* What is SOAP [Simple Object Access Protocol]?
Ans. SOAP is an XML-based messaging protocol. It defines a set of rules for structuring messages that can be used for simple one-way messaging but is particularly useful for performing RPC-style (Remote Procedure Call) request-response dialogues. It is not tied to any particular transport protocol though HTTP is popular. Nor is it tied to any particular operating system or programming language so theoretically the clients and servers in these dialogues can be running on any platform and written in any language as long as they can formulate and understand SOAP messages. As such it is an important building block for developing distributed applications that exploit functionality published as services over an intranet or the internet.
* What are Web service protocols?
Ans. (a) HTTP GET, (b) HTTP POST & (c) SOAP.
* Can you give example for SOAP Format?
Ans.
< soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
< soap:Header>
...
...
< /soap:Header>
< soap:Body>
...
...
< soap:Fault>
...
...
< /soap:Fault>
...
< /soap:Body>
< /soap:Envelope>
* what is the difference between Synchronous and Asynchronous web methods?
Ans. A synchronous method call waits for the method to complete before continuing with program flow,whereas an asynchronous method call will return immediately so that the program can perform other operations while the called method completes its work.
-Synchronous means that you trigger your NSURLConnection request and wait for it to be done.
Asynchronous means that you can trigger the request and do other stuff while NSURLConnection downloads data.
-Synchronous is very straightforward: you set it up, fire it, and wait for the data to come back. But your application sits there and does nothing until all the data is downloaded, some error occurs, or the request times out. If you're dealing with anything more than a small amount of data, your user will sit there waiting, which will not make for a good user experience.
-Asynchronous requires just a little more work, but your user can do other stuff while the request does its thing, which is usually preferable. You set up some delegate methods that let you keep track of data as it comes in, which is useful for tracking download progress. This approach is probably better for most usage cases.
Also refer this link : - https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html
* Difference between GET and POST methods -
Ans. • Fundamental Difference is probably the Visibility - GET request is sent via the URL string (appended to the URI with a question-mark as separator), which is visible whereas POST request is encapsulated in the body of the HTTP request and can't be seen.
• Length - Since, GET request goes via URL, so it has a limitation for its length. It can't be more than 255 characters long (though this is browser dependent, but usually the max is 255 characters only). Whereas no such maximum length limitation holds for the POST request for the obvious reason that it becomes a part of the body of the HTTP request and there is no size limitation for the body of an HTTP request/response.
• Performance - GET request is comparatively faster as it's relatively simpler to create a GET request and the time spent in the encapsulation of the POST request in the HTTP body is saved in this case. In addition, the maximum length restriction facilitates better optimization of GET implementation.
• Type of Data - GET request is sent via URL string and as we all know that URL can be text-only, so GET can carry only text data whereas POST has no such restriction and it can carry both text as well as binary data.
• Caching/Bookmarking - again for the obvious reason that a GET request is nothing but an URL hence it can be cached as well as Bookmarked. No such luxuries with a POST request.
• FORM Default - GET is the default method of the HTML FORM element. To submit a FORM using POST method, we need to specify the method attribute and give it the value "POST".
• Data Set - GET requests are restricted to use ASCII characters only whereas POST requests can use the 'enctype' attribute with a value "multipart/form-data" to use
Also refer this link:- http://www.diffen.com/difference/Get_vs_Post
* What is NSThread?
Ans. An NSThread object controls a thread of execution. Use NSThread when you want to have an Objective-C message run in its own thread of execution or if you need to terminate or delay the current thread. A thread is an executable unit. A task is made up of one or more threads. Each thread has its own execution stack and is capable of independent input/output. All threads share the virtual memory address space and communication rights of their task. When a thread is started, it is detached from its initiating thread. The new thread runs independently. That is, the initiating thread does not know the new thread's state.
Ans. SOAP is an XML-based messaging protocol. It defines a set of rules for structuring messages that can be used for simple one-way messaging but is particularly useful for performing RPC-style (Remote Procedure Call) request-response dialogues. It is not tied to any particular transport protocol though HTTP is popular. Nor is it tied to any particular operating system or programming language so theoretically the clients and servers in these dialogues can be running on any platform and written in any language as long as they can formulate and understand SOAP messages. As such it is an important building block for developing distributed applications that exploit functionality published as services over an intranet or the internet.
* What are Web service protocols?
Ans. (a) HTTP GET, (b) HTTP POST & (c) SOAP.
* Can you give example for SOAP Format?
Ans.
< soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
< soap:Header>
...
...
< /soap:Header>
< soap:Body>
...
...
< soap:Fault>
...
...
< /soap:Fault>
...
< /soap:Body>
< /soap:Envelope>
* what is the difference between Synchronous and Asynchronous web methods?
Ans. A synchronous method call waits for the method to complete before continuing with program flow,whereas an asynchronous method call will return immediately so that the program can perform other operations while the called method completes its work.
-Synchronous means that you trigger your NSURLConnection request and wait for it to be done.
Asynchronous means that you can trigger the request and do other stuff while NSURLConnection downloads data.
-Synchronous is very straightforward: you set it up, fire it, and wait for the data to come back. But your application sits there and does nothing until all the data is downloaded, some error occurs, or the request times out. If you're dealing with anything more than a small amount of data, your user will sit there waiting, which will not make for a good user experience.
-Asynchronous requires just a little more work, but your user can do other stuff while the request does its thing, which is usually preferable. You set up some delegate methods that let you keep track of data as it comes in, which is useful for tracking download progress. This approach is probably better for most usage cases.
Also refer this link : - https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html
* Difference between GET and POST methods -
Ans. • Fundamental Difference is probably the Visibility - GET request is sent via the URL string (appended to the URI with a question-mark as separator), which is visible whereas POST request is encapsulated in the body of the HTTP request and can't be seen.
• Length - Since, GET request goes via URL, so it has a limitation for its length. It can't be more than 255 characters long (though this is browser dependent, but usually the max is 255 characters only). Whereas no such maximum length limitation holds for the POST request for the obvious reason that it becomes a part of the body of the HTTP request and there is no size limitation for the body of an HTTP request/response.
• Performance - GET request is comparatively faster as it's relatively simpler to create a GET request and the time spent in the encapsulation of the POST request in the HTTP body is saved in this case. In addition, the maximum length restriction facilitates better optimization of GET implementation.
• Type of Data - GET request is sent via URL string and as we all know that URL can be text-only, so GET can carry only text data whereas POST has no such restriction and it can carry both text as well as binary data.
• Caching/Bookmarking - again for the obvious reason that a GET request is nothing but an URL hence it can be cached as well as Bookmarked. No such luxuries with a POST request.
• FORM Default - GET is the default method of the HTML FORM element. To submit a FORM using POST method, we need to specify the method attribute and give it the value "POST".
• Data Set - GET requests are restricted to use ASCII characters only whereas POST requests can use the 'enctype' attribute with a value "multipart/form-data" to use
Also refer this link:- http://www.diffen.com/difference/Get_vs_Post
* What is NSThread?
Ans. An NSThread object controls a thread of execution. Use NSThread when you want to have an Objective-C message run in its own thread of execution or if you need to terminate or delay the current thread. A thread is an executable unit. A task is made up of one or more threads. Each thread has its own execution stack and is capable of independent input/output. All threads share the virtual memory address space and communication rights of their task. When a thread is started, it is detached from its initiating thread. The new thread runs independently. That is, the initiating thread does not know the new thread's state.
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