DuraCloud Release 0.8 : Image Server Service Design
This page last changed on Oct 28, 2010 by bbranan.
OverviewWhen deployed in your DuraCloud server, the Image Server (imgserver) deploys an instance of the Djatoka JPEG2000 image server. This Djatoka server is itself a web application that needs to be deployed into a servlet container. That is why the System WebApp Utility (webapputil) must already be deployed/running on your DuraCloud server before it is possible to deploy the imgserver. In the process of deploying the imgserver, the webapputil installs a new instance of Apache Tomcat running on the next available port. See the design description of the webapputil service for more details. Then the Djatoka image server is deployed into the newly installed Tomcat. Along with the Djatoka image server, an IIPImage Viewer configured to reference the newly deployed Djatoka image server is deployed into the newly created Tomcat. Integration with external applicationsUsing DuraCloud image viewer and image serverA common use case for the Image Server service is to integrate it with your existing website to serve the JP2 files that are hosted in your DuraCloud account. In order to do this you need to provide a link in your existing website to the imgserver viewer with an HTTP parameter specifying the direct DuraCloud URL of the image item. An example link would be <a href="http://180.12.34.56/adore-djatoka-p18080/viewer.html?rft_id=http://my.duracloud.org:80/durastore/jp2s/image-file.jp2%3FstoreID%3D0">My Image</a><br> So in this example, the DuraCloud server has domain name "my.duracloud.org" with associated I.P. address of "180.12.34.56". The content is accessible through this address and the Djatoka image server is running (on a separate Tomcat/port) at the same address. Using your own image viewer with DuraCloud image serverIf on the other hand you would prefer to use your own image viewer instead of the IIPImage viewer deployed with the imgserver, this is also an option. In this case, within your viewer code, you need to configure it to reference the DuraCloud-hosted Djatoka resolver. In the example above, the resolver URL would be http://180.12.34.56/adore-djatoka-p18080/resolver Other considerationsPerformanceThe basic flow of interaction with the imgserver is that a
In this flow, there is considerable latency in the Djatoka resolver retrieving the image file from the underlying cloud content store. This latency is only experienced the first time the image is requested. After the initial request, the tiles are cached by the Djatoka server. Therefore, improved user performance can be achieved by pre-caching the images requesting them when they are made publicly available. AccessWhen the Djatoka resolver is retrieving web-based content, the Djatoka software is not currently designed to supply authentication credentials with the HTTP request. As a result, the Djatoka server will not be able to serve content that resides in a "closed" DuraCloud space. We have a patch to the Djatoka baseline to address this issue and are working with the Djatoka developers to have it incorporated. In the meantime, all content that you would like to be served via the imgserver must reside in an "open" DuraCloud space. |
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Document generated by Confluence on Apr 27, 2011 14:55 |