What is Correlation

What is Correlation

Correlation is used to manage dynamic values like session ids which cause failure during script playback. Correlation makes sure dynamic values are not hardcoded.
Note1 : In loadrunner Manual Correlation uses a function named Web_reg_save_param() in code to handle the issue.
Note2 : In Jmeter Regular expression extractor is used to handle this where server response will be parsed by Regular expression extractor

Web server vs Application server vs Database server

Web server vs Application server vs Database server

Web server serves a web content (HTML and static content) over the HTTP protocol.

Application server is a container on which one can build and expose business logic and processes to client applications through various protocols like HTTP. Some cases it will have internal web server. Application server is heavy in terms of resource usage.

Database server refers to the back-end system of a database application using client/server architecture. The database server performs tasks such as data analysis, storage, data manipulation, archiving, and other non-user specific tasks

Apache vs NGINX 

Both Apache and NGINX are web servers and used to serve the page contents back to users. NGINX has more efficiency in terms response especially when it comes to larger set of static pages. NGINX caching makes the contents ready available to user’s browser without going back to server to process the requsts from scratch.

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Selenium jenkins integration
Protractor vs Selenium

Jenkins

Jenkins is a continuous integration (CI) tool. It is the leading open source automation server. Jenkins provides hundreds of plugins to support building, deploying, and automating any project.

Apache poi selenium webdriver supports Selenium projects

Apache poi selenium webdriver supports Selenium projects. Apache POI gives Java libraries for creating, reading and writing Microsoft format files such as Word, PowerPoint and Excel using Java language.

You can read/write on excel after importing sheet data in selenium web driver. For running Selenium scripts, Eclipse IDE can be used, Apache POI gives Java libraries/ jar files should be loaded to Eclipse IDE / current project in IDE.