Tibco EMS-FAQS

EMS FAQS
1. what are the two storage methods used by Tibco EMS server?
Ans : File based and database
2. what files are created in file based data storage method?
Ans . sync.db,async.db,meta.db
3. what information does Meta.db contain?
Ans . durable subscribers, fault tolerant connections and other meta data.
4. what does flow control property specifies ?
ans . specifies the maximum size of the pending messages in server.
5. what are the destinations of messages?
Ans : topics and queues.
6. in how many ways destinations for messages can be created?
Ans . static : administrator creates destinations and client programs uses the destinations
Dynamic: here client program creates destinations during runtime
Temporary: servers connected through routes communicate through temporary destinations.
7. what are the messaging models supported by ems serve?
Ans . point to point ( queues), pubsub (topics), multicast (topic).
8.What is the diff between exclusive queues and non exclusives ?
Ans . in exclusive – only one receiver can take message where as in non exclusive many receivers can receive msg.
9.how long the message will be stored for durable subscribers?
Ans . as long as durable subscriber exists or until msg expiration time reached or storage limit has been reached.
10. what are the different delivery modes supported by ems?
Ans . persistent, non persistent and reliable.
11.what is the dis advantage of reliable mode delivery?
Ans . in reliable , with out knowing the status of the consumer the producer keeps sending msg to server
12. what is the condition for persistent message to be stored on disk in topics?
Ans . there must be atleast one durable subscriber or one must be connected to fault tolerant connection to ems server.
13. how do you distinguish dynamic queues and static queues.?
Ans . dynamic queues have * before the queue name.
14. what happens if npsend_checkmode parameter in tibemsd.conf file is enabled?
Ans. Server sends acknowledgement for non persistent message.
15. what is shared state in fault tolerant operation ?
Ans . primary server and backup server have connection to shared state which contain information about client connection and persistant messages.
16. how many ways a back up server detects failure of primary server?
Ans. Hearbeat failure:-Primary server sends a heartbeat message to backup server to indicate primary server is working .
connection failure :-backup server detects the failure of tcp connection with primary server
17.what is the use of locking in fault tolerant operation?
Ans.Inorder to prevent the backup server to take the role of primary server, the primary server logs the shared state in normal operation and during the failure of primary server backup server takes the lock and access primary server.
18.If authorization is enabled in tibemsd.config file what is the condition to configure ems server as fault tolerance?
Ans.Server name and password for both primary and backup server should be same and username and password for both servers should match the server and password parameters in tibemsd.config file.
19. what are the changes to be made in config file for ems fault tolerant operation?
Ans . in primary server give url of backup server to ft_active parameter and in backup server give url of primary server for ft_active parameter.
20. different types of zones?
Ans. Multihop zone and 1hop zone.
21. what is fail safe?
Ans. In fail safe mode messages are frist stored in disk before sending messages so that no messages are lost.
22.what is the default port number for ems server?
Ans 7222.
23. difference between rendezvous and ems?
Ans. Rvd is bus based architecture , ems is centralized architecture
24.what are different acknowledge modes?
Ans. Dups_ok_acknowlwdge,auto_acknowlwdge,client_acknowledge,no_acknowledge.
25. How many ways we can determine the life span of the message in a queue. What are they?
Ans: expiration parameter in queue configuration file.
JMS expiration time in queue sender.
The JMS expiration time in queue sender overrides any value given in config.
26. What are the message storing mechanisms of queues?
Ans: persistent and non-persistent.
Persistent: messages are stored to external storage before sending.
Non-persistent: not stored to any external storage. The information will not be available for retrieval.
27.what is condition to create bridge?
Ans. Queus and topics must be defined as global.
28. why do we need routers ?
Ans. To transfer messages between different ems servers.
29. what is the default maximum size of message?
Ans. 512mb
30. how do you configure client for fault tolerant connection?
Ans. Specify multiple server as a comma-separated list of URLs and both URLs must use same protocol either tcp or ssl.
31. What are the different types of acknowledgement modes in EMS message delivery

• Auto
• Client
• Dups_ok
• No_ack
• Explciit
• Explicit_client_dups_ok
• Transitional
• Local transitional.

