2013, Graf, Sebastian, Rain, Andreas, Scharon, Daniel, Waldvogel, Marcel

Cloud storage promises unlimited, flexible and cheap storages, including alltime availability and accessibility with the help of various technologies. Free-of-charge o ffers for endusers allure customers the same way as professional, pay-as-you-go storages do. The delocalization of the data provokes security concerns especially regarding the con dentiality of the data. Even though encryption offers a straight-forward solution to this problem, the performance questions its applicability when it comes to the utilization of professional storage-approaches like iSCSI. In this white-paper, we propose a utilization of NoSQL-based cloudstorages like Amazon S3 or Microsoft Azure for iSCSI. We evaluate the costs of a direct, bucket-based encryption and show, that in complex systems like iSCSI, the distance to the cloud represents the bottleneck instead of the encryption. Performance-boosting techniques like prefetching and caching improve the access and result in no practical overhead within such an utilization. Based on our own developed fully Java-based iSCSI target (jSCSI) and jClouds, our prototype represents, to the best of our knowledge, the rst, free available, cloud-deployable iSCSI.

2010, Graf, Sebastian, Lewandowski, Lukas, Grün, Christian

REST nowadays represents, besides SOAP, one common way to access distributed resources in a web-affine manner. While SOAP can be easily utilized by high-level programming languages like Java (e.g. JAX-WS as one common standardized way), REST catches up regarding straight usages (e.g JAX-RS regarding Java).
With the clean and direct usage of JAX-RS, common layers for standardised access on heterogeneous XML-resources can be defined. This is what the project JAX-RX stands for: Based on XML as modern resource in the WWW, we defined a common application programming interface to access Java enabled XML resource easily in a common way. Using a common architecture for the uniform resource locator on the one hand and defining suitable interfaces on the other hand, every XML generating resources can be \RESTified\ with nearly no effort. This technical report describes the motivation, the architecture and the usage of our XML-enabling API called JAX-RX.

2013, Graf, Sebastian, Rain, Andreas, Waldvogel, Marcel

Being a part of any social network becomes a necessity especially for the sake of self-presentation. Specialized social networks like LinkedIn are aware of these needs and offer tailored functionalities like referencing to relevant projects and topics including specific searching functionalities.
Since the social data stored within any centralized social network represents an alluring mass of information, security and privacy concerns come up within their utilization. As a consequence, guidelines for their usage are deployed within institutions to increase awareness related to these concerns. Unfortunately, the specific toolsets deployed within universities for presenting users and projects support neither the sharing of group-based or public information nor the ability to create social connections between users especially not over the borders of single institutions.
To combine the need of self-presentation with the ability of virtual social interaction, we present a prototype of a federated, distributed, social network tailored to the need of researchers. Our prototype is based on Diaspora, representing the largest distributed social platform nowadays. Enriched with automated, user-related profiles, our Diaspora-pod offers all members of the University of Konstanz the ability to interact in combination with automated university-profiles.
Tightly integrated in the existing infrastructure of the University of Konstanz and hosted on trusted infrastructure, the described prototype offers not only user-defined sharing of personal profiles in a federated way. It also leverages from the centralized handling of profiles and reduces as a consequence the administrative overhead of maintaining any personal information.
Based on its simple usage and the tight integration into the services of the University of Konstanz, our prototype has the potential to push university life to a new social level without generating concerns about security and privacy.

2009, Graf, Sebastian, Brend amour, Patrice, Waldvogel, Marcel

In 2007 we introduced jSCSI 1.0 to the public. The use case was to access block-patterns directly from Java without any third party JNI invoked software. In the last 2 years we explored the capabilities to assimilate multithreading in jSCSI. The goal was to leverage the outstanding features of the new Java multithreading extension introduced with Java5/Java6 and incorporate them into our proven block-level accessing framework. Today, we present the next incarnation of jSCSI 1.0, jSCSI 2.0 which yields significant performance improvements by utilizing Java s advanced multithreading capabilities. We show that our Java based implementation of a low-level architecture is not only a proposing alternative in terms of performance but also in the ease-of-use compared to common JNI-invoked system calls. Therefore, we argue that jSCSI 2.0 is not only a platform independent implementation of the iSCSI protocol, but
also a fast and robust proof for implementing low-level applications in Java.

2013, Graf, Sebastian, Miller, Wolfgang, Waldvogel, Marcel

Cloud Storages combine high availability with the unences- sity to maintain any own infrastructure and all-time availability. A wide field of different providers offer a flexible portfolio for any technical need and financial possibility. Yet, the possibilities of different cloud storage providers have all one issue in common: Basic storage is cheap whereas the costs increase with the storage consumed adhering the pay-as-you- go paradigm. Photo sharing websites such as Facebook, Picasa-Web, and Flickr leverage from own cloud infrastructure and offer unlimited storage for less or no charge. Obviously pictures can be used to store information in, which has been used for steganography and watermarking at low data rates. We propose a general framework for storing large amounts of data, its data density and error-correcting mechanisms tunable to the properties of the photo sharing website of your choice. Our cost- performance-analysis shows that photo sharing websites compare favorably to professional cloud storage services such as Amazon S3. Thanks to the integration of our software as a backend to the widely-used jClouds framework, everyone can now use photo sharing websites as one component for low-cost purposes, including archival.