|
| 1 | +--- |
| 2 | +categories: |
| 3 | +- docs |
| 4 | +- develop |
| 5 | +- stack |
| 6 | +- oss |
| 7 | +- rs |
| 8 | +- rc |
| 9 | +- oss |
| 10 | +- kubernetes |
| 11 | +- clients |
| 12 | +description: Connect your .NET application to a Redis database |
| 13 | +linkTitle: Connect |
| 14 | +title: Connect to the server |
| 15 | +weight: 2 |
| 16 | +--- |
| 17 | + |
| 18 | +Start by creating a connection to your Redis server. There are many ways to achieve this using Lettuce. Here are a few. |
| 19 | + |
| 20 | +## Basic connection |
| 21 | + |
| 22 | +```java |
| 23 | +import io.lettuce.core.*; |
| 24 | +import io.lettuce.core.api.StatefulRedisConnection; |
| 25 | +import io.lettuce.core.api.sync.RedisCommands; |
| 26 | + |
| 27 | +public class ConnectBasicTest { |
| 28 | + |
| 29 | + public void connectBasic() { |
| 30 | + RedisURI uri = RedisURI.Builder |
| 31 | + .redis("localhost", 6379) |
| 32 | + .withAuthentication("default", "yourPassword") |
| 33 | + .build(); |
| 34 | + RedisClient client = RedisClient.create(uri); |
| 35 | + StatefulRedisConnection<String, String> connection = client.connect(); |
| 36 | + RedisCommands<String, String> commands = connection.sync(); |
| 37 | + |
| 38 | + commands.set("foo", "bar"); |
| 39 | + String result = commands.get("foo"); |
| 40 | + System.out.println(result); // >>> bar |
| 41 | + |
| 42 | + connection.close(); |
| 43 | + |
| 44 | + client.shutdown(); |
| 45 | + } |
| 46 | +} |
| 47 | +``` |
| 48 | + |
| 49 | +### Asynchronous connection |
| 50 | + |
| 51 | +```java |
| 52 | +package org.example; |
| 53 | +import java.util.*; |
| 54 | +import java.util.concurrent.ExecutionException; |
| 55 | + |
| 56 | +import io.lettuce.core.*; |
| 57 | +import io.lettuce.core.api.async.RedisAsyncCommands; |
| 58 | +import io.lettuce.core.api.StatefulRedisConnection; |
| 59 | + |
| 60 | +public class Async { |
| 61 | + public static void main(String[] args) { |
| 62 | + RedisClient redisClient = RedisClient.create("redis://localhost:6379"); |
| 63 | + |
| 64 | + try (StatefulRedisConnection<String, String> connection = redisClient.connect()) { |
| 65 | + RedisAsyncCommands<String, String> asyncCommands = connection.async(); |
| 66 | + |
| 67 | + // Asynchronously store & retrieve a simple string |
| 68 | + asyncCommands.set("foo", "bar").get(); |
| 69 | + System.out.println(asyncCommands.get("foo").get()); // prints bar |
| 70 | + |
| 71 | + // Asynchronously store key-value pairs in a hash directly |
| 72 | + Map<String, String> hash = new HashMap<>(); |
| 73 | + hash.put("name", "John"); |
| 74 | + hash.put("surname", "Smith"); |
| 75 | + hash.put("company", "Redis"); |
| 76 | + hash.put("age", "29"); |
| 77 | + asyncCommands.hset("user-session:123", hash).get(); |
| 78 | + |
| 79 | + System.out.println(asyncCommands.hgetall("user-session:123").get()); |
| 80 | + // Prints: {name=John, surname=Smith, company=Redis, age=29} |
| 81 | + } catch (ExecutionException | InterruptedException e) { |
| 82 | + throw new RuntimeException(e); |
| 83 | + } finally { |
| 84 | + redisClient.shutdown(); |
| 85 | + } |
| 86 | + } |
| 87 | +} |
| 88 | +``` |
| 89 | + |
| 90 | +Learn more about asynchronous Lettuce API in [the reference guide](https://redis.github.io/lettuce/#asynchronous-api). |
| 91 | + |
| 92 | +### Reactive connection |
