Building Blocks for Integration IST 421 Spring 2009

Building Blocks for Integration IST 421 Spring 2009

Building Blocks for Integration There are four basic building blocks for integration: ◦ Communications models (logical middleware models) ◦ Method of integration ◦ Middleware ◦ Services

Communications Model Two basic choices for communications: ◦ Synchronous – tightly coupled to applications ◦ Asynchronous – decoupled from the applications

Synchronous Communication Requires a sender and a receiver Sender of a request waits until a reply is received before processing continues Requires a reliable network infrastructure

Synchronous Communication Typically used for interactive systems ◦ Web sites connected to a database ◦ Java applications interacting with mainframe applications ◦ Windows applications interacting with an ERP package like SAP R/3

Synchronous Communication Three popular types of synchronous communications: ◦ Request / reply ◦ One-way ◦ Polling

Synchronous Communication Request / reply

Synchronous Communication Request / Reply ◦ Sender must stop and wait for a response ◦ If receiver’s processing takes too long, performance will be impacted ◦ If receiver not able to comply with request, sender might not be able to continue at all ◦ Uses a lot of bandwidth on the network

Synchronous Communication One-Way

Synchronous Communication One-Way ◦ No information other than acknowledgment sent ◦ Receipt of acknowledgment should be faster than waiting for processing to complete

Synchronous Communication Synchronous Polling

Asynchronous Communication Does not require the sender and receiver to coordinate their processing with any communications Sender communicates the request and then continues processing Used when there is no need to coordinate activities or responses

Asynchronous Communication Three popular types of asynchronous communication: ◦ Message passing ◦ Publish / subscribe ◦ Broadcast

Asynchronous Communication Useful when just transferring information Can operate in an unreliable environment

Asynchronous Communication Message Passing

Asynchronous Communication Message Passing ◦ Simplest form of asynchronous communication ◦ Must provide guaranteed delivery Continue to try to send until complete the communication Without guaranteed delivery, request may be lost

Asynchronous Communication Publish / Subscribe

Asynchronous Communication Publish / Subscribe ◦ ◦ Messages sent based on interest of receiver Developer of application defines interests Design complexity No reply is required Uses ◦ Notifying an order has been shipped ◦ Subscribe to news service for type of news

Asynchronous Communication Broadcast

Asynchronous Communication Broadcast ◦ Message is sent to every application in the system ◦ Can become a performance bottleneck since each possible receiver must look at each broadcast message

Building Blocks for Integration ¡ There are four basic building blocks for integration: l Communications models l Method of integration l Middleware l Services

Methods of Integration Approach used to construct a request from a sender to a receiver Two primary methods of integration: ◦ Messaging ◦ Interface definitions

Methods of Integration - Messaging o Contains: ◦ Information like $174. 39 and account number 017359 ◦ Action such as deposit in checking o Message needs to be coded and decoded same way by all senders and receivers

Methods of Integration Messaging Designers must predefine the messages Application that sends a message must be able to: ◦ ◦ ◦ Create message in appropriate format Place message into communications system Receive message from communications system Parse message into its action and information Determine what to do with message

Methods of Integration – Interface Definition o Sender communicates through an interface which defines actions that can be invoked Interface is associated with an application Interfaces make application look like a procedure or an object using C, C++, or Java

Methods of Integration – Interface Definition Process for using interfaces: ◦ Create an invocation or call to the component Call account. Deposit with parameters account. Number and value ◦ Execute the call Asynchronous communication ◦ Receive a remote invocation or call ◦ Execute the action based on interface used

Methods of Integration Connectors – logic that is programmed into an application to provide access to: ◦ Presentation ◦ Data ◦ Functionality of the application in a structured manner

Building Blocks for Integration ¡ There are four basic building blocks for integration: Communications models l Method of integration l Middleware l Services l

Middleware Allows one entity (application or database) to communicate with another entity or entities using messages or interfaces. ◦ Originally designed for intra-enterprise integration ◦ New demand for inter-enterprise integration

Middleware There are five basic types of middleware in the market today: ◦ Remote procedure calls ◦ Database access middleware ◦ Message oriented middleware ◦ Distributed object technology ◦ Transaction processing monitors

Middleware Communications model and method of integration are closely tied to middleware that is employed Five types of middleware represent a basic level of infrastructure capabilities

Middleware RPC (Remote Procedure Call) ◦ Invoke a function within one program & have the function execute within another program on a remote machine ◦ Synchronous process ◦ Best know RPC is the Distributed Computing Environment (DCE) from the Open Software Foundation (OSF) ◦ Popularity peaked in the late 1980 s

Middleware RPC (Remote Procedure Call) cont. ◦ DCE is not scalable & difficult to administer ◦ RPCs not well-performing Require tremendous processing power

Middleware Database Access Middleware ◦ Ability to access remote data files and databases ◦ Each database vendor developed its own middleware solution ◦ Standard mechanisms like ODBC and JDBC recent ◦ Vendors like Oracle still have proprietary solutions

Middleware Message Oriented Middleware ◦ ◦ ◦ MOM is queuing software Units of information move between applications Decoupled from applications Asynchronous communication Messages have actions & data IBM’s MQSeries & Microsoft MSMQ

Middleware Distributed Objects ◦ CORBA & COM 2 types of distributed objects in use ◦ CORBA (Common Object Request Broker Architecture) is a standard Rules for developers to follow when creating distributed objects which may be used for application development ◦ COM is Microsoft distributed object standard

Middleware Transaction Processing Monitors ◦ First employed on mainframes with IBM’s IMS and CICS products ◦ Used by organizations with large transaction volume to ensure ACID (atomicity, consistency, isolation, durability) ◦ Tend to be tightly coupled ◦ BEA’s Tuxedo example of TP middleware ◦ Most complex of all types of middleware

Middleware Message Brokers ◦ “nirvana” of B 2 B integration ◦ Move information between multiple applications ◦ Account for differences in semantics and platforms ◦ Use common rules and routing engines ◦ Transform schema & content as it flows between applications & databases

Building Blocks for Integration ¡ There are four basic building blocks for integration: l Communications models l Method of integration l Middleware l Services

Services A functional extension to basic communication or middleware capability Intended to reduce the burden of applying core technology

Services Directory – used to track key information about system Lifecycle – aids developer by automating creation of objects or messages and disposal of on completion Security – provides capabilities required to secure any integration

Services Conversion and transformation – properly format data for integration Persistence – ensure that state information and data are safely stored Events – identify and track events

Services Notification – event is detected, notify any interested component Workflow – manage set of requests or messages across components in a prescribed order as a single action