My 100 th post

Boom, it's my 100 th post. I just wanna share my happiness at this time. I started this blog two year ago with no idea where to start and where to end. Later I came to know this will be my never ending one till my life end.

I began to love this blog. It has a peaceful place place for me to learn.

Sharing these things with you has done so much for me. I hope whoever reads this blog, learn it, feels encouraged because of what I write here.

'I hope it brings some good to the world'.

Application programming interface 1

What is an API?

An application-programming interface (API) is a set of programming instructions and standards for accessing a Web-based software application or Web tool. A software company releases its API to the public so that other software developers can design products that are powered by its service.

For example, Amazon.com released its API so that Web site developers could more easily access Amazon's product information. Using the Amazon API, a third party Web site can post direct links to Amazon products with updated prices and an option to "buy now."

An API is a software-to-software interface, not a user interface. With APIs, applications talk to each other without any user knowledge or intervention. When you buy movie tickets online and enter your credit card information, the movie ticket Web site uses an API to send your credit card information to a remote application that verifies whether your information is correct. Once payment is confirmed, the remote application sends a response back to the movie ticket Web site saying it's OK to issue the tickets.

As a user, you only see one interface -- the movie ticket Web site -- but behind the scenes, many applications are working together using APIs. This type of integration is called seamless, since the user never notices when software functions are handed from one application to another [source: TConsult, Inc.]

An API resembles Software as a Service (SaaS), since software developers don't have to start from scratch every time they write a program. Instead of building one core application that tries to do everything -- e-mail, billing, tracking, etcetera -- the same application can contract out certain responsibilities to remote software that does it better.­

Let's use the same example of Web conferencing from before. Web conferencing is SaaS since it can be accessed on-demand using nothing but a Web site. With a conferencing API, that same on-demand service can be integrated into another Web-based software application, like an instant messaging program or a Web calendar.

The user can schedule a Web conference in his Web calendar program and then click a link within the same program to launch the conference. The calendar program doesn't host or run the conference itself. It uses a conferencing API to communicate behind the scenes with the remote Web conferencing service and seamlessly delivers that functionality to the user.

Mapplets

A mapplet is a reusable object that you create in the Mapplet Designer. It contains a set of transformations (more than 1 transformation) and lets you reuse the transformation logic in multiple mappings.

For example, you a similar logic need to add more than 1 mapping. Like concatenate First_Name & Last_Name, Address_Street_1 & Address_Street_2 etc and this logic is need for Employee_Table, Student_Table, Patient_Table 3 mappings.

In this scenario instead of repeating the logic, we can have a mapplet for concatenate (Merge) columns and use this mapplet instance for the above mentioned 3 mappings.

When you use a mapplet in a mapping, you use an instance of the mapplet. Like a reusable transformation, any change made to the mapplet is inherited by all instances of the mapplet.

Mapplets help simplify mappings in the following ways:

Include source definitions. Use multiple source definitions and source qualifiers to provide source data for a mapping.
Accept data from sources in a mapping. If you want the mapplet to receive data from the mapping, use an Input transformation to receive source data.
Include multiple transformations. A mapplet can contain as many transformations as you need.
Pass data to multiple transformations. You can create a mapplet to feed data to multiple transformations. Each Output transformation in a mapplet represents one output group in a mapplet.
Contain unused ports. You do not have to connect all mapplet input and output ports in a mapping.

To use a mapplet in a mapping, first we need to configure it for input and output. In addition to transformation logic that you configure, a mapplet has the following components:

1. Mapplet input
2. Mapplet output
3. Mapplet ports

Mapplet Input

Mapplet input can originate from a source definition and/or from an Input transformation in the mapplet. You can create multiple pipelines in a mapplet. Use multiple source definitions and source qualifiers or Input transformations. You can also use a combination of source definitions and Input transformations.

Mapplet Output

Mapplet Output transformation in a mapplet to pass data through the mapplet into a mapping. A mapplet must contain at least one Output transformation with at least one connected port in the mapplet. Each connected port in an Output transformation displays as a mapplet output port in a mapping. Each Output transformation in a mapplet displays as an output group in a mapping. An output group can pass data to multiple pipelines in a mapping.

Use the following rules and guidelines when you add transformations to a mapplet:
If you use a Sequence Generator transformation, you must use a reusable Sequence Generator transformation.

