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JAVA MESSAGING SYSTEM & TIBCO EMS

TERMINOLOGY

„Client „Producer/Publisher „Consumer/Subscriber „Stores
„Queue
„Topic „Data(message)

JMS MESSAGE MODELS

Point-to-Point (Queues)
Publish Subscribe (Topics) Multicast (Topics)

POINT-TO-POINT(QUEUES)

TIBCO EMS Server

Send Message

Receive Message Acknowledge

PUBLISH-SUBSCRIBE( TOPICS)

TIBCO EMS Server

Publish Message

Subscribe to Topic

Deliver Message Acknowledge

MULTIC AS T( TOPICS)

TIBCO EMS Server

Broadcast Message

Publish Message

Subscribe to Message

EMS : AN EXTENSION TO JMS

EMS EXTENSIONS TO JMS MESSAGES – I

  • JMS provides 2 delivery modes for messages
    • PERSIS TEN T
    • NON_PERSIS TEN T
  • EMS adds the 3rd delivery mode RELIABLE_DELIVERY

EMS EXTENSIONS TO JMS MESSAGES – II For restriction of acknowledge messages in JMS

NO_ACKNOWLEDGE mode
To restrict acknowledgement in EMS, there are also

  • EXPLICIT_CLIENT_ACKNOWLEDGE mode
  • EXPLICIT_CLIENT_DUPS_OK_ACKNOWLEDGE mode

EMS EXTENSIONS TO JMS MESSAGES – III

  • EMS extends MapMessage and StreamMessage body types of JMS which allow EMS to exchange messages with TIBCO RV and ActiveEnterprise formats.
  • The extensions are :
    • Can nest a MapMessage or StreamMessage
    • Can use arrays as well as primitive types for values

MESSAGE STRUCTURE

MESSAGE STRUCTURE

HEADER PROPER TIES

BODY

MESSAGE HEADERS

JMSDestination
Destination to which message is sent.

JMSDeliveryMode

  • Persistent, Non-persistent or Reliable.
  • Default is Persistent.

    JMSExpiration

  • Length of time the message will live before expiry.
  • If the server expiration property is set for a destination, it will override the JMSExpiration value set by the message producer.

MESSAGE HEADERS

JMSPriority
Priority of the message. Larger numbers indicate higher

priority.

JMSMessageID
Unique identifier for a message.

JMSTimeStamp

Timestamp of the time when the message was handed off to a provider to send. Message may actually be sent later than this timestamp.

MESSAGE HEADERS

JMSCorrelationID
This ID can be used to link messages, such as linking a

response message to a request message.

JMSReplyTo
A destination to which a message reply should be sent.

JMSRedelivered

If this field is set, it is possible that the message has been delivered to the client earlier, but not acknowledged at that time.

MESSAGE PROPERTIES

  • JMS_ TIBCO_CM_PUBLISHER
  • JMS_ TIBCO_CM_SEQUENCE

JMS_TIBCO_COMPRESS


JMS_ TIBCO_DIS ABLE_SENDER

  • JMS_ TIBCO_IMPORTED

    JMS_TIBCO_MSG_TRACE

  • JMS_ TIBCO_MSG_EX T
  • JMS_ TIBCO_SENDER
  • JMS_ TIBCO_SS_SENDER

    JMS_TIBCO_PRESERVE_UNDELIVERED

MESSAGE TYPE

CONTENTS OF BODY MESSAGE

Message

No Body

Text Message

Java. lang. String

Map Message

Name/Value pairs

Bytes Message

Stream of bytes

Stream Message

Stream of primitive data types

Object Message

Serializable object

“EMS supports messages up to a maximum size of 512MB”

MESSAGE DELIVERY MODES

PERSIS TEN T

When a producer sends a PERSIS TEN T message, the must wait for the server to reply with a confirmation.

producer

  • The message is persisted on disk by the server. This delivery mode ensures delivery of messages to the destination on the server in almost all circumstances.
  • However, the cost is that this delivery mode incurs two-way network traffic for each message or committed transaction of a group of messages.

