Lecture 7 MGMT 6180 - © 2012 Houman Younessi Understanding the Technological Infrastructure (Part 2) “Understanding Information TECHNOLOGY” (Part 2)

Lecture 7

MGMT 6180 - © 2012 Houman Younessi

Understanding the Technological Infrastructure (Part 2)

“Understanding Information TECHNOLOGY”(Part 2)

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Spreading our wings

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Middleware

• Access Middleware- RPC (Remote Procedure Call)

• Transaction Managers

- MSDTC (MS Distributed Transaction Coordinator)

• Data Exchange- MOM (Message Oriented Middleware)

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Access Middleware

• Hiding Distribution

• Hiding heterogeneity

• Providing uniform interface

Examples: RPC, RMI

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RPC Remote Procedure Call

A protocol by which a computer program causes a procedure to be invoked in another program.

The programs may be on different machines on a Local Area Network, across the world and connected through the internet or on the same machine.

Host Remote Program Version of RP Procedure Number Parameters Results

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RPC Remote Procedure Call

DCOM – Distributed Component Object Model

CORBA – Common Object Request Broker Architecture’s ORB

Enabled Distributed Computing

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Transaction Manager

Transaction managers are systems that ensure integrity of transaction by monitoring proper completion or roll-back of transactions.

Example: MSDTC (Microsoft Distributed Transaction Coordinator)

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• MSDTC uses the two-phase commit protocol. Phase one involves the transaction manager requesting each enlisted component to prepare to commit; in phase two, if all enlistees successfully prepare, the transaction manager broadcasts the commit decision.

• In general, transactions involve the following steps: • Applications call the transaction manager to begin a transaction.

• When the application has prepared its changes, it asks the transaction manager to commit the transaction. The transaction manager keeps a sequential transaction log so that its commit or abort decisions will be durable.

– If all components are prepared, the transaction manager commits the transaction and the log is cleared.

– If any component cannot prepare, the transaction manager broadcasts an abort decision to all elements involved in the transaction.

– While a component remains prepared but not committed or aborted, it is in doubt about whether the transaction committed or aborted. If a component or transaction manager fails, it reconciles in-doubt transactions when it reconnects.

MSDTC

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Data Exchange

Data Exchange middleware usually uses message queues as the central mechanism.

Message queues provide an asynchronous communications protocol, meaning that the sender and receiver of the message do not need to connect to the message queue at the same time. Messages placed onto the queue are stored until the recipient retrieves them.

Example: JMS (Java Message Service)

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System Level Applications and Protocols

Applications and protocols belonging to the top (layer 7) of the OSI model.

System level applications provide generic application services such as file transfer, web-browsing, security, email, etc.

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FTP File Transfer Protocol

An almost universal protocol to transfer files from one process to another. This is usually done over a TCP/IP enabled network.

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HTTP Hypertext Transfer Protocol

HTTP is an internet protocol and its implementation as a mechanism of transferring display information on the World Wide Web.

HTTP is a request/response protocol between clients and servers. An HTTP client initiates a request by establishing a Transmission Control Protocol (TCP) connection to a particular port on a remote host (port 80 by default). An HTTP server listening on that port waits for the client to send a request message. Upon receiving the request, the server sends back a status line, such as "HTTP/1.1 200 OK", and a message of its own, the body of which is perhaps the requested file, an error message, or some other information.

Resources to be accessed by HTTP are identified using Uniform Resource Identifiers (URLs) employing the http: or https URL schemes.

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URI/URLA Uniform Resource Identifier (URI), is a short string of characters used to identify (e.g. name or locate) resources over a network, typically the World Wide Web, using specific protocols.

A Uniform Resource Name (URN) is a URI that identifies a resource by name in a particular namespace. A URN can be used to talk about a resource without implying its location or how to dereference it.

A Uniform Resource Locator (URL) is a URI that, in addition to identifying a resource, provides means of acting upon or obtaining a representation of the resource by describing its primary access mechanism or network "location".

Examples:

urn:isbn:0-395-36341-1 (A URN) http://www.rpi.edu/ (A URL)

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DNSA system that translates domain names to IP addresses. It also lists mail exchange servers accepting resources for each domain.

