Unit XI: ISP Simulation - Linux - BCA Notes (Pokhara University)

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Tuesday, May 28, 2019

Unit XI: ISP Simulation - Linux

Introduction:

ISP offers simulation services to help reduce the uncertainty involved in deciding how to approach production logging jobs, or to confirm whether DTS (Distributed Temperature Sensor) is going to be of value.

Production Logging Tools Selection:

ISP’s analysts are very proficient in using the powerful emulation capabilities of PLATO. During the simulation of different production scenarios for a specific well, the possible measurements from the various tools selected are calculated using the Monte-Carlo method. After a simulation study, the ISP’s analyst will produce a complete report, including observations and recommendations to allow for more effective planning of logging jobs, removing the uncertainty involved in selecting the most appropriate set of tools for the good in question.

Permanent Fiber Installation:

DTS is often identified as a potential technology to help overcome the challenges with field surveillance. PLATO-DTS’s simulation service delivers a feasibility study to assess the potential application of DTS. The objective of such a study is to confirm if the investment will derive any value. Indeed, it is possible to ascertain whether the DTS fibre will be able to measure the temperature with enough precision to differentiate between several production/injection scenarios.

During a DTS feasibility study, various scenarios are modelled based on known reservoir and well behaviours within a given field. PLATO will compute resulting flowing temperatures for each one of the scenarios. A comparison study will follow to identify whether DTS alone is sufficient for surveillance, or if additional measurements need to be considered.

Integration of Servers:

An integration server is a type of server that enables the integration and interaction of different operating systems, application and services within an enterprise IT environment. It enables applications and services to communicate with each other, regardless of their underlying platform. It eliminates compatibility and interoperability issues between different platforms.

An integration server is primarily implemented in IT environments that are composed of IT products and solutions from different platforms and/or architectures. It also serves as a middleware server, serving as an intermediate server between different layers.
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An integration server is typically deployed in two different models:

1. Hub and Spoke Model:

In this model, all applications and services connect to an integration server through a central server. The integration server provides and manages the interoperations, integration, translation and other services between distinct applications and services.

2. Network-centric Bus Model:

In this model, applications and services connect to the integration server through the core network medium. The integration server communicates and provides interoperability between applications and services over the network.

DNS (Domain Name System):

Introduction:

The Domain Name Systems (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).
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How does DNS work?

The process of DNS resolution involves converting a hostname (such as www.example.com) into a computer-friendly IP address (such as 192.168.1.1). An IP address is given to each device on the Internet, and that address is necessary to find the appropriate Internet device - like a street address is used to find a particular home. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example.com) and the machine-friendly address necessary to locate the example.com webpage.

In order to understand the process behind the DNS resolution, it’s important to learn about the different hardware components a DNS query must pass between. For the web browser, the DNS lookup occurs “behind the scenes” and requires no interaction from the user’s computer apart from the initial request.
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Fig: Working of DNS

Types of DNS Servers Involved in Loading a Webpage:

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1. DNS Recursor:

The recursor can be thought of as a librarian who is asked to go find a particular book somewhere in a library. The DNS recursor is a server designed to receive queries from client machines through applications such as web browsers. Typically the recursor is then responsible for making additional requests in order to satisfy the client’s DNS query.

2. Root Nameserver:

The root server is the first step in translating (resolving) human-readable hostnames into IP addresses. It can be thought of like an index in a library that points to different racks of books - typically it serves as a reference to other more specific locations.

3. TLD Nameserver:

The top-level domain server (TLD) can be thought of as a specific rack of books in a library. This nameserver is the next step in the search for a specific IP address, and it hosts the last portion of a hostname (In example.com, the TLD server is “com”).

4. Authoritative Nameserver:

This final nameserver can be thought of as a dictionary on a rack of books, in which a specific name can be translated into its definition. The authoritative nameserver is the last stop in the nameserver query. If the authoritative name server has access to the requested record, it will return the IP address for the requested hostname back to the DNS Recursor (the librarian) that made the initial request.

Types of DNS Queries:

In a typical DNS lookup, three types of queries occur. By using a combination of these queries, an optimized process for DNS resolution can result in a reduction of distance travelled. In an ideal situation, cached record data will be available, allowing a DNS name server to return a non-recursive query.
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1. Recursive Query:

In a recursive query, a DNS client requires that a DNS server (typically a DNS recursive resolver) will respond to the client with either the requested resource record or an error message if the resolver can't find the record.

2. Iterative Query:

In this situation, the DNS client will allow a DNS server to return the best answer it can. If the queried DNS server does not have a match for the query name, it will return a referral to a DNS server is authoritative for a lower level of the domain namespace. The DNS client will then make a query to the referral address. This process continues with additional DNS servers down the query chain until either an error or timeout occurs.

3. Non-Recursive Query:

Typically this will occur when a DNS resolver client queries a DNS server for a record that it has access to either because it's authoritative for the record or the record exists inside of its cache. Typically, a DNS server will cache DNS records to prevent additional bandwidth consumption and load on upstream servers.

