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Dealt with issue eclipse-archived#5 (ETag convenience). Added an inte…
…rface ETagSupport and a default implementation ETagDefaultSupport and JUnit tests. A CoapResource now has a ETagSupport object that generates ETags if required. If an incoming request has ETags, the resource automatically validates them against the current value in the ETagSupport object and responds with a 2.03 (Valid) if an ETag matches.
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123 changes: 123 additions & 0 deletions
123
...-core/src/main/java/org/eclipse/californium/core/server/resources/ETagDefaultSupport.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| package org.eclipse.californium.core.server.resources; | ||
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| import java.util.Random; | ||
| import java.util.concurrent.atomic.AtomicLong; | ||
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| /** | ||
| * This is e default ETag support implementation for a resource. An instance of | ||
| * this class holds the current ETag. If the content of a resource changes, it | ||
| * should call {@link #nextETag()} to increase the ETag value by 1. This class | ||
| * is thread-safe. | ||
| */ | ||
| public class ETagDefaultSupport implements ETagSupport { | ||
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| /** The maximum size allowed by the coap-18 draft. */ | ||
| public static final int MAX_BYTES = 8; | ||
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| /** The minimum size allowed by the coap-18 draft. */ | ||
| public static final int MIN_BYTES = 0; | ||
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| /** A static instance of random to set random initial ETag values. */ | ||
| private static final Random rand = new Random(); | ||
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| /** The size of the ETag. */ | ||
| private int bytes; | ||
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| /** The current ETag value. */ | ||
| private AtomicLong current; | ||
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| /** | ||
| * Instantiates a new instance of ETagDefaultSupport that generates 8 bytes | ||
| * and starts with a random value. long ETags. | ||
| */ | ||
| public ETagDefaultSupport() { | ||
| this(MAX_BYTES); | ||
| } | ||
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| /** | ||
| * Instantiates a new instance of ETagDefaultSupport that generates ETags of | ||
| * the specified size and starts with a random value. | ||
| * | ||
| * @param bytes the size of the ETags | ||
| */ | ||
| public ETagDefaultSupport(int bytes) { | ||
| this(bytes, rand.nextLong()); | ||
| } | ||
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| /** | ||
| * Instantiates a new instance of ETagDefaultSupport that generates ETags of | ||
| * the specified size and starts with the specified value. | ||
| * | ||
| * @param bytes the size of the ETags | ||
| * @param initialValue the initial value | ||
| */ | ||
| public ETagDefaultSupport(int bytes, long initialValue) { | ||
| current = new AtomicLong(initialValue); | ||
| if (bytes > MAX_BYTES) | ||
| throw new IllegalArgumentException("ETags must not be longer than 8 bytes but is "+bytes); | ||
| if (bytes < MIN_BYTES) | ||
| throw new IllegalArgumentException("ETags must be at least 0 bytes long but is "+bytes); | ||
| this.bytes = bytes; | ||
| } | ||
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| /* (non-Javadoc) | ||
| * @see org.eclipse.californium.core.server.resources.ETagSupport#nextETag() | ||
| */ | ||
| public byte[] nextETag() { | ||
| return long2bytes(current.incrementAndGet(), bytes); | ||
| } | ||
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| /* (non-Javadoc) | ||
| * @see org.eclipse.californium.core.server.resources.ETagSupport#getCurrentETag() | ||
| */ | ||
| public byte[] getCurrentETag() { | ||
| return long2bytes(current.get(), bytes); | ||
| } | ||
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| /* (non-Javadoc) | ||
| * @see org.eclipse.californium.core.server.resources.ETagSupport#setCurrentETag(byte[]) | ||
| */ | ||
| public void setCurrentETag(byte[] etag) { | ||
| long cur = 0; | ||
| for (int i=0;i<etag.length && i<bytes;i++) | ||
| cur |= (etag[i] << (etag.length - i - 1)*8); | ||
| this.current.set(cur); | ||
| } | ||
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| /* (non-Javadoc) | ||
| * @see org.eclipse.californium.core.server.resources.ETagSupport#getCurrentETagAsString() | ||
| */ | ||
| public String getCurrentETagAsString() { | ||
| byte[] etag = getCurrentETag(); | ||
| StringBuffer string = new StringBuffer(""); | ||
| for(byte b:etag) string.append(String.format("%02x", b&0xff)); | ||
| return string.toString(); | ||
| } | ||
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| /** | ||
| * Converts the specified long value to a byte array of maximum maxSize | ||
| * length. Cuts off leading zeros. | ||
| * | ||
| * @param value the value | ||
| * @param maxSize the max size of the byte array | ||
| * @return the byte[] the byte array | ||
| */ | ||
| private byte[] long2bytes(long value, int maxSize) { | ||
| int length = maxSize; | ||
| // reduce length so that there will be no leading zeros | ||
| for (;( (value >>> (length-1)*8) & 0xFF) == 0 && length > 0;length--); | ||
| byte[] etag = new byte[length]; | ||
| for (int i=0;i<length;i++) { | ||
| etag[length - i - 1] = (byte) (value >>> i*8); | ||
| } | ||
| return etag; | ||
| } | ||
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| /* (non-Javadoc) | ||
| * @see java.lang.Object#toString() | ||
| */ | ||
| public String toString() { | ||
| return "DefaultETagSupport(current: 0x"+getCurrentETagAsString()+", bytes: "+bytes+")"; | ||
| } | ||
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| } |
37 changes: 37 additions & 0 deletions
37
...fornium-core/src/main/java/org/eclipse/californium/core/server/resources/ETagSupport.java
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| @@ -0,0 +1,37 @@ | ||
| package org.eclipse.californium.core.server.resources; | ||
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| /** | ||
| * An ETag Support object supports a resource in generating and maintaining | ||
| * ETags. | ||
| */ | ||
| public interface ETagSupport { | ||
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| /** | ||
| * Generates the next ETag. | ||
| * | ||
| * @return the ETag as byte array | ||
| */ | ||
| public byte[] nextETag(); | ||
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| /** | ||
| * Gets the current ETag. | ||
| * | ||
| * @return the current ETag | ||
| */ | ||
| public byte[] getCurrentETag(); | ||
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| /** | ||
| * Sets the current ETag. | ||
| * | ||
| * @param etag the new ETag | ||
| */ | ||
| public void setCurrentETag(byte[] etag); | ||
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| /** | ||
| * Gets the current ETag as string. | ||
| * | ||
| * @return the current ETag as string | ||
| */ | ||
| public String getCurrentETagAsString(); | ||
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| } |
118 changes: 118 additions & 0 deletions
118
...fornium-core/src/test/java/org/eclipse/californium/core/test/ETagSupportResourceTest.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,118 @@ | ||
| package org.eclipse.californium.core.test; | ||
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| import java.util.Arrays; | ||
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| import org.eclipse.californium.core.CoapClient; | ||
| import org.eclipse.californium.core.CoapResponse; | ||
| import org.eclipse.californium.core.CoapServer; | ||
| import org.eclipse.californium.core.coap.CoAP.ResponseCode; | ||
| import org.eclipse.californium.core.network.CoAPEndpoint; | ||
| import org.eclipse.californium.core.server.resources.CoapExchange; | ||
| import org.eclipse.californium.core.server.resources.ConcurrentCoapResource; | ||
| import org.junit.After; | ||
| import org.junit.Assert; | ||
| import org.junit.Before; | ||
| import org.junit.Test; | ||
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| public class ETagSupportResourceTest { | ||
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| public static final String TARGET = "test"; | ||
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| private CoapServer server; | ||
| private int serverPort; | ||
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| private TestResource testResource; | ||
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| @Before | ||
| public void startupServer() throws Exception { | ||
| System.out.println("\nStart "+getClass().getSimpleName()); | ||
