Understanding WSDL and UDDI
Web Services Description Language (WSDL) is one of the prime specifications in web services, the other two being SOAP and UDDI. WSDL is the description language for web services that describes a set of SOAP messages and how these messages are exchanged across network. WSDL will be in XML format; therefore it can be easily understood and edited by humans and machines.
Another advantage of WSDL being in XML format is that it is programming language independent and also platform independent. In addition, WSDL defines where the web service is available from and what communications protocol has been used to talk to the web service. As a result the WSDL file describes everything that is required to write a program for an XML Web service.
There are tools available in Microsoft Visual Studio .NET to read a WSDL file and generate the code required to communicate with an XML Web service.
Universal Discovery Description Language (UDDI) is a directory where you can expose your web services for other users to easily access it. You can also consume the web service that is already posted in UDDI. However, you can also post a web service without registering it in UDDI.
DISCO is another directory where you can post your web service. But if you want to reach to maximum of customers, you can place it in UDDI. The UDDI directory offers three parts for you to register:
• White Pages
• Yellow Pages
• Green Pages
The white pages consist of the description such as name and address of the company offering the service.
The yellow pages consist of industrial categories based on standard taxonomies such as North American Industry Classification System and Standard Industrial Classification.
The green pages describe the interface to the web service in detail so that anyone can write an application after using the web service.
Web services are described in UDDI directory through a document called Type Model or tmodel. Normally, this tModel contains a WSDL file that describes a SOAP interface to an XML Web service, but the tModel is flexible enough to describe almost any kind of web service.
Apart from using the web services from UDDI, you can also search a particular web service in UDDI. In addition, you can search for companies’ information that posted web services. In certain times, you might know the names of the companies that offer web services but you may not be aware of the web services that they offer.
The WS Inspection is a specification in UDDI that allows you to search for a collection of web services that are located in a particular company name. You can evaluate these web services according to your requirements.
Thursday, August 23, 2007
Wednesday, August 8, 2007
WI-FI
Why / Where Should We Use Wi-Fi
The Wi-Fi LAN has a broad application nowadays. Because of the comfortable and quick installation people often replace old wired LANs with Wi-Fi. Such connection allows to move your machine around the place without losing the Internet or other network resources. Working on your laptop you can check your mail from anywhere in your home or office.
Some highly attended places like airports, libraries, schools or even coffee bars offer you constant Internet connection using exactly wireless LAN, so retrieving new files, cruising the global network or corresponding with others will not be a problem anymore in those (and many other) places.
The most important shortcoming in Wi-Fi is the range. So far we may have difficulties in making a connection with a receiver which is more than 50-75 meters away (inside the buildings).
The signal should be stronger to provide larger connectable spaces. Additionally, some of the wireless adapters works on the frequencies that are currently used by many other wireless devices. It can cause a serious interference, so the connection performance can be quite poor.
However, building Wi-Fi network is often the cheapest way to achieve the desired connection with the surroundings. The price of a single wireless adapter is decreasing almost every day, so making a large network area by means of Wi-Fi is the most reasonable way. You will not need to arrange all the wires around and profit by the installation time. By the way, most of the Wi-Fi adapters have user-friendly configuration and diagnostic tools which can help you to adjust or change your WLAN settings or even can do everything for you.
Security:
What about the security? Is there a possibility of stealing our data? Security is your personal decision, but having a wireless connection we should pay attention to protect our private files and encrypt sent messages.
Actually, the security modules were very important since the beginning of the Wi-Fi projection. In order to prevent intercepting your data by the others the designers implemented many security techniques, like Wi-Fi Protected Access (based on encryption), Virtual Private Network (making virtual "tunnels"), Media Access Control Filtering (rejecting unknown MAC addresses), RADIUS Authentication and Authorization (using login and password) or Kerberos (key distribution).
There is also a possibility to combine some of these security mechanisms making your transmissions even more secure.On the other hand providing such security in public places (like Internet cafes) may not meet its expectations. Connecting to protected wireless network you will be asked about a security code, encryption key or a password. If you do not know them, you will not be able to establish a communication link and use Internet resources.
Most of public areas do not use security modules because of that reason making Wi-Fi users data unsafe.
The Wi-Fi LAN has a broad application nowadays. Because of the comfortable and quick installation people often replace old wired LANs with Wi-Fi. Such connection allows to move your machine around the place without losing the Internet or other network resources. Working on your laptop you can check your mail from anywhere in your home or office.
Some highly attended places like airports, libraries, schools or even coffee bars offer you constant Internet connection using exactly wireless LAN, so retrieving new files, cruising the global network or corresponding with others will not be a problem anymore in those (and many other) places.
The most important shortcoming in Wi-Fi is the range. So far we may have difficulties in making a connection with a receiver which is more than 50-75 meters away (inside the buildings).
The signal should be stronger to provide larger connectable spaces. Additionally, some of the wireless adapters works on the frequencies that are currently used by many other wireless devices. It can cause a serious interference, so the connection performance can be quite poor.
However, building Wi-Fi network is often the cheapest way to achieve the desired connection with the surroundings. The price of a single wireless adapter is decreasing almost every day, so making a large network area by means of Wi-Fi is the most reasonable way. You will not need to arrange all the wires around and profit by the installation time. By the way, most of the Wi-Fi adapters have user-friendly configuration and diagnostic tools which can help you to adjust or change your WLAN settings or even can do everything for you.
Security:
What about the security? Is there a possibility of stealing our data? Security is your personal decision, but having a wireless connection we should pay attention to protect our private files and encrypt sent messages.
Actually, the security modules were very important since the beginning of the Wi-Fi projection. In order to prevent intercepting your data by the others the designers implemented many security techniques, like Wi-Fi Protected Access (based on encryption), Virtual Private Network (making virtual "tunnels"), Media Access Control Filtering (rejecting unknown MAC addresses), RADIUS Authentication and Authorization (using login and password) or Kerberos (key distribution).
There is also a possibility to combine some of these security mechanisms making your transmissions even more secure.On the other hand providing such security in public places (like Internet cafes) may not meet its expectations. Connecting to protected wireless network you will be asked about a security code, encryption key or a password. If you do not know them, you will not be able to establish a communication link and use Internet resources.
Most of public areas do not use security modules because of that reason making Wi-Fi users data unsafe.
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