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Chapter 5: Architectural requirements of EC IT 357 Electronic Commerce 1 Chapter 5: Architectural requirements of EC IT 357 Electronic Commerce 1

Architectural requirements of EC 1. 2. 3. 4. 5. Telecommunication infrastructure Decision support systems Architectural requirements of EC 1. 2. 3. 4. 5. Telecommunication infrastructure Decision support systems Interoperability Storage and retrieval of multi media information Markup languages 27 June 2008 IT 357 - Chapter 5 2

Architectural requirements of EC • • Scalable Enables resource sharing Supports asymmetrical protocols Provides Architectural requirements of EC • • Scalable Enables resource sharing Supports asymmetrical protocols Provides transparency of data locations and decision support • Also supports multi-media information, allow mix and match of various software and hardware platforms 27 June 2008 IT 357 - Chapter 5 3

Telecommunication infrastructure • • OSI - Open Systems Interconnection: Proposed by the International Standards Telecommunication infrastructure • • OSI - Open Systems Interconnection: Proposed by the International Standards Organization The goal - to allow one computer to communicate with another irrespective of its origin or manufacturer. 27 June 2008 IT 357 - Chapter 5 4

Cont’d: Telecommunication infrastructure Open Systems Interconnection 1. Physical Layer – Consists of the transmission Cont’d: Telecommunication infrastructure Open Systems Interconnection 1. Physical Layer – Consists of the transmission media for the bit streams and its interface with computers, e. g. fiber optic cables 2. Data link layer – Concerned with information transmission over a single channel or link. • • Acknowledgement of transmissions Error detection Sequencing E. g. Ethernet, ATM – The data link layer is often implemented in software as a "network card driver". 27 June 2008 IT 357 - Chapter 5 5

Cont’d: Telecommunication infrastructure Open Systems Interconnection 3. Network Layer – Enables simultaneous use of Cont’d: Telecommunication infrastructure Open Systems Interconnection 3. Network Layer – Enables simultaneous use of multiple links to increase transmission performance. • • • Routing Flow control End to end ack for multi link paths • Host to network interfaces Data link layer – Responsible for end to end packet delivery 4. Transport Layer – Network addressing – Establishment of virtual circuits – Procedures for entering and departing from the network. 27 June 2008 IT 357 - Chapter 5 6

Cont’d: Telecommunication infrastructure Open Systems Interconnection 5. Session Layer – Concerned with establishing communications Cont’d: Telecommunication infrastructure Open Systems Interconnection 5. Session Layer – Concerned with establishing communications between given pair of users – Starting, stopping and controlling the communication. 6. Presentation Layer – Display formatting and editing of inputs and outputs 7. Application Layer – Concerned with the business functions the users are trying to perform. 27 June 2008 IT 357 - Chapter 5 7

Cont’d: Telecommunication infrastructure TCP/IP • Covers the top layers of the OSI excluding the Cont’d: Telecommunication infrastructure TCP/IP • Covers the top layers of the OSI excluding the Physical and Data link layers ATM • Real-time transmission of multi-media data • Interoperable with local, metropolitan and wide area networks 27 June 2008 IT 357 - Chapter 5 8

Decision support systems Data warehouses • Refers to a collection of data that is Decision support systems Data warehouses • Refers to a collection of data that is – – – • Subject oriented Integrated Time varying Non volatile and Designed to support faster and better decision making Data warehouses Vs. Transaction Systems – – – 27 June 2008 A data warehouse application focuses on data analysis (Online analytical processing - OLAP) A traditional database application emphasizes on Online transaction processing – OLTP Data warehouse applications require summarized historical data derived from internal and external sources. OLTP applications require detailed current data derived primarily from internal sources. Data warehouse is several orders of magnitude larger than an operational data base. IT 357 - Chapter 5 9

Decision support systems Developing OLAP applications: • Multiple sources of data pose difficulties: – Decision support systems Developing OLAP applications: • Multiple sources of data pose difficulties: – Inconsistency in data representation coding and format – Erroneous and incomplete data • Data Cleansing – Done by data migration tools such as Warehouse Manager that rely on the user to define the mappings between source and target data. • Loading and uploading data – Refers to the process of populating the data warehouse from external data sources. – Preprocessing needed for integrity checking, sorting summarization aggregation and data partitioning (for parallel loading). 27 June 2008 IT 357 - Chapter 5 10

Decision support systems Developing OLAP applications • Refreshing data warehouses – Refreshing the data Decision support systems Developing OLAP applications • Refreshing data warehouses – Refreshing the data warehouse based on the changes to the operational database is important. – Can be done by: • Synchronous replication – Provides tight consistency between data stores with zero latency – Expensive and not essential in many applications • Asynchronous replication – A table in the warehouse is treated as a remote copy of the table in the operational database. – The actual updating is done at a later time. 27 June 2008 IT 357 - Chapter 5 11

