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| <div class="col-sm-9 col-sm-offset-3 col-md-10 col-md-offset-2 main"> |
| <h1>Java API</h1> |
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| <h2 id="introduction">Introduction</h2> |
| |
| <p>Ozone ships with it own client library, that supports both RPC(Remote |
| Procedure call) and REST(Representational State Transfer). This library is |
| the primary user interface to ozone.</p> |
| |
| <p>It is trivial to switch from RPC to REST or vice versa, by setting the |
| property <em>ozone.client.protocol</em> in the configuration or by calling the |
| appropriate factory method.</p> |
| |
| <h2 id="creating-an-ozone-client">Creating an Ozone client</h2> |
| |
| <p>The Ozone client factory creates the ozone client. It allows the user to |
| specify the protocol of communication. For example, to get an REST client, we |
| can use</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java">OzoneClient ozClient <span style="color:#f92672">=</span> OzoneClientFactory<span style="color:#f92672">.</span><span style="color:#a6e22e">getRestClient</span><span style="color:#f92672">();</span></code></pre></div> |
| |
| <p>And to get a a RPC client we can call</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java">OzoneClient ozClient <span style="color:#f92672">=</span> OzoneClientFactory<span style="color:#f92672">.</span><span style="color:#a6e22e">getRpcClient</span><span style="color:#f92672">();</span></code></pre></div> |
| |
| <p>If the user want to create a client based on the configuration, then they can |
| call</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java">OzoneClient ozClient <span style="color:#f92672">=</span> OzoneClientFactory<span style="color:#f92672">.</span><span style="color:#a6e22e">getClient</span><span style="color:#f92672">();</span></code></pre></div> |
| |
| <p>and an appropriate client based on configuration will be returned.</p> |
| |
| <h2 id="writing-data-using-ozone-client">Writing data using Ozone Client</h2> |
| |
| <p>The hierarchy of data inside ozone is a volume, bucket and a key. A volume |
| is a collection of buckets. A bucket is a collection of keys. To write data |
| to the ozone, you need a volume, bucket and a key.</p> |
| |
| <h3 id="creating-a-volume">Creating a Volume</h3> |
| |
| <p>Once we have a client, we need to get a reference to the ObjectStore. This |
| is done via</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java">ObjectStore objectStore <span style="color:#f92672">=</span> ozClient<span style="color:#f92672">.</span><span style="color:#a6e22e">getObjectStore</span><span style="color:#f92672">();</span></code></pre></div> |
| |
| <p>An object store represents an active cluster against which the client is working.</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java"><span style="color:#75715e">// Let us create a volume to store our game assets. |
| </span><span style="color:#75715e">// This uses default arguments for creating that volume. |
| </span><span style="color:#75715e"></span>objectStore<span style="color:#f92672">.</span><span style="color:#a6e22e">createVolume</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>assets<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Let us verify that the volume got created. |
| </span><span style="color:#75715e"></span>OzoneVolume assets <span style="color:#f92672">=</span> objectStore<span style="color:#f92672">.</span><span style="color:#a6e22e">getVolume</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>assets<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span></code></pre></div> |
| |
| <p>It is possible to pass an array of arguments to the createVolume by creating volume arguments.</p> |
| |
| <h3 id="creating-a-bucket">Creating a Bucket</h3> |
| |
| <p>Once you have a volume, you can create buckets inside the volume.</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-bash" data-lang="bash">// Let us create a bucket called videos. |
| assets.createBucket<span style="color:#f92672">(</span>“videos”<span style="color:#f92672">)</span>; |
| Ozonebucket video <span style="color:#f92672">=</span> assets.getBucket<span style="color:#f92672">(</span>“videos”<span style="color:#f92672">)</span>;</code></pre></div> |
| |
| <p>At this point we have a usable volume and a bucket. Our volume is called assets and bucket is called videos.</p> |
| |
| <p>Now we can create a Key.</p> |
| |
| <h3 id="reading-and-writing-a-key">Reading and Writing a Key</h3> |
| |
| <p>With a bucket object the users can now read and write keys. The following code reads a video called intro.mp4 from the local disk and stores in the video bucket that we just created.</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-bash" data-lang="bash">// read data from the file, this is a user provided <span style="color:#66d9ef">function</span>. |
| byte <span style="color:#f92672">[]</span> vidoeData <span style="color:#f92672">=</span> readFile<span style="color:#f92672">(</span>“into.mp4”<span style="color:#f92672">)</span>; |
| |
| // Create an output stream and write data. |
| OzoneOutputStream videoStream <span style="color:#f92672">=</span> video.createKey<span style="color:#f92672">(</span>“intro.mp4”, <span style="color:#ae81ff">1048576</span><span style="color:#f92672">)</span>; |
| videoStream.write<span style="color:#f92672">(</span>videoData<span style="color:#f92672">)</span>; |
| |
| // Close the stream when it is <span style="color:#66d9ef">done</span>. |
| videoStream.close<span style="color:#f92672">()</span>; |
| |
| |
| // We can use the same bucket to read the file that we just wrote, by creating an input Stream. |
| // Let us allocate a byte array to hold the video first. |
