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@ -178,9 +178,9 @@ Typical use cases for supported user roles are following:
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### Exercise evaluation chain
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The most important part of the system is evaluation of solutions submitted by
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students. Concepts of consecutive steps from source code to final results
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is described in more detail below to give readers solid overview of what have to
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happen during evaluation process.
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students. The process leading from source code to final results (score) is
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described in more detail below to give readers a solid overview of what happens
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during the evaluation process.
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First thing students have to do is to submit their solutions through web user
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interface. The system checks assignment invariants (deadlines, count of
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@ -190,9 +190,9 @@ configuration variant is chosen (one exercise can have multiple variants, for
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example C and Java languages). This exercise configuration is then used for
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taking care of evaluation process.
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There is a pool of uniform worker engines dedicated to evaluation jobs. Incoming
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jobs are kept in a queue until a free worker picks them. Worker is capable of
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sequential evaluation of jobs, one at a time.
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There is a pool of uniform worker machines dedicated to evaluation jobs.
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Incoming jobs are kept in a queue until a free worker picks them. Workers are
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capable of sequential evaluation of jobs, one at a time.
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The worker obtains the solution and its evaluation configuration, parses it and
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starts executing the contained instructions. It is crucial to keep the worker
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@ -212,9 +212,9 @@ Current system is old, but robust. There were no major security incidents
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during its production usage. However, from today's perspective there are
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several drawbacks. The main ones are:
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- **web interface** -- The web interface is simple and fully functional. But
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rapid development in web technologies opens new horizons of how web interface
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can be made.
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- **web interface** -- The web interface is simple and fully functional.
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However, recent rapid development in web technologies opens new horizons of
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how web interfaces can be made.
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- **web API** -- CodEx offers a very limited XML API based on outdated
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technologies that is not sufficient for users who would like to create custom
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interfaces such as a command line tool or mobile application.
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@ -224,8 +224,8 @@ several drawbacks. The main ones are:
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parallelism is a very important area of computing, so there is requirement to
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test multi-threaded applications too.
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- **instances** -- Different ways of CodEx usage scenarios requires separate
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instances (Programming I and II, Java, C#, etc.). This configuration is not
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user friendly (students have to register in each instance separately) and
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installations (Programming I and II, Java, C#, etc.). This configuration is
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not user friendly (students have to register in each instance separately) and
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burdens administrators with unnecessary work. CodEx architecture does not
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allow sharing hardware between instances, which results in an inefficient use
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of hardware for evaluation.
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@ -234,7 +234,6 @@ several drawbacks. The main ones are:
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which have a more difficult evaluation chain than simple
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compilation/execution/evaluation provided by CodEx.
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## Requirements
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There are many different formal requirements for the system. Some of them
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@ -352,7 +351,7 @@ annoyed if they did not.
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The survey shows that there are a lot of different requirements and wishes for
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the new system. When the system is ready, it is likely that there will be new
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ideas of how to use the system and thus the system must be designed to be easily
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ideas on how to use the system and thus the system must be designed to be easily
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extendable, so that these new ideas can be easily implemented, either by us or
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community members. This also means that widely used programming languages and
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techniques should be used, so that users can quickly understand the code and
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@ -430,7 +429,7 @@ implies that only a subset of all the features will be implemented in the first
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version, and more of them will come in the following releases.
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Gathered features are categorized based on priorities for the whole system. The
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highest priority is the functionality presente in current CodEx. It is a base
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highest priority is the functionality present in current CodEx. It is a base
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line for being useful in production environment. The design of the new solution
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shall allow extending the system easily. Ideas from faculty staff have secondary
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priority, but most of them will be implemented as part of the project. The most
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@ -458,17 +457,17 @@ reasonable wishes of university users and our major design choices.
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- modern HTML5 web frontend written in JavaScript using a suitable framework
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- REST API communicating with database, evaluation backend and a file server
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- evaluation backend implemented as a distributed system on top of a message
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queue framework with master-worker architecture
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- multi-platform worker supporting Linux and Windows environment (latter
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without sandbox, no general purpose suitable tool available yet)
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- evaluation backend implemented as a distributed system on top of a messaging
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framework with master-worker architecture
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- multi-platform worker supporting Linux and Windows environment (latter without
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sandbox, no general purpose suitable tool available yet)
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- evaluation procedure configured in a human readable text file, compound of
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small tasks connected into an arbitrary oriented acyclic graph
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The reasons supporting these decisions are explained in the rest of analysis
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chapter. Also a lot of smaller design choices are mentioned including possible
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options, what is picked to implement and why. But first, discuss basic concepts
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of the system.
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options, what is picked to implement and why. But first, we discuss basic
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concepts of the system.
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## Basic concepts
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