What are the differences between testing WEB application and testing client-sever application?

Web application as we know are the kind of applications that can be accessed by one over a computer or internet or intranet network. Some of the web applications are also coded in to the web browser via web browser supported language like HTML or JavaScript. 

There are so many reasons that make web application quite famous with its users like:

1. Because of web browsers’ ubiquity.
2. Because web applications provide a means to use web browsers as a client that are usually termed as thin clients.
3. Because they can be updated and maintained without having to disturb and install the software system or application on 1000s of client systems.
4. And also because they support cross platform compatibility.

Now that we have discussed regarding the web applications, let us see what client server applications are! 

- A client server application is actually not an application rather it is a computing model that acts like a distributed application whose purpose is to partition the work loads or the tasks among the resource or service providers that are merely servers and clients (the service requester).

- The communication among the server and the client is established over a computer network and in most of the cases the servers as well as the client reside in the same system.  

In this article we are going to discuss the differences between testing the two types of the above mentioned applications. It is very necessary to test these applications since our personal as well as commercial needs are much dependent on these. 

First we will be talking about web application testing and then later regarding client server application testing so that the differences between the two will be clear to you! 

About Web Application Testing

- Web application testing is a combo of the following types of testings:

1. Usability testing
2. Compatibility testing
3. Security testing
4. Performance testing
5. Interface testing and
6. Functionality testing

- All these above mentioned tests make up a complete testing path for web applications. 

- These two types of testing i.e., the web application testing and testing client server application, differ on the basis of the environment in which they are carried out. 

- Testing a web application proves to be more difficult when compared to testing a web client server application and is quite complex too! This is so because the testers do not hold much control over the web application under question. 

- In web application testing, the application to be tested is loaded on a server whose location either or not may be known to the testers. 

- The .exe file is not installed on the client side and therefore it is to be tested on different web browsers. 

- Web applications are mostly tested for their compatibility with different OS platforms, error handling, back end testing, and load testing and static pages. 

About Client Server Testing

- Client server application testing is quite simple as compared to the web application testing and basically involves testing of two components.

- Here, like the web application testing is loaded on the server machine but unlike the web application testing, the exe file is installed on all the client machines. 

- The testing here is carried out broadly in categories mentioned below:

1. GUI on both the sides.
2. Functionality
3. Client server interaction
4. Functionality
5. Back end testing and so on.

- The kind of environment that is used in client server application testing is pretty much like the one that is found in intranet networks. 

- The testing team knows all about the location of the servers in the test scenario. 

What are different HTML errors?

HTML or hyper text mark up language is perhaps one of the most used mark up languages for the web pages, sites and applications with which most of us are familiar. This language is written using the HTML elements which mainly constitute of the tags enclosed in the angle brackets like:

These elements are housed in the web page or site. Most of the HTML tags are implemented in pairs of two.

HTML ELEMENTS AND CONTENT
- Some tags are even empty and are commonly known as empty elements.
- These are usually unpaired unlike the filled elements which are paired.
- In the paired tags, the first tag is called the start tag and the second one is then called the end tag.
- Between these two tags, any text, comments, tags etc can be added by the designer of the web sites.
- The content that is to be added should only be of textual type.
- Due to some wrong designing principles often some errors are introduced in to the html of the web site or the page.
- One of the most common errors is the insertion of the graphical content in to the html.
- Such content is neither displayed nor is it interpreted.
- It simply causes the malfunctioning of the web site.
- Other elements of the html allow the addition of the graphical content and only these should be used whenever some graphics are to be inserted in to the page.
- Html elements provide a means for the creation of the structured documents that denote the structural semantics for textual content like:

1. Lists
2. Links
3. Paragraphs
4. Headings
5. Quotes and so on.

DIFFERENT HTML ERRORS AND THEIR IMPACT

- Html can also be embedded in to the scripts like javascript which also some times leads to errors when inserted incorrectly.
- Such errors affect the behaviour of the web sites and cause them to behave abnormally.
- Whenever the site is affected by an error or a bug is encountered, a set of error messages is generated by the business logic component which is then stored as a string in any of the available scopes.
- For using such functions, you need to define an application scope with the name of default attribute, because if such a scope is not found, then nothing is to be rendered by the business logic.
- Some designers forget to define such scopes and therefore end up with unnecessary errors in their web sites.
- Many more errors occur whenever a requested is generated by the client to the web server.
- In such cases the server responds with some status messages, few of which have been mentioned below along with the possible errors:

1. 400:
Bad syntax of the request is preventing the server to process it.

2. 401:
The request though being cannot be processed because of unavailability of the authentication processes.

3. 404 not found:
The page requested by the client is found to be unavailable at that moment.

4. 405 method not allowed:
The client made request in such a way that is not supported by that site.

5. 407 proxy authentication required:
The client has not authenticated its proxy.

6. 408 request time out:
The server’s request time expired while waiting for the client to generate one.

7. 409 conflict:
The server is not able to process the request because of the presence of some conflict in it.

8. 410 gone:
The page that was requested is no longer available on the web.

How to test Graphical User Interface and Client Server Architecture?

The complexity of graphical user interface has grown leading to more difficulty in the design and execution of test cases. As new age graphical user interface have a same kind of look and feel, standard test cases can be written. A strategy that is similar to random or partition testing can also be used for testing graphical user interface. Finite state modeling graphs can also be used to derive test cases. Testing should be approached using automated tools.

Testing of client server architecture is a challenging job. The distributed nature, performance issues associated with transaction processing, presence of different hardware platforms, network communication, servicing multiple clients, coordination requirements makes the testing more difficult. testing of client server occurs at three levels:
- individual client applications are tested in disconnected mode.
- client and associated server applications are tested in concert.
- complete client server including operations is tested.

Different tests that are conducted for client/server systems are:
- Application function tests.
- Server tests.
- Database tests.
- Transaction tests.
- Network communication tests.

Overview of Performance Testing Tools

In client/server applications, many users access the server application simultaneously. In such a case, the software has to be tested for its performance.
The server application continues to run on the server but only one or a few clients will be running the client application but on these client machines, many virtual users are simulated, effectively simulating an environment in which 100 users access the database.
Today many enterprise applications such as ERP software, web services, web sites, CRM software etc. need to be tested for performance testing. Performance testing is also called load testing or stress testing. These tools display the performance of the application using graphs and charts so that analysis will become easy. You can plot a graph which shows the response time as a function of the number of simultaneous users who access the database.
WAPT 6.0 is a load and stress testing tool that provides you with an easy-to-use, consistent and cost-effective way of testing web sites, web servers, and intranet applications with web interfaces. WAPT has a set of features to test web sites with dynamic content and secure HTTPS pages. It provides informative test results through descriptive graphs and reports.
The performance tools that are widely used in the software industry are Mercury Interactive's LoadRunner and Apache's JMeter.

Network Virtual Terminal (NVT)

Telnet is designed for terminal to terminal communication and distributed computer processing. Each host sets up a Network Virtual Terminal (NVT) and a host at one end assumes that an NVT has been set up at the other end. The NVT defines a set of rules for how information is formatted and sent, such as character set, line termination, and how information about the Telnet session itself is sent.There is the mechanism to negotiate options so that the hosts can operate a more elaborate interface at each end using different fonts etc. than the NVT. The User Host is the one that initiates a conversation whilst the Server Host is the one that is providing services.

The Network Virtual Terminal (NVT) is a bi-directional character device. The NVT has a printer and a keyboard. The printer responds to incoming data and the keyboard produces outgoing data which is sent over the TELNET connection and, if echoes are desired, to the NVT's printer as well. Any code conversion and timing considerations are local problems and do not affect the NVT.

Brief NVT description

- NVT comands are inserted to the data stream via TCP/IP before sending to the TCP/IP connection.
- Every NVT command is prefixed by character "0xFF".
- There are some basic commands with 2 byte interpretation only (EOF, ABORT, BRK, AYT, NOP, EC), and others with defined start ( = 0xFF 0xFA) and defined end ( = 0xFF 0xF0) commands.
- The TCP/IP device separates NVT commands and processes them without delay, while the data stream stores to the output stack.
- The NVT commands can't be found in the serial port data, if the device is Serial / TCP/IP converter.
- If you are sending character "0xFF" (255), the PC will just double it, because in NVT "0xFFFF" means send character "0xFF" to the output.
- NVT uses a negotiation process. It's a way of testing if terminals on the opposite side use ECHO or not ar if there are specific terminals etc.

What are Client Server Applications ? A more detailed description

Client server applications are very suitable for the current web world. It is very easy to translate modern web applications into a client server model. For example, if you consider the usage of Yahoo mail that you access through your favorite browser, it is also a client server architecture, at multiple levels. If you consider the case of the Yahoo mail, your browser or mobile runs a client software that connects to a program running at the server which renders the web pages; then the web server itself acts as a client to a database running at the server farm which supplies the actual data that is returned back to the server program, from where it is returned to the client running at the browser.
If you consider the technology of the client server architecture, it is also referred to as a 2 tier architecture, with the 2 tiers being the client and the server. This is the most basic form of the client server architecture, and it can be expanded to go upto using multiple levels such as described in the Yahoo mail program explained above. Both the client and server softwares are normally considered as part of the same software, but they can be modified separately and yet the network keeps on working.
The client server model allows the setting up of such networks that can span across multiple locations, with the client software residing in one location, and the server application in another location. The advantage and simplicity of the client server architecture has made it the prominent architecture behind most modern business and non-business applications. In a mark of how important this model is, even the mainframes of the past have now started using a client server model.

Client Server Applications: The definition

What is Client Server Architecture ? What is some of the defining characteristics of Client Server Applications, especially since there is a buzz for the past many years about web applications, or a mixed breed (using applications such as Adobe AIR).
Client Server applications are literally define by the names used where one software application, at the client end (or at the user end) makes a service request to another software application that sits at the server (typically a machine with a much higher configuration). However, the separation between the client and server is logical, since both of them could exist on the same machine. There is a process to separate the work load of the application between the server application, and the client application. Client server applications are one of the central concepts behind network computing. Initially, the term was used to differentiate between the mainframe model or the Unix model where the entire work was done at the server, and the client was typically dumb, with no capability to do any processing.