Web:

History:

The World Wide Web (WWW) was created in 1990 by the British CERN physicist Tim Berners-Lee. On 30 April 1993, CERN announced that the World Wide Web would be free to use for anyone. Before the introduction of HTML and HTTP, other protocols such as File Transfer Protocol and the gopher protocol were used to retrieve individual files from a server. These protocols offer a simple directory structure which the user navigates and where they choose files to download. Documents were most often presented as plain text files without formatting or were encoded in word processor formats.
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Introduction:

A website or Web site is a collection of related network web resources, such as web pages, multimedia content, which is typically identified with a common domain name, and published on at least one web server. Notable examples are wikipedia.org, google.com, and amazon.com.

Websites can be accessed via a public Internet Protocol (IP) network, such as the Internet, or a private local area network (LAN), by a uniform resource locator (URL) that identifies the site.

Websites can have many functions and can be used in various fashions; a website can be a personal website, a corporate website for a company, a government website, an organization website, etc. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and social networking to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically part of an intranet.

Web pages, which are the building blocks of websites, are documents, typically composed in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). They may incorporate elements from other websites with suitable markup anchors. Web pages are accessed and transported with the Hypertext Transfer Protocol (HTTP), which may optionally employ encryption (HTTP Secure, HTTPS) to provide security and privacy for the user. The user's application, often a web browser, renders the page content according to its HTML markup instructions onto a display terminal.

Types of Websites:

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A. Functionality:

In terms of functionality, there are five main types of websites:
1. Brochure:
A brochure website is the simplest type of website in terms of functionality. Brochure websites typically only have a few pages, and will be used by small businesses that need a simple online presence. For example, a small plumbing company would only need a brochure website with a homepage displaying contact information, an ‘about us’ page and perhaps a couple of photos of their work. Their website is like an online business card for potential customers.

2. eCommerce:
An eCommerce website is a website through which users are able to pay for a product or service online. This will normally involve one company selling to multiple users, but can also take the form of a multi-vendor eCommerce website, commonly known as ‘marketplace’ websites. Marketplace websites allow multiple vendors to sell to customers through the same site. Well known examples include eBay and Etsy.

3. Portal:
A portal website brings together information from lots of different sources on the web. Early examples include AOL and Yahoo, who offer emails, forums, search engines and news all through their homepage. Portals can also be for internal use in a school, university or company, allowing students or employees to access their emails, alerts and files all in one place.

4. Wiki:
A wiki website is one which allows people to collaborate online and write content together. The most popular example is Wikipedia itself, which allows anyone to amend, add and assess the content of their articles.

5. Social media:
Social media websites are platforms which allow the sharing of images or ideas. They encourage online interaction and sharing. The most popular social media website is Facebook, with a staggering 2.07 billion active users. Other social media sites include YouTube, Twitter, Instagram and LinkedIn.

B. Design: Content

In terms of how often the content of a website needs to be updated, it will fall into one of two categories:

1. Static/fixed
Static, or ‘fixed’, websites are the most simplistic. Their content does not change depending on the user and is not regularly updated. Static websites are built using simple HTML code and typically provide information.

2. Dynamic
A dynamic website or web page will display different content each time it is visited. Examples include blogs and eCommerce sites, or generally any site that is updated regularly. Dynamic websites can also be set up to show different content to different users, at different times of the day etc. Dynamic websites make for a more personal and interactive experience for the user, although they can be a little more complex to develop and may load slightly slower than static ones.

C. Design: Responsiveness

And in terms of how optimised the website is for all devices, its design will fall into one of three categories:

1. Static/ Fixed
A fixed website is not well-optimised for different sized screens. It is built to be a fixed width of pixels. If we open a website which is static/fixed on a mobile, we will have to zoom in to see what is written on each page. Again, static websites may load slightly faster due to their simplicity. However, they are not recommended due to the poor user experience for those on mobiles or tablets. It is believed that over 50% of all searches are now conducted on mobile, so this is an important consideration.

2. Fluid or liquid
A website built with a fluid or liquid design ensures that the site looks the same in terms of proportions no matter what the screen size. Each element of the website, such as the navigation bar, will take up the same relative amount of space on every device.

3. Responsive
A website with a responsive design goes one step further than one which is fluid or liquid. A website with responsive design is one which is completely optimised for mobiles and tablets, to the point where the website will actually look different on each device. It is especially important that our website is responsive if a large proportion of our audience use devices other than a computer to view our site, as it offers the best experience to these users.

D. Content:

When categorising websites by content, the list could literally go on forever. These are some of the most common ‘themes’ for website content to take, although there is potential for overlap between the categories:

1. Blog:
A blog is a website or web page that is regularly updated. Typically, a blog will be run by an individual or a small group. It can be on any topic, but will often be written in an informal or conversational style. Professional blogging has increased massively in popularity in recent years.

If we’re looking to start a blog, take a look at Wix. We can build our own website for free in just an hour, and it’s got blog-specific analytics and supports comments and social bookmarking, too.