Internet Corporation for Assigned Names and Numbers

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POP 3 - IMAPApplication-layer Internet standard protocols, to retrieve e-mail from a remote server over a TCP/IP connection

POP 3 is much more popular and most internet service providers offer this standard protocol to their users. It implements a “Connected” protocol

IMAP is newer and more feature-full but very few users actually offer it. It implements both a “connected” and a “disconnected” protocol. IMAP supports encrypted login mechanisms.

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SMTP Simple Mail Transfer Protocol

This is the almost universally used and therefore de facto standard email delivery protocol over a network or internetwork – including the internet. It uses TCP for transport and resolves addresses through DNS.

SMTP is a push technology, to retrieve email users must use POP3 or IMAP.

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SSL (TLS) Secure Socket Layer – Transport Layer Security

Cryptographic protocol that provides endpoint authentication and communications privacy over the Internet for data exchanges such as email and internet fax applications. It safeguards against tampering, eavesdropping and forgery by using a public key encryption method..

SSL involves three basic phases:

1. Peer negotiation for algorithm support 2. Public key encryption-based key exchange and certificate- based authentication 3. Symmetric cipher-based traffic encryption

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Public Key Encryption

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WWW World Wide Web

The World Wide Web is an information exchange service on the internet.

Each uniquely identified individual piece of information – such as text, images, digitized sound, applications, and video frames – is called a resource.

Each resource is identified by a URI.

A resource’s URI may be called by invoking a hyperlink embedded in another resource.

A mark-up language would allow the explicit insertion of hyperlinks and other semantic, action and structural information into a resource.

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• When a viewer wants to access a web page or other resource on the World Wide Web, he normally begins either by typing the URL of the page into his or her web browser, or by following a hypertext link to that page or resource. The first step, behind the scenes, is for the server-name part of the URL to be resolved into an IP address by the global, distributed Internet database known as the Domain name system or DNS.

• The next step is for an HTTP request to be sent to the web server at that IP address, for the page required. In the case of a typical web page, the text, graphics and any other files that form a part of the page will be requested and returned to the client (the web browser) in quick succession.

• The web browser's job is then to render the page as described by a mark-up language call the HTML, incorporating the images, links and other resources as necessary. This produces the on-screen 'page' that the viewer sees.

• Most web pages will themselves contain hyperlinks to other relevant and informative pages and perhaps to downloads, source documents, definitions and other web resources. Such a collection of useful, related resources, interconnected via hypertext links, is what has been dubbed a 'web' of information.

WWW World Wide Web

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Dynamic Web-pages

ASP (Active Server Pages)

JSP (Java Server Pages)

PHP (Perl-based Hypertext Pre-processor)

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HTML

HTML is a markup language designed for the creation of web pages with hyperlinks and other semantic, action and structural information inserted into a resource to be displayed in a web browser. HTML is used to structure information — denoting certain text as headings, paragraphs, lists and so on — and can be used to describe, to some degree, the appearance and semantics of a document.

HyperText Markup Language

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VM Virtual Machine

Common Language Runtime (CLR)

Java Virtual Machine (JVM)

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XML Extensible Mark-up Language

XML is a standard to encode structured information. Its primary purpose is to facilitate the sharing of data across different systems, particularly systems connected via the Internet

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Some features of XML that make it well-suited for data transfer are:

• Its simultaneously human- and machine-readable format;• It has support for Unicode, allowing almost any information in any written human language to be

communicated;• The ability to represent the most general computer science data structures: records, lists and trees;• The self-documenting format that describes structure and field names as well as specific values;• The strict syntax and parsing requirements that allow the necessary parsing algorithms to remain

simple, efficient, and consistent.

XML is also heavily used as a format for document storage and processing, both online and offlineand offers several benefits:

• Its robust, logically-verifiable format is based on international standards;• The hierarchical structure is suitable for most types of documents;• It manifests as plain text files, unencumbered by licenses or restrictions;• It is platform-independent, thus relatively immune to changes in technology;• It and its predecessor, SGML, have been in use since 1986, so there is extensive experience and

software available

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SOAPSOAP is a middleware protocol for exchanging XML-based messages over a computer network, normally using HTTP. The mechanism used to do so is usually RPC.

