Thursday, August 7, 2014

How Mocking works

Enter Mock Objects

The concept behind mock objects is that we want to create an object that will take the place of the real object. This mock object will expect a certain method to be called with certain parameters and when that happens, it will return an expected result. Using the above code as an example, let's say that when I pass in 1234 for my key to the service.lookupByKey call, I should get back a List with 4 values in it. Our mock object should expect lookupByKey to be called with the parameter "1234" and when that occurs, it will return a List with four objects in it.

How Mock Objects Work

There are many different mocking frameworks in the Java space. I am not going to discuss any of them in great detail here. However, I will discuss how they work and design considerations you need to take in mind because of their implementations.
There are essentially two main types of mock object frameworks, ones that are implemented via proxy and ones that are implemented via class remapping. Let's take a look at the first (and by far more popular) option, proxy.
A proxy object is an object that is used to take the place of a real object. In the case of mock objects, a proxy object is used to imitate the real object your code is dependent on. You create a proxy object with the mocking framework, and then set it on the object using either a setter or constructor. This points out an inherent issue with mocking using proxy objects. You have to be able to set the dependency up thru an external means. In other words, you can't create the dependency by calling new MyObject() since there is no way to mock that with a proxy object. This is one of the reasons Dependency Injection frameworks like Spring have taken off. They allow you to inject your proxy objects without modifying any code.
The second form of mocking is to remap the class file in the class loader. The mocking framework jmockit is the only framework I am aware of that currently exploits this ability for mock objects. The concept is relatively new (since JDK 1.5 although jmockit supports jdk1.4 thru other means as well) and is provided by the new java.lang.Insturment class. What happens is that you tell the class loader to remap the reference to the class file it will load. So let's say that I have a class MyDependency with the corresponding .class file called MyDependency.class and I want to mock it to use MyMock instead. By using this type of mock objects, you will actually remap in the classloader the reference from MyDependency to MyMock.class. This allows you to be able to mock objects that are created by using thew new operator. Although this approach provides more power than the proxy object approach, it is also harder/more confusing to get going given the knowledge of classloaders you need to really be able to use all its features.


Mock objects are a very valuable tool in testing. They provide you with the ability to test what you write without having to address dependency concerns.
Ref :

Wednesday, August 6, 2014

We can have multiple level security in enterprise application
1. data level security with masking (enrypting data)

Another thing is how we organize how to store private keys

Advanced protection of Web applicationsagainst the following threats:
  • Web, HTTPS and XML attacks
  • SQL Injection
  • session hijacking
  • cross site scripting (XSS)
  • abuse of form fields
  • known worms
  • Zero Day worms
  • buffer overflow
  • cookie poisoning
  • Denial of Service
  • parameter tampering
  • brute force login
  • malicious code
  • directory traversal
  • attacks on Web servers and operating systems
  • scanning
  • command injection
  • illegal coding
  • identity theft
  • data theft
  • data disclosure
  • corporate espionage
  • phishing
data destruction

Wednesday, July 2, 2014

How to achieve reverse navigation flow within user Tasks in aciviti BPM

Achieving reverse workflow movement is tricky in BPM workflow. I tried such use case. I am providing potential approach for same in below write-up.

Reverse flow for sequential workflow

Reverse flow for Parallel workflow

Reverse flow can be achieved in  activiti task  using adding conditional links with appropriate source references.

e.g flow can be directed from Pay back to First task using conditions like

${sourceEvent == 'XXX'} etc.

flow can be directed from Xtask to approve using appropriate conditional statements.

Parallel gateway have behavior of  fork and join.

So extra logic need to build to keep taking of waiting and completed tasks.

Please see attached sample BPMN and Test case to run this logic.

