web技术概论第一周作业

HW1.
Wiki gives a definition to “Netscape plug-in” technology. It’s atechnology that offers an interface for web developers. It says,”Netscape Plugin Application Programming Interface (NPAPI) is an application programming interface (API) that allow plug-ins (more specifically, browser extensions) to be developed for web browsers.”It was first developed for Netscape browsers, starting in 1995 with Netscape Navigator 2.0, but was subsequently adopted by other browsers.
From my point of view, I think “Netscape plug-in” belongs to the third category, say, it belongs to distribute object technologies.
First, it’s notbasic web protocol suite like URL, HTML, HTTP, MIME and CGI. Because it was developed to help programmers handle browsers more easily. It has nothing to do with basic information transfer through internet.On the other hand, This technology is developed based on browser,which means it should take a higher layer than basic web protocol suite.
Secondly, it doesn’t aim at creating quality web services more effectively like java and javascript. It can actually use javascript to program.
Thirdly,It belongs to distribute object technologies. Because it is a model to handle the communication between browser and user process.It has similar function like ActiveX.

HW2.
Advantages: First, connection to different servers is swift. Second, internet connection is released fast so that a server can offer service to many users at a time.
Disadvantages: First, every time before we get a document, we need to request a TCP link between browser and client. It waste a lot of time. Second, communication is unstable because we connect and disconnect frequently.
A web server cannot exactly know how many browsers are reading its document. As mentioned above, the link is disconnected automatically. It has nothing to do with client or server behavior. Although a user may be reading the document, it doesn’t have to connect to the server. The Server cannot know about that.