Simple Object Access Protocol

http://searchwebservices.techtarget.com/searchWebServices/downloads/what_is_soap.swf

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Web ServersAlthough sometimes referred to the physical machine performing this function, a Web Server – more correctly – is a software application that is responsible for accepting HTTP requests from clients, which are known as Web Browsers, and serving them Web pages, which are usually HTML documents and their linked resources/objects (images, etc.).

Every Web Server program operates by accepting HTTP requests from the network, and providing an HTTP response to the requester. The HTTP response typically consists of an HTML document, but can also be a raw text file, an image, or some other type of document; if something bad is found in client request or while trying to serve the request, a Web Server has to send an error response which may include some custom HTML or text messages to better explain the problem to end users.

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Commercially available Web Servers usually also provide the following services:

• Authentication, optional authorization request (request of user name and password) before allowing access to some or all kind of resources.

• Handling of not only static content (file content recorded in server's filesystem(s)) but of dynamic content too by supporting one or more related interfaces (SSI, CGI, SCGI, FastCGI, PHP, JSP, ASP .NET, Server API such as NSAPI, ISAPI, etc.).

• Module support, in order to allow the extension of server capabilities by adding or modifying software modules which are linked to the server software or that are dynamically loaded (on demand) by the core server.

• HTTPS support (by SSL or TLS) in order to allow secure (encrypted) connections to the server on the standard port 443 instead of usual port 80.

• Content compression (i.e. by gzip encoding) to reduce the size of the responses (to lower bandwidth usage, etc.).

• Virtual Host to serve many web sites using one IP address.• Large file support to be able to serve files whose size is greater than 2 GB on 32 bit OS.• Bandwidth throttling to limit the speed of responses in order to not saturate the network

and to be able to serve more clients.

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Web Servers

Apache

Microsoft IIS (internet Information Service)

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EXERCISE:

What technologies would you use to implement your IS plan?

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MANAGING DIVERSE IS

RESOURCES

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We are now ready to look at IS as an organizational resource.

We should therefore learn how to manage this resources. We shall learn:

What does/should IS do? Where should IS be? How is/should be IS organized?

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In one word:

INTEGRATE!!!

or at least lead the effort of integration to ensure effectiveness and sustainability. Of course ensuring effectiveness, subsumes the requirements for efficiency and quality.

The strategic planning stage should ensure that such integration takes place (or at least when the plan is correctly put to effect, such integration ensues).

Here, we focus on the role of the IS resource itself and what it does.

What Should IS Do?

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How might IS be viewed within the organization?

The Service-provider model: This formalizes the interaction between IS and its user community into a service obligation on the part of IS. This model has been traditionally very appealing to the organization that feels IS just another operational function.

This is inherently a “Level 2” view of the world, indicating an immature but developing organization. The organization views IS as a “production system”, akin to the assembly line (hence level 2). The assumptions are that if IS is efficient (a level 2 concern), then all is well.

Progressive organizations have moved on from this view.

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The partnership model: This breaks down the functional lines of the service model in order integrate IS and its business user community.

This is inherently a “Level 3” view of the world, indicating a maturing organization. The organization views IS as an “ integrated enterprise component”, akin to Finance or Legal (hence level 3). The assumptions are that if IS is effective (a level 3 concern), then all is well.

Many organizations view IS at this level but some very progressive organizations have moved on from this view.

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The vendor model : There are two versions of this model.

Version 1:One version is a “Level 1” view of the world, indicating an immature organization in which the IS markets and sells its services to the user community. The organization views IS products as a “commodity”, akin to the product raw materials for manufacture (a Level 1 or at best a level 2). The assumptions are that if the IS product is of sufficient quality (a level 1 concern), then all is well.

Progressive organizations have moved on from this view.

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The vendor model : There are two versions of this model.