2. Corporate:
Businesses are waking up to the fact that they must have at least a basic website to ensure they appear credible and professional. Businesses may not sell directly through these corporate websites, but they will use the site to provide information about themselves and let people know how they can get in touch. Credible websites needn’t cost the earth; with 1&1, we can build a website that looks great and delivers results, all for as little as £1/month.

3. Crowdfunding:
In the past, funding a new business venture or project involved seeking large amounts of money from only a few people (think Dragon’s Den). Crowdfunding is the practice of funding a project or venture by raising small amounts of money from lots of people. It involves creating a pitch video for our project, setting a target and hoping to reach it by our set deadline. Those who believe in what we are working will pledge a small amount of money to be a part of it. Crowdfunding websites are becoming a go-to resource for new start-ups.

4. eCommerce:
An eCommerce site may be combined with a blog or a corporate website, but ultimately its aim is to sell a product or service over the internet. A website that is purely corporate with no eCommerce functionality is still indirectly encouraging users to buy a product or service, but the difference is that they are unable to do this through the site itself. Shopify is the most comprehensive and versatile eCommerce platform on the market today. As well as having our own online store, Shopify allows us to sell across multiple channels including Facebook, Instagram and Pinterest. We can try it for free, then prices start at £23/month.

5. Educational:
‘What are the different types of websites?’, ‘How to boil an egg’… chances are that typing these into a search engine will produce a selection of websites that are informative or educational. Their aim is to provide the user with the information they are looking for.

6. News or Magazine:
News and magazine websites need little explanation. The primary purpose of a news website is to keep its readers up to date on current affairs. The same can be true of an online magazine website, to some extent, although there is much more of a focus on entertainment. If we’re looking to start a local newspaper or online zine, take a look at Wix – with striking templates, a news app option, and paid plans starting at just £3, we really can’t go wrong.

7. Social Media:
Social media websites are pretty unique in terms of both functionality and content. Social media sites were created as a place to share thoughts, images and ideas, and are increasingly become the go-to destination for people to read up about things like the news. Their creation has led to the invention of new words and terms, such as ‘fake news’, which Collins Dictionary named as their word of 2017.

8. TV or Video Streaming:
Video streaming sites have soared in popularity in recent years. Netflix and similar sites have revolutionised the way the world watches TV. Catch-up sites such as iPlayer and All 4 are more traditional examples of this popular type of site.

Email:

Introduction:

Short for electronic mail, e-mail or email is information stored on a computer that is exchanged between two users over telecommunications. More plainly, e-mail is a message that may contain text, files, images, or other attachments sent through a network to a specified individual or group of individuals.

The first e-mail was sent by Ray Tomlinson in 1971. Tomlinson sent the e-mail to himself as a test e-mail message, containing the text "something like QWERTYUIOP." However, despite sending the e-mail to himself, the e-mail message was still transmitted through ARPANET.
By 1996, more electronic mail was being sent than postal mail.
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How To Send And Receive E-Mail?

E-Mail Program:

To send and receive e-mail messages, we can use an e-mail program, also known as an e-mail client, such as Microsoft Outlook or Mozilla Thunderbird. When using an e-mail client, we must have a server that stores and delivers our messages, hosted by our ISP or in some cases, another company. An e-mail client needs to connect to a server to download new e-mail, whereas e-mail stored online is always available, from any of our devices connected to the Internet. For more information about cloud e-mail service, see the difference between webmail and an e-mail client, below.

Online E-Mail:

An alternative way of sending and receiving e-mail (and the more popular solution for most people) is an online e-mail service or webmail. Examples include Hotmail (now Outlook.com), Gmail, and Yahoo Mail. Many of the online e-mail services, including the ones we mentioned, are free or have a free account option.

Writing An E-Mail:

When writing an e-mail message, it should look something like the example window below. As we can see, several fields are required when sending an e-mail:


1. The To field is where we type the e-mail address of the person who is the recipient of our message.

2. The From field should contain our e-mail address.

3. If we are replying to a message, the To: and From: fields are automatically filled out. If it's a new message, we'll need to specify the recipients in the To: field, either by selecting them from our contact list or manually typing the full email addresses. If we are manually specified more than one recipient (as in a group e-mail), the addresses should be separated by a comma and a space, or by pressing the Tab key.

4. The Subject should consist of a few words describing the e-mail's contents. The Subject lets the recipient see what the e-mail is about, without opening and reading the full e-mail. This field is optional.

5. The CC ("Carbon Copy") field allows us to specify recipients who are not direct addressees (listed in the "To" field). For instance, we can address an e-mail to Jeff and CC Linda and Steven. Although the e-mail is addressed to Jeff, Linda and Steven will also receive a copy of the message, and their addresses will be visible to Jeff, and to each other. This field is optional.

6. The BCC ("blind carbon copy") field is similar to CC, except the recipients are secret. Each BCC recipient will receive the e-mail, but will not see who else received a copy. The addressees (anyone listed in the "To" field) remain visible to all recipients. This field is optional.

7. Finally, the Message Body is the location we type our main message. It often contains our signature at the bottom; similar to a handwritten letter.
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