Wednesday, 10 September 2014

Message Throttling, Service Virtualisation, Load Balancing and Service Result Cache features of OSB

Message Throttling, Service Virtualisation ,Load Balancing and Service Result caching features of OSB are some of the main features of OSB which gives it an added advantage over other integration tools..


Message Throttling -
A common problem with integration is the risk of overloading a particular web service. When the capacity of a web service is reached and it continues to accept connections, it will most likely start to deteriorate.

Limiting the Concurrent Number of Requests
Limiting the concurrent requests for a Business Service cannot be set at design time so you have to use the built-in Oracle Service Bus Administration Console to do it (/sbconsole). Follow these steps to enable it:
In Change Center, click Create to start a new Session
Select Project Explorer, and navigate to the Business Service you want to limit
Select the Operational Settings tab of the View a Business Service page
lIn this tab, under Throttling, select the Enable check box. By enabling throttling you
pSpecify a value for Maximum Concurrency
pSpecify a positive integer value for Throttling Queue to backlog messages that has exceeded the message concurrency limit
pSpecify the maximum time in milliseconds for Message Expiration a message can spend in Throttling Queue
lClick Update
lClick Active in Change Center to active the new settings


Service Virtualisation - 
Service virtualization is an approach to deploying and managing services.

A core principle of SOA is to ensure that any service consumer can access any service provider - and from any platform. This has been considered as key principle in OSB and it provides robust way of Vitalizing the Service. It’s a great value add in SOA Architecture.

This we can achieve in OSB, by doing,  protocol transformation, message transformation and by routing the service to the end system(backend) dynamically. 

Service Result Cache - 
Service Result Caching is one of the options that you can use when you want to improve Oracle Service Bus performance. Service Result caching is used when we have business service which connects to external service which returns somewhat static response. So by using Service Result Caching we don’t hit external service for same request instead it will take the response from cache which improve the OSB performance

Load Balancing:
lIn Oracle Service Bus you must define at least one endpoint URI for a business service. When you define multiple endpoint URIs for a business service you must define one of the following load balancing algorithm:
pRound robin
pRandom
pRandom-weighted
pNone

lThe load balancing algorithm controls the manner in which business service tries to access the endpoint URI. 
Round-robin - This algorithm dynamically orders the URLs that you enter in the Endpoint URI field for this business service. If the first one fails, it tries the next one, and so on until the retry count is exhausted. For every new message, there is a new order of URLs.
Random - This algorithm randomly orders the list of URLs that you enter in the Endpoint URI field for this business service. If the first one fails, it tries the next one, and so on until the retry count is exhausted.
Random-weighted - This algorithm randomly orders the list of URLs that you enter in the Endpoint URI field for this business service, but some are retried more than others based on the value you enter in the Weight field.
  None - This algorithm orders the list of URLs that you enter in the Endpoint URI field for this business service from top to bottom.


Some quick FAQs :


1. when you deploy the service does caching get refreshed ?
Ans: It will not be refreshed, when proxy service is redeployed. But will be refreshed when BusinessService(where actual caching is happening) is deployed.

2. When you change the service through console and then redeploy the service from eclipse does it overwrite the changes like monitoring and throtlling, endpoint uri  ?
Ans : It will overwrite endpoint uri.
Monitoring - no
Throttling - no

As Monitoring and throttling are done from SB console these values will remain as is.

3. For Load balancing when we set offline URI option for the unavailable business service , Will offline URL will be offline after deployment ?
Ans. yes it will be offline, till its time is over or we make it online through console.

4. Load balancing algorithm in OSB Business service ?
 Round-robin - This algorithm dynamically orders the URLs that you enter in the Endpoint URI field for this business service. If the first one fails, it tries the next one, and so on until the retry count is exhausted. For every new message, there is a new order of URLs.

Random - This algorithm randomly orders the list of URLs that you enter in the Endpoint URI field for this business service. If the first one fails, it tries the next one, and so on until the retry count is exhausted.
Random-weighted - This algorithm randomly orders the list of URLs that you enter in the Endpoint URI field for this business service, but some are retried more than others based on the value you enter in the Weight field.
None - This algorithm orders the list of URLs that you enter in the Endpoint URI field for this business service from top to bottom.

5.  In result caching, what is the TTL(Time to live) by default?
Ans; Default expiration time is taken from OSB coherence config file- //config/osb/coherence/osb-coherence-cache-config.xml
By default it is set to 5 minutes,

6. In Result caching how and where we use xquery expression for  Expiration time ?
Ans. It is worth noting that the Cache Token may be specified as any expression you like, using the XQuery functional programming language.
XQuery has a rich syntax for constructing queries, including the use of many system libraries with common functions such as numeric operations and string manipulation.
Clear the cache explicitly
It might be that you can’t risk the cache becoming stale under certain circumstances.  If that is the case, rather than using a time parameter to manage the lifetime of the cached responses, mark critical requests with an additional flag and select XQuery Expression in the expiration time options to test for the existence of this flag.

7.where we will set the persistent level and priority while calling JMS queue ?
Ans: In JMS transport page of Business service we can set the message persistence.