If you use a Stored Procedure transformation, you must configure the Stored Procedure Type to be Normal.
You cannot include PowerMart 3.5-style LOOKUP functions in a mapplet
You cannot include the following objects in a mapplet:

Normalizer transformations
COBOL sources
XML Source Qualifier transformations
XML sources
Target definitions
Other mapplets

Although reusable transformations and shortcuts in a mapplet can be used, to protect the validity of the mapplet, use a copy of a transformation instead. Reusable transformations and shortcuts inherit changes to their original transformations. This might invalidate the mapplet and the mappings that use the mapplet.

Note:

• Use the following rules and guidelines when you edit a mapplet that is used by mappings:
• Do not delete a port from the mapplet. The Designer deletes mapplet ports in the mapping when you delete links to an Input or Output transformation or when you delete ports connected to an Input or Output transformation.
• Do not change the datatype, precision, or scale of a mapplet port. The datatype, precision, and scale of a mapplet port is defined by the transformation port to which it is connected in the mapplet. Therefore, if you edit a mapplet to change the datatype, precision, or scale of a port connected to a port in an Input or Output transformation, you change the mapplet port.
• Do not change the mapplet type. If you remove all active transformations from an active mapplet, the mapplet becomes passive. If you add an active transformation to a passive mapplet, the mapplet becomes active. 

Application programming interface

In computer programming, an application programming interface (API) specifies how some software components should interact with each other.

In addition to accessing databases or computer hardware, such as hard disk drives or video cards, an API can be used to ease the work of programming graphical user interface components. In practice, many times an API comes in the form of a library that includes specifications for routines, data structures, object classes, and variables. In some other cases, notably for SOAP and REST services, an API comes as just a specification of remote calls exposed to the API consumers

Another one.,

API, an abbreviation of application program interface, is a set of routines, protocols, and tools for building software applications. The API specifies how software components should interact and are used when programming graphical user interface (GUI) components.  A good API makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together.

Popular API Examples

Programmable Web, a site that tracks more than 9,000 APIs, lists Google Maps, Twitter, YouTube, Flickr and Amazon Product Advertising as the most popular APIs (view all sorted by popularity).

1. Google Maps API: Google Maps APIs lets developers embed Google Maps on webpages using a JavaScript or Flash interface. The Google Maps API is designed to work on mobile devices and desktop browsers.

Example API Use : Charting Your Course Using the Google Maps API.

2. YouTube APIs: YouTube API: Google's APIs lets developers integrate YouTube videos and functionality into websites or applications. YouTube APIs include the YouTube Analytics API, YouTube Data API, YouTube Live Streaming API, YouTube Player APIs and others.

3. Flickr API: The Flickr API is used by developers to access the Flick photo sharing community data. The Flickr API consists of a set of callable methods, and some API endpoints.

4. Twitter APIs: Twitter offers two APIs. The REST API allows developers to access core Twitter data and the Search API provides methods for developers to interact with Twitter Search and trends data.
Example API Use : Using the Twitter API to Create an Early Alert System.

5. Amazon Product Advertising API: Amazon's Product Advertising API gives developers access to Amazon's product selection and discovery functionality to advertise Amazon products to monetize a website.

What is a Surrogate key?

A surrogate key is a substitution for the natural primary key.

It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table.

Data warehouses typically use a surrogate, (also known as artificial or identity key), key for the dimension tables primary keys. They can use Infa sequence generator, or Oracle sequence, or SQL Server Identity values for the surrogate key.

It is useful because the natural primary key (i.e. Customer Number in Customer table) can change and this makes updates more difficult.

Some tables have columns such as AIRPORT_NAME or CITY_NAME which are stated as the primary keys (according to the business users) but ,not only can these change, indexing on a numerical value is probably better and you could consider creating a surrogate key called, say, AIRPORT_ID. This would be internal to the system and as far as the client is concerned you may display only the AIRPORT_NAME.

Router Transformation

• The Router Transformation is an Active and Connected Transformation.

• A Router transformation is similar to a Filter transformation because both transformations allow you to use a condition to test data. A Filter transformation tests data for one condition and drops the rows of data that do not meet the condition. However, a Router transformation tests data for one or more conditions and gives you the option to route rows of data that do not meet any of the conditions to a default output group.

