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The Distributed Retrieval Evaluation Server builds uppon the work of to provide the means to evaluate interactive retrieval approaches in various settings, both on-site and distributed.

We provide a dedicated client DRES OpenApi specifications for systems to be evaluated with DRES. Please refer to the example repo for further information and do not forget to cite our work when using them.


To deploy and run DRES, a JRE of at least Java 11 is required, e.g. the OpenJDK 11. For development, besides the JDK, addtitionally NPM and the Angular CLI is recommended.


We kindly ask you to refer to the following paper in publications mentioning or employing DRES:

Rossetto L., Gasser R., Sauter L., Bernstein A., Schuldt H. (2021) A System for Interactive Multimedia Retrieval Evaluations. In: Lokoč J. et al. (eds) MultiMedia Modeling. MMM 2021. Lecture Notes in Computer Science, vol 12573. Springer, Cham.



author="Rossetto, Luca
and Gasser, Ralph
and Sauter, Loris
and Bernstein, Abraham
and Schuldt, Heiko",
editor="Loko{\v{c}}, Jakub
and Skopal, Tom{\'a}{\v{s}}
and Schoeffmann, Klaus
and Mezaris, Vasileios
and Li, Xirong
and Vrochidis, Stefanos
and Patras, Ioannis",
title="A System for Interactive Multimedia Retrieval Evaluations",
booktitle="MultiMedia Modeling",
publisher="Springer International Publishing",


DRES consists of two components: The backend and the frontend, each subdirectories of this repository. The backend is written in Kotlin, hence requires a JVM, and the frontend is written in Angular using Angular-CLI. However, the entire setup process is Gradle based. To setup DRES, follow these steps:

  1. Clone or Download this repository
  2. Build the backend using Gradle $> ./gradlew distZip (alternatively $> ./gradlew distTar)
  3. Extract the generated archive (see backend/build/distributions)
  4. Run the backend (it serves the frontend) by starting the backend script in the bin directory

If you want to run DRES from your IDE (e.g. for debuging or development), please remember to run $> ./gradlew setupFFMpeg to download the required FFMpeg dependencies!


Both the backend and the frontend have several properties which can be configured using a json configuration file.

Backend Configuration

The backend looks for a file named config.json at the location from where it is started. If this file is not found, default values are used for all configurable settings. To use a different configutation file, pass its path as the first parameter when starting the backend. The configuration file is structured as follows. All values are optional and overwrite the defaults listed below, if set.

  "httpPort":         8080,           //the port to be used for HTTP
  "httpsPort":        8443,           //the port to be used for HTTPS, if enabled
  "enableSsl":        true,           //specifies if HTTPS is supposed to be enabled. If set to true, HTTP connections will be upgraded
  "keystorePath":     "keystore.jks", //path to the Java Key Store file to be used for the SSL certificate
  "keystorePassword": "password",     //password for the Key Store file
  "externalPath":     "./external",   //path for external media items
  "dataPath":         "./data",       //path where the local database is to be stored
  "cachePath":        "./cache"       //path where pre-rendered media items are to be stored

First Steps

Using the DRES CLI, the help command lists available commands and their usage. If one would like to know more about a certain command $cmd, use the argument -h: DRES> $cmd -h Following the first steps towards a successful installment of a (distributed) retrieval evaluation campaign. A prerequisit is the previous deployment, see Setup and a running DRES instance.

Create User

Using the CLI, the following command creates your first administrator user with the username admin and the password password (Do not use this user in production).

DRES> user create -u admin -p password -r ADMIN

Additional users are required in order to perform an evaluation. At least one user per participating system instance (i.e. with -r PARTICIPANT). To simply have a user to view evaluation runs, but otherwise not interact with the system, we recommend to create a viewer user: -r VIEWER.

Create Media Collection

Again, using the CLI one can create the very first media collection, called first. This assumes you already have a folder with multimedia content for the collection at path/to/media.

DRES> collection create -n first -d "A desription of the collection" -p path/to/media

Then, there are several ways to import the actual multimedia content. The easiest way (but might take a while) is to use the scan command:

DRES> collection scan -c first -vt mp4

Obviously, for an image collection one would replace -vt mp4 with -it png or -it jpg. For mixed collections, use both.

Create Evaluations

Below instructions require an admin user and are performed in the UI |

The next step is to create an evaluation template. This is done using the web frontend of DRES. Using your browser, navigate to your DRES address and perform the login using the administrator user created previously.

Then, navigate to Evaluation Template Builder and create a new competition. Follow the instructions there.

Create Competition Run

An evaluation template serves as the template for one or more evaluation runs. Please keep in mind, that once a run was created, changes on the template are not reflected in that run.

Evaluation runs are created from the Evaluation Template Overview view, where one uses the "Exit" (a running person) button to create a new one.

In a non distributed setting, it might be desirable, that participants cannot view the actual run from the frontend, but require an external source for the query hints (e.g. a large monitor). This could be achieved by unchecking the corresponding option in the dialog. A run must be of either type SYNCHRONOUS or ASYNCHRONOUS. The former has task presentation and task execution syncrhonised for all participants and the latter enables task execution individually per participant.

Runnig the evaluation

As evaluation operator, one has to first start the run, then switch to a fitting task and ultimately start the task. Query hints are displayed as configured to all viewers, once they are all loaded (depending on the setup, this might take a brief moment). Viewers and participants are shown the message "Waiting for host to start task". In case this seems to take too long, the operator can switch to the admin view and force all participants to be ready, by clicking the red ones.

Examples and API Usage

We provide a bunch of examples on how to use the DRES OpenApi specifications for various languages. It is recommended that all programmatic interaction with the DRES server is done via generated code, similar as showcased in the examples.


Notice: We strongly recommend the usage of the client OpenApi Specification to generate the code to submit (and generally interact with the server)!

Notice: With version 2.0.0, we provide a new POST submission endpoint which is more flexible than the legacy GET one. That is, for version 2.0.0 the legacy submission endpoint remains in the API version 1 and is deprecated. We highly encourage to move to the new POST-based endpoint.

For legacy reasons, we provide further information below:

In order to submit a result to be evaluated, the submission endpoint is accessed via HTTP(S) in one of the following ways:

  • http(s)://{server}/api/v1/submit?item={item} where {item} is the identifier for the retrieved media item
  • http(s)://{server}/api/v1/submit?item={item}&shot={shot} where {shot} is the identifier for a pre-defined temporal segment within the {item}
  • http(s)://{server}/api/v1/submit?item={item}&frame={frame} where {frame} is the frame number within the {item}, in case it is a video
  • http(s)://{server}/api/v1/submit?item={item}&timecode={timecode} where {timecode} is a temporal position within the {item} in the form HH:MM:SS:FF. In case just a plain number is passed, the behavior is equivalent to passing the same value as {frame}

In case no session cookie is passed as part of the request, an additional session parameter can be passed to transmit the session id token. The session id can be found via the UI in the User Profile, accessible via the top-right menu. Alternatively, the information about the currently authenticated user, including the session token, can be accessed via http(s)://{server}/api/v1/user which will return the information in JSON format.

Interaction Logging

Notice: We strongly recommend the usage of the client OpenApi Specification to generate the code to submit logging information (and generally interact with the server)!

Analogously to the VBS server, the logging of interaction sequences and complete result lists is supported. The specification of the messages can be found in this working document as well as the OpenApi specifications.

Known Issues




  • Task duration greater than 9999999 break things. Do not use such long tasks.
  • Safari is NOT supported