Workflow 2

Repository Setup & Import 3D procedural models, exported via python from CityEngine, into a Fedora repository.

Server Software

Note these instructions are intended to help set up this proof of concept software environment on your own development machine or server. This is why we use example URLs like http://localhost:8080/ and http://host.domain.tld/, which may differ for your environment. Replace the example url with the correct prefix to match your domain.

Apache Tomcat

This application uses Apache Tomcat 8.5 to deploy the Fedora web application. Other versions of Tomcat may be compatible but have not been tested.

Tomcat dependencies include Java which may be installed from the official site or via:

DNF/YUM	APT	Homebrew
sudo dnf install java-openjdk	sudo apt-get install default-jdk	brew cask install java

Tomcat 8.5 Downloads

Tomcat 8.5 Install Documentation

Though the version may differ, Tomcat may also be installed via:

DNF/YUM	APT	Homebrew
sudo dnf install tomcat	sudo apt-get install tomcat	brew install tomcat

Fedora Repository

Fedora Downloads

This application uses the "Web Application" variant of Fedora 4.7.5

Note that the name of this .war file determines which sub-URI of Apache Tomcat the Fedora Repository software will be accessible at when deployed. We recommend renaming the file to fedora.war before moving it into Tomcat's webapps/ directory for this reason. This will result in the Fedora Repository being accessible at http://localhost:8080/fedora/, as in our example URLs.

Fedora Installation Instructions

Important:Add Fedora config options to the Tomcat startup environment to ensure Fedora data will be stored in the desired location via the fcrepo.home option (e.g.) sudo vim /path/to/tomcat/bin/setenv.sh:

# Configure Tomcat Environment
##############################

# Apps
######
FCREPO="-Dfcrepo.modeshape.configuration=classpath:/config/file-simple/repository.json -Dfcrepo.home=/var/local/fedora-data"

# Memory
########
# Min Overall
MEM_MIN="128m"

# Max Overall
MEM_MAX="2g"


# Set Environment
export CATALINA_OUT=/var/log/tomcat/catalina.out
export CATALINA_PID=/var/run/tomcat-catalina.pid
export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms${MEM_MIN} -Xmx${MEM_MAX} ${FCREPO}"

Tomcat Reverse Proxy

If one wants to reverse proxy the Tomcat webapp through Apache at a sub-URI (e.g. https://host.domain.tld/fedora/ ) as we did, additional Tomcat and Apache configuration is necessary due to the webapp generating links that Apache can't rewrite via mod_proxy_html, mod_rewrite, and mod_substitute. In this case, we must deploy the webapp separately from the drop-in auto-deploy directory /path/to/tomcat/webapps and utilize a custom Connector added to the Tomcat server config in /path/to/tomcat/conf/server.xml .

Add a reverse proxy Connector to Tomcat server config

sudo vim /path/to/tomcat/conf/server.xml :

…
  <Service name="Catalina">
…
    <!-- Reverse proxy connector -->
    <Connector port="8081" protocol="HTTP/1.1"
               connectionTimeout="20000"
               proxyName="hostname" proxyPort="80" />
…
    <Engine name="Catalina" defaultHost="localhost">
…
    </Engine>
  </Service>
</Server>

Place the webapp's .war file in a new, separate directory such as /path/to/tomcat/proxied-webapps/ and define the webapp's Context XML file for deployment. Be careful that the .war file should be re-named the same as your sub-URI and Context's path values. For our purposes, the file should be re-named fedora.war , so that it unpacks to the directory /path/to/tomcat/proxied-webapps/fedora/ .

sudo vim /path/to/tomcat/Catalina/localhost/fedora.xml :

<Context docBase="/path/to/tomcat/proxied-webapps/fedora"
   path="/fedora" reloadable="false" useHttpOnly="true"></Context>

Add the reverse-proxy configuration to Apache paying extra attention to proxy traffic to port 8081 rather than 8080

sudo vim /path/to/apache/conf.d/fedora.conf:

RedirectMatch ^/fedora$ /fedora/

Location /fedora/>
  # Reverse proxy to serve example webapp requests
  # Port 8081 reverse-proxies with consisent app-generated URLs
  ProxyPass http://(ServerName):8081/fedora
   ProxyPassReverse / 
</Location>

Some additional directives may still be necessary to fix http:// and doubled sub-URIs in URLs

sudo vim /path/to/apache/conf.d/fedora.conf:

…
  <Location /fedora/>
    …
    # Use mod_substitute to fix http:// in URLs
    AddOutputFilterByType SUBSTITUTE text/html text/plain
    Substitute s|http://(ServerName)|https://(ServerName)|

    # Fix doubled sub-URIs
    RewriteRule /fedora/fedora/(.*) /fedora/$1 [L,R] 
  </Location>

Dependencies

Common

RDFLib

The python code requires the RDFLib library

Fedora	EL	Pip
sudo dnf install python-rdflib	sudo yum install python-rdflib	sudo pip install rdflib

Bottle

Fedora	EL	Pip
sudo dnf install python-bottle	sudo yum install python-bottle	sudo pip install bottle

Usage

Fedora

Adding Data

Testing files were generated with the CityEngine Export Workflow and added to separate containers via the Fedora REST API web interface's "Create New Child Resource" form, available at http://localhost:8080/fedora/rest/ or https://host.domain.tld/fedora/rest/ depending on whether one deploys Tomcat standalone or through Apache.

Each container's Identifier value may differ from the exported file names, so feel free to be descriptive or more brief for some of the longer model names. Click the Add button at the bottom of the form. The container should be created and its page loaded.

Repeat these steps until all exported files have been added:

From the Type select, choose "Binary"
For the Identifier, enter the full file name including extension
Click the File button and select the matching file
Click the Add button below
To add another file to the same container, click the parent container's name in the gray bar with breadcrumb links just below the large page header with the current URL

If there are individual models nested within an export's files or textures stored within subdirectories, create containers with Identifier values that match the subdirectory names exactly.

Deleting Data

If one wants to permanently delete a resource from the Fedora repository or re-use a previously deleted resource, Fedora's tombstone resource must be deleted first. This is a resource Fedora creates in the background any time a resource is deleted or moved to prevent a URL from ever representing more than one resource.

If a container resource with the Identifier derp is created and deleted subsequently, it's URL /fedora/rest/derp , will return the plaintext response:

Discovered tombstone resource at /derp, departed: 2018-10-12T18:42:09.684-05:00

This resource may be deleted with

curl via the command line:

curl -X DELETE http://localhost:8080/fedora/rest/derp/fcr:tombstone

or one may use Firefox's Network Monitor development tool:

Visit the tombstone URL http://localhost:8080/fedora/rest/derp/fcr:tombstone
Open Network Monitor via keyboard shortcut with Ctrl + Shift + E or Command + Option + E
Click the row with fcr:tombstone under the File column
Click "Edit and Resend" in the pane opened to the right
Replace the GET method with DELETE
Click "Send" in the upper right corner of the New Request pane

Now, if one tries to visit the URL /fedora/rest/derp , a Tomcat 404 error page should be returned. This means the tombstone resource has been successfully deleted. The identifier may remain permanently deleted or be re-used now.

Workflow 2

Server Software

Apache Tomcat

DNF/YUM

APT

Homebrew

DNF/YUM

APT

Homebrew

Fedora Repository

Tomcat Reverse Proxy

Add a reverse proxy Connector to Tomcat server config

Dependencies

Common

RDFLib

Fedora

EL

Pip

Bottle

Fedora

EL

Pip

Usage

Fedora

Deleting Data