| byte<span style="color:#f92672">[]</span> data <span style="color:#f92672">=</span> new byte<span style="color:#f92672">[(</span>int<span style="color:#f92672">)</span><span style="color:#ae81ff">1048576</span><span style="color:#f92672">]</span>; |
| OzoneInputStream introStream <span style="color:#f92672">=</span> video.readKey<span style="color:#f92672">(</span>“intro.mp4”<span style="color:#f92672">)</span>; |
| // read intro.mp4 into the data buffer |
| introStream.read<span style="color:#f92672">(</span>data<span style="color:#f92672">)</span>; |
| introStream.close<span style="color:#f92672">()</span>;</code></pre></div> |
| |
| <p>Here is a complete example of the code that we just wrote. Please note the close functions being called in this program.</p> |
| |
| <div class="highlight"><pre style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-java" data-lang="java"><span style="color:#75715e">// Let us create a client |
| </span><span style="color:#75715e"></span>OzoneClient ozClient <span style="color:#f92672">=</span> OzoneClientFactory<span style="color:#f92672">.</span><span style="color:#a6e22e">getClient</span><span style="color:#f92672">();</span> |
| |
| <span style="color:#75715e">// Get a reference to the ObjectStore using the client |
| </span><span style="color:#75715e"></span>ObjectStore objectStore <span style="color:#f92672">=</span> ozClient<span style="color:#f92672">.</span><span style="color:#a6e22e">getObjectStore</span><span style="color:#f92672">();</span> |
| |
| <span style="color:#75715e">// Let us create a volume to store our game assets. |
| </span><span style="color:#75715e">// This default arguments for creating that volume. |
| </span><span style="color:#75715e"></span>objectStore<span style="color:#f92672">.</span><span style="color:#a6e22e">createVolume</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>assets<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Let us verify that the volume got created. |
| </span><span style="color:#75715e"></span>OzoneVolume assets <span style="color:#f92672">=</span> objectStore<span style="color:#f92672">.</span><span style="color:#a6e22e">getVolume</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>assets<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Let us create a bucket called videos. |
| </span><span style="color:#75715e"></span>assets<span style="color:#f92672">.</span><span style="color:#a6e22e">createBucket</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>videos<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| Ozonebucket video <span style="color:#f92672">=</span> assets<span style="color:#f92672">.</span><span style="color:#a6e22e">getBucket</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>videos<span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// read data from the file, this is assumed to be a user provided function. |
| </span><span style="color:#75715e"></span><span style="color:#66d9ef">byte</span> <span style="color:#f92672">[]</span> vidoeData <span style="color:#f92672">=</span> readFile<span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>into<span style="color:#f92672">.</span><span style="color:#a6e22e">mp4</span><span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Create an output stream and write data. |
| </span><span style="color:#75715e"></span>OzoneOutputStream videoStream <span style="color:#f92672">=</span> video<span style="color:#f92672">.</span><span style="color:#a6e22e">createKey</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>intro<span style="color:#f92672">.</span><span style="color:#a6e22e">mp4</span><span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">,</span> 1048576<span style="color:#f92672">);</span> |
| videoStream<span style="color:#f92672">.</span><span style="color:#a6e22e">write</span><span style="color:#f92672">(</span>videoData<span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Close the stream when it is done. |
| </span><span style="color:#75715e"></span> videoStream<span style="color:#f92672">.</span><span style="color:#a6e22e">close</span><span style="color:#f92672">();</span> |
| |
| |
| <span style="color:#75715e">// We can use the same bucket to read the file that we just wrote, by creating an input Stream. |
| </span><span style="color:#75715e">// Let us allocate a byte array to hold the video first. |
| </span><span style="color:#75715e"></span> |
| <span style="color:#66d9ef">byte</span><span style="color:#f92672">[]</span> data <span style="color:#f92672">=</span> <span style="color:#66d9ef">new</span> <span style="color:#66d9ef">byte</span><span style="color:#f92672">[(</span><span style="color:#66d9ef">int</span><span style="color:#f92672">)</span>1048576<span style="color:#f92672">];</span> |
| OzoneInputStream introStream <span style="color:#f92672">=</span> video<span style="color:#f92672">.</span><span style="color:#a6e22e">readKey</span><span style="color:#f92672">(</span><span style="color:#960050;background-color:#1e0010">“</span>into<span style="color:#f92672">.</span><span style="color:#a6e22e">mp4</span><span style="color:#960050;background-color:#1e0010">”</span><span style="color:#f92672">);</span> |
| introStream<span style="color:#f92672">.</span><span style="color:#a6e22e">read</span><span style="color:#f92672">(</span>data<span style="color:#f92672">);</span> |
| |
| <span style="color:#75715e">// Close the stream when it is done. |
| </span><span style="color:#75715e"></span>introStream<span style="color:#f92672">.</span><span style="color:#a6e22e">close</span><span style="color:#f92672">();</span> |
| |
| <span style="color:#75715e">// Close the client. |
| </span><span style="color:#75715e"></span>ozClient<span style="color:#f92672">.</span><span style="color:#a6e22e">close</span><span style="color:#f92672">();</span></code></pre></div> |
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