocal | Default: false |
| boundto |
Element List "subscriber", Parent Element: "tempqueue"
Topic Subscriber created by this Session. This element list contains zero or more "subscriber" elements with this template definition:
Definition
| Attribute | Type | Mandatory | Description |
|---|---|---|---|
| name | java.lang.String | Yes | Name of this Topic Subscriber |
| clientid | java.lang.String | No | Client Id |
| topic | java.lang.String | No | Topic Name |
| selector | java.lang.String | No | Message Selector |
| nolocal | java.lang.Boolean | No | Receives no local published Messages |
| temptopic | java.lang.Boolean | No | Is Temporary Topic |
| boundto | java.lang.String | No | Is bound to Queue |
Values
| Attribute | Values |
|---|---|
| clientid | |
| topic | |
| selector | |
| nolocal | Default: false |
| temptopic | Default: false |
| boundto |