Wednesday, November 9, 2011

How Bluetooth Creates a Connection


­Bluetooth takes small-area networking to the next level by removing the need for user intervention and keeping transmission power extremely low to save battery power. Picture this: You're on your Bluetooth-enabled cell phone, standing outside the door to your house. You tell the person on the other end of the line to call you back in five minutes so you can get in the house and put your stuff away. As soon as you walk in the house, the map you received on your cell phone from your car's Bluetooth-enabled GPS system is automatically sent to your Bluetooth-enabled computer, because your cell phone picked up a Bluetooth signal from your PC and automatically sent the data you designated for transfer. Five minutes later, when your friend calls you back, your Bluetooth-enabled home phone rings instead of your cell phone. The person called the same number, but your home phone picked up the Bluetooth signal from your cell phone and automatically re-routed the call because it realized you were home. And each transmission signal to and from your cell phone consumes just 1 milliwatt of power, so your cell phone charge is virtually unaffected by all of this activity.
Bluetooth is essentially a networking standard that works at two levels:
  • It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.
  • It provides agreement at the protocol level, where products have to agree on when bits are sent, how many will be sent at a time, and how the parties in a conversation can be sure that the message received is the same as the message sent.
The big draws of Bluetooth are that it is wireless, inexpensive and automatic. There are other ways to get around using wires, including infrared communication. Infrared (IR) refers to light waves of a lower frequency than human eyes can receive and interpret. Infrared is used in most television remote control systems. Infrared communications are fairly reliable and don't cost very much to build into a device, but there are a couple of drawbacks. First, infrared is a "line of sight" technology. For example, you have to point the remote control at the television or DVD player to make things happen. The second drawback is that infrared is almost always a "one to one" technology. You can send data between your desktop computer and your laptop computer, but not your laptop computer and your PDA at the same time. (See How Remote Controls Work to learn more about infrared communication.)
These two qualities of infrared are actually advantageous in some regards. Because infrared transmitters and receivers have to be lined up with each other, interference between devices is uncommon. The one-to-one nature of infrared communications is useful in that you can make sure a message goes only to the intended recipient, even in a room full of infrared receivers.
Bluetooth is intended to get around the problems that come with infrared systems. The older Bluetooth 1.0 standard has a maximum transfer speed of 1 megabit per second (Mbps), while Bluetooth 2.0 can manage up to 3 Mbps. Bluetooth 2.0 is backward-compatible with 1.0 devices.

Friday, October 21, 2011

Tips to Secure Email



 Tips to Make You More Secure and Productive

Everyday, and some not everyday, tips on how you can keep your email safe
and secure.

When people read out a phone number, they use “phone rhythm.” No one has to explain “phone rhythm,” we all just
seem to do it automatically, “…713...555...12…34”. Similarly, when we answer a phone call we all say, “Hello.” No one
taught us to do that, but somehow we all seemed to pick it up.

So why is it that when it comes to emails, there are no accepted standards? Even though 6 billion emails are sent every day, almost no one agrees about simple things like email etiquette, how to organize a note, or whether emails are considered private or not.

The 99 tips in this article make up the best in email practices. From how to ethically use the ‘BCC:’ to what attachments will make your mobile emailing compatible with everyone else’s, this list covers everything you need to know about emailing.

Etiquette

We’re all guilty of bad manners once in a while, but when it comes to emailing, some people are downright clueless.

1)Don’t send private messages with the company account. If you want to send personal messages from
work (and you should probably try to minimize this), use a freebie account like Hotmail, Gmail, Yahoo!, or
Excite, if your office permits it. The content of your emails is less visible to employers through these accounts,
so the private messages you send will stay private.

2)Use BCC if necessary. If you must send a group email to people who do not know each other, don’t add
their addresses to the form’s CC field; this is one method spammers use to harvest email addresses. Instead,
use BCC (Blind Carbon Copy) for their addresses, and put your own email in the form’s “to” field.

3)Don’t send form letters. Its impolite to send form letters, especially to your friends and colleagues unless
they are all part of a group that is expecting them.

4)Don’t forward chain letters. Just don’t do it. Enough said. That includes the email that says that if you don’t
forward it to 10 people you’ll die. I don’t care how superstitious you are, don’t send them.

5)Be professional. Ensure your work emails don’t contain ‘u’, ‘afk’, ‘ty’, ‘jk’ and/or several million other texting/chatroom acronyms. These developed because cell phones’ keypads aren’t well-suited to writing fully-formed words, sentences and paragraphs. In business communications, however, they may give the impression of childishness and illiteracy.

6)Be professional, part 2: Check tone. Be aware of the professional (or not) relationship between yourself
and the recipient before starting an email. Use that to gauge what topics are appropriate to write or not, as
well as the tone of your writing. This may be common sense to most, but you’d be surprised at how often the
rule is ignored.

7)Be careful. Email is not private; it can be intercepted anywhere en route to its recipient. In addition, it can live on for years in recipient email boxes, later to return to its sender in choice quotations. Think before sending email you will later regret.

8) Cut down on sigs. Signature files, especially in business, should contain as few lines as possible. Four lines
is a figure generally agreed-upon. Email that consists of a two-line statement and a ten-line signature will have
its recipients rolling their eyes.

