Software, Programming, Architecture & More
Continuing with the Computing the Services Part – 1, We shall take a look at what each characteristics of services means in the computer world. Defining characteristics is very important aspect in any design. You have to define your design, to work in the way you describe and you expect to it.
The characteristics can be further grouped into
Our HiTech bank needs a enterprise application to be designed, which obviously requires a lot of design. But our HiTech bank will provide basic services like withdrawal and deposits, via various interfaces like Online, ATM and Card Readers.
The services defined should be granular in nature. Granularity comes when comes the matter of re-usability and maintainability. More granular is the service, more the re-usability and maintainability.Consider the services which does the deposit & withdraw transaction in our HiTech Bank.
Bank.deposit( username, password, PIN, deposit-amount, account# ):
if PIN = BLANK //Online mode
Check if the username, password is valid
Check if the username, password is valid for account#
if PIN IS NOT BLANK
Check if PIN is valid for the account
Open #account
Add deposit-amount to the existing amount in #account
Close #account
Bank.withdraw( username, password, PIN, withdraw-amount, account# ):
if PIN = BLANK: //Online mode
Check if the username, password is valid
Check if the username, password is valid for account#
if PIN IS NOT BLANK:
Check if PIN is valid for the account
Open account#
Reduce withdraw-amount to the existing amount in #account
Close account#
The above code is not granular and not re-usable. The reason is, lets assume that in future the HiTech bank is adding more user interface devices and has different authentication system, say biometrics. Now, you are ought to change the authentication code in your module. Now, you can feel the pain of modifying it.Also, the transaction are tied with the authentication process, which logically shouldn’t be. Because, transaction is a separate Unit of Work. If you transaction fails, it’s not necessary that your authentication also fails.
Fig 1. Decomposing the methods to create more granular methods.
Bank.authenticate( username, password, PIN, account#) :
if PIN = BLANK : //Online mode
Check if the username, password is valid
Check if the username, password is valid for account#
if PIN IS NOT BLANK :
Check if PIN is valid for the account
Bank.deposit( deposit-amount, account# ):
Open account#
Add deposit-amount to the existing amount in #account
Close account#
Bank.withdraw( withdraw-amount, account# ):
Open account#
Reduce withdraw-amount to the existing amount in #account
Close account#
Bank.doTransaction( transaction, account, amount, username, password, PIN ):
Bank.authenticate( username , password, PIN)
if transaction = Deposit
Bank.deposit( amount, account# )
if transaction = Withdraw
Bank.withdraw( amount, account# )
This is the how you make granular services. The advantages of this is you have good maintainability, easy code modification and more re-usability. In future, you change the authentication code to authenticate with another device / interface, no matter what you change , your change is evenly applied across the service.
An Interface will enable a device or program enabling a program to communicate with another program. In UNIX, one of the cool interface is the “|” pipe symbol. You can combine more than one UNIX command via the “|” ( pipe ). Pipe acts as an interface between two programs.
cat *.java | grep “String.to”
It is one of the most important characteristics to define. When a service is defined, make sure that it has proper interface to communicate to the business services. In our bank ( HiTech Bank) banking situation, you need services to authenticate the user / customer before accessing the account. You should at least define these service, which in turn does the appropriate authentication.
| Human Interface | Services | Interfaces | Contract between Service & Interface Matches? |
| ATM Machine / Card Reader | Bank.authenticate ( PIN , account# ) | BankInterface.authenticate ( PIN, Name ) | The contract doesn’t match |
| Online / Mobile app | Bank.authenticate ( username, password, account# ) | BankInterface.authenticate( username,password, account#) | Contract matches |
If the HiTech Bank haven’t defined a proper interface to read the card but just to type in the PIN, the customers will not be able to use the ATM machines / Card readers even if the service to authenticate is available.
Fig 2. Bank implementing Bank Interface and other User Interfaces using the bank interface
We shall continue with the remaining characteristics in the next post.
Every civilization had their own representation of numbers in their age. Like what we have now , the Arabic Numerals 1 2. This representation is no more in use as universally as the arabic numerals that are taught now. Though different civilizations had different glyphs to represent number, everyone have understood the importance of numbers and found a way to represent them and did known how to handle it.
In Tamil, Number is called as “EN” ( Tamil:???) and “Digit” is called as Illakangal ( Tamil: ??????? )
Tamil language instructs to write numbers based on how the pronunciation is made rather than how the digits are spelled.
Fig 1. How a number is spelled and pronounced
Below list maps the modern number we use, to the tamil glyphs that was used by the Tamils. It is interesting to find that the list doesn’t contain a tamil representation for equivalent for zero. I’m wondering why the tamil havent created any glyph for “ZERO”. Did they think that it’s not mandatory that one should require ZERO to write down numbers? or did they find ZERO is ‘evil’? or ZERO is not necessarily to write down any number in this world, other than ZERO.
Fig 2. Listing the tamil glyphs for modern numbers we use
Even in our modern world, we don’t use zero when we pronounce the number. We don’t say , “One Hundred Zero Three” for 103. If that is the text, it would literally means “One followed by Hundred Zeros and a Three“. So, we are accustomed to say, “One Hundred and Three“. We can see that we don’t require ZERO when we say a number. It’s only required when we spell the number. But Tamils haven’t or ‘didn’t wanted’ to have two formats to say a number ( pronouncing & spelling ). This could be one reason that I can think of why ZERO is missing in the number set.
INFITT ( International Forum for Information Technology in Tami) aka “??????? (Uttamam)” have made proposal to include ZERO into the tamil number glyph’s list and createa UNICODE symbol for it in the tamil language font.
I tried to translate few numbers from arabic to tamil 3and here is on how to write numbers in tamil. You can also try few and if possible share it.
Fig 3. Some sample on how to write a number
One thing I could realize is that, in olden days people in any civilization ( not Babylons ) who didn’t had ZEROs in their set, to write / speak about any number.
In my team we were talking about services and then the web services, and when I was talking to a friend of mine about the services stuff, he posted a blank question. “What is a service? and how different is that from a method”. His question is correct, I feel that most of the people who design services in this complex computing world are not still clear what is a service and not sure of how different is a programming language methods from the service and what it is intent to do?
Lets start exploring the service. Let me take you to the understanding of what does a service means in the real world and how is that transformed into the computing world. Consider a simple banking situation, where the customer is willing to get some service to fulfil his / her needs. interaction between a customer and the service provider A person needs to deposit some money into the account of the person. Hence , deposit is a service provided by the bank to make customer safe guard the money into the bank’s vault. Similarly, withdrawal, money transfers etc., are some of the service provided by a service provider i.e bank.
In layman’s term , A service is “an act of assistance”.
But some service oriented company, does exactly same job as this.
So, you place computers in the place of humans. But still, how do you make sure that the computers perform the same task as of humans ( of-course, not the one like above ) and deliver the expected service as good as a human ( is it?? ). Hence this will lead to define some of the characteristics of good service.
This table give you an complete idea on how a delivered service should be. Just gathering together.
|
What do the customer expect |
What does it mean in the computer world |
| Provide a well defined mode / way to receive the data to start the service | Interface |
| Information collected to process the request should be minimal | Granular |
| Ability to process information without asking too much questions | Mostly stateful & sometimes stateless |
| Ability to finish the process as quick as possible and respond back to customer | Speed |
| Should finish the requested transaction flawless | Correct |
| Should finish the requested transaction without any interruption | Robust |
| Should finish the transaction successfully and completely | Complete |
I will detail out the each of the characteristics in the next article.
[ Updated: Updated the description of the “State” of the service ]
