SOA Overview Part-1

 

Middleware

It provides a mechanism for the process to interact with other processes running on multiple network machines.

Advantages that middleware could provide are:

- Independence from network services

- Independence from operating system calls

- Reliability

- Availability

- Scalability 

There are four basic types of middleware

TP           Transaction Processing Monitor

RPC        Remote Procedure call

MOM    Message oriented Middleware

ORB       Object request Broker

Enterprise resource planning (ERP)

Enterprise resource planning (ERP) is business process management software that allows an organization

"To use a system of integrated applications to manage the business and automate many back office functions

 Related to technology, services and human resources."

It is a business software system that allows an organization to automate and integrate with the various business processes sharing common data across enterprises.

ERP software typically integrates the different facets of an operation like product planning, development, and manufacturing, sales, marketing etc.

Using a single database, application, and interface. 

Oracle Fusion Middleware?

Oracle Fusion Middleware is a collection of standards-based software products that spans a range of tools and services.

Oracle Fusion Middleware offers complete support for development, deployment, and management.

What is Oracle SOA Suite Tool

" SOA Suite tool is a middleware tool from Oracle which is based upon SOA concept comes under Oracle  Fusion Middleware stack. We use this tool for integration purpose. i.e. This tool is used to integrate two system/applications etc."

What is SOA? 

Service oriented Architecture 

"SOA stands for Service Oriented Architecture. SOA is not any tool, rather is a concept and there are many tools in the market based upon this concept. In this SOA Concept, we use SOA layer as middle or intermediate layer between services so that these service can communicate with each other" 

Service Oriented Architecture (SOA) is used to develop Enterprise applications by using a collection of services which communicates each other. Service-Oriented Architecture (SOA) is a set of principles and methodologies for designing and developing software in the form of interoperable services.

è It is a design pattern or software architecture which provide service to other application.

è It is implemented as web service.

This enables to

Ø  Reuse functionality

Ø  Have loose coupling between functionalities

Ø    Abstract implementation

Ø  Allow multiple protocols to talk to each other 

SOA:

Ø  Reusability

Ø  Distributed deployment

Ø  Interoperability

Ø  Compensability

Key Role:

Ø  Service consumer

Ø  Service provider

Ø  Service registry

SOA key technologies include:

  ØXML

ØWebservice

ØSOAP

 ØWSDL

ØUDDI

ØXPATH

ØQUERRY

SOA Benefits:

Ø  Increase response time

Ø  Help businesses become more cost effective

Ø  Separate consumers and services

Ø   Loose Coupling: This means that the service requester has no knowledge of the technical details of the provider’s implementation, such as the programming language, deployment platform, and so forth. The service requester typically invokes operations by way of messages — a request message and the response — rather than through the use of APIs or file formats.

Ø  Cost Cutting

Ø  Better reuse: Build new client functionality on top of existing Business Services.

Ø  Well defined interfaces: Make changes without affecting clients

Ø  Easier to maintain : Changes/Versions are not all-or-nothing

Ø  Better flexibility

SOA Principles:

Ø  Loose Coupling

Ø  Reusability

     Interoperability: In SOA, We can easily communicate btn different component in SOA.

Ø  Flexible

Ø   Service Autonomy

Ø  Service Contract

Ø  Service Abstraction

Ø  Discoverability

Ø  Service statelessness

     Scalability: Without affecting code we can add different adapter

Architecture of SOA:

Service Oriented Architecture is an architectural design which includes collection of services in a network which communicate with each other. 

It’s an architecture solution to build an integrate systems, applications, process and businesses.

 

SOA architecture is viewed as five horizontal layers. These are described below:

·         Consumer Interface Layer:

o   This layer is used by customer

o   These are GUI based apps for end users accessing the applications. 

·         Business Process Layer:

o   Provide the business process flow. Also accommodates new changes in business easily.

o   These are business-use cases in terms of application.

·         Services Layer: These are whole-enterprise, in service inventory.

·         Service Component Layer: are used to build the services, such as functional and technical libraries.

·         Operational Systems Layer: It contains the data model.

 

Basic architecture of a Service Composite in Oracle SOA Suite.

·        Service components − BPEL Processes, Business Rule, Human Task, Mediator. These are used to construct a SOA composite application.

·        Binding components − Establish connection between a SOA composite and external world.

·        Services − Provides an entry point to SOA composite application.

·        Binding − Defines the protocols that communicate with the service like SOAP/HTTP, JCA adapter, etc.

·        WSDL − Defines the service definition of a web service.

·        References − Enables a SOA composite application to send messages to external services

·        Wires − Enables connection between service components.

What is SCA

Ø  Assembling the service components into a SOA composite application.