For Message Priority, we can use transport header activity in Proxy service to set the priority for a message



8. what is this Tracing option in monitoring page ?
By using tracing option, we can actuallly see the message flow for that particular service in logs.Tracing messages in the Oracle Service Bus can give you a very good insight of what’s really happening inside your services. Message tracing can be very valuable for detailed monitoring the content of the requests (full) and give you insight on the amount of service calls going in your service (headers or terse).
The tracing information is stored in the server directory logs at the following location:
DOMAIN_HOME/domain/servers/server_name/logs/server_name.log

Source: http://jvzoggel.wordpress.com/2012/01/23/osb_tracing_runtime/

9. In Sbconsole, inside General Configuration, what is the use of state ?
Ans. It actually say whether the service is online(available) or offline.



Very useful brief Usage of operational settings,
"Copied From Oracle " - http://docs.oracle.com/cd/E28280_01/admin.1111/e15867/monitoring_ops.htm

Operational Settings for Services in the Administration Console
Operational SettingsUsageDefault Value When a Service is Created
State
Use this to enable or disable a service.
Enabled
Monitoring
Use this to enable service monitoring at a specific level or above. You can also use this to disable service monitoring for proxy services.
Disabled
Aggregation Interval
Use this to set the aggregation interval for the service.
10 minutes
SLA Alerts
Use this to enable SLA alerting for services at a specific level of severity or above. You can also use this to disable SLA alerting for a service.
Enabled
Pipeline Alerts
Use this to enable pipeline alerting for proxy services at a specific severity level or above. You can also use this to disable pipeline alerting for proxy services.
Enabled at Normal level or higher
Reports
Use this to enable or disable message reporting for proxy services.
Enabled at Normal level or higher
Logs
Use this to enable logging at a specific severity level or above. You can also use this to disable logging for proxy services.
In proxy service log actions, the severity level of the log actions must match the Logging severity level on the proxy service operational settings.
Note: To see log data in the log file or standard out (server console), Oracle WebLogic Server logging must be set to the following severity levels:
  • Minimum severity to log: Info
  • Log file: Info
  • Standard out: Info
For information on setting log severity levels, see "Using Log Severity Levels" in Oracle Fusion Middleware Configuring Log Files and Filtering Log Messages for Oracle WebLogic Server.
Enabled at Debug level or higher
Execution Tracing
Use this to enable or disable execution tracing for proxy services.
Note: To see tracing in the log file or standard out (server console), Oracle WebLogic Server logging must be set to the following severity levels:
  • Minimum severity to log: Info
  • Log file: Info
  • Standard out: Info
For information on setting log severity levels, see "Using Log Severity Levels" in Oracle Fusion Middleware Configuring Log Files and Filtering Log Messages for Oracle WebLogic Server.
Disabled
Message Tracing
Use this to enable or disable message tracing for proxy services at a specific detail level or above. You can also set the payload limit (in kilobytes) and the default encoding.
Note: See note for Execution Tracing.
Disabled
Offline Endpoint URIs
Use this to enable or disable non responsive endpoints for business services. You can also specify the interval of time to wait before retrying the offline endpoint URI. You can enable or disable offline URIs for business services only.
Disabled
Throttling State
Use this to enable or disable throttling for a business service.
Disabled
Maximum Concurrency
Use this to restrict the number of messages that can be concurrently processed by a business service.
0
Throttling Queue
Use this to restrict the maximum number of messages in the throttling queue.
0
Message Expiration
The maximum time interval (in milliseconds) for which a message can be placed in throttling queue.
0
Result Caching State
Use this to enable or disable result caching for a business service
Enabled
Result caching is globally enabled by default

Tuesday, 2 September 2014

OSB VS BPEL, Which one to go for and Why...

OSB and oracle BPEL both are very popular tools for integrating the systems.

After going through some blogs, here is the quick info:

Basic Differences:

1. OSB is stateless and BPEL can be made stateless by setting the audit settings. However the audit settings turning off doesn't apply to mediator. 
2. OSB is far more superior in performance because it is stateless. In addition, it offers capabilities not supported in composite development such caching, throttling, and service virtualisation.
3. OSB has some severe limitations; the most serious being within transaction visibility, tracing, and metrics. It is either difficult, cumbersome, or impossible to find out if transactions have gone through the OSB engine and detailed, dynamic metrics are unavailable. 
4. OSB 11g cannot reference artifacts in the MDS (MetaData Store). Custom code is required for DVM support.
5. SOA Suite provides a better capability to handle transactions, compensation and asynchronous flows.
6. BPEL is better when the logic is complex as it has many inbuilt activities.
7. You dont get any monitoring and SLA management capability with Mediator and SOA. 
8. SOA Suite provides a better capability to handle transactions, compensation and Asynchronous.
9.As BPEL uses dehydration store to store the life cycle of a BPEL instance, it is very useful for long running processes.

Coming Back to OSB...
Few Features of OSB such as Service Result Caching, Message Throttling and service Virtualisation, makes it an ideal choice where Service Virtualization and 
 Message-Oriented Solutions are required.