9)May I quote you? When you respond to an email, the original email is quoted. Cut the most relevant
sentence from the message to which you are responding, preface it with a ‘>’ (if it’s not already there) and
paste the quote above your response. Delete the rest of the original email from your response, unless you are
responding to other points in the original.

10) Don’t use email when you are angry. This is a tip from Joan Tunsall’s Better, Faster Email (non-affiliate

11) Get clarification. If someone sends you an email that upsets you, make sure you haven’t misunderstood. As mentioned previously, emotion and tone do not always carry over well in email. Instead of responding angrily, in your response, quote the portion of text that you are unsure of and ask the sender to clarify. Indicate what you think it means, if you like, then ask if you’ve misunderstood.

12) Don’t spam friends. Occasionally, company mail servers go on the fritz and send forty-five copies of the
same email to the recipient (personal experience). Even if it’s not your fault, it is polite to apologize profusely to your friend, family, or roommate.

13) Consider the quirks of other email systems. For example, say that you have a friend with a Hotmail
account and want to send a list of hyperlinks. Hotmail doesn’t handle hyperlinks inside of an email very
well. For example, you cannot easily copy the actual URL, without a bit of effort. So anyone used to tabbed
browsing, such as with all recent web browsers (including, finally, IE7.x), may find it frustrating trying to open
a link in a new tab or window. It’s hard to know about all types of email systems, but some awareness reduces frustrating situations for recipients.

14) Respond to group email appropriately. If someone has sent a group email that requires a response, but
only to the sender or a couple of parties, don’t copy everyone on your reply.

15) Don’t respond to every group email. More specifically, it is alright to sit out a thread of group conversation if you are not being addressed directly. However, read the emails carefully to make sure that you are not being expected to respond.

16) Respect email laws and regulations. Some countries have very specific rules about bulk emailing. If
you use email to promote your business, you need to know the laws for not only your country but probably
wherever you are emailing to. It’s a tall order, given the global village of the Internet, but its importance cannot
be overstated.

17) Use meaningful subject lines. Write something “meaningful” in the subject line, to give recipients a clue
as to what your email is about. This is increasingly necessary to distinguish legit emails from spam. The latter’s
subject lines are are often deceptive.

18) Be brief. Do not send excessively long emails if at all possible. Try to summarize your information so that
your recipients are more likely to read the email and actually respond. When possible, break long emails into
numbered point form so that recipients can respond by reference number.

19) Summarize. Precede a long email with a short summary.
20) Cheat with templates. In his Five Fast Email Productivity Tips, author Merlin Mann recommends ‘cheating’

21) Use ‘Reply All’ when necessary. Usually, the common advice is to not use “reply all” if other recipients of a group email do not need your response. But forgetting to use “reply all” when appropriate is simply inefficient. If the vast majority of a group needs to hear a message, writing in individual emails addresses will waste your time and increase the chances that you’re going to leave someone important out of the email.

22) Remember the telephone. Unless you need a written record of a given communication (or if the person
you’re communicating with is long distance), consider calling (or sending a letter to) your intended recipient
instead of an email. People often default to writing an email because it is quick and easy; but sometimes a
handwritten letter or phone call can provide the personal touch your communication really needs.

23) If it’s urgent, say so. Writing ‘URGENT’ in front of your email’s subject will make it stand out from the
crowd, and most likely get timely attention from the recipient. Make certain it is urgent, however; remember
how much attention was paid to the boy who cried wolf when his cries really mattered.

24) On vacation? If you will be out of your office for a lengthy period of time, set up an autoresponder to inform whomever emails you of your absence and your expected return. This is polite (the message is only sent to a given email once), and it prevents a lot of “I’m waiting for your response” emails. A quick warning, however, to not use an autoresponder for your home email; you shouldn’t advertise an empty house.

25) Use smileys. If you think that something you’ve written might be misunderstood in tone or emotion, use the appropriate smiley. It should be obvious, but this tip does not apply to work or other professional emails, or if the person doesn’t know you already. Marketing genius Seth Godin wrote the The Smiley Dictionary
and there are several sites with something similar: Helvig’s smiley dictionary, the unofficial smiley dictionary,
and EFF’s unofficial smiley dictionary.



Friday, August 12, 2011

Input Output stream in java

An I/O Stream represents an input source or an output destination. A stream can represent many different kinds of sources and destinations, including disk files, devices, other programs, and memory arrays.
Streams support many different kinds of data, including simple bytes, primitive data types, localized characters, and objects. Some streams simply pass on data; others manipulate and transform the data in useful ways.
No matter how they work internally, all streams present the same simple model to programs that use them: A stream is a sequence of data. A program uses an input stream to read data from a source, one item at a time:
Reading information into a program.
 A program uses an output stream to write data to a destination, one item at time:
Writing information from a program.
In this lesson, we'll see streams that can handle all kinds of data, from primitive values to advanced objects.
The data source and data destination pictured above can be anything that holds, generates, or consumes data. Obviously this includes disk files, but a source or destination can also be another program, a peripheral device, a network socket, or an array.