Ø  SCA provides a programming model that model allows creating service components written with a wide range of technologies

Ø  Provide a framework for building applications using SOA

Ø  Define a composite application where set of services are assemble together

Ø  Provide a assemble model to wire together new services and existing services

Ø    Extend and compliments existing approaches to implements services.

Ø  Designed based on open standards such as webservices.

SCA can made up of:

Ø  BPEL Process

Ø  Mediator

Ø  Human task

Ø  Business Rules

SCA simplified the entire lifecycle

Development:

è JDev can be used to develop all components.

Deployment:

è All components are grouped together in a composite and during compilation, we get a single file called SAR

è SAR can be versioned as one, deployed as one and managed as one

Monitoring:

è EM allows to trace the entire flow, giving ability to drill down into components of a composite

5 key element of SCA

1) composite: Deployment unit

2) Service: Entery point into the composite,

Exposed Service:Service expose by the component that are callable from outside.

3) Components: Provides the logic to be used with in the composite.

4) Refrence: Refers to internal and external services.

5) wire : Connects services,components and references.

3 sections in composite.xml

Exposed Services | Service Components | External References

Binding Components

Exposed Services & External References

Responsible to interact with outer world from SOA

Benefits of SCA?

 Below are the major benefits of SCA.

1. Easier Development: No need to write lengthy code as we get all components prebuilt.

2. Easily compose a assembly (composite) by just linking different these prebuilt components.

3. Better re-usability

Composite

Ø  Basic unit of SCA

Ø  It is collection of different service component ex:BPEL, Mediator etc.

Ø   SOA composite is a assembly comprises of one or more than one pre-build components. In SOA composite we wires different components together to perform required business functionality.

Ø  Service Component that implement business logic

Ø  Binding to enable communication between Service Component and external service or between composites.

Ø  Wiring that connects components with the composite to enable communications.

 

Mediator

"The mediator component enables data routing between the service consumers and provide based on routing rules"

It support both Synchronous and Asynchronous routing of data.

VETO- Validate, Enrich, Transform, and Operate. 

BPEL

 Business process Execution Language

Process Orchestration

Ability to build and deploy business process.

Coordinates multiple service to complete a business process. 

Oracle Business rules

Enables business to change their decisions and policies 

Human Task

It enable business processes to involve human interactions.

It involves assigning and routing tasks to correct users and groups 

SOA PATTERNS
Synchronous
Asynchronous

One-way

BPEL - Adapters

Adapters enable to integrate the BPEL process service component with access to file systems, FTP servers, database tables, database queues, sockets, Java Message Services (JMS), MQ, and Oracle E-Business Suite.  

Advanced Queuing (AQ)

For interaction with a queue. AQ provides a flexible mechanism for bidirectional, asynchronous communication between participating applications.

Oracle Business Activity Monitoring (BAM)

For publishing data to data objects in an Oracle BAM Server.

Database

For interaction with Oracle and non-Oracle databases through JDBC and Oracle Business Intelligence (which is a special data source type).

FTP and File

For file exchange (read and write) on local file systems and remote file systems (through use of the file transfer protocol (FTP)).

Java Messaging Service (JMS)

For interaction with JMS. The JMS architecture uses a one client interface to many messaging servers architecture.

Message Queue (MQ)

For message exchange with WebSphere MQ queuing systems.

Oracle Applications

For interaction with Oracle Application's set of integrated business applications.

Oracle B2B

For browsing B2B metadata in the metadata service (MDS) repository and selecting document definitions.

Sockets

For modeling standard or nonstandard protocols for communication over TCP/IP sockets.

Adapter

Transactional Adapter
Ø  Database
Ø  JMS
Ø  WebService
Non Transactional Adapter
Ø  File
Ø  FTP

There are two types of request

Inbound: something which is coming from outer world toward us.

It will be always implicit (we need not to be initiated)

Outbound: where we r sending

It will be always explicit (need to be initiated)

Database Adapter

->It is used to communicate with oracle database or 3rd party database by leveraging underlying jdbc connector/drivers.

-> Has the input/ output messages that are easily converted into xml.

 ->Support synchronous calls from BPEL/mediator.

Operation type:

o   Call a stored procedure or functions

o   Perform an operation on a table.

o   Poll for new or changes records in a table.

o   Execute pure sql.

DB Adapter Configuration in weblogic server

In weblogic server console

Create JDBC Data Source

o   Set JDBC data Source Properties.

o   Configure transaction options- XA or Non-XA

o   Configure connection  properties

o   Test Connections      

 Deploy new JDBC Data Sources by selecting target server

 Create an outbound connection pool for DB adapter.

 Add JNDI name of new JDBC data source in properties values of outbound connection pool.

 

JMS Adapter

   Is used to send or receive messages from JMS queue or topic.