| 93 | + |
| 94 | +```java |
| 95 | +package org.example; |
| 96 | +import java.util.*; |
| 97 | +import io.lettuce.core.*; |
| 98 | +import io.lettuce.core.api.reactive.RedisReactiveCommands; |
| 99 | +import io.lettuce.core.api.StatefulRedisConnection; |
| 100 | + |
| 101 | +public class Main { |
| 102 | + public static void main(String[] args) { |
| 103 | + RedisClient redisClient = RedisClient.create("redis://localhost:6379"); |
| 104 | + |
| 105 | + try (StatefulRedisConnection<String, String> connection = redisClient.connect()) { |
| 106 | + RedisReactiveCommands<String, String> reactiveCommands = connection.reactive(); |
| 107 | + |
| 108 | + // Reactively store & retrieve a simple string |
| 109 | + reactiveCommands.set("foo", "bar").block(); |
| 110 | + reactiveCommands.get("foo").doOnNext(System.out::println).block(); // prints bar |
| 111 | + |
| 112 | + // Reactively store key-value pairs in a hash directly |
| 113 | + Map<String, String> hash = new HashMap<>(); |
| 114 | + hash.put("name", "John"); |
| 115 | + hash.put("surname", "Smith"); |
| 116 | + hash.put("company", "Redis"); |
| 117 | + hash.put("age", "29"); |
| 118 | + |
| 119 | + reactiveCommands.hset("user-session:124", hash).then( |
| 120 | + reactiveCommands.hgetall("user-session:124") |
| 121 | + .collectMap(KeyValue::getKey, KeyValue::getValue).doOnNext(System.out::println)) |
| 122 | + .block(); |
| 123 | + // Prints: {surname=Smith, name=John, company=Redis, age=29} |
| 124 | + |
| 125 | + } finally { |
| 126 | + redisClient.shutdown(); |
| 127 | + } |
| 128 | + } |
| 129 | +} |
| 130 | +``` |
| 131 | + |
| 132 | +Learn more about reactive Lettuce API in [the reference guide](https://redis.github.io/lettuce/#reactive-api). |
| 133 | + |
| 134 | +## Connect to a Redis cluster |
| 135 | + |
| 136 | +```java |
| 137 | +import io.lettuce.core.RedisURI; |
| 138 | +import io.lettuce.core.cluster.RedisClusterClient; |
| 139 | +import io.lettuce.core.cluster.api.StatefulRedisClusterConnection; |
| 140 | +import io.lettuce.core.cluster.api.async.RedisAdvancedClusterAsyncCommands; |
| 141 | + |
| 142 | +// ... |
| 143 | + |
| 144 | +RedisURI redisUri = RedisURI.Builder.redis("localhost").withPassword("authentication").build(); |
| 145 | + |
| 146 | +RedisClusterClient clusterClient = RedisClusterClient.create(redisUri); |
| 147 | +StatefulRedisClusterConnection<String, String> connection = clusterClient.connect(); |
| 148 | +RedisAdvancedClusterAsyncCommands<String, String> commands = connection.async(); |
| 149 | + |
| 150 | +// ... |
| 151 | + |
| 152 | +connection.close(); |
| 153 | +clusterClient.shutdown(); |
| 154 | +``` |
| 155 | + |
| 156 | +### TLS connection |
| 157 | + |
| 158 | +When you deploy your application, use TLS and follow the [Redis security guidelines]({{< relref "/operate/oss_and_stack/management/security/" >}}). |
| 159 | + |
| 160 | +```java |
| 161 | +RedisURI redisUri = RedisURI.Builder.redis("localhost") |
| 162 | + .withSsl(true) |
| 163 | + .withPassword("secret!") // use your Redis password |
| 164 | + .build(); |
| 165 | + |
| 166 | +RedisClient client = RedisClient.create(redisUri); |
| 167 | +``` |
| 168 | + |
| 169 | +## Connection Management in Lettuce |
| 170 | + |
| 171 | +Lettuce uses `ClientResources` for efficient management of shared resources like event loop groups and thread pools. |
