# An Experimental Implementation of a Resilient Graphic Rendering Cluster
## 1 Introduction  
Up to the point of writing this paper, we have published a lot of work on the cluster/grid rendering thematic. One of our published papers in the _Journal of Circuits, Systems and Computers_ titled \"Distributed Reliable Rendering Method for Parametric Modeling\" [1] describes a proof-of-concept model of rendering using the parametric Persistence of Vision Ray model [2, 3], client-server on-demand rendering architecture with SMTP (originally defined in RFC 821 and 822, updated in RFC 5321 [4]) and HTTP (originally defined in RFC 2616 [5], updated by RFC 2817, 5785, 6266 and 6585). This includes extensible protocol with the TCP connection keep-alive functionality, using open-source elements, configurable rendering architecture available at no cost besides the cost of hardware, with new solutions for simple configuration file mechanisms, and resilient software behavior based on best effort strategy of work distribution. Similar to SMTP and HTTP protocols, Internet protocol is not a requirement, and any reliable stream will suffice. Just like those protocols, and unlike FTP, GRC protocol transfers data such as an uploaded rendering model source package and resulting rendered images over the control connection stream. The abovementioned paper presented an innovative way of creating a distributed reliable rendering method using a huge range of computers for parametric modeling. The main aim of the paper was to present a proof-of-concept solution that would use existing resources in order to make the modeling method more appropriate for applying complex computer services/jobs under distributed architecture. The implementation also included logistics and support for automatic computer clustering and for service/ job program execution. The primary goal was to use existing resources for useful applications in the 3 Dparametric modeling, image programming and simulation rendering. The logical extension to that work was our research in the field of a cloud-like service. The grid's complex scheduling introduced some stochastic behaviors in terms of unpredictable load, lags, delays and failures to deliver service. Yet, the greatest motivation to develop a cloud-like service was to justify investment and produce visible results for users who were not able to or not interested in obtaining a grid certificate in an institution that was not primarily about computer science, but accepted computer graphics [6]. Our choice of Persistence of Vision Ray as the rendering agent was motivated by the open source and free license of the program, which was also popular in the grid community and compatible with the Linux environment as well. The goal was to popularize new technology in a way that would be friendly to graphic design professionals and the student community. Our initial models included Tesla's electric motors, inspired by the anniversary of the [PERSON]'s year of birth. Early work involved the first attempt at a \"Balkanized\" grid using heterogeneous and asymmetrical implementation, demanding only a working GCC compiler and an OS with POSIX system calls. Later, a cluster was donated to explore advantages of grid architecture in the field of graphic rendering. The cluster had a total of 32 cores, which served as the render farm in the rack-mounted blade server architecture. The second implementation was a major rewrite of the first render farm client. The goal was to implement the client efficiently enough so it would not be a bottleneck when the render farm would theoretically be expanded. The first implementation had a text terminal interface, after which a more user-friendly web front-end was designed. Models were typically cyclic clock animations. The animation was divided into frames, each frame rendered independently. At the beginning of the process, all frames are in the \"unrendered\" state and in the UnrenderedFramePool object.