I have loaded an embedded instance of Neo4j with some data, and would like to know how I can now view this graph. I saw an intro video here: http://video.neo4j.org/m9FD/how-to-get-started-with-neo4j-119/. Here the guy opened an instance in his web browser via Heroku and was able not only see the data in the graph, but also enter new data and search for both nodes and relationships. How do I see the data I have entered into the graph-database?
graphDb = new GraphDatabaseFactory().newEmbeddedDatabase( "var/graphDb" );
registerShutdownHook(graphDb);
WrappingNeoServerBootstrapper srv = new WrappingNeoServerBootstrapper( graphDb );
srv.start();
for (Statement s : statements){
Transaction tx = graphDb.beginTx();
try{
firstNode = graphDb.createNode();
firstNode.setProperty("message", s.getFirstTerm());
secondNode = graphDb.createNode();
secondNode.setProperty( "message", s.getSecondTerm());
relation = firstNode.createRelationshipTo(secondNode, s.getRelationshipType());
//relation.setProperty("message", "crazy cruel");
tx.success();
}
finally{
tx.finish();
}
}
srv.stop();
}
you could either
fire up a server as part of your embedded instance, see http://docs.neo4j.org/chunked/snapshot/server-embedded.html
use Neoclipse and point it to your (shut down) database, see http://vimeo.com/12014944 aand https://github.com/neo4j/neoclipse
install Neo4j Server http://docs.neo4j.org/chunked/snapshot/server.html, point out your database and use the webadmin tool for visualization.
Would that work?
Related
I'm trying to manage a decentralized DB around a huge number of partial DB instances. Each instance has a subset of the whole data and they are all nodes and clients, thus asking for some data the query must be spread to every (group) instance and which one have it will return the data.
Due to avoid lost of data if one instance goes down, I figured out they must replicate its contents with some others. How this scenario can be configured with Ignite?
Supose I have a table with the name and last access datetime of users in a distributed application, like ...
class UserLogOns
{
string UserName;
DateTime LastAccess;
}
Now when the program starts I prepare Ingite for work as a decentralizad DB ...
static void Main(string[] args)
{
TcpCommunicationSpi commSpi = new TcpCommunicationSpi();
// Override local port.
commSpi.LocalPort = 44444;
commSpi.LocalPortRange = 0;
IgniteConfiguration cfg = new IgniteConfiguration();
// Override default communication SPI.
cfg.CommunicationSpi = commSpi;
using (var ignite = Ignition.Start(cfg))
{
var cfgCache = new CacheConfiguration("mio");
cfgCache.AtomicityMode = CacheAtomicityMode.Transactional;
var cache = ignite.GetOrCreateCache<string, UserLogOns>(cfgCache);
cache.Put(Environment.MachineName, new UserLogOns { UserName = Environment.MachineName, LastAccess = DateTime.UtcNow });
}
}
And now ... I want to get LastAccess of other "computerB" when ever it was ..
Is this correct? How can it be implemented?
It depends on the exact use-case that you want to implement. In general, Ignite provides out of the box everything that you mentioned here.
This is a good way to start with using SQL in Ignite: https://apacheignite-sql.readme.io/docs
Create table with "template=partitioned" instead of "replicated" as it is shown in the example here: https://apacheignite-sql.readme.io/docs/getting-started#section-creating-tables, configure number of backups and select a field to be affinity key (a field that is used to map specific entries to cluster node) and just run some queries.
Also check out the concept of baseline topology if you are going to use native persistence: https://apacheignite.readme.io/docs/baseline-topology.
In-memory mode will trigger rebalance between nodes on each server topology change (node that can store data in/out) automatically.
Our team's application development involves using Effort Testing Tool to mock our Entity Framework's DbContext. However, it seems that Effort Testing Tool needs to be see the actual SQL Server Database that the application uses in order to mock our Entity Framework's DbContext which seems to going against proper Unit Testing principles.
The reason being that in order to unit test our application code by mocking anything related to Database connectivity ( for example Entity Framework's DbContext), we should Never need a Database to be up and running.
How would I configure Effort Testing Tool to mock Entity Framework's DbContext withOut the actual SQL Server Database up and running?
*
Update:
#gert-arnold We are using Entity Framework Model First approach to implement the back-end model and database.
The following excerpt is from the test code:
connection = Effort.EntityConnectionFactory.CreateTransient("name=NorthwindModel");
jsAudtMppngPrvdr = new BlahBlahAuditMappingProvider();
fctry = new BlahBlahDataContext(jsAudtMppngPrvdr, connection, false);
qryCtxt = new BlahBlahDataContext(connection, false);
audtCtxt = new BlahBlahAuditContext(connection, false);
mockedReptryCtxt = new BlahBlahDataContext(connection, false);
_repository = fctry.CreateRepository<Account>(mockedReptryCtxt, null);
_repositoryAccountRoleMaps = fctry.CreateRepository<AccountRoleMap>(null, _repository);
The "name=NorthwindModel" pertains to our edmx file which contains information about our Database tables
and their corresponding relationships.
If I remove the "name=NorthwindModel" by making the connection like the following line of code, I get an error stating that it expects an argument:
connection = Effort.EntityConnectionFactory.CreateTransient(); // throws error
Could you please explain how the aforementioned code should be rewritten?
You only need that connection string because Effort needs to know where the EDMX file is.
The EDMX file contains all information required for creating an inmemory store with an identical schema you have in your database. You have to specify a connection string only because I thought it would be convenient if the user didn't have to mess with EDMX paths.
If you check the implementation of the CreateTransient method you will see that it merely uses the connection string to get the metadata part of it.
public static EntityConnection CreateTransient(string entityConnectionString, IDataLoader dataLoader)
{
var metadata = GetEffortCompatibleMetadataWorkspace(ref entityConnectionString);
var connection = DbConnectionFactory.CreateTransient(dataLoader);
return CreateEntityConnection(metadata, connection);
}
private static MetadataWorkspace GetEffortCompatibleMetadataWorkspace(ref string entityConnectionString)
{
entityConnectionString = GetFullEntityConnectionString(entityConnectionString);
var connectionStringBuilder = new EntityConnectionStringBuilder(entityConnectionString);
return MetadataWorkspaceStore.GetMetadataWorkspace(
connectionStringBuilder.Metadata,
metadata => MetadataWorkspaceHelper.Rewrite(
metadata,
EffortProviderConfiguration.ProviderInvariantName,
EffortProviderManifestTokens.Version1));
}
We noticed a slight oddity in the Sitecore API code. The code is below for your reference. The code is trying to get a database by doing new Database(database). But randomly it was failing.
This code worked for a while with Database db = new Database(database); but started failing randomly yesterday. When we changed the code to Database db = Database.GetDatabase(database);, the code started working again. What is the difference between the two approaches and what is recommended by Sitecore?
I've seen this happen twice now - multiple times in production and a couple of times in my development environment.
public static void DeleteItem(string id, stringdatabase)
{
//get the database
Database db = new Database(database);
//get the item
item = db.GetItem(new ID(id));
if (item != null)
{
using(new Sitecore.SecurityModel.SecurityDisabler())|
{
//delete the item
item.Delete();
}
}
}
A common way you will see people get a specific database is:
Sitecore.Data.Database master = Sitecore.Configuration.Factory.GetDatabase("master");
This is equivalent to Sitecore.Data.Database.GetDatabase("master").
When you call either of these methods it will first check the cache for the database. If not found it will build up the database with all of the configuration values within the config file via reflection. Once the database is created it will be placed in the cache for future use.
When you use the constructor on the database it is simply creating a rather empty database object. I am rather suprised to hear it was working at all when you used this method.
The proper approach to get a specific database would be to use:
Sitecore.Configuration.Factory.GetDatabase("master");
// or
Sitecore.Data.Database.GetDatabase("master");
If you are looking to get the database used with the current request (aka context database) you can use Sitecore.Context.Database. You can also use Sitecore.Context.ContentDatabase.
Here is some background about my app:
I am developing an Android app that will display a random quote or verse to the user. For this I am using an SQLite database. The size of the DB would be approximately 5K to 10K records, possibly increasing to upto 1M in later versions as new quotes and verses are added. Thus the user would need to update the DB as and when newer versions are of the app or DB are released.
After reading through some forums online, there seem to be two feasible ways I could provide the DB:
1. Bundle it along with the .APK file of the app, or
2. Upload it to my app's website from where users will have to download it
I want to know which method would be better (if there is yet another approach other than these, please do let me know).
After pondering this problem for some time, I have these thoughts regarding the above approaches:
Approach 1:
Users will obtain the DB along with the app, and won't have to download it separately. Installation would thereby be easier. But, users will have to reinstall the app every time there is a new version of the DB. Also, if the DB is large, it will make the installable too cumbersome.
Approach 2:
Users will have to download the full DB from the website (although I can provide a small, sample version of the DB via Approach 1). But, the installer will be simpler and smaller in size. Also, I would be able to provide future versions of the DB easily for those who might not want newer versions of the app.
Could you please tell me from a technical and an administrative standpoint which approach would be the better one and why?
If there is a third or fourth approach better than either of these, please let me know.
Thank you!
Andruid
I built a similar app for Android which gets periodic updates with data from a government agency. It's fairly easy to build an Android compatible db off the device using perl or similar and download it to the phone from a website; and this works rather well, plus the user gets current data whenever they download the app. It's also supposed to be possible to throw the data onto the sdcard if you want to avoid using primary data storage space, which is a bigger concern for my app which has a ~6Mb database.