| 172 | +For connection pooling, Lettuce leverages `RedisClient` or `RedisClusterClient`, which can handle multiple concurrent connections efficiently. |
| 173 | + |
| 174 | +## Connection pooling |
| 175 | + |
| 176 | +A typical approach with Lettuce is to create a single `RedisClient` instance and reuse it to establish connections to your Redis server(s). |
| 177 | +These connections are multiplexed; that is, multiple commands can be run concurrently over a single or a small set of connections, making explicit pooling less practical. |
| 178 | +See |
| 179 | +[Connection pools and multiplexing]({{< relref "/develop/connect/clients/pools-and-muxing" >}}) |
| 180 | +for more information. |
| 181 | + |
| 182 | +Lettuce provides pool config to be used with Lettuce asynchronous connection methods. |
| 183 | + |
| 184 | +```java |
| 185 | +package org.example; |
| 186 | +import io.lettuce.core.RedisClient; |
| 187 | +import io.lettuce.core.RedisURI; |
| 188 | +import io.lettuce.core.TransactionResult; |
| 189 | +import io.lettuce.core.api.StatefulRedisConnection; |
| 190 | +import io.lettuce.core.api.async.RedisAsyncCommands; |
| 191 | +import io.lettuce.core.codec.StringCodec; |
| 192 | +import io.lettuce.core.support.*; |
| 193 | + |
| 194 | +import java.util.concurrent.CompletableFuture; |
| 195 | +import java.util.concurrent.CompletionStage; |
| 196 | + |
| 197 | +public class Pool { |
| 198 | + public static void main(String[] args) { |
| 199 | + RedisClient client = RedisClient.create(); |
| 200 | + |
| 201 | + String host = "localhost"; |
| 202 | + int port = 6379; |
| 203 | + |
| 204 | + CompletionStage<BoundedAsyncPool<StatefulRedisConnection<String, String>>> poolFuture |
| 205 | + = AsyncConnectionPoolSupport.createBoundedObjectPoolAsync( |
| 206 | + () -> client.connectAsync(StringCodec.UTF8, RedisURI.create(host, port)), |
| 207 | + BoundedPoolConfig.create()); |
| 208 | + |
| 209 | + // await poolFuture initialization to avoid NoSuchElementException: Pool exhausted when starting your application |
| 210 | + AsyncPool<StatefulRedisConnection<String, String>> pool = poolFuture.toCompletableFuture() |
| 211 | + .join(); |
| 212 | + |
| 213 | + // execute work |
| 214 | + CompletableFuture<TransactionResult> transactionResult = pool.acquire() |
| 215 | + .thenCompose(connection -> { |
| 216 | + |
| 217 | + RedisAsyncCommands<String, String> async = connection.async(); |
| 218 | + |
| 219 | + async.multi(); |
| 220 | + async.set("key", "value"); |
| 221 | + async.set("key2", "value2"); |
| 222 | + System.out.println("Executed commands in pipeline"); |
| 223 | + return async.exec().whenComplete((s, throwable) -> pool.release(connection)); |
| 224 | + }); |
| 225 | + transactionResult.join(); |
| 226 | + |
| 227 | + // terminating |
| 228 | + pool.closeAsync(); |
| 229 | + |
| 230 | + // after pool completion |
| 231 | + client.shutdownAsync(); |
| 232 | + } |
| 233 | +} |
| 234 | +``` |
| 235 | + |
| 236 | +In this setup, `LettuceConnectionFactory` is a custom class you would need to implement, adhering to Apache Commons Pool's `PooledObjectFactory` interface, to manage lifecycle events of pooled `StatefulRedisConnection` objects. |
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