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="" xmlns:xsi="" xmlns:activiti="" xmlns:bpmndi="" xmlns:omgdc="" xmlns:omgdi="" typeLanguage="" expressionLanguage="" targetNamespace="">
  <process id="SampleReverse" name="SampleReverse" isExecutable="true">
    <startEvent id="startevent1" name="Start"></startEvent>
    <userTask id="FirstLevel" name="FirstLevel"></userTask>
    <exclusiveGateway id="exclusivegateway1" name="Exclusive Gateway"></exclusiveGateway>
    <sequenceFlow id="flow1" sourceRef="FirstLevel" targetRef="exclusivegateway1"></sequenceFlow>
    <userTask id="SecondLevel" name="SecondLevel"></userTask>
    <exclusiveGateway id="exclusivegateway2" name="Exclusive Gateway"></exclusiveGateway>
    <sequenceFlow id="flow2" sourceRef="SecondLevel" targetRef="exclusivegateway2"></sequenceFlow>
    <userTask id="ThirdLevel" name="ThirdLevel"></userTask>
    <sequenceFlow id="flow3" sourceRef="exclusivegateway2" targetRef="ThirdLevel">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${backButton == 'false'}]]></conditionExpression>
    <sequenceFlow id="flow4" sourceRef="exclusivegateway1" targetRef="SecondLevel"></sequenceFlow>
    <sequenceFlow id="flow6" sourceRef="startevent1" targetRef="FirstLevel"></sequenceFlow>
    <sequenceFlow id="flow7" sourceRef="exclusivegateway2" targetRef="FirstLevel">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${backButton == 'false'}]]></conditionExpression>
    <exclusiveGateway id="exclusivegateway3" name="Exclusive Gateway"></exclusiveGateway>
    <sequenceFlow id="flow8" sourceRef="ThirdLevel" targetRef="exclusivegateway3"></sequenceFlow>
    <endEvent id="endevent1" name="End"></endEvent>
    <sequenceFlow id="flow9" sourceRef="exclusivegateway3" targetRef="endevent1">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${backButton == 'false'}]]></conditionExpression>
    <sequenceFlow id="flow10" sourceRef="exclusivegateway3" targetRef="SecondLevel">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${backButton == 'false'}]]></conditionExpression>
  <bpmndi:BPMNDiagram id="BPMNDiagram_myProcess">
    <bpmndi:BPMNPlane bpmnElement="myProcess" id="BPMNPlane_myProcess">
      <bpmndi:BPMNShape bpmnElement="startevent1" id="BPMNShape_startevent1">
        <omgdc:Bounds height="35.0" width="35.0" x="70.0" y="111.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="FirstLevel" id="BPMNShape_FirstLevel">
        <omgdc:Bounds height="55.0" width="105.0" x="150.0" y="100.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="exclusivegateway1" id="BPMNShape_exclusivegateway1">
        <omgdc:Bounds height="40.0" width="40.0" x="287.0" y="107.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="SecondLevel" id="BPMNShape_SecondLevel">
        <omgdc:Bounds height="55.0" width="105.0" x="350.0" y="100.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="exclusivegateway2" id="BPMNShape_exclusivegateway2">
        <omgdc:Bounds height="40.0" width="40.0" x="488.0" y="107.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="ThirdLevel" id="BPMNShape_ThirdLevel">
        <omgdc:Bounds height="55.0" width="105.0" x="563.0" y="100.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="exclusivegateway3" id="BPMNShape_exclusivegateway3">
        <omgdc:Bounds height="40.0" width="40.0" x="699.0" y="107.0"></omgdc:Bounds>
      <bpmndi:BPMNShape bpmnElement="endevent1" id="BPMNShape_endevent1">
        <omgdc:Bounds height="35.0" width="35.0" x="780.0" y="110.0"></omgdc:Bounds>
      <bpmndi:BPMNEdge bpmnElement="flow2" id="BPMNEdge_flow2">
        <omgdi:waypoint x="455.0" y="127.0"></omgdi:waypoint>
        <omgdi:waypoint x="488.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow3" id="BPMNEdge_flow3">
        <omgdi:waypoint x="528.0" y="127.0"></omgdi:waypoint>
        <omgdi:waypoint x="563.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow4" id="BPMNEdge_flow4">
        <omgdi:waypoint x="327.0" y="127.0"></omgdi:waypoint>
        <omgdi:waypoint x="350.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow6" id="BPMNEdge_flow6">
        <omgdi:waypoint x="105.0" y="128.0"></omgdi:waypoint>
        <omgdi:waypoint x="150.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow7" id="BPMNEdge_flow7">
        <omgdi:waypoint x="508.0" y="147.0"></omgdi:waypoint>
        <omgdi:waypoint x="507.0" y="204.0"></omgdi:waypoint>
        <omgdi:waypoint x="115.0" y="204.0"></omgdi:waypoint>
        <omgdi:waypoint x="115.0" y="128.0"></omgdi:waypoint>
        <omgdi:waypoint x="150.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow8" id="BPMNEdge_flow8">
        <omgdi:waypoint x="668.0" y="127.0"></omgdi:waypoint>
        <omgdi:waypoint x="699.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow9" id="BPMNEdge_flow9">
        <omgdi:waypoint x="739.0" y="127.0"></omgdi:waypoint>
        <omgdi:waypoint x="780.0" y="127.0"></omgdi:waypoint>
      <bpmndi:BPMNEdge bpmnElement="flow10" id="BPMNEdge_flow10">
        <omgdi:waypoint x="719.0" y="147.0"></omgdi:waypoint>
        <omgdi:waypoint x="718.0" y="187.0"></omgdi:waypoint>
        <omgdi:waypoint x="321.0" y="187.0"></omgdi:waypoint>
        <omgdi:waypoint x="321.0" y="129.0"></omgdi:waypoint>
        <omgdi:waypoint x="350.0" y="127.0"></omgdi:waypoint>