Decision support systems Knowledge Discovery in Databases (KDD) – Refers to the tools and Decision support systems Knowledge Discovery in Databases (KDD) – Refers to the tools and techniques used to analyze data in organizational databases to find useful patterns in data. Data Mining • Deals with specific algorithms and methodologies for data analysis with the intent of finding useful patterns. • Consists of two tasks: – Prediction - Identification of unknown values for the variables of interest – Description - Analysis of data in humanly interpretable forms. 27 June 2008 IT 357 - Chapter 5 12

Interoperability • Interoperability provided by: • CORBA – Common Object Request Broker Architecture – Interoperability • Interoperability provided by: • CORBA – Common Object Request Broker Architecture – Object Management Group’s (OMG) open distributed object computing infrastructure. – Allows applications to communicate with one another irrespective of the location or design. • Software agents – Computer programs that employ AI techniques to provide active assistance to users with computer based tasks. 27 June 2008 IT 357 - Chapter 5 13

Interoperability How does CORBA ensure interoperability? • The clients and objects interact using one Interoperability How does CORBA ensure interoperability? • The clients and objects interact using one or more Object Request brokers (ORB) • ORB is the middleware that establishes the client server relationships between objects. • Using an ORB a client can invoke a method on a server object, which can be on the same machine or across a network. • The ORB intercepts the call and is responsible for – – 27 June 2008 finding an object that can implement the request passing the parameters invoking its method returning results IT 357 - Chapter 5 14

Interoperability Software Agents • Assist users in different ways • • • Information filtering Interoperability Software Agents • Assist users in different ways • • • Information filtering Information retrieval Mail management Meeting scheduling Selection of books, music etc. Example: Maxims - An agent that helps with e-mails. – Learns to prioritize, delete, forward, sort and archive mail messages on behalf of the user. • • • Persona. Logic - Persona. Logic allows users to specify product features uses a constraint satisfaction algorithm to filter through product space to retrieve an ordered set of products. Firefly - uses an automated collaborative filtering method to rate and recommend products to shoppers. Bargain. Finder and Jango – Takes a product name as input, obtains price information from other web sites and offers a price comparison. 27 June 2008 IT 357 - Chapter 5 15

Storage and retrieval of multi media information • • Based on collecting content representative Storage and retrieval of multi media information • • Based on collecting content representative metadata - data about media objects stored Metadata is classified as: – – – • • • Content dependant Content descriptive Content independent The metadata has to have efficient linkages with the physical location of the information. The data retrieved should be presented to the users in the decreasing order of retrieval status value Objects are stored in digital libraries based on feature similarity. A feature is a set of characteristics such as text strings in text documents, colour texture and objects in video frames. These features can be used to index and retrieve objects 27 June 2008 IT 357 - Chapter 5 16

Storage and retrieval of multi media information • Storage strategy is based on: – Storage and retrieval of multi media information • Storage strategy is based on: – Type of object – Retrieval requirements of the stored object. • Storage strategies can be classified under: – Single disk storage – Multiple disk storage with data striping 27 June 2008 IT 357 - Chapter 5 17

Markup Languages • Markup - originally used to describe annotations or other marks within Markup Languages • Markup - originally used to describe annotations or other marks within a text to instruct a typist how a passage should be laid out. • Markup language - a set of mark up conventions used for encoding of texts. • A markup language must specify: – – 27 June 2008 What markups are allowed What markups are required How markups are distinguished from text What markup means IT 357 - Chapter 5 18

Markup Languages • SGML – Describes a generalized mark up scheme for representing the Markup Languages • SGML – Describes a generalized mark up scheme for representing the logical structure of the document in a system and platform independent manner. – Uses a Document Type Definition (DTD) model to describe each element of the document – Different documents of the same DTD can be processed uniformly. – Programs can be written to take advantage of the structure information and made to behave more intelligently. 27 June 2008 IT 357 - Chapter 5 19

Markup Languages • HTML – Invented by Tim Bernes Lee – The publishing language Markup Languages • HTML – Invented by Tim Bernes Lee – The publishing language of the WWW. – Gives users means to: • • Publish online documents Retrieve online information Design forms for conducting transactions with remote services Include spread sheets, video clips etc in the documents – Drawbacks • Does not support encoding of the structure and meaning of structured documents -e. g. spread sheets, address books, technical drawings etc. • Thus such documents cannot be effectively indexed or searched. • Formal descriptions of content and services are absent - Automated information extraction from HTML pages is therefore difficult 27 June 2008 IT 357 - Chapter 5 20

Markup Languages • XML – Relatively New – Combines the merits of HTML and Markup Languages • XML – Relatively New – Combines the merits of HTML and SGML – Used for designing text formats for structured data such as spread sheets and address books. • XML vs HTML – Uses tags ()and attributes (name=“value”) just like HTML – But the interpretation of the tags is left to the application entirely. • XML Characteristics – – – • XML files are text files meant to be read by programs or programmers. Programmers can debug applications more easily in XML. Unlike HTML errors are not tolerated XML files are larger than comparable binary formats. Is license free, platform independent and well supported XBRL 27 June 2008 IT 357 - Chapter 5 21