PERSIS TEN T

Message

Message Producer

EMS Server

Acknowledgement

NON PERSISTENT

  • Sending a NON_PERSIS TEN T message omits the overhead of persisting the message on disk to improve performance.
  • If authorization is disabled on the server, the server does not send a confirmation to the message producer.
  • If authorization is enabled on the server, the default condition is for the producer to wait for the server to reply with a confirmation in the same manner as when using PERSISTENT mode.

NON PERSISTENT

Regardless of whether authorization is enabled or disabled, you can

use the
specify the conditions under which the server is to send confirmation of NON_PERSISTENT messages to the producer.

npsend_check_mode parameter in the

.

tibemsd

conf file to

Message

Message Producer

EMS Server

Depending on

npsend_check_mode

RELIABLE DELIVERY

EMS extends the JMS delivery modes to include reliable delivery. Sending a RELIABLE_DELIVERY message omits the server confirmation to improve performance regardless of the authorization setting.

Message Producer

Message

EMS Server

RELIABLE DELIVERY

  • When using RELIABLE_DELIVERY mode, the server never sends the producer a receipt confirmation or access denial and the producer does not wait for it.
  • Reliable mode decreases the volume of message traffic, allowing higher message rates, which is useful for messages containing time-dependent data, such as stock price quotations.
  • When you use the reliable delivery mode, the client application does not receive any response from the server. Therefore, all publish calls will always succeed (not throw an exception) unless the connection to the server has been terminated.

RELIABLE DELIVERY

  • In some cases a message published in reliable mode may be disqualified and not handled by the server because the destination is not valid or access has been denied.
  • In this case, the message is not sent to any message consumer. However, unless the connection to the server has been terminated, the publishing application will not receive any exceptions, despite the fact that no consumer received the message.

EMS DELIVERY MODES REVIEWED

NON_PERSIS TEN T and RELI ABLE_DELI VER Y messages are never written to persistent storage.

PERSIS TEN T messages are written to persistent storage when they are received by the EMS server.

PERSISTENT MODE REVISITED

EMS PERSISTENT MODE MANAGEMENT

Persistent Messages Sent to Queues

Persistent messages sent to a queue are always written to disk. Should the server fail before sending persistent messages to consumers, the server can be restarted and the persistent messages will be sent to the consumers when they reconnect to the server.

TIBCO EMS Server

Send Message

Receive Message Acknowledge

Disk

EMS PERSISTENT MODE MANAGEMENT

Persistent Messages Sent to Topics
Persistent messages published to a topic are written to disk ONLY

PERSISTENT MESSAGES & SYNCHRONOUS STORAGE

  • When using file storage, persistent messages received by the EMS server are by default written asynchronously to disk.
  • When a producer sends a persistent message, the server does not wait for the write-to-disk operation to complete before returning control to the producer.
  • This means that the producer has no way of detecting the failure of persisting the message and take corrective action if the server fails before completing the write-to-disk operation.

PERSISTENT MESSAGES & SYNCHRONOUS STORAGE

What do you do if you want to SYNCHRONOUSLY write to disk?

  • You can set the mode parameter to sync for a given file storage in the stores.conf file to specify that persistent messages for the topic or queue be synchronously written to disk.
  • When mode = sync, the persistent producer remains blocked until the server has completed the write-to-disk operation.

  • File based stores are enabled by default.
  • Server automatically defines 3 default stores
    • $sys. nonfailsafe

      Server writes messages using asynchronous I/O calls.

    • $sys. failsafe

      Server writes messages using synchronous I/O calls.

    • $sys. meta

      Server writes state information about durable subscribers & tolerant connections.

MESSAGE COMPRESSION

  • TIBCO Enterprise Message Service allows a client to compress the body of a message before sending the message to the server.
  • EMS supports message compression/decompression across client types (Java, C and C#). For example, a Java producer may compress a message and a C consumer may decompress the message.
  • Message compression is supported in .NET clients when using the install package for Visual C++ 8 / .NET 2.0 or above.

MESSAGE COMPRESSION

  • Less memory storage for PERSIS TEN T queue messages or DURABLE topic subscribers.
  • Compression option only compresses the BODY content. Headers and properties are NEVER compressed.
  • When messages are not stored, compression is not a good option. Why?

