unit 1

One page summary on this power point, MLA format

Unit 1: Intersystem Communications
COP4858 PROGRAM & TECH ENHANCED 463773
Gilbert Mancilla
Hughval Williams

Define the role of Distributed Component Object Model (DCOM), CORBA and Remote Method Invocation (RMI), in distributed processing.

DCOM enables component applications to operate across the Internet
Speeding development
Lowering integration costs
Improving deployment flexibility

Cobra
COBRA owned by Object Management Group OMG is middleware
CORBA Interface Definition Language IDL provides the language- and
OS-neutral inter-object commication it supports the construction and
integration of object-oriented software components in mixed
distributed environments. object request broker

Cobra’s client to object implementation

Remote Method Invocation
RMI provides ORB functionality that is fully integrated with the Java language and runtime environment. Unlike CORBA, however, the RMI
ORB is fully integrated with the Java language and runtime environment.

Cobra vs RMI

B)
Describe how web services are used to integrate disparate applications in an organization: for example, describe the role of the WSDL Web Service Definition Language, SOAP Simple Object Access Protocol, and UDDI Universal Description, Discovery and Integration ,architectures in creating and using web services.

WSDL ( Web Service Definition Language)
WSDL is a document written in XML. The document describes a Web service. It specifies the location of the service and the operations (or methods) the service exposes.
Web service as collections of network endpoints or ports
Messages are abstract descriptions of data being exchanged
Port types are abstraction collection of operations
Concrete protocol and data format specification for a particular port type constitutes a binding

SOAP
SOAP is an XML based protocol for accessing Web Services.
SOAP stands for Simple Object Access Protocol
SOAP simply a procedural call
SOAP is a stateless protocol

SOAP Body
SOAP
SOAP
header
SOAP envelope
Header
block
Header
data
Header
data
Header
data
Body child element
Body child element

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UDDI (Universal Description, Discovery and Integration)
UDDI is a platform-independent framework for describing services.
It’s a directory service where companies are in search of web services.
 
UDDI uses WSDL to describe interfaces to web services

SOAP, WSDL and UDDI together make systems flexible

Together is more of a declarative type of programming

UDDI working with WSDL AND SOAP

C) Describe the role of socket programming in communicating between systems and  
contrast the protocols and uses of TCP/IP sockets and Datagram sockets.

A socket is one of the most fundamental technologies of computer networking. Sockets allow applications to communicate using standard mechanisms built into network hardware and operating systems. 
Three socket types are available:
Stream sockets provide a bidirectional, reliable, sequenced, and unduplicated flow of message data.
Datagram sockets support bidirectional data flow, but don’t guarantee that the message data is sequenced, reliable, or unduplicated.
Raw sockets give you access to the underlying communication protocols that support socket abstractions.

Role of Socket programming
In a nutshell, a socket represents a single connection between exactly two pieces of software. 
 A socket provides a bidirectional communication endpoint for sending and receiving data with another socket. Socket connections normally run between two different computers on a LAN or across the Internet, but they can also be used for inter process communication on a single computer.

What do you need for socket communication ?
Basically 4 parameters
Source Identifier (IP address)
Source Port
Destination Identifier
Destination Port

Software applications that rely on the Internet and other computer networks continue to grow in popularity. The following software packages  rely on sockets:
Web browsers
 instant messaging applications
peer to peer file sharing systems

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Contrast the protocols and uses
of TCP/IP sockets and Datagram sockets

There are two types of Internet Protocol (IP) traffic. They are TCP or Transmission Control Protocol and UDP or User Datagram Protocol. TCP is connection oriented – once a connection is established, data can be sent bidirectional. UDP is a simpler, connectionless Internet protocol. Multiple messages are sent as packets in chunks using UDP

Describe the purpose of message and queuing services and how they work

One popular messaging services is Short messaging services (SMS)

Short message service is a mechanism of delivery of short messages over the mobile networks.
This messaging services has a store and forward way of transmitting messages to and from mobiles.
The message (text only) from the sending mobile is stored in a central short message center (SMS) which then forwards it to the destination mobile. This means that in the case that the recipient is not available, the short message is stored and can be sent later. Each short message can be no longer than 160 characters.

Short Message Service:
How does SMS work?
A typical organization of network elements in a GSM network supporting SMS

How does it work:

The SMC (Short Message Center) does the job of store and forward of messages between the mobile station. On the other hand the SME which can be found in the fixed network or a mobile station, sends and receives short messages.
The SMS GWMS (SMS gateway MSC) is a gateway MSC that can also receive short messages. The gateway MSC is a mobile network’s point of contact with other networks. On receiving the short message from the short message center, GMSC uses the SS7 network to interrogate the current position of the mobile station form the HLR, the home location register.

HLR : The main database in a mobile network.
Functions:
It holds information of the subscription profile of the mobile and also about the routing information for the subscriber, i.e. the area (covered by a MSC) where the mobile is currently situated. The GMSC is thus able to pass on the message to the correct MSC.
MSC (Mobile Switching Center) is the entity in a GSM network which does the job of switching connections between mobile stations or between mobile stations and the fixed network.
A VLR (Visitor Location Register) corresponds to each MSC and contains temporary information about the mobile, information like mobile identification and the cell (or a group of cells) where the mobile is currently situated.

The present state of SMS
SMS has seen unprecedented growth in the last few years. In Europe SMS has already crossed three billion messages per month mark. The current figures and future projections in the European market below, clearly demonstrate the popularity of SMS in Europe.

Message Queuing 
Purpose
Message Queuing technology enables applications running at different times to communicate across heterogeneous networks and systems that may be temporarily offline. Applications send messages to queues and read messages from queues. The following illustration on the next page shows how a queue can hold messages that are generated by multiple sending applications and read by multiple receiving applications.
Message Queuing provides guaranteed message delivery, efficient routing, security, and priority-based messaging.

Figure above represent Message queuing service

What Is JMS?
The Java Message Service is a Java API that allows applications to create, send, receive, and read messages. 
It provides enough features to support sophisticated messaging applications. 

JMS server can communicate between client using many protocols the following protocols:
RMI, TCP/IP, HTTP

E) List commonly used low level data communications protocols (e.g. RS232), state conditions for when each protocol should be used
Female “DB-9” connector (properly known as DE9F):
A VGA connector for monitors

Male “DB-9” connector (properly known as DE9M): COM1 and COM2

female DB-25 connector (also known as DB25S):
the parallel (printer) port

male DB-25P connector (also known as DB25P): Printer cable that connects to the
Parallel port