Write extensions

What if you want to add features to Datashare backend?

Unlike plugins that are providing a way to modify the Datashare frontend, extensions have been created to extend the backend functionalities. There are two extension points that have been defined :

• NLP pipelines : you can add a new java NLP pipeline to Datashare

• HTTP API : you can add HTTP endpoints to Datashare and call the Java API you need in those endpoints

Since version 7.5.0, instead of modifying Datashare directly, you can now isolate your code with a specific set of features and then configure Datashare to use it. Each Datashare user could pick the extensions they need or want, and have a fully customized installation of our search platform.

Getting started

When starting, Datashare can receive an extensionsDir option, pointing to your extensions' directory. In this example, let's call it /home/user/extensions:

mkdir /home/user/extensions
datashare --extensionsDir=/home/user/extensions

Installing and Removing registered extensions

Listing

You can list official Datashare extensions like this :

$ datashare extension list
extension datashare-extension-nlp-opennlp
        OPENNLP Pipeline
        7.0.0
        https://github.com/ICIJ/datashare-extension-nlp-opennlp/releases/download/7.0.0/datashare-nlp-opennlp-7.0.0-jar-with-dependencies.jar
        Extension to extract NER entities with OPENNLP
        NLP
...

You can filter by name: datashare extension list nlp

Installing

You can install an extension with its id and providing where the Datashare extensions are stored:

$ datashare extension install datashare-extension-nlp-mitie

Note: if a custom --extensionsDir is needed, it goes before the subcommand:

$ datashare --extensionsDir /home/user/extensions extension install datashare-extension-nlp-mitie

Then if you launch Datashare with the same extension location, the extension will be loaded.

Removing

When you want to stop using an extension, you can either remove by hand the jar inside the extensions folder or remove it with datashare extension delete :

$ datashare extension delete datashare-extension-nlp-mitie

Create your first extension

NLP extension

You can create a "simple" java project like https://github.com/ICIJ/datashare-extension-nlp-opennlp (as simple as a java project can be right), with you preferred build tool.

You will have to add a dependency to the last version of datashare-api.jar to be able to implement your NLP pipeline.

With the datashare API dependency you can then create a class implementing Pipeline or extending AbstractPipeline. When Datashare will load the jar, it will look for a Pipeline interface.

Unfortunately, you'll have also to make a pull request to datashare-api to add a new type of pipeline. We will remove this step in the future.

Build the jar with its dependencies, and install it in the /home/user/extensions then start datashare with the extensionsDir set to /home/user/extensions. Your plugin will be loaded by datashare.

Finally, your pipeline will be listed in the available pipelines in the UI, when doing NER.

HTTP extension

For making a HTTP extension it will be the same as NLP, you'll have to make a java project that will build a jar. The only dependency that you will need is fluent-http because datashare will look for fluent http annotations @Get, @Post, @Put...

For example, we can create a small class like :

package org.myorg;

import net.codestory.http.annotations.Get;
import net.codestory.http.annotations.Prefix;

@Prefix("myorg")
public class FooResource {
    @Get("foo")
    public String getFoo() {
        return "hello from foo extension";
    }
}

Build the jar, copy it to the /home/user/extensions then start datashare:

$ datashare --extensionsDir /home/user/extensions/
# ... starting logs
2020-08-29 11:03:59,776 [Thread-0] INFO  ExtensionLoader - loading jar /home/user/extensions/my-extension.jar
2020-08-29 11:03:59,779 [Thread-0] INFO  CorsFilter - adding Cross-Origin Request filter allows *
2020-08-29 11:04:00,314 [Thread-0] INFO  Fluent - Production mode
2020-08-29 11:04:00,331 [Thread-0] INFO  Fluent - Server started on port 8080

et voilà 🔮 ! You can query your new endpoint. Easy, right?

$ curl localhost:8080/myorg/foo
hello from foo extension

Installing and Removing your custom Extension

You can also install and remove extensions with the Datashare CLI.

Then you can install it with:

$ datashare extension install /home/user/src/my-extension/dist/my-extension.jar

And remove it:

$ datashare extension delete my-extension.jar