Because, Compression takes TIME…!

MESSAGE COMPRESSION

  • Compression specific for individual messages.
  • Not on a per-queue or per-topic basis.
  • To set message compression

    JMS_TIBCO_COMPRESS to

TRUE

MESSAGE ACKNOWLEDGEMENT

MESSAGE ACKNOWLEDGEMENT

Message Confirmation

TIBCO EMS Server

Message

Acknowledgement

Confirmation of Acknowledgement

JMS

EMS (JMS +

Below mentioned

modes)

CLIEN T_ ACKNO WLEDGE

NO_ ACKNO WLEDGE

AU TO_ ACKNO WLEDGE

EXPLICIT_CLIENT_ACKNOWLEDGE

DUPS_OK_ ACKNO WLEDG E

EXPLICIT_CLIENT_DUPS_OK_ACKNOWLE DGE

JMS : CLIENT_ACKNOWLEDGE
Consumer is to acknowledge all messages that have been delivered

so far by the session.

Possible for the consumer to fall behind in its message processing and build up a large number of unacknowledged messages

Message 312 Message 321

Acknowledgement # 1,2,3

JMS : AUTO_ACKNOWLEDGE

Session is to automatically acknowledge consumer receipt of messages when message processing has finished

MESSAGE SELECTORS

  • A message selector is a string that lets a client program specify a set of

    messages, based on the values of message headers and properties.

  • A selector matches a message if, after substituting header and property values from the message into the selector string, the string evaluates to true.
  • Consumers can request that the server deliver only those messages that match a selector.

DES TIN ATIONS

TYPES OF DESTINATIONS

Static Destinations
Dynamic Destinations
Temporary Destinations

STATIC DESTINATIONS

Purpose
Allows administrators to configure EMS behavior at enterprise level

Scope of delivery
Supports concurrent use

Creation
Using config files, tibemsadmin or by API’s by administrator

Duration
Until explicitly deleted by the administrator

DYNAMIC DESTINATIONS

Purpose
Provide flexibility to define them as needed for short term use

Scope of delivery
Supports concurrent use

Creation
Client programs create it if permitted by server configuration

Duration
As long as at least 1 client actively uses it

TEMPORARY DESTINATIONS

Purpose
Ideal for limited scope usage, like reply subjects (in routing)

Scope of delivery
Supports local use

Creation
Client programs create it

Duration
Explicit deletion by the client or disconnection from the server

MIXED BAG – DESTINATIONS

  • Clients can obtain references to static destinations through a naming service such as JNDI or LDAP
  • But they cannot obtain the references to dynamic or temporary destinations
  • Dynamic topics and queues have an asterisk (*) marked in front of them, when you use the commands show queues or show topics in tibemsadmin
  • If a property of a queue or topic has an asterisk (*) character in front of its name, it means that the property was inherited from the parent queue or topic

TIBEMSD – TIBCO EMS SERVER

STARTING THE EMS SERVER

“Running this service starts the EMS Server” This service starts tibemsd.exe located in

<EMS HOME>/bin folder
tibemsd.exe reads tibemsd.conf for server settings

USING TIBEMSD TO START EMS SERVER

TIBEMSADMIN – TIBCO EMS ADMIN

STARTING TIBEMSADMIN

USING CONNECT

USING HELP

USING DISCONNECT

USING EXIT

USING SHUTDOWN

USING SHOW

USING CREATE

USING DELETE

USING ADDPROP

USING REMOVEPROP

USING SETPROP

USING PURGE

USING WHOAMI & INFO

show server

USING SET

Parameters in

tibemsd. conf

USING TIME & TIMEOUT

USING COMMIT & AUTOCOMMIT

USING COMPAC T

USING ADD

USING REMOVE

USING GRANT & REVOKE

USING ECHO

DESTINATION PROPERTIES

CH ANNEL

CH ANNEL

  • Channel property determines the multicast channel over which messages sent to the topic are broadcast
  • Configure multicast channels in channels.conf file and enable this feature in tibemsd. conf
  • Cannot create channel by any command in tibemsadmin
  • Only 1 channel allowed for each topic
  • Available only for topics