     Supports both inbound and outbound adapter service.

An inbound adapter service receive data from an external messaging system and transforms it into a xml message.

An outbound adapter service sends data to a target application by transforming an XML message into the native format of the given adapter. 

Supports byte,text, and map message types.

Supports JMS headers and properties.

Support  jca.message .encoding  property 

Operation Types:

o   Consumer message

o   Produce message

o   Request/reply 

JMS Adapter Configuration in Weblogic server:

Create an outbound connection pool for JMS Adapter.

In the JNDI name field, enter the JNDI name that you want to use to obtain the new connection instance.

 Ex: eis/wls/queue

Add JNDI name of new JDBC Data source in properties values of the outbound connection pool.

 

FILE and FTP Adapter

   It is used to exchange (read\write) files on local systems or remote file system using FTP(File transfer protocol).

Operation types:

 Oracle File adapter:

o   Read file (inbound operation)

o   Write file (outbound operation)

o   Synchronous read file (outbound operation)

o   List files (outbound operation)

Oracle FTP Adapter:

o   Get File (inbound operation)

o   Put File (outbound operation)

o   Synchronous Get File (outbound operation)

o   List Files (outbound operation) 

   The oracle file and FTP adapter can read and write the following file formats

o   Xml(both xsd and dtd based)

o   Delimited

o   Fixed positional

o   Binary data

o   COBOL Copybook data 

FTP adapter configuration in weblogic server console

Update the deployment profile for FTP adapter.

Creat a new security credential Map entry for  eis/FTP/FTPAdapter.

Enter EIS username and password details.

How to Poll Single file from FTP/File location which has multiple files ?

Lets take one example if we have include file wild card as *.txt and there are 2 files available at File/FTP Location. So read operation will read both the file and create two instance and created time will be same for both the instance. To avoid such scenario and read only one file at a time, we need to use below property in jca file.

<property name="SingleThreadModel" value="true"/>

      <property name="MaxRaiseSize" value="1"/>

SOA Templates

With the introduction of templates sharing of code between teams become earlier and development efforts reduced. There are three types o

f templates introduced.

Project Template

Component Template

Custom Activity Template

Template is term used for re-usable component. When we talk about templates in SOA these refers to re-useable stuff related to services, project and component.

Project Template:  This template contains full project along with all the artefact’s, components and references. We can create project template from Jdeveloper 12c, when we create this template from Jdeveloper 12c then template location gets added to the Jdeveloper preferences automatically but when we need to use external templates then we need to add external template location in the Jdeveloper. We can build new application from this project template, this new application imports all the artefact’s, components and references which are there in project template.

Component Template:  This template contains service components. We can create template from any composite component. It also contains all reference components and resources which are there inside that component. You can find this template in the SOA composite application's Components window and it appears as a custom service component. 

E.g. a BPEL process which calls database adapter can be used as component template. Once we build template from this BPEL, that template contains all the components, references and artefacts which are inside that BPEL process. Please note that this BPEL need not to be complied and need not to be complete.

Custom activity Template: This template contains an activity of a BPEL process which may include assign, transform, invoke, and receive and partner link. We can use this template in the same BPEL or in any other BPEL. This template also contains all the variables, references and artefacts which are related to that activity. Custom activities will be available in the BPEL palette. 

BPEL Sub-process

Sub-process is introduced in this launch which helps to reduce redundancy. Suppose we need to update database table 3 times in one flow so instead of add 3 different invoke to same BPEL, create sub-process which update the database table and use that sub-process 3 times in that BPEL. There are two types of sub-processes.

Standalone sub-process

Inline sub-process

Sub Process act like a bundle which contain a piece of BPEL code which we can re-use inside same BPEL or different BPEL in same composite. Sub process contains fragment of BPEL code.  Benefit of sub process is that it increases developer productivity and chances of human error got reduced. Suppose we have a piece of code which we need to use at multiple places in one BPEL or in one composite so instead of writing same logic/code again and again in BPEL, we can create sub process of the logic/code and call it where ever required in that BPEL or in different BPEL but in same composite. So whenever we need to make any change into the logic/code we need not to do that change at all places, we just need to do that change in sub process and that change will reflect at all place wherever we call that sub process.

Sub processes are supported for only BPEL 2.0; it is not supported for 1.1 version. In the first release of 12c, we cannot use sub processes across multiple composites i.e. sub processes can be used inside same composite only.

Inline Sub-Process

  As name suggests this sub process is in line to parent BPEL process means this can’t be used outside parent BPEL process. Inline sub process contains group of activities which we can re-use within one BPEL process only. This sub process is not visible in composite view as this is part of parent BPEL.  This sub process is visible in palette under sub process. We need to use call activity to call this sub process inside BPEL process. Below is real time example which explains the use of inline sub processes. 

