Sterowniki .NET i C++ dla Apache Cassandra

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Sterowniki .NET i C++ dla Apache Cassandra

dr inż. Paweł Kapłański

Cognitump.kaplanski@cognitum.eu

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CognitumAutoryzowany dystrybutor DataStax Enterprise w Polsce

Dostarczamy:

Wysoce skalowalne aplikacje w chmurze

Rozwiązania Big Data

Systemy zarządzania wiedzą

Aplikacje dedykowane

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Konsulting IT

strong partnerships:

Customers from: US, CH, FL, DE

Big Data

Cloud

Semantics

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Spis treści (Agenda)1. Cassandra

2. Jak działają stare sterowniki oparte o Thrift

3. Asynchroniczność

4. Binarny protokół klient-serwer w Cassandrze

5. Przykład (driver .Net)

6. Plany na przyszłość

7. Driver C++

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Cassandra1. noSql – BigTable (Google 2005)

2. Stworzona w FB – obecnie Apache

3. Rozproszona

4. Skalowalna - Duże (100PB) dane

5. Obecnie już istnieją instalacje po 1000 nodów

6. Symetryczna (odporna na awarie)

7. Klaster (możliwość instalacji „multidatacenter”)

8. Elastyczna – duże możliwości konfiguracji

9. CQL – Cassandra Query Language – podobny do SQL

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Multidatacenter

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Typowa aplikacja (serwis www .Net)

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Ważne!1. Driver to nie tyko „smart socket” - posiada

rozbudowaną logikę działania2. Driver zarządza połączeniami do klastra

– load balancer3. Użytkownik nie musi martwić się o

połączenie i strategię – wystarczy ze użyje jednej z dostaraczanych np. RoundRobin

4. Driver potrafi automatycznie powtórzyć zapytanie w razie potrzeby

5. Można tworzyć własne strategie6. Lock-free (wysoka wydajność)

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Interfejsy C*: Thrift1. IDL (interface definition language)

2. Pozwala na automatyczne generowanie kodu w różnych językach

3. Sam Thrift to nie wszystko – trzeba obsłużyć zapytania do klastra

4. Zapytanie blokuje połączenie (podobnie jak zapytanie http) w oczekiwaniu na odpowiedź

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Interfejsy C*: Protokół binarny1. Operacje asynchroniczne

2. Pojedyncze polaczenie do 128 jednoczesnych zapytan

3. Lepsze wykorzystanie zasobów (połączenia są kosztowne)

4. Cassandra może lepiej optymizować

5. Wsparcie dla programowania asynchronicznego – powszechne obecnie w podejsciu client-server

6. Zdarzenia z Cassandy są „pushowane”

• zmiana schematu bazy

• zmiana w topologii klastra

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Wspierane języki1. Native Protocol Drivers (Datastax)

• Java driver (with ORM)

• .Net driver (Cql2Linq, ORM)

• Python

• C++ Driver – early stage of development

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Przykład – połączenie (driver .Net)1. public class NerdMovie {

[PartitionKey] public string Movie;

[ClusteringKey(1)] public string Director;

public string MainActor;

public int Year;

}

2. var cluster = Cluster.Builder().AddContactPoints("192.168.13.1", "192.168.13.1").Build();

3. using (var session = cluster.Connect("test")){ var nerdMovieTable = session.GetTable<NerdMovie>(); nerdMovieTable.CreateIfNotExists();

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Zapytaniavar batch = session.CreateBatch();

batch.Append(nerdMovieTable.Insert(

new NerdMovie() { Movie = "Serenity", Director = "Joss Whedon", MainActor = "Nathan Fillion", Year = 2005 }));

batch.Append(nerdMovieTable.Insert(

new NerdMovie() { Movie = "Pulp Fiction", Director = "Quentin Tarantino", MainActor = "John Travolta", Year = 1994 }));

batch.Append(nerdMovieTable.Insert(

new NerdMovie() { Movie = "Zero Charisma", Director = "Katie Graham", MainActor = "Nathan Fillion", Year = 2013 }));

var query = from m in nerdMovieTable select m;

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Wywołanie synchronicznebatch.Execute();

var result = query.Execute();

foreach (var e in result)

Console.WriteLine("Movie " + e.Movie + "[" + e.Director + "]");

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Wywołanie asynchroniczneManualResetEventSlim ev = new ManualResetEventSlim();

batch.BeginExecute((ar1) => {

batch.EndExecute(ar1);

query.BeginExecute((ar2) => {

var result = query.EndExecute(ar2);

foreach (var e in result)

Console.WriteLine("Movie " + e.Movie + "[" + e.Director + "]");

ev.Set();

}, null);

}, null);

ev.Wait();

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Co dalej? (driver .Net)Protokół binarny: wersja 2 (Cassandra 2.x)

- Batch

- Autentykacja poprzez SASL

- Lekkie transakcje – implementacja protokołu Paxos

IINSER … IF NOT EXISTS, UPDATE … IF

<column>=<value>

- Strumieniowanie wyników

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Driver C++ (w drodze)

1. Wieloplatformowość (np. embedded)

2. Oparty o boost::asio3. Mała liczba zależności od innych

bibliotek

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Kontakt

Cognitum | CH, St. Gallenswiss-office@cognitum.eu

abroad sales representatives:

Cognitum | PL, Warszawaoffice@cognitum.eu+48 22 250 2541

www.cognitum.eu/semantics

Cognitum | UK, Bristoluk-office@cognitum.eu