Early methods for displaying ``animation'' in Web pages, include server push and client pull, both developed by Netscape Communications Corporation. Server push and client pull are described in [65].
When using server push, the connection between the browser and the server is kept open. The server, or a CGI-program running at the server side, splits data in chunks, and sends the chunks one by one in a multi-part MIME-message. The browser handles each part as it arrives.
Client pull works by forcing the browser to reload a document, or load a new document in a given amount of seconds. The delay is passed to the browser using the HTTP response from the server, or as a special META-tag within the HTML-document being passed.
To transfer video using any of these methods, the server will either have to decode the video stream, and recode it as single images in a format the Web browser in the other end can handle, or store the images pre-encoded.
There are several drawbacks making these methods inappropriate for
transferring video on the World Wide Web: First of all, they are not
bandwidth friendly. According to table 2.2 in
section 2.5 on
page 
, GIF and JPEG requires several
times the bandwidth of the original MPEG stream.
In addition to requiring a high bandwidth, and thus putting a big load on the network, the process of decoding and recoding images may take up most of the CPU time of the server. If several people request movies at the same time, the server will have a hard time serving them all. Decoding is better left off at the client side.
The timing resolution using client pull is one second; the ``next'' image may be loaded in any number of whole seconds, or immediately. For real-time video, this is not accurate enough.
A semester project at the University of Illinois at Urbana-Champaign included testing server push and client pull of MPEG streams recoded to GIF images [66]. The results demonstrate that server push and client pull are not usable for transferring video.
Even if inappropriate for large scale video, server push and client pull have been used extensively for highlighting Web pages by adding small, animated widgets drawing the spectator's attention. However, using server push or client pull for this purpose, is currently being overtaken by animated GIFs.