Selasa, 6 Oktober 2009
kUliAh pAdA 30 SepTembEr
Jumaat, 11 September 2009
Mesh Topology
An example of a Mesh Network is the Mobile Adhoc Network or MANet. The entire Mesh Network is continuously connected. Being completely connected does not mean that Mesh Network is dependant on each and every node of the network. Even if one node fails in the Mesh Network the network finds an alternate route to transfer the data. It is called the self healing technology where it receives data one way or the other.
The Mesh Network is based on a very sensible concept and has lesser chances of a network breakdown. There are so many possible combinations of routes and hops a data transfer can take that it will reach the destination one way or the other. It is highly unlikely that all the nodes in a single Mesh Network will break down at any given point of time.
Wireless Mesh Networks
Wireless Mesh Networks work based on the radio frequencies and was originally developed by the army to be able to communicate. The reliability factor is high in any kind of Mesh Network. There are three types of wireless Mesh Topologies.
• Fixed Wireless Connections
• Peer to Peer or Adhoc Networks
• Node to Node
Fixed Mesh Networks
The fixed Mesh Networks will work only in the specified location and they are not mobile networks. They are meant to be used in a limited surrounding with boundaries. The location of nodes in affixed Mesh Network is all pre determined and they are not interchangeable.
The fixed Mesh Network does not work on line of sight like the other types of Mesh Networks. The total number of hops in a fixed Mesh Network is usually fixed and also short. There may not be many nodes as this kind of Mesh Networks exist within an office or building. More often than not the data travels ion a specific direction.
Peer to Peer Mobile Networks
In a peer to peer mobile network the individual devices connect to each other using the Mesh Network. The peer does not require connecting to the main node and they can still communicate from one device to another device by taking the shortest possible data transfer route. However many experts believe that in the peer to peer Mesh Networks the problems with scalability in terms of time taken for data transfer is questionable. The device has to know to transmit the data in the most optimal path and the entire data transfer or depends on this single factor. If the device is incapable then the whole purpose of using it in a peer to peer connection is lost.
Tree Topology
A Tree Structure suits best when the network is widely spread and vastly divided into many branches. Like any other topologies, the Tree Topology has its advantages and disadvantages. A Tree Network may not suit small networks and it may be a waste of cable to use it for small networks. Tree Topology has some limitations and the configuration should suit those limitations.
Tree Network topology Benefits
• A Tree Topology is supported by many network vendors ad even hardware vendors.
• A point to point connection is possible with Tree Networks.
• All the computers have access to the larger and their immediate networks.
• Best topology for branched out networks.
Tree Topology Limitations
• In a Network Topology the length of the network depends on the type of cable that is being used.
• The Tree Topology network is entirely dependant on the trunk which is the main backbone of the network. If that has to fail then the entire network would fail.
• Since the Tree Topology network is big it is difficult to configure and can get complicated after a certain point.
The Tree Topology follows a hierarchical pattern where each level is connected to the next higher level in a symmetrical pattern. Each level in the hierarchy follows a certain pattern in connecting the nodes. Like the top most level might have only one node or two nodes and the following level in the hierarchy might have few more nodes which work on the point to point connectivity and the third level also has asymmetrical node to node pattern and each of these levels are connected to the root level in the hierarchy. Think of a tree that branches out in various directions and all these branches need the roots and the tree trunk to survive. A Tree Structured network is very similar to this and that is why it is called the Tree Topology.
Tree Topology Features
• There will be at least three levels of hierarchy in the Tree Network Topology and they all work based on the root node.
• The Tree Topology has two kinds of topology integral in it, the star and the linear way of connecting to nodes.
• The Tree Topology functions by taking into account the total number of nodes present in the network. It does not matter how many nodes are there on each level. Nodes can be added to any level of the hierarchy and there are no limitations a far as the total number of nodes do not exceed.
• The higher levels in the hierarchy are expected to perform more functions than the lower levels in the network.
bab:6
BAB: KomUniKasi DaTa
Selasa, 8 September 2009
bentuk tranmisi data (penghantaran bersiri)
Also known as a star bus topology, tree topology is one of the most common types of network setups that is similar to a bus topology and a star topology. A tree topology connects multiple star networks to other star networks. Below is a visual example of a simple computer setup on a network using the star topology.In the above example picture if the main cable or trunk between each of the two star topology networks failed, those networks would be unable to communicate with each other. However, computers on the same star topology would still be able to communicate with each other.A type of network setup where each of the computers and network devices are interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down. This type of topology is not commonly used for most computer networks as it is difficult and expensive to have redundant connection to every computer. However, this type of topology is commonly used for wireless networks. Below is a visual example of a simple computer setup on a network using a mesh topology.
