Inspecting Solr Index in WSO2 API Manager

Introduction

Apache Solr project [1] helps you to run a full-featured search server on a server. Also you can integrate Solr with your project to make searching faster. In WSO2 API Manager, Solr is using to make searching faster in store and publisher. In WSO2 API Manager, Solr indexing keeps the frequently using meta-data of APIs. Thereafter, to retrieve complete information about an API, API Manager uses its database. This mechanism makes searching faster and less burden on the databases.

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However, in some situations things may go wrong. We have seen several cases Solr indexing does not tally with the information at database. Due to that, when displaying complete information about an API, you may see inconsistent information. In such situations you may want to inspect the Solr index at API Manager.

Setting Up Solr Server

Setting up the solr server is quite easy, as its a matter of downloading binary file from the project page [1]. The important thing here is to make sure you download the proper version. WSO2 API Manager 2.0.0 version is using Solr 5.2.1 version. I figured out it by going through the API Manager release tag pom, identify the registry version and searching registry pom file.

Once you download the binary package, extract it. You can start the Solr server by going to solr-5.2.1/bin directory and execute “./solr start“. Then Solr server will start as a background process. Then access its admin UI by location “http://localhost:8983/solr” in your browser.

Inspecting WSO2 API Manager Index

Before doing so, you must stop WSO2 API Manager and Solr server. To stop Solr server, execute command “./solr stop” inside bin directory. Then you need to copy Solr indexing configs and index from API Manager.

  • To copy configs, go to location “APIM_HOME/repository/conf/solr” and copy “registry-indexing” to “solr-5.2.1/server/solr” folder.
  • To copy indexed data, go to the location “APIM_HOME” and copy “solr” folder to same folder “solr-5.2.1” resides. This is done to comply the “dataDir” value at “solr-5.2.1/server/solr/registry-indexing/core.properties” file.

Now start the Solr server and go to admin UI. You should see a drop-down on the left pane and “registry-indexing” menu item in that. Select “registry-indexing” and now you will be able to query indexed data by going to Query section. To query Solr index you need to use specific query language, which is not actually difficