SYSTEM repository not showing repository details

Question

In my machine, base/data directory contains multiple repositories. But when I access this data directory from java program it gives me only SYSTEM repository record.

Code to retrieve the repositories :

String dataDir = "D:\\SesameStorage\\data\\"
LocalRepositoryManager localManager = new LocalRepositoryManager(new File(dataDir));
localManager.initialize();

// Get all repositories

Collection<Repository> repos = localManager.getAllRepositories();

System.out.println("LocalRepositoryManager All repositories : "
                + repos.size());
for (Repository repo : repos) {
    System.out.println("This is : " + repo.getDataDir());

    RepositoryResult<Statement> idStatementIter = repo
            .getConnection().getStatements(null,
                    RepositoryConfigSchema.REPOSITORYID, null,
                    true, new Resource[0]);
    Statement idStatement;
    try {
        while (idStatementIter.hasNext()) {
            idStatement = (Statement) idStatementIter.next();
            if ((idStatement.getObject() instanceof Literal)) {
                Literal idLiteral = (Literal) idStatement
                        .getObject();
                System.out.println("idLiteral.getLabel() : "
                        + idLiteral.getLabel());
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Output :    
LocalRepositoryManager All repositories : 1
This is : D:\SemanticStorage\data\repositories\SYSTEM
idLiteral.getLabel() : SYSTEM

Adding repository to LocalRepositoryManager :

String repositoryName = "data.ttl";

RepositoryConfig repConfig = new RepositoryConfig(repositoryName);
SailRepositoryConfig config = new SailRepositoryConfig(new MemoryStoreConfig());
repConfig.setRepositoryImplConfig(config);
manager.addRepositoryConfig(repConfig);

Getting the repository object :

Repository repository = manager.getRepository(repositoryName);
repository.initialize();

I have successfully added new repository to LocalRepositoryManager and it shows me the repository count to 2. But when I restart the application it shows me only one repository and that is the SYSTEM repository.

My SYSTEM repository is not getting updated, Please suggest me, how should I load that data directory in my LocalRepositoryManager object.

Answer 1

You haven't provided a comprehensive test case, just individual snippets of code with no clear indication of the order in which they get executed, which makes it somewhat hard to figure out what exactly is going wrong.

I would hazard a guess, however, that the problem is that you don't properly close and shut down resources. First of all you are obtaining a RepositoryConnection without ever closing it:

  RepositoryResult<Statement> idStatementIter = repo
        .getConnection().getStatements(null,
                RepositoryConfigSchema.REPOSITORYID, null,
                true, new Resource[0]);

You will need to change this to something like this:

  RepositoryConnection conn = repo.getConnection();
  try {
     RepositoryResult<Statement> idStatementIter =
              conn.getStatements(null,
                  RepositoryConfigSchema.REPOSITORYID, null,
                  true, new Resource[0]);

    (... do something with the result here ...)
  }
  finally {
    conn.close();
  }

As an aside: if your goal is retrieve repository meta-information (id, title, location), the above code is far too complex. There is no need to open a connection to the SYSTEM repository to read this information at all, you can obtain this stuff directly from the RepositoryManager. For example, you can retrieve a list of repository identifiers simply by doing:

 List<String> repoIds = localManager.getRepositoryIDs();

 for (String id: repoIds) {
      System.out.println("repository id: " + id);
 }

Or if you want to also get the file location and/or description, use:

 Collection<RepositoryInfo> infos = localManager.getAllRepositoryInfos();
 for (RepositoryInfo info: infos) { 
       System.out.println("id: " + info.getId());
       System.out.println("description: " + info.getDescription());
       System.out.println("location: " + info.getLocation());
 }

Another problem with your code is that I suspect you never properly call manager.shutDown() nor repository.shutDown(). Calling these when your program exits allows the manager and the repository to properly close resources, save state, and exit gracefully. Since you are creating a RepositoryManager object yourself, you need to care to do this on program exit yourself as well.

An alternative to creating your own RepositoryManager object is to use a RepositoryProvider instead (see also the relevant section in the Sesame Programmers Manual). This is a utility class that comes with a built-in shutdown hook, saving you from having to deal with these manager/repository shutdown issues.

So instead of this:

LocalRepositoryManager localManager = new LocalRepositoryManager(new File(dataDir));
localManager.initialize();

Do this:

LocalRepositoryManager localManager = 
       RepositoryProvider.getRepositoryManager(new File(datadir));