CH ANNEL

tibemsd. conf

channels.conf

CH ANNEL

EXCLUSIVE

EXCLUSIVE

  • Available only for queues
  • Set the exclusive property using addprop or setprop
  • When exclusive is set for the queue, the server sends all the messages on that queue to one consumer. No other consumer can receive messages from the queue.
  • Instead, these additional consumers act in a standby role; if the primary consumer fails, the server selects one of the standby consumers as the new primary and begins delivering messages to it.

EXCLUSIVE

EXPIR ATION

EXPIR ATION

If an expiration property is set for a destination, the server honors the overridden expiration period

If expiration property for the server is set, the server overrides the JMSExpiration value set by the producer in the message header

expiration=time[msec|sec|min|hour|day]

EXPIR ATION

MAXBYTES

MAXBYTES
Topics & queues can specify the maxbytes property in the form

maxbytes=value[KB|MB|GB]

FOR QUEUES

  • maxbytes: maximum size (in bytes) that the queue can store, summed over all the messages in the queue
  • If this limit is exceeded, the messages will be rejected by the server and the producer send calls will return an error

MAXBYTES FOR TOPICS

  • maxbytes: maximum size(in bytes) that the topic can store for delivery to each durable or non-durable online subscriber on that topic
  • The limit applies separately to each subscriber on the topic
  • Example :

    offline durable subscriber messages accumulate until they exceed

    maxbytes

    non durable subscriber maxbytes limits the number of pending messages that can accumulate while the subscriber is online

MAXBYTES

M AXMSGS

M AXMSGS
Topics & queues can specify the maxmsgs property in the form

maxmsgs=value

  • maxmsgs: maximum number of messages that can be waiting in a queue
  • When adding a message into a queue/topic would exceed this limit, the server would

    reject the message and the producer’s send call returns an error

  • Can set both maxmsgs and maxbytes properties on the same queue. Exceeding either limit causes server to reject new messages until consumers reduce the queue size to below these limits.

M AXMSGS

MAXREDELIVERY

MAXREDELIVERY

  • The number of attempts the server should make to deliver a message sent to a destination

    maxRedelivery=count

    count is between 2 & 255

  • For messages that have been redelivered,

    v JMSRedelivered header property is set to true

    v JMSXDeliveryCount property is set to the number of times the message has been delivered to the destination

MAXREDELIVERY

O VERFLO WPOLIC Y

O VERFLO WPOLIC Y
To change the effect of exceeding the message capacity

established by maxbytes or maxmsgs

overflowpolicy=default|discardOld|rejectIncoming

default

For TOPICS

v maxbytes or maxmsgs exceed for a subscriber, that subscriber does not receive message v No error returned to producer

For QUEUES

v New messages are rejected by the server if maxbytes or maxmsgs are exceeded v Error returned to producer

O VERFLO WPOLIC Y

discardOld For TOPICS

v Oldest messages are discarded before they are delivered to the subscriber
v Impacts subscribers individually. 3 subscribers, 1 exceeds the message limit. So, only the oldest

messages for the one subscriber are discarded, while other two continue to receive all messages v No error returned to producer, as message can be delivered to some and discarded for others

For QUEUES
v Error returned to producer if maxbytes or maxmsgs are exceeded

v Oldest messages are discarded from the queue by the server

O VERFLO WPOLIC Y

rejectIncoming For TOPICS

v If ANY of the subscribers have an outstanding number of undelivered messages on the server that are over the message limit, all new messages are rejected

v Error is returned to producer For QUEUES

v Error returned to producer if maxbytes or maxmsgs are exceeded v Newest messages are rejected from the queue by the server

O VERFLO WPOLIC Y

QUICK QUIZ

  • How do I discard messages on myQueue when the number of queued

    messages exceeds 2500 ?
    setprop queue myQueue maxmsgs=2500, overflowpolicy=discardOld

  • How do I reject all new messages published to myTopic when the memory used by undelivered messages for any of the topic subscribers exceeds 3 MB?