32. What are the different types of messages that can be used in EMS
• Text
• Simple
• Bytes
• Map
• XML test
• Object
• Object ref
• Stream

33. Tell me about bridges. Why do we use them, Syntax to create bridges, use of message selector
? Some applications require the same message to be sent to more than one destination possibly of different types. So we use bridges.

34. What is the purpose for stores.conf
a. This file defines the locations either store files or a database, where the EMS server will store messages or metadata.
b. Each store configured is either a file-based or a database store.
35. How many modes are the messages written to store file.
2 modes.. sync or async. When absent , the default is async
36. What is tibemsd.conf
It is the main configuration file that controls the characteristics of the EMS server
37. How many delivery modes for messages?
Persistent, Non-persistent, Reliable-delivery.
38. What is the maximum messagesize?
Ems supports max message size of 512 mb
39. Name 3 destination properties and explain them.
Global, secure, maxmsgs, maxbytes, flowcontrol, sender_name, sender_name_enforced, trace,maxRedelivery

40. What are the different modes of installation in Ems?
a. GUI mode
b. Console mode
c. Silent mode
41. What are the messaging models supported by JMS
a. Point-to-point
b. Publish-subscribe
c. Multicast
42. Tell me about routes
What is the purpose of routes, what kind of destinations can be used in routes? Topics and queues m-hops
43. What happens if the message expires/exceeded the value specified by maxredelivery property on queue?
If the jms_preserve_undelivered property is set to true, then it moves he message to undelivered message queue, if set to false, the message is deleted by the server.
44. In how many ways can a destination be created?
a. Static-created by user
b. Dynamic-created by ems server on the fly.
c. Temporary destinations.

45. What are the wild cards that we use in ems?how do they work for queues and topics
*,>
U can subscribe to wildcard topics but cant publish to them. Where as in case of queues we can’t either send /receive.
46. Are bridges transitive?
NO
47. Tell me about flow control on destinations
Some times the producer may send messages faster than the consumers can receive them. So, the message capacity on the server will be exhausted. So we use flow control. Flow control can be specified on destinations.
48. Tell me about flow control on bridges and routes
Flow control has to be specified on both sides of bridges where as on routes it operates differently on sender side and receiver side.
49. Name 3 configuration files and tell me what it consists of
a. Queues.conf
b. Topics.conf
c. Routes.conf
d. Factories.conf
e. Stores.conf
f. Groups.conf,users.conf,transports.conf
50. Name some administrative level destination properties
a. View
b. Create
c. Delete
d. Modify
e. Purge
51. How can you change the configuration properties of EMS server
You can change in the tibemsd.conf file or you can change using the ems admin console.
52. What are the permissions that you can grant to users to access queues
a. Receive
b. Send
c. Browse
53. What are the permissions that you can grant to users to access topics
a. Subscribe
b. Publish
c. Durable
d. Use_durable
54. Tell me about multicasting in EMS
a. Multicast is a messaging model that broadcasts messages to many consumers at once rather than sending messages individually to each consumer. EMS uses Pragmatic general multicast to broadcast messages published to multicast enabled topics.
b. Each multicast enabled topic is associated with a channel.
55. What are the advantages and disadvantages of multicasting..
a. Advantages: as the message broadcasts only once thereby reducing the amount of bandwidth used in publish and subscribe model. Reduces the network traffic.
b. Disadvantages: Offers only last-hop delivery. So can’t be used to send messages between servers.
56. On what destinations can you use multicast?
a. Topics
57. Suppose, you got an error while accessing a queue, that you don’t have necessary permissions to access the queue. What might be the solution/reason?
a. The user that is assigned to the queue and the user used while creating
58. How does the secondary server know that the primary server is failed?
a. Based on heartbeat intervals

59. What is JMS queue requestor?
a. The JMS Queue Requestor activity is used to send a request to a JMS queue name and receive a response back from the JMS client
60. What is JMS topic requestor?
a. The JMS Topic Requestor activity is used to communicate with a JMS application’s request-response service. This service invokes an operation with input and output. The request is sent to a JMS topic and the JMS application returns the response to the request.
61. How do you add ems server to administrator?
a. Using domain utility
62. How do you remove individual messages from destinations?
a. Using purge command.