Thursday, June 27, 2013

When to not use static

Sunday, November 18, 2012

How to delete records in join sql query in oracle.

How to delete records in join sql query in oracle.

      from role_resource_privilege
      where exists (select rrp.*
      FROM role_resource_privilege rrp
      LEFT JOIN role r
      ON r.role_id = rrp.role_id
      LEFT JOIN resource_privilege rp
      ON rp.resource_id     = rrp.resource_id
      AND rp.privilege_id   = rrp.privilege_id
      where rp.resource_id is null
      OR r.role_id         IS NULL); 

ORA-01779: cannot modify a column which maps to a non key-preserved table

Oracle issue :
ORA-01779: cannot modify a column which maps to a non key-preserved table

Reason : 

      update (
      select ur.sysadmin FROM user_role ur
      INNER JOIN user_profile up
      ON up.user_id = ur.user_id
      INNER JOIN role r
      ON r.role_id      = ur.role_id
      WHERE ur.sysadmin = 1
      and ( up.sysadmin = 0
      or r.sysadmin     = 0 )) t
      SET t.sysadmin = 0;
   Because inline view returns 0 rows and oracle could figure out records to be updated.
Solution :
   update user_role usr set usr.sysadmin = 0
      where exists (
      select ur.* FROM user_role ur
      INNER JOIN user_profile up
      ON up.user_id = ur.user_id
      INNER JOIN role r
      ON r.role_id      = ur.role_id
      WHERE ur.sysadmin = 1
      and ( up.sysadmin = 0
      or r.sysadmin     = 0 ));
We can also use merge statement to update rows in join

          merge INTO resource_master c USING resource_master p ON (p.resource_id = c.parent_id)
        WHEN matched THEN
          UPDATE SET = 0;   

Why do we need 64 bit JVM

Why do we need 64 bit JVM:
The primary reason would be if you wanted to write an app capable of using a large amount of memory (e.g. over 4GB, or whatever the per-process limit on your operating system is).
1. When we need to handle more memory ptentially more than 4G.
2. Note, however, that due to the larger adresses (32-bit is 4 bytes, 64-bit is 8 bytes) a 64-bit JVM will require more memory than a 32-bit JVM for the same task.
3. The Java compiler produces byte code which is same whether you use the 32-bit or 64-bit JDK and plan to use the 32-bit or 64-bit JRE.
4. One way to use a 64-bit JVM efficiently is to use the -XX:+UseCompressedOops which uses 32-bit references in a way which can still access 32 GB of memory. It can do this because every object in the Sun/Oracle JVM is allocated on a 8-byte boundary (i.e. the lower 3 bits of the address are 000) By shifting the bits of the 32-bit reference, it can access 4GB * 8 or 32 GB in total. It has been suggested that this should be the default for Java 7.
Support for 32-bit programs
Programs written and compiled for a 32-bit JVM will work without re-compilation. However any native libraries used will not. A 64-bit JVM can only load 64-bit native libraries.