Tak Segerak
Dikenali sebagai protokol mula-akhir. Protokol jenis ini selalunya digunakan pada terminal dungu (dumb terminal dan selalunya tidak mempunyai penimbal untuk menyimpan aksara tersebut. Penghantaran data dilakukan dengan menghantar satu bit tambahan pada permulaan (bit mula) dan akhir data (bit akhir). Bit mula akan memaklumkan kepada penerima bahawa selepas bit tersebut akan ada bit-bit data yang berbentuk aksara akan dihantar, kemudian diikuti oleh satu bit pariti dan kemudian bit akhir. Bit akhir menandakan berakhirnya penghantaran data tersebut.Bit mula menggunakan bit 0, bit akhir menggunakan bit 1 dan bit pariti pula bergantung kepada keadaan pengecaman ralat. Rajah menunjukkan penghantaran aksara menggunakan kaedah penghantaran data tak segerak.Dengan menggunakan protokol tak segerak setiap bit mesti disetkan untuk menghantar dan menerima data melalui kadar data yang diberikan. Kadar data ini diukur dalam unit bit per saat (bps). Bila peranti protokol tak segerak menghantar data, ia dimulakan dengan bit mula yang akan sentiasa 0, diikuti dengan 8 bit data dalam bait ( 7 bit [aksara] dan 1 bit pariti) dan kemudian bit 1 yang menunjukkan bit akhir. Jumlah kesemua bit yang akan dihantar ialah 10 bit. Rajah 1.10 di atas menunjukkan bahawa aksara A dihantar dengan diikuti aksara B daripada terminal dungu ke komputer perumah dengan menggunakan kod ASCII. Masa melahu (idle) akan wujud antara satu aksara dengan aksara yang lain semasa berlakunya penghantaran data.Kaedah penghantaran data jenis ini tidak sesuai digunakan untuk penghantaran data yang banyak, sedangkan kebanyakkan aplikasi komputer memerlukan penghantaran data yang banyak. Untuk mengatasi masalah ini kaedah protokol segerak lebih sesuai digunakan.
Protokol Segerak
Kaedah segerak boleh digunakan untuk membuat penyegerakan menghantar satu blok data (banyak aksara) yang besar. Kaedah ini tidak menggunakan bit mula-akhir, tiada masa melahu (idle) antara satu aksara dengan aksara yang lain.Kaedah segerak menggunakan beberapa aksara dipermulaan blok data yang hendak dihantar. Aksara ini dinamakan SYN. Ia mempunyai corak bit khas seperti 10101010. Corak bit ini akan memberitahu penerima bahawa ada satu blok aksara yang akan tiba selepas itu. Pada bahagian penghantar, satu bingkai (frame) akan dibentuk terlebih dahulu sebelum membuat penghantaran data. Dalam bingkai tersebut, beberapa aksara SYN dan aksara kawalan lain akan dimasukkan. 10 aksara kawalan diperlukan untuk untuk satu blok penghantaran. .Selain daripada itu kita juga boleh menggunakan aksara SYN untuk membuat penyegerakan, ada juga yang menggunakan isyarat jam pada talian berasingan. Apa yang dimaksudkan dengan talian berasingan ialah saluran/wayar yang berbeza digunakan untuk menghantar maklumat dan menghantar data. Isyarat jam akan dihantar bersama setiap bit data yang dihantar. Bila penerima menerima isyarat jam dari talian berkenaan, penerima akan membaca data dari talian penghantaran data.
Isnin, 31 Ogos 2009
e- commerce C2C
Consumer-to-consumer
Consumer-to-consumer (C2C) (or citizen-to-citizen) electronic commerce involves the electronically-facilitated transactions between consumers through some third party. A common example is the online auction, in which a consumer posts an item for sale and other consumers bid to purchase it; the third party generally charges a flat fee or commission. The sites are only intermediaries, just there to match consumers. They do not have to check quality of the products being offered.
e- commerce C2B
Consumer-to-business
Consumer-to-business (C2B) is an electronic commerce business model in which consumers (individuals) offer products and services to companies and the companies pay them. This business model is a complete reversal of traditional business model where companies offer goods and services to consumers (business-to-consumer = B2C).
This kind of economic relationship is qualified as an inverted business type. The advent of the C2B scheme is due to major changes:
*Connecting a large group of people to a bidirectional network has made this sort of commercial relationship possible. The large traditional media outlets are one direction relationship whereas the internet is bidirectional one.
*Decreased cost of technology : Individuals now have access to technologies that were once only available to large companies ( digital printing and acquisition technology, high performance computer, powerful software)
e- commerce B2B
Business-to-business
Business-to-business (B2B) describes commerce transactions between businesses, such as between a manufacturer and a wholesaler, or between a wholesaler and a retailer. Contrasting terms are business-to-consumer (B2C) and business-to-government (B2G).
The volume of B2B transactions is much higher than the volume of B2C transactions. The primary reason for this is that in a typical supply chain there will be many B2B transactions involving subcomponent or raw materials, and only one B2C transaction, specifically sale of the finished product to the end customer. For example, an automobile manufacturer makes several B2B transactions such as buying tires, glass for windshields, and rubber hoses for its vehicles. The final transaction, a finished vehicle sold to the consumer, is a single (B2C) transaction.
The term "business-to-business" was originally coined to describe the electronic communications between businesses or enterprises in order to distinguish it from the communications between businesses and consumers (B2C). It eventually came to be used in marketing as well, initially describing only industrial or capital goods marketing. Today it is widely used to describe all products and services used by enterprises. Many professional institutions and the trade publications focus much more on B2C than B2B. This is a strange development as most sales and marketing people work in B2B.
kuliah 5
Rabu, 26 Ogos 2009
window dan mac(apple), portal rilek, & portal MyEG
Window dan Apple dah mula wujud pada tahun 80an. Syarikat Window dan Apple mempunyai tujuan yang berbeza. Syarikat Window tujuan adalah memfokus terhadap masyarakat yang umum untuk meluaskan pasaran. Manakala, Apple pula memfokus masyarakat atau pengguna yang mementingkan kepuasan yang dibawa oleh sesebuah produk atau barang.Window dan MAC mempunyai perbezaaan dari segi iaitu konsep design yang dipamerkan di internet. Penggunaan Apple kompatibililitas yang baik dan handal. Ini dapat menarik ramai pengguna mengguna MAC. Manakala Misroccoft hanya mencapai 90% pada tahun 2008 penggunaan pengguna. Misrocoft sebuah syarikat beroperasi yang dapat berkontriibusi untuk promosi besar-besaran adopsi dari komputer peribadi. Window mudah diceburi oleh hacker dan mudah membawa virus seperti trojan.Sistem Apple memenuhi kepuasan dan kehendak pengguna manakala Window ialah sebuah sistem yang sederhana dan pengguna dapat menggunakannya dengan aamn dan tenang.
PORTAL RILEK
Portal rilek sebuah rangkaian interaktif dan laman elektronik kerajaan. Ia terdiri daripada Tenaga Nasional, Telekom Malaysia, Jabatan Pengangkutan Jalan, Polis Diraja Malaysia dan lain-lain lagi.rakyat boleh membayar bil-bil melalui perkhidmatan ini.
PORTAL MyEG
Portal my eg service berhad merupakan sebuah syarikat pemegang konsesi dan eletronik Malaysia di bawah aplikasi perdana MSC . Berperanan sebagai pembekal aplikasi E-khidmat yang menghubungkan pihak kerajaan, rakyat dan syarikat perkhidmatan. Melalui portal ini, rakyat Malaysia berpeluang untuk berinteraksi kepada mana-mana badan kerajaan melalui satu pusat sehenti. Malah rakyat Malaysia dapat berinteraksi dengan pelbagai agensi
Khamis, 6 Ogos 2009
kuliah 4
kuliah pd 7 ogos kami belajar mengenai definisi komputer.komputer adalah alat memproses data. bit&bait adalah bahasa komputer.perkakasan komputer- alatan input, unit sistem,alatan output & alatan storan.contoh komputer- PDA,pelayan,kerangka utama,superkomputerµpengawal.komputer penting kerana media storan,pangkalan data dan rangkaian utk komunikasi.kerjaya di bidang perkomputeran perniagaan,pertanian,seni,perundangan dan perubatan.kami juga belajar ttg contoh2 penggunaan komputer dalam bidang tertentu.teknologi baru ialah nanosains,biomedical chrp implants dan artificial intelligence.
kami juga belajar secara mendalam ttg kompenen2 komputer dan jenis2 perkakasan komputer spt papan kekunci,tetikus.selain itu kami juga belajar ttg jenis2 & kegunaan alat pengimbas & printer. ergonomik-kajian mengenai hubungan fizikal antara manusia dan tempat kerja.dalam topic ini kami juga dapat mengetahui kesan apabila menggunakan komputer dan langkah mengatasinya.organisasi pintar pula mengenai mengenai organisasi2 syarikat yg mahu pekerja2nya mahir menggunakan komputer.kerajaan elektronik di malaysia pula diperkenalkan utk menambahbaikkan perkhidmatan2 yg disediakan oleh pihak kerajaan dan utk maklumat yg disampaikan oleh kerajaan kpd masyarakat dapat disampaikan dgn cepat,jelas dan tepat