Adding API endpoint to SUSI.AI for Skill Historization

SUSI Skill CMS is an editor to write and edit skill easily. It follows an API centric approach where the Susi server acts as API server. Using Skill CMS we can browse history of a skill, where we get commit ID, commit message  and name the author who made the changes to that skills. In this blogpost we will see how to fetch complete commit history of a skill in the susi skill repository. A skill is a set of intents. One text file represents one skill, it may contain several intents which all belong together. Susi skills are stored in susi_skill_data repository. We can access any skill based on four tuples parameters model, group, language, skill.  For managing version control in skill data repository, the following dependency is added to build.gradle . JGit is a library which implements the Git functionality in Java.

dependencies {
 compile 'org.eclipse.jgit:org.eclipse.jgit:'

To implement our servlet we need to extend our servlet to AbstractAPIHandler. In Susi Server, an abstract class AbstractAPIHandler extending HttpServelets and implementing API handler interface is provided.

public class HistorySkillService extends AbstractAPIHandler implements APIHandler {}

The AbstractAPIHandler checks the permissions of the user using the userroles of and comparing it with the value minimum base role of each servlet. Thus to specify the user permission for a servlet we need Override the getMinimalBaseUserRole method.

    public BaseUserRole getMinimalBaseUserRole() {
        return BaseUserRole.ANONYMOUS;

UserRoles can be Admin, Privilege, User, Anonymous. In our case it is Anonymous. A User need not to log in to access this endpoint.

    public String getAPIPath() {
        return "/cms/getSkillHistory.json";

This methods sets the api endpoint path. One need to send requests at to get the modification history of skill. Next we will implement The ServiceImpl method where we will be processing the user request and giving back the service response.

    public ServiceResponse serviceImpl(Query call, HttpServletResponse response, Authorization rights, final JsonObjectWithDefault permissions) {

        String model_name = call.get("model", "general");
        File model = new File(DAO.model_watch_dir, model_name);
        String group_name = call.get("group", "knowledge");
        File group = new File(model, group_name);
        String language_name = call.get("language", "en");
        File language = new File(group, language_name);
        String skill_name = call.get("skill", "wikipedia");
        File skill = new File(language, skill_name + ".txt");
        JSONArray commitsArray;
        commitsArray = new JSONArray();
        String path = skill.getPath().replace(DAO.model_watch_dir.toString(), "models");
        //Add to git
        FileRepositoryBuilder builder = new FileRepositoryBuilder();
        Repository repository = null;
        try {
            repository = builder.setGitDir((DAO.susi_skill_repo))
                    .readEnvironment() // scan environment GIT_* variables
                    .findGitDir() // scan up the file system tree
            try (Git git = new Git(repository)) {
                Iterable<RevCommit> logs;
                logs = git.log().addPath(path).call();
                int i = 0;
                for (RevCommit rev : logs) {
                    commit = new JSONObject();
                    commit.put("commitRev", rev);
                    commit.put("commitName", rev.getName());
                    commit.put("commitID", rev.getId().getName());
                    commit.put("commit_message", rev.getShortMessage());
                    commitsArray.put(i, commit);
                } success=true;
            } catch (GitAPIException e) {
           } if(commitsArray.length()==0){
        JSONObject result = new JSONObject();
        return new ServiceResponse(result);

To access any skill we need parameters model, group, language. We get this through call.get method where first parameter is the key for which we want to get the value and second parameter is the default value. Based on received model, group and language browse files in that folder we build the susi_skill_data repository path read the git variables and scan up the file system tree using FileRepositoryBuilder build() method. Next we fetch all the logs of the skill file and store them in json commits array and finally pass as a server response with success messages. In case of exceptions, pass service with success flags as false.

We have successfully implemented the servlet. Check the working of endpoint by sending request like and checking the response.

Susi skill cms uses this endpoint to fetch the skill history, try it out at