In order to make Android happy with the DB, I believe you have to do the following (I build my DB using perl).
$st = $db->prepare( "CREATE TABLE \"android_metadata\" (\"locale\" TEXT DEFAULT 'en_US')");
$st->execute();
$st = $db->prepare( "INSERT INTO \"android_metadata\" VALUES ('en_US')");
$st->execute();
I have an update activity which checks weather updates are available and if so presents an "update now" screen. The download process looks like this and lives in a DatabaseHelperClass.
public void downloadUpdate(final Handler handler, final UpdateActivity updateActivity) {
URL url;
try {
close();
File f = new File(getDatabasePath());
if (f.exists()) {
f.delete();
}
getReadableDatabase();
close();
url = new URL("http://yourserver.com/" + currentDbVersion + ".sqlite");
URLConnection urlconn = url.openConnection();
final int contentLength = urlconn.getContentLength();
Log.i(TAG, String.format("Download size %d", contentLength));
handler.post(new Runnable() {
public void run() {
updateActivity.setProgressMax(contentLength);
}
});
InputStream is = urlconn.getInputStream();
// Open the empty db as the output stream
OutputStream os = new FileOutputStream(f);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024 * 1000];
int written = 0;
int length = 0;
while (written < contentLength) {
length = is.read(buffer);
os.write(buffer, 0, length);
written += length;
final int currentprogress = written;
handler.post(new Runnable() {
public void run() {
Log.i(TAG, String.format("progress %d", currentprogress));
updateActivity.setCurrentProgress(currentprogress);
}
});
}
// Close the streams
os.flush();
os.close();
is.close();
Log.i(TAG, "Download complete");
openDatabase();
} catch (Exception e) {
Log.e(TAG, "bad things", e);
}
handler.post(new Runnable() {
public void run() {
updateActivity.refreshState(true);
}
});
}
Also note that I keep a version number in the filename of the db files, and a pointer to the current one in a text file on the server.
It sounds like your app and your db are tightly bound -- that is, the db is useless without the database and the database is useless without the app, so I'd say go ahead and put them both in the same .apk.
That being said, if you expect the db to change very slowly over time, but the app to change quicker, and you don't want your users to have to download the db with each new app revision, then you might want to unbundle them. To make this work, you can do one of two things:
Install them as separate applications, but make sure they share the same userID using the sharedUserId tag in the AndroidManifest.xml file.
Install them as separate applications, and create a ContentProvider for the database. This way other apps could make use of your database as well (if that is useful).
If you are going to store the db on your website then I would recommend that you just make rpc calls to your webserver and get data that way, so the device will never have to deal with a local database. Using a cache manager to avoid multiple lookups will help as well so pages will not have to lookup data each time a page reloads. Also if you need to update the data you do not have to send out a new app every time. Using HttpClient is pretty straight forward, if you need any examples please let me know
Is it possible to change the connection string of a published sql reporting services report? I can see the binary field called DataSource in the ReportServer database, but since it's stored as binary I don't think it's easily updatable.
Do I need to republish the report with the correct data source? I'm hoping not since I do not want to have to install VS2003.
EDIT: The client is running SQL Server 2000 Reporting Services with all of the service packs installed.
SQL Reporting Services 2000 has a [web service](http://msdn.microsoft.com/en-us/library/aa274396(SQL.80).aspx) that you can use to change the data source. Given that, the following, allows for changing of a data source to a shared data source. This was [adapted from MSDN](http://msdn.microsoft.com/en-us/library/aa225896(SQL.80).aspx).
// Create our reporting services class
ReportingService theRS = new ReportingService();
theRS.Credentials = System.Net.CredentialCache.DefaultCredentials;
// We need to setup a data source reference to an existing shared data source
DataSourceReference theDSRef = new DataSourceReference();
theDSRef.Reference = "/Path/To/ExistingSharedDataSource";
DataSource[] theDSArray = new DataSource[1];
DataSource theDS = new DataSource();
theDS.Item = (DataSourceReference)theDSRef;
theDS.Name = "NameOfSharedDataSource";
theDSArray[0] = theDS;
try
{
// Attempt to change the data source of the report
theRS.SetReportDataSources("/Path/To/ReportName", theDSArray);
Console.Out.WriteLine("We have changed the data source");
}
catch (System.Web.Services.Protocols.SoapException e)
{
Console.Out.WriteLine(e.Message);
Console.Out.WriteLine(e.Detail.InnerXml.ToString());
}
In this example, the ReportingService class is taken from the Proxy class that I generated to talk to the web service, which is described [here](http://msdn.microsoft.com/en-us/library/aa256607(SQL.80).aspx).
I hope this helps some. Let me know if you're looking for something different.