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| CoAPEndpoint serverEndpoint = new CoAPEndpoint(); | ||
| server = new CoapServer(); | ||
| server.addEndpoint(serverEndpoint); | ||
| server.add(testResource = new TestResource(TARGET)); | ||
| server.start(); | ||
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| serverPort = serverEndpoint.getAddress().getPort(); | ||
| } | ||
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| @After | ||
| public void shutdownServer() { | ||
| server.destroy(); | ||
| System.out.println("End "+getClass().getSimpleName()); | ||
| } | ||
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| @Test | ||
| public void test() { | ||
| String currentContent = "AAAA"; | ||
| testResource.setContent(currentContent); | ||
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| // First GET request expects a 2.05 response with an ETag. | ||
| CoapClient client = new CoapClient("coap://localhost:"+serverPort+"/"+TARGET); | ||
| CoapResponse res1 = client.get(); | ||
| Assert.assertNotNull(res1); | ||
| Assert.assertEquals(ResponseCode.CONTENT, res1.getCode()); | ||
| Assert.assertEquals(currentContent, res1.getResponseText()); | ||
| Assert.assertTrue(res1.getOptions().getETagCount() > 0); | ||
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| // Second request validates that the ETag from the first response is still valid. | ||
| byte[] etag1 = res1.getOptions().getETags().get(0); | ||
| CoapResponse res2 = client.validate(etag1); | ||
| Assert.assertNotNull(res2); | ||
| Assert.assertEquals(ResponseCode.VALID, res2.getCode()); | ||
| Assert.assertTrue(res2.getResponseText().isEmpty()); | ||
| Assert.assertTrue(res2.getOptions().getETagCount() > 0); | ||
| Assert.assertArrayEquals(etag1, res2.getOptions().getETags().get(0)); | ||
|
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| // The content changes | ||
| currentContent = "BBBB"; | ||
| testResource.setContent(currentContent); | ||
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| // The third request attempts to validate that the ETag from the first response is still valid. | ||
| // However, since the content has changed, the server responds a 2.05 with the new content and a new ETag. | ||
| CoapResponse res3 = client.validate(etag1); | ||
| Assert.assertNotNull(res3); | ||
| Assert.assertEquals(ResponseCode.CONTENT, res3.getCode()); | ||
| Assert.assertEquals(currentContent, res3.getResponseText()); | ||
| Assert.assertTrue(res3.getOptions().getETagCount() > 0); | ||
| Assert.assertFalse(Arrays.equals(etag1, res3.getOptions().getETags().get(0))); // has another ETag | ||
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| // The forth request validates the ETags from the first and third response. | ||
| // The server responds that the third ETag is still valid. | ||
| byte[] etag3 = res3.getOptions().getETags().get(0); | ||
| CoapResponse res4 = client.validate(etag1, etag3); | ||
| Assert.assertNotNull(res4); | ||
| Assert.assertEquals(ResponseCode.VALID, res4.getCode()); | ||
| Assert.assertTrue(res4.getResponseText().isEmpty()); | ||
| Assert.assertTrue(res4.getOptions().getETagCount() > 0); | ||
| Assert.assertArrayEquals(etag3, res4.getOptions().getETags().get(0)); | ||
|
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| } | ||
|
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| private static class TestResource extends ConcurrentCoapResource { | ||
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| private String content; | ||
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| public TestResource(String name) { | ||
| super(name, ConcurrentCoapResource.SINGLE_THREADED); | ||
| } | ||
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| @Override | ||
| public void handleGET(CoapExchange exchange) { | ||
| exchange.setETag(getETagSupport().getCurrentETag()); | ||
| exchange.respond(content); | ||
| } | ||
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| public void setContent(final String newContent) { | ||
| // This Changes the content and update the ETag. This is executed by | ||
| // the same thread that also handles requests so that there are no | ||
| // race conditions! | ||
| execute(new Runnable() { | ||
| public void run() { | ||
| content = newContent; | ||
| getETagSupport().nextETag(); | ||
| } | ||
| }); | ||
| } | ||
| } | ||
| } |
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