Sequence Generator Transformation

• Sequence Generator is an Passive and Connected.
• The Sequence Generator transformation generates numeric values. Use the Sequence Generator to create unique primary key values, replace missing primary keys, or cycle through a sequential range of numbers.
• It contains two output ports that you can connect to one or more transformations. The Integration Service generates a block of sequence numbers each time a block of rows enters a connected transformation. If you connect CURRVAL, the Integration Service processes one row in each block. When NEXTVAL is connected to the input port of another transformation, the Integration Service generates a sequence of numbers. When CURRVAL is connected to the input port of another transformation, the Integration Service generates the NEXTVAL value plus the Increment By value.

Common Uses for Sequence Generator

You can complete the following tasks with a Sequence Generator transformation:

• Create keys.
• Replace missing values.
• Cycle through a sequential range of numbers.

Creating Keys

We can create primary or foreign key values with the Sequence Generator transformation by connecting the NEXTVAL port to a target or downstream transformation. You can use a range of values from 1 to 9,223,372,036,854,775,807 with the smallest interval of 1.

When we create primary or foreign keys, use the Cycle option to prevent the Integration Service from creating duplicate primary keys. You might do this by selecting the Truncate Target Table option in the session properties or by creating composite keys.

To create a composite key, you can configure the Integration Service to cycle through a smaller set of values. For example, if you have three stores generating order numbers, you might have a Sequence Generator cycling through values from 1 to 3, incrementing by 1. When you pass the following set of foreign keys, the generated values then create unique composite keys:

COMPOSITE_KEY	ORDER_NO
1	12345
2	12345
3	12345
1	12346
2	12346
3	12346

Sequence Generator Ports

The Sequence Generator transformation has two output ports: NEXTVAL and CURRVAL. You cannot edit or delete these ports. Likewise, you cannot add ports to the transformation.

NEXTVAL

Connect NEXTVAL to multiple transformations to generate unique values for each row in each transformation. Use the NEXTVAL port to generate sequence numbers by connecting it to a downstream transformation or target. You connect the NEXTVAL port to generate the sequence based on the Current Value and Increment By properties. If the Sequence Generator is not configured to cycle through the sequence, the NEXTVAL port generates sequence numbers up to the configured End Value.

Note: When you run a partitioned session on a grid, the Sequence Generator transformation skips values depending on the number of rows in each partition.

CURRVAL

CURRVAL is NEXTVAL plus the Increment By value. You typically only connect the CURRVAL port when the NEXTVAL port is already connected to a downstream transformation. When a row enters a transformation connected to the CURRVAL port, the Integration Service passes the last created NEXTVAL value plus one.

Note: When you run a partitioned session on a grid, the Sequence Generator transformation might skip values depending on the number of rows in each partition.

Sequence Generator Transformation Properties

The Sequence Generator transformation is unique among all transformations because you cannot add, edit, or delete the default ports, NEXTVAL and CURRVAL.

Start Value and Cycle

Use Cycle to generate a repeating sequence, such as numbers 1 through 12 to correspond to the months in a year.

To cycle the Integration Service through a sequence:

1. Enter the lowest value in the sequence that you want the Integration Service to use for the Start Value.
2. Enter the highest value to be used for End Value.
3. Select Cycle.

As it cycles, the Integration Service reaches the configured end value for the sequence, it wraps around and starts the cycle again, beginning with the configured Start Value.

NOTE:

Start Value: By default it is 0, It starts sequence generating values up to Maximum value is 9,223,372,036,854,775,806.

Increment By: By Default is 1, It is difference between two consecutive values from the NEXTVAL port and Maximum value is 2,147,483,647.

End Value: Maximum value is 9,223,372,036,854,775,807.

Current Value: Integration Service to use as the first value in the sequence, the value must be greater than or equal to the start value and less than the end value.

b If enabled, the Integration Service cycles through the sequence range.

Number of Cached Values: Number of sequential values the Integration Service caches at a time.

Reset: Integration Service generates values based on the original current value for each session, Otherwise, the Integration Service updates the current value to reflect the last-generated value for the session plus one, and then uses the updated current value as the basis for the next session run. Disabled for reusable Sequence Generator transformations.