E.g. suppose we receive the sales order from source system, once we receive the sales order, first we update the source system that we receive the sales order successfully, secondly after we receive the order, we do required validations and submit the order to target system, after we submit, we again send status back to source system that order is successfully submitted. In both the cases we update database flag in source system. Here we can use inline sub process, we can put activities which update the status in source database in one scope and create an inline sub process from it. Once we have inline sub process created, we can use call activity to call that sub process to update the receive status and submit status. So if in future there is any change in table structure or table columns then we need to make that change only in sub process and that will reflect at both the places.

Standalone Sub-Process

As name suggests this sub process act as standalone inside one composite. Standalone sub process is similar to inline sub process, except we can use it outside of parent process. This sub process contains group of activities that can be re-used across other BPEL processes. Similar to inline sub process we use call activity to invoke standalone sub process. This sub process is also visible in palette under sub process. 

Parallel Flow in a BPEL Process

Parallel flows are especially useful when you must perform several time-consuming and independent tasks.

A BPEL process service component must sometimes gather information from multiple asynchronous sources.

Because each callback can take an undefined amount of time (hours or days), it may take too long to call each service one at a time.

By breaking the calls into a parallel flow, a BPEL process service component can invoke multiple web services at the same time, and receive the responses as they come in. This method is much more time efficient.

Execution of Parallel Flow Branches in a Single Thread

Branches in flow, flowN, and forEach activities are executed serially in a single thread.

To achieve pseudo-parallelism, you can configure invoke activities to be nonblocking with the nonBlockingInvoke deployment descriptor property. When this property is set to true,

the process manager creates a new thread to perform each branch's invoke activity in parallel.

Creating a Parallel Flow

You can create a parallel flow in a BPEL process service component with the flow activity.

The flow activity enables you to specify one or more activities to be performed concurrently. 

The flow activity also provides synchronization. 

The flow activity completes when all activities in the flow have finished processing.

Note: Branches in a flow activity are executed serially in a single thread.

A flow activity typically contains many sequence activities.

Each sequence is performed in parallel.

FLOW

The BPEL Code determines the number of parallel branches.

The flow activity provides a mechanism to specify one or more sequence of activities to be performed concurrently.

The BPEL Code determines the number of parallel branches. However the number of required branches could vary depending on the available information.

flowN

Create multiple flows equal to the value of N. which defined at run time based on data available and logic within within the process.

An index variable increments each time a new branch is created, until the index variable reaches the value of N.

Types of Faults

Let us now see the different types of faults.

Business faults

Occurs when application executes THROW activity or an INVOKE receives fault as response. Fault name is specified by the BPEL process service component. The fault handler using Fault name and Fault variable catches this fault.

Runtime faults

This is thrown by the system. These faults are associated with RunTimeFaultMessage and are included in

http://schemas.oracle.com/bpel/extensionnamespace. 

Ways of Fault Handling

Throw Activity

Throw activity explicitly throws the fault. The catch block catches this fault and the corresponding actions get executed thereby.

·        Using throw activity, you can throw business faults & within the created scope, you can catch this fault and redirect to the caller (consumer) to take action.

·        Instead of the above approach, you throw the same fault caught in catch activity of the created scope. In the main scope, you can catch this fault using the catchall activity. 

Error Handler Framework (EHF)

The 2 main files used in EHF are −

Fault-Policy.xml

Fault-Bindings.xml 

Whenever the BPEL process throws an error, the EHF will check whether the error exists in Fault-Bindings.xml files. If so, the action in the Fault-Policy.xml file will be taken. If the action is not found, the fault will the thrown and it will be handled in the catch block.

Fault management framework (Fault-Policy.xml and Fault-Bindings.xml) is kept inside a SOA Composite.

Fault-handlers like catch and catchall are inside a BPEL to catch all faults, but 

fault policies will only be executed when an invoke activity fails. 

BPEL - Multiple Application Interactions

Correlation

multiple application interactions with BPEL

·        When there are more than two applications involved in a transaction.

·        This A-to-B-to-C-to-A transaction pattern can handle many transactions at the same time. Therefore, a mechanism is required for keeping track of which message goes where.

·        This can be handled using WS-Addressing or correlation sets.

Note − The difference between responding from a synchronous and asynchronous BPEL process is that the synchronous service uses a reply activity to respond to the client and an asynchronous service uses an invoke activity.

Correlation Sets

Correlation sets are used to uniquely identify process instances. You provide each correlation set with a unique name and then define it by one or more properties. Each property has a name and a type (for example, string or integer).

Property Alias

The property alias for each property in the correlation set needs to be defined. A property alias is a mapping that binds the property with the input or output values.