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Image server, image indexing system and network protocol
Please refer to the published article for general information
regarding
the image server and image data transfer. Here you can find details
on some topics that are only briefly described in the article:
Image server:
The Image Web Server software (Earth Resource
Mapping
Pty, West Perth, Australia) described in the article runs on a IIS
(Internet
Information Server, Microsoft Corp.). The image server is connected
to the
Finnish University and Research Network (FUNET,
www.funet.fi),
and
physically
situated in Helsinki in the National Library of Health Sciences.
The
server is maintained by and completely under the control of our
informatics research group. The server is scaled to allow hundreds or
even thousands of concurrent users.
Image indexing:
The virtual slides were indexed on the server
with a custom
archiving system based on standard SQL-database software and
server-side
coding.
Network protocol:
A network protocol (ecwp, enhanced compression wavelet
protocol, Earth Resource
Mapping
Pty, West Perth, Australia) working on top
of the hyper text
transfer protocol (http)
ensures bandwidth-efficient image data
transfer. Only the data
required for
the current view field in the client browser at
the current
magnification is
transferred, and in a compressed form. The protocol
enables the
decoupling
of the image block data requesting and reading from
the image
decompression
phase. This allows the client application to continue
using whatever
data is
available in the cache whilst the server is performing
the read
operation
and sending the image block data to the client. This even
allows the
client
to cancel reading of a block asynchronously if the application
has
changed
the view, for example in response to user input (zooming or
panning).
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