    setprop topic myTopic maxbytes=3MB,overflowPolicy=rejectIncoming

FLOWCONTROL

FLOWCONTROL

  • Specifies the target maximum size the server can use to store pending messages for the destination
  • If number of messages > flowControl then

    slow down the producers to the rate required by the message consumers

  • Useful when message producers send messages more quickly than message consumers can consume them

FLOWCONTROL

tibemsd. conf

PREFETCH

PREFETCH

Consumer and the EMS Server cooperate to regulate message fetching through this property

prefetch=value

Value

Description

2 or more

Never fetches more than specified number (Auto Fetch)

1

Fetch only if it has no message (Auto Fetch)

none

Disable Auto Fetch. Cannot be used with topics or global queues

0 (default)

Destination inherits the prefetch value. Default value for
queues = 5 & topics = 64

PREFETCH

54321

PREFETCH

PREFETCH

  • Improves performance by decreasing or eliminating client idle time while the server transfers a message
  • When a queue consumer prefetches a group of messages, the server does not deliver them to other queue consumers (unless the first queue consumer’s connection to the server is broken)

PREFETCH

Even when prefetch = none, a queue consumer can hold a message Example

A receive call initiates a fetch, but its timeout elapses before the server finishes transferring the message

This leaves a fetched message waiting in the message consumer

A second receive call does not fetch another message; instead it accepts the message already waiting

The third receive call initiates another fetch

PREFETCH

  • A waiting message still belongs to the queue consumer, and the server does not deliver it to another queue(unless the first queue consumer’s connection to the server is broken)
  • To prevent messages from waiting in this state for long periods
    • Call receive with no timeout
    • Call receive with timeout repeatedly and shorten the interval

PAREN T

CHILD

all parents : none

none

any parent : non-zero numeric value

highest

does not set any value

default
(5 : queues, 64 : topics)

PREFETCH

SECURE

SECURE
If secure is enabled for a destination, it instructs the server to check the user

permissions whenever a user attempts to perform an operation on that destination

tibemsd. conf

SENDER_N AME

SENDER_N AME

  • Server may include the sender’s username for messages sent to this destination
  • When connection between producer and server is established, server takes the username supplied by the producer and places it in the JMS_TIBCO_SENDER property of the message
  • But if producer sets the JMS_ TIBCO_DIS ABLE_SENDER to true for a message, server will not add the sender name to the message

SENDER_N AME

SENDER_N AME_ENFORCED

SENDER_N AME_ENFORCED

  • Specifies that the messages sent to this destination MUST include the sender’s username
  • Unlike sender_name property, there is no way for message producers to override this property
  • This property overrides sender_name if already set.

SENDER_N AME_ENFORCED

STORE

STORE

  • Specifies where the messages sent to this destination are stored
  • Configure stores in stores.conf

DESTINATION BRIDGES

BRIDGES

Some applications require the same message to be sent to more than one destination, possibly of different types.

Example

An application can publish messages to several topics. All messages however, must also be sent to a database for backup and for data mining. A queue is used to collect all messages and send them to the database.

BRIDGES

  • Bridges are created between one destination and one or more other destinations of the same or of different types.
  • That is, you can create a bridge from a topic to a queue or from a queue to a topic. You can also create a bridge between one destination and multiple destinations.
  • For example, you can create a bridge from topic a.b to queue q.b and topic a.c.

BRIDGING TOPIC TO QUEUE

BRIDGING TOPIC TO MULTIPLE DES TIN ATIONS

BRIDGING QUEUE TO MULTIPLE DES TIN ATIONS

BRIDGES

  • When a bridge exists between two queues, the message is delivered to both queues. The queues operate independently; if the message is retrieved from one queue, that has no effect on the status of the message in the second queue.
  • Bridges are not transitive

    Topic A.B has a bridge to queue Q.B. Queue Q.B has a bridge to topic B.C. Messages delivered to A.B are also delivered to Q.B, but not to B.C.