Version 2:The other version is a “Level 3” view of the world, indicating a maturing organization in which the IS is deemed an integrated supplier (hence level 3). The organization views IS itself and not the individual product as the basis of the supply partnership. The assumptions are that if the IS partner is effective (a level 3 concern), then all is well. A correctly-formed model of this view is similar to the the partnership model.

Many organizations hold this view.

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The Crucible model : A model in which IS creates a flexible architecture that will support common systems to accommodate a user community’s growing IS needs.

This can be at any level other than a level 4. Depending on what view is held of the nature of the support needed and how it is used.

Needless to say, many organizations hold this view, and at various levels of organizational maturity.

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The strategic advantage model: Where the identification between IS, its user community, the organization etc. is so close and integrated that competitive (IS, business and extra-business) products, processes, partnerships and strategies are jointly developed.

This is at least a “Level 3”, in some well-developed cases, a “level 4” view of the world, indicating a mature organization. The organization views IS as integral to the enterprise (level 3), or the meta-enterprise (Level 4)

Some organizations have reached such levels

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As you might have guessed, what model is chosen is a function of the strategic maturity of the organization, and the organizational

governance principles

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Some of the functions IS performs:

IS strategic planningIS strategy executionIS process improvementIS business process re-engineeringBusiness area analysisTechnology analysisSystem and software developmentArchitecture managementSupplier and service provider managementResource administrationData and communication security assuranceQuality assurance

Can you think of some others?

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Where Should IS Reside?Where IS capability may reside is a function of the IS/Organizational co-strategy. There are however a number of options:

Centralized (re-centralized):

The centralized approach is effective in gaining control over IS from a resources viewpoint (e.g. cost-effective hardware purchases), compatibility, security, and access. It reduces redundancy, may entail building core expertise which may enhance organizational competitiveness. Business process redesign of centralized operations would be easier.

On the other hand, IS function tends to be divorced from the “coal-face”, any organization that reaches a critical mass, develops its own culture, language and BOUNDARIES. Centralization gives little scope for personal attention to any individual or group. Attention is given inversely to power base. Access to services (either machines, e.g. response time, or staff, e.g. help-desk getting back to you) may be slow.

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Noncentralized :

The proliferation of multiple IS departments, brings IS closer to the user community. Understanding user needs improves. It has a better chance of motivating and involving users. It focuses less on IT, even on IS costs, and more on user effectiveness (being a good neighbor). It generally results in a “small is elegant” solutions.

On the other hand, there will be cost duplications and redundancies (hardware, licenses, management, etc.). Potential for incompatibilities increases. There tends to be less in-house expertise and as such potential for producing sub-optimal solutions may increase. There may be cultural and other interpersonal issues within and between nodes.

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Pressures and trends such as:

Downtrend in processing power costs Growth of standards Greater IS awareness and greater availability of IS expertise Growth in empowerment (the need to match organizational unit autonomy) The drive to manage costs

Have all contributed towards progressive noncentralization

There are three types of “Noncentralization”

Decentralization (geographical/physical)Devolution (functional/authoritative)

Externalization (economical and tactical)

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How is/should be IS Organized?IS has been led under different organizational schemas, over the years.

Approach Timeframe

Traditional 1960s-early 70s

Database Driven Late 1970s

Functional Project Groups Early to mid 1980s

Information Centers Mid to late 1980s

Decision Support Early to mid 1990s

Economic Project Units Mid 1990s to early 2000s

Enterprise (ERP) Early 2000s -

Sustainable (meta-enterprise) Mid 2000s -

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IS Leadership

Likely Title Reported/Reports to Timeframe

Computer Center Manager Director of Engineering Ops 1950s-early 60s

DP Manager Director of Admin./Finance Mid 1960s-early 1980s

Director of IS / MIS VP of Finance Mid 1980s-mid 1990s

VP of IS EVP of Finance/Operations Late 1990s–mid 2000s

CIO CEO/Board Mid 2000s-

Documents

Lecture 7 MGMT 6180 - © 2012 Houman Younessi Understanding the Technological Infrastructure (Part 2) “Understanding Information TECHNOLOGY” (Part 2)