Deleting SUSI Skills from Server

SUSI Skill CMS is a web application to create and edit skills. In this blog post I will be covering how we made the skill deleting feature in Skill CMS from the SUSI Server.
The deletion of skill was to be made in such a way that user can click a button to delete the skill. As soon as they click the delete button the skill is deleted it is removed from the directory of SUSI Skills. But admins have an option to recover the deleted skill before completion of 30 days of deleting the skill.

First we will accept all the request parameters from the GET request.

        String model_name = call.get("model", "general");
        String group_name = call.get("group", "Knowledge");
        String language_name = call.get("language", "en");
        String skill_name = call.get("skill", "wikipedia");

In this we get the model name, category, language name, skill name and the commit ID. The above 4 parameters are used to make a file path that is used to find the location of the skill in the Susi Skill Data repository.

 if(!DAO.deleted_skill_dir.exists()){
            DAO.deleted_skill_dir.mkdirs();
   }

We need to move the skill to a directory called deleted_skills_dir. So we check if the directory exists or not. If it not exists then we create a directory for the deleted skills.

  if (skill.exists()) {
   File file = new File(DAO.deleted_skill_dir.getPath()+path);
   file.getParentFile().mkdirs();
   if(skill.renameTo(file)){
   Boolean changed =  new File(DAO.deleted_skill_dir.getPath()+path).setLastModified(System.currentTimeMillis());
     }

This is the part where the real deletion happens. We get the path of the skill and rename that to a new path which is in the directory of deleted skills.

Also here change the last modified time of the skill as the current time. This time is used to check if the skill deleted is older than 30 days or not.

    try (Git git = DAO.getGit()) {
                DAO.pushCommit(git, "Deleted " + skill_name, rights.getIdentity().isEmail() ? rights.getIdentity().getName() : "[email protected]");
                json.put("accepted", true);
                json.put("message", "Deleted " + skill_name);
            } catch (IOException | GitAPIException e) {

Finally we add the changes to Git. DAO.pushCommit pushes to commit to the Susi Skill Data repository. If the user is logged in we get the email of the user and set that email as the commit author. Else we set the username “[email protected]”.

Then in the caretaker class there is a method deleteOldFiles that checks for all the files whose last modified time was older than 30 days. If there is any file whose last modified time was older than 30 days then it quietly delete the files.

public void deleteOldFiles() {
     Collection<File> filesToDelete = FileUtils.listFiles(new         File(DAO.deleted_skill_dir.getPath()),
     new 
(DateTime.now().withTimeAtStartOfDay().minusDays(30).toDate()),
            TrueFileFilter.TRUE);    // include sub dirs
        for (File file : filesToDelete) {
               boolean success = FileUtils.deleteQuietly(file);
            if (!success) {
                System.out.print("Deleted skill older than 30 days.");
            }
      }
}

To test this API endpoint, we need to call http://localhost:4000/cms/deleteSkill.txt?model=general&group=Knowledge&language=en&skill=<skill_name>

Resources

JGit Documentation: https://eclipse.org/jgit/documentation/

Commons IO: https://commons.apache.org/proper/commons-io/

Age Filter: https://commons.apache.org/proper/commons-io/javadocs/api-1.4/org/apache/commons/io/filefilter/AgeFileFilter.html

JGit User Guide: http://wiki.eclipse.org/JGit/User_Guide

JGit Repository access: http://www.codeaffine.com/2014/09/22/access-git-repository-with-jgit/

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Getting SUSI Skill at a Commit ID

Susi Skill CMS is a web app to edit and create new skills. We use Git for storing different versions of Susi Skills. So what if we want to roll back to a previous version of the skill? To implement this feature in Susi Skill CMS, we needed an API endpoint which accepts the name of the skill and the commit ID and returns the file at that commit ID.

In this blog post I will tell about making an API endpoint which works similar to git show.

First we will accept all the request parameters from the GET request.

        String model_name = call.get("model", "general");
        String group_name = call.get("group", "Knowledge");
        String language_name = call.get("language", "en");
        String skill_name = call.get("skill", "wikipedia");
        String commitID  = call.get("commitID", null);

In this we get the model name, category, language name, skill name and the commit ID. The above 4 parameters are used to make a file path that is used to find the location of the skill in the Susi Skill Data repository.

This servlet need CommitID to work and if commit ID is not given in the request parameters then we send an error message saying that the commit id is null and stop the servlet execution.

    Repository repository = DAO.getRepository();
    ObjectId CommitIdObject = repository.resolve(commitID);

Then we get the git repository of the skill from the DAO and initialize the repository object.

From the commitID that we got in the request parameters we create a CommitIdObject.

   (RevWalk revWalk = new RevWalk(repository)) {
   RevCommit commit = revWalk.parseCommit(CommitIdObject);
   RevTree tree = commit.getTree();


Now using commit’s tree, we will find the find the path and get the tree of the commit.

From the TreeWalk in the repository we will set a filter to find a file. This searches recursively for the files inside all the folders.

                revWalk = new RevWalk(repository)) {
                try (TreeWalk treeWalk = new TreeWalk(repository)) {
                    treeWalk.addTree(tree);
                    treeWalk.setRecursive(true);
                    treeWalk.setFilter(PathFilter.create(path));
                    if (!treeWalk.next()) {
                        throw new IllegalStateException("Did not find expected file");
                    }

If the TreeWalk reaches to an end and does not find the specified skill path then it returns anIllegal State Exception with an message saying did not found the file on that commit ID.

       ObjectId objectId = treeWalk.getObjectId(0);
       ObjectLoader loader = repository.open(objectId);
       OutputStream output = new OutputStream();
       loader.copyTo(output);

And then one can the loader to read the file. From the treeWalk we get the object and create an output stream to copy the file content in it. After that we create the JSON and put the OutputStream object as as String in it.

       json.put("file",output);

This Servlet can be seen working api.susi.ai: http://api.susi.ai/cms/getFileAtCommitID.json?model=general&group=knowledge&language=en&skill=bitcoin&commitID=214791f55c19f24d7744364495541b685539a4ee

Resources

JGit Documentation: https://eclipse.org/jgit/documentation/

JGit User Guide: http://wiki.eclipse.org/JGit/User_Guide

JGit Repository access: http://www.codeaffine.com/2014/09/22/access-git-repository-with-jgit/

JGit Github: https://github.com/eclipse/jgit

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