CREATING A BRIDGE Configured in bridges.conf file

Use

All messages sent to a destination with a bridge are sent to all bridged destinations. This can cause unnecessary network traffic if each bridged destination is only interested in a subset of the messages sent to the original destination.

of

Selector

ROU TING

ROU TING

  • EMS servers can route messages to other servers
  • Topic messages can travel server
  • Queue messages can travel queue

one

multiple
ONE
hop to and from the home

hop or

hops from the first

ONL Y

ROUTING : BASIC OPERATION

  • Each route connects two TIBCO EMS servers.
  • Each route forwards messages between corresponding destinations (that is, global topics with the same name, or explicitly routed queues) on its two servers.
  • Routes are bidirectional; that is, each server in the pair forwards messages along the route to the other server.

ROUTING : HAWK EYE VIEW

Server : A Server : B

GLOB AL DES TIN ATIONS : TOPICS

“Routes forward messages only between global destinations”

“For TOPICS, the global property must be set on both servers”

UNIQUE ROUTING PATH

It is illegal to define a set of routes that permit a message to reach a server by more than one path. TIBCO EMS servers detect illegal duplicate routes and report them as configuration errors.

ABCPQR

DE ST

ZONES

  • A zone is a named set of routes.
  • Every route belongs to a zone.
  • Zones restrict the behavior of routes, so you can configure complex routing paths.
  • Zones affect topic messages, but NOT queue messages.

ZONES : BASIC OPERATION

  • In a one-hop (1hop) zone, first server).
  • Queue messages travel only one hop, even within multi-hop zones.

In a multi-hop (mhop) zone,
routes to all servers connected by routes within the zone.

topic messages travel along all applicable topic messages travel only one hop (from the

ELIMINATING REDUNDANT PATHS WITH ONE- HOP ZONE

B1 B2

MR

GOAL : Forward messages from B1 and B2 to both M and R

OVERLAPPING ZONES

M3 M2

M4 M1

B2 B3

B1 B4

D1 D2

D4 D3

CREATING ROUTES

Syntax
create route
EMS-SERVER url=tcp://ipserver:7222 zone_name=zoneName
zone_type=1hop|mhop

route name MUST be the name of the EMS server which is specified in tibemsd.conf

url indicates the other server by the URL

ACTIVE & PASSIVE ROUTES

• • •

A route connects two servers.
You may configure a route at either or both of the servers.

A route is active from the perspective of the server where it is configured. This server actively initiates the connection to the other server, so we refer to it as the active server, or initiating server.

A route is passive from the perspective of the other server. This server passively accepts connection requests from the active server, so we refer to it as the passive server.

ACTIVE – ACTIVE ROUTES

  • Two servers can both configure an active route one to the other. This

    arrangement is called an active-active configuration.

    For example, server A specifies a route to server B, and B specifies a route to A. Either server can attempt to initiate the connection. This configuration results in only one connection; it does not result in redundant routes.

  • You can promote an active-passive route to an active-active route by using this command on the passive server

    create route name url=url

  • The url argument is required, so that the server (where the route is being promoted) can connect to the other server if the route becomes disconnected

ROUTED TOPIC MESSAGES

A server forwards the message along the routes only when the global property is defined by the topic

ROUTED TOPIC MESSAGES

  • Topic messages can traverse multiple hops.
  • When a route becomes disconnected (for example, because of network problems), the forwarding server stores topic messages. When the route reconnects, the server forwards the stored messages.
  • Servers connected by routes do exchange messages sent to temporary topics.

ROUTING : PROPAGATING SUBSCRIBERS

ROUTED QUEUES

How is routing in queues different from that in topics?

  • Servers route queue messages between the queue owner and adjacent servers.
  • The concept of zones and hops does not apply to queue messages (only to topic messages).

ROUTED QUEUES

  • In routing topics, the declaration of the topic is identical on all servers
  • Queue declarations make a distinction between the server that owns the queue and other servers with routed queues that reference both the queue name and the owning server

ROUTED QUEUES

ROUTED QUEUES

  • Routed queues serve as proxies for the real queue
  • Messages published to the proxy queue are forwarded to the real queue, and are not eligible for delivery until they reach the real queue

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