SDLC: Systems Development Life Cycle

Systems Development Life Cycle, is the process of creating a software and this the one which is followed in Software Testing.

Phases of software project: A software project is made up of series of phases.

(1)Requirements gathering and analysis

(2)Planning

(3)Design

(4)Development or coding

(5)Testing

(6)Deployment and maintenance

(1)Requirement gathering and analysis:

·The requirements of the software to be built are gathered and documented.

·If the software is bespoke software then there is a single customer who can give these requirements.

·If the product is general-purpose software, then a product marketing team within the software product organization specifies the requirements by aggregating the requirements of multiple potential customers.

·The requirements get documented in the form of a system requirements specification (SRS) document.

·The document acts as a bridge between the customer and the designers chartered to build the product.

(2)Planning:

·The purpose of the planning phase as to come up with a schedule, the scope, and resource requirements for a release.

·A plan explains how the requirements will be met and by which time.

·It needs to take in to the account the requirements- what will be met and what will not be met- for the current release to decide on the scope for the project.

·The planning phase is applicable for both development and testing activate

·At the end of this phase, both project plan and test plan documents are delivered.

(3)Design:

·The design phase produces a representation that will be used by the following phase, the development phase.

·This representation should serve two purposes. First, fro this representation, it should be possible to verity that all the requirements are satisfied. Second, this representation should give sufficient information for the development phase to proceed with the coding and implementation of the system.

·Design is usually spilt in to two levels high level design an low level design or detailed design .

·The step produces the system design description (SDD) document that will be used by development teams to produce the programs that realize the design.

(4)Development or coding:

·Design acts as a blueprint for the actual coding to proceed.

·In addition to programming, this phase also involves the creation of product documentation.

(5)Testing:

·As the programs are coded, they are also tested.

·In addition, after the coding is complete, the product is subjected to testing.

·Testing is a process of exercising the software product in pre-defined ways to check if the behavior is the same as the expected behavior.

·By testing the product, an organization identifies and removes as many defects as possible before shipping it out.

(6)Deployment and maintenance:

·Once the product is tested it is given to the customer who deploys it in their environments.

·As the users start using the product in their environments, they may observe discrepancies between the actual behavior of the product and what they were give to expect.

·Such discrepancies could end up as product defects, which need to be corrected.

·Now the product enters in to the maintenance phase.

·Maintenance is made up of corrective maintenance (for example, fixing customer-reported problems).

·Adaptive maintenance (for example, making the software run on a new version of an operating system or database),

·Preventive maintenance (for example, changing the application program code to avoid a potential security hole in an operating system code).

In the database design stage, you can design th entity-Relationship(E-R) model of the database. An entity-Relationship model is used to represent the logical structure of a database in the form of a diagram. This diagram is known as an entity-relationship diagram. An entity-relationship diagram consist of many shapes, such as oval, rectangle, arrows and diamond to represent attributes of the database, entity of the database, relationship between entities and the scope of the entities. After designing the entity-relationship model of the database, you have to check the correctness of the entity-relationship model. To check the correctness of the entity-relationship model, you need to use normalization, which helps to remove redundancy and provides consistency of the entities in the database. The result is used the entity-relationship diagram. After designing an accurate entity-relationship model of the database, you have to define the set of tables, which are required to manage the data in the conceptual level of the database. After defining all the tables of the database, you have to create those tables using different language of RDBMS. You can also specify primary key, foreign key, different constraints and integrity rules, such as Not Null and Unique for the tables in a database.

DELETED FROM RECYCLE BIN?WANT TO GET BACK THE FILE?

Many of the people think that once we delete a file from the recycle bin,its gone for ever.But the truth is we can still recover that file.Most of us are also aware of the fact that if we pressdown shift when we delete ,the file will not go into recycle bin but will get deleted ‘permenanlty’,as per the computer.Still in any case we can get that file back!!!

So what is happening?If file is still present after deletion,Then how come that the space in hard drive is not running out?So what actually happens to that file.?

Answer: The file is actually not deleted.It is shown as deleted by the system.Only the records are changed by the system and file remains in the system…but…only upto a time when a new file is written over it..yes..Once you delete a file and later when you add a new file,its getting overwritten by the new file and then only it is lost for ever.!

So if we have to recover a file,we have to do it as soon as we can.

Time and activty will reduce the chance of sucessful recovery.

How to recover a deleted file

1.Install a FILE RECOVERY SOFTWARE.i would recommend a freeware called RECUVA.Its free,very efficient and can be download from http://www.filehippo.com/download_recuva

2.Its very simple to use.just give the file name if you remember and the drive in which it was located during deletion.or just select the drive,no file name needed.Click scan

3.A list of deleted files will come up.Look for your file.If the round in the side of file name is green the chance of successful recovery is great.Check(tick) the box of your file.Click RECOVER

4.Give the location for file recovery

*make sure that when you give the location to which the recovered file has to be saved, never select the same place where it was during its deletion.It will reduce the chance of recovery.”a message will come to warn you”.A usb drive will be the best location you can give or any other drive.

Voila! The file is back

Remember these Points

*The faster the recovery better the quality of the recovered file.

*Best works for small sized files.ex. documents

So now stop worrying about accidental deletion and get back the file then and there itself.

Portable application is a different form of a normal software.The difference is that we dont have to install it like normal software inorder to use it,but can run it and use it like a installed software.Now most of the softwares are releasing their portable version.

Usually we install a software in order to use it.In portable application of that software a compressed zip file will be the installation file.When you click on the zip and unzip it the software will be temporarily installed in the computer.You can do all the functions of that software and once you close the window no trace will be left by the software in the system.Even registry entry will be erased.

for example lets take a file recovery software RECUVA

http://www.piriform.com/recuva/builds

we can see different kinds of installation file like

INSTALLER

PORTABLE

Download the portable version and put in a pen drive and carry it.

Suppose your friend is crying for a lost file because of accidental deletion.You can come as a rescuer.You will put your pen-drive on his/her system,run the portable application.Recover file and close the program!!

Thus for people who dont know about a recovery software your action will be like a magic!.They wont understand what you have done and no traces of that software will be in that system.now thats cool!!

There are many such portable applications.Even browsers like mozilla firefox are available in portable form.When you browse from Internet cafe you can use it.

for more portable application visit  http://portableapps.com