Distributed Computing and Mobile Client

Distributed Computing – Mobile Client, the idea lead towards Pervasive Computing

Pervasive Computing termed as Universal Computing

            We have discussed the composition of mobile and pervasive computing. The existence of mobile and pervasive computing doesn’t even happen overnight. Most of the inventions and techniques invented over the time and the idea of pervasive computing was brought into the picture with clarity.

            Researchers and technology oriented industry make their all efforts together to enhance the technology keeping in mind the perspectives as of pervasive computing. The objective was to provide the computing infrastructure embedded into everyday used things in routine for various purposes.

 The Journey from Traditional standalone Desktop Computer to Networked Distributed                 Computing

By the birth of the idea of ubiquitous or pervasive computing, the initial step taken was to access the data and information from multiple platforms at distant places. Consequently, the objective was met by devising computing infrastructure merged into or divided into distributed architecture.

With the existing technologies available at that time was one important field which was termed as distributed computing. Later on the distributed computing and distributed mobile computing environment brought into the idea of removing the limitation of wire based connectivity.

Mobile computing has lots of features which directly maps the requirements of pervasive computing. Hence few other requirements will required to be met which was not yet evolved and no solutions were available also.

There are certain limitations that came with mobile computing. The first most is unpredicted network quality, when we are going to use mobile computing we must have to remove the dependency of infrastructure like wire based connection, power supply, larger screen size and massive computing speed.

The invention of wireless internet was taken place. Wi-Fi and WiMAX came into existence and some related technology. When we start using wireless network the quality of the network become unpredictable due to certain limitations in connectivity.

Connectivity in open space is much more as compared to connectivity in closed space. It happened due to the obstructions like walls, wooden items like tables, cabinets within the offices. While in the open space the signal can be transmitted due to clear line of sight so that the wireless signal can be travelled easily. At some points we can get good connectivity and at some points we have limited connectivity. 

This is the inherit nature of wireless network.

Another aspect of mobile elements is that they are less trustable as these mobile elements are by nature moveable. For example if we move the wireless router from one place to another the devices connected to that router will be disconnected or may be facing less connectivity. So these wireless elements can be said less-robust.

Mobile elements uses battery as power source and in such a case power of battery is running out the mobile element using that battery will be automatically turned off.

Privacy is also another aspect in mobile network. When we are transmitting data over the air, then anybody can have the possibility to catch the private data. Radio and TV signals are such examples. 

     Few of security measures were available but lots of others were required.

    Then the limitation brought into by the mobile network if we want to travel with your computer but actually this is not possible to move your desktop computer with you. So the idea of shrinking the technology came into existence.

§   The race was started among different companies to design such a technology that would be smaller in size, efficient in use, invisible so it can be carried with that mobile component. The required technology must be so invincible that everyone can use it with ease.

     The size of the computer was required to be reduced that they can be easily carried. The size of screen, hard disk, processor, power battery was required to be minimized so that they can fit into a small unit and can be carried out by a travelling user.

§  Consequently, the processing, storage capacity was also decreased as the technology used in for manufacturing laptop computers was newly designed and going through the evolution phase.

    That new technology at that time was little behind the desktop technology. The hardware of laptop was not able to extensible, upgraded at that time.

     Limited RAM, Processors, Hard disk and other essential components were reduced in size and there was a performance tradeoff too.

    Then there is a concern of power consumption. Once we have gone mobile that the battery must be capable of providing battery power approximately one to two hours. So after sometime the user would be able to get the chargeable source of power.

Inventions of Mobile computing while going wireless

We need connectivity if we are going to use wireless network as our wireless computer or element would be a source as sender of data as well as receiver for receiving the data packets. We have to exchange the information by connecting other computers.

In traditional computing IP address is assigned to the computers to uniquely identify the nodes over the network. Using fix networking its working is very fine.

Mobile computing allows us to move around but the problem arises as we are continuously switching or changing the network. The computer or mobile device identification will be remained same but network id would be changed when we are switching to another network.

While we are sending data on the go and the network id is changed as we switch to another network, the solution to this problem is Dynamic assignment of IP or DHCP.

2^nd scenario is different if we are sending a file using laptop over Wi-Fi and we are going to some other office where another Wi-Fi network is available; the file which is being transferred or in transition phase should not lost its data packets while switching over to another network. To understand that scenario we need to know the mobile or cellular network first.

Mobile or cell phone is embedded with home location register (HLR), whenever we turn on our phone our phone will be registered with Telecom service provider using HLR, then there is another register visitor location register (VLR). VLR start working when the user of that cell phone use roaming/travelling and VLR in turn connected with HLR.

Visitor Location Register while on the go, register itself with a network and inform the Home Location Register HLR that now this mobile is in this domain now. When a mobile probe, it tries to find out the HLR and sends back the information that it is actually located at that point with following VLR and then the connection is made through that VLR to that mobile phone.

Same concept is used with mobile IP networking. The idea is when we move from our home/office, the IP information will be given to HLR and we are now leaving the office/home and connected to new IP using VLR then this IP will be sent to HLR so that if some information is in transition when we were at home or office then that traffic will be routed at the new IP address.

Using that scenario, whenever new packet of data arrived at the HLR and it knows that no mobile devices is connected to it, it will find out the current IP information retrieving through VLR and that packed of data will be transmitted to that device. This mechanism was called mobile IP and it was the initial solution for assigning wireless IP addresses.