This post look on how applications components typically interact. Event-based programming, also called event-driven architecture (EDA) is an architectural style in which one or more components in a software system execute in response to receiving one or more event notifications.

 

1. Request-response interactions

Client formulate a request, It is sent across the internet to a web server. Client wait while the server constructs a response. This response is returned across the internet to client.

 

image

In a synchronous interaction the provider is expected to send a response back

image

 

2. Events and the principle of decoupling

Events are sometimes used to represent changes of state. The system being monitored is represented as a set of resources each of which is associated with state information. Event producers send events then internal state values change. This allows monitoring applications to be notified immediately when something happens, without their having to continually poll all the resources.

In a decoupled event processing system an event producer does not depend on a particular processing or course of action being taken by an event consumer. Moreover, an event consumer does not depend on processing performed by the producer other than the production of the event itself.

 

Above chart shows Decoupling of Entities from Object-Orientation to Event-Driven Architecture.

 

3. Push-style event interactions
 
In here events are often sent as one-way messages. It pushes the event to each consumer as a one-way message as below diagram. Event producer wait for a response from the consumer

image

 

4.  Channel-based event distribution

In 3 model, producer has to send multiple copies of the same event to consumers. The event producer can find their identities by consulting an external information source.

image

 

5. Request-response interactions to distribute events

In pull-style distribution, the consumer uses the standard request-response pattern to request an event from a producer, or from an intermediary channel.To avoid having to hold on to events and to avoid having to service requests from multiple consumers, event consumer 1 sending a pull request directly to the event producer (message 1).
producer uses a regular push (message 3) to send the event to the channel, and consumer 2 requests it (message 3.1) from the channel. This approach can be extended to send multiple events in
the response messages.

image

Where is this useful

  • A consumer that is only available occasionally
  • A producer that is unable to distribute events
  • A consumer that is physically unable to receive unsolicited incoming events(eg: due to firewall)
  • A consumer that wants to regulate its processing of events and have control
    over exactly when it receives them
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Labels: CEP Complex Event Processing Event Driven Architecture Event Processing
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NOTE

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1.  Start SMSC

2.  Create custom inbound end point with below parameter. (Make sure you pick correct system-id and password correct for your SMSC)

3. Create Sequence for Inbound EP.

4. Once ESB or EI start.

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Vehicles registration services using REST services on government TAX department system. That REST services give the TAX information for the Vehicle.

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There is few thing that make my work enjoyable with WSO2 ESB as it provides support for JavaScript Object Notation (JSON) payloads in messages. It is not very new feature and it old feature.

Working on an Alienvault IDS system or OSSIM you can come across over huge amount of alarms are created will system migrations.

If you’re familiar with SEIM tools or OSSEC, then you know syscheck. Syscheck is the integrity checking daemon within OSSEC. It’s purpose is simple, identify and report on changes within the system files.

Triggering action over the event occurrence in OSSIM is going to explain in this article.

There is agent in the system with IP, 192.168.80.22. Email is to be send to server admins whenever this agent disconnect and reconnect to SEIM server.

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Pre request

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In here I am using well known decoder in OSSEC if you need new OSSEC decoder you can write new decoder also [1]. Add new file to  rules directory in OSSEC.

Creating new OSSEC rule set

$ vi var/ossec/rules/custom_access_rules.xml

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A brute-force attack consists of an attacker trying many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct one is found.

Unfortunately Windows does not support Fdisk anymore. But there is another good command line tool to solve this problem. DiskPart in windows is useful format unallocated spaces in USB pen.

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Then disk part will start

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list disk

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Count line when words has been matched

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2. Make bootable pen with OSSIM ISO file

3. Boot drive

Make sure you have internet connection

4. Select OSSIM server to install

5. Just follow the the wizard

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Finding the logs in my server. I generally use lsof to list what is my server.

lsof | grep log

I check which log are reading by OSSEC

Check cat /var/ossec/etc/ossec.conf  |grep "<location>/"

Add new access log to OSSCE.

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