HAL - HW abstraction layer.Regardless of brand names it linux uses its own naming system for similar hardawre. HAL database is stored in /sys dir
Ex: If you plug 3 diff Ethernet cards it will be eth0, eth1 and eth2. Thats it
dbus - via dbus hw can communicate between applications and...
OData based web services (Open Data)
Odata is a combination of SOAP and REST. Therefore request messages are in a format of URIs and parameters. Response messages can be either ATOM or JSON.
OData was initially created by Microsoft and later it was delivered to the open source community.
Current version of OData specification...
RESTful web services
REST (Representational State Transfer) is a web services architecture. If we take SOAP , it is specification for messages used in WS. But REST is a complete architecture of web services which has all the details how it is done in web service invocation.
W3 rest wiki is a one good place for...
Web Service Description Language (WSDL)
WSDL which is xml based contains the information about the web service. Typically WSDL is generated by the server in which the service is held at. After generation of WSDL it can read by SOAP library at client side.
Official WSDL specification can be found in here.
http://www.w3.org/TR/wsdl
Sample...
SOAP message format
Schema for the SOAP 1.1 message can be found in here.
http://schemas.xmlsoap.org/soap/envelope/
This says all about the SOAP message format.
Example SOAP message
<?xml version="1.0"?>
<soap:Envelopexmlns:soap="http://www.w3.org/2001/12/soap-envelope"soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:Body xmlns:m="http://www.example.org/stock">
<m:GetStockPrice>
<m:StockName>IBM</m:StockName>
</m:GetStockPrice>
</soap:Body>
</soap:Envelope>
Code...
SOAP based web services
One major category of web services is SOAP based web services. (Simple Object Access Protocol)
SOAP is a message format specification. (Which is also XML based)
SOAP WS can process over HTTP, FTP,SMTP etc.. (But HTTP is being the popular protocol)
SOAP has 2 major versions. See specs...
Message formats used in web services
In web services what happens in client request a service from a server over the web. So various data (messages ) can be exchanged in requester and responder. They can be in various formats in WS.
Open Formats
RSS (XML based format used in web feeds)
ATOM (XML based format used in web feeds)
POX (Plain Old XML - raw xml format)
JSON (Java Script Object Notation - light weigh - especially used...
Web services and Transport layer protocols
Image obtained from : http://www.highteck.net/images/45-Transport-layer.jpg
Because web services operate over internet the role of TCP/IP stack is aslo essential. In TCP/IP layers Transport layer protocols can play a huge role because it helps to move data between machines...
Brief understanding of web services
Normally when you want to communicate with another computer from our computer we can use a computer network.
Web services are just like that.
We have a client who request a service x.
A server who has the service x implemented in its server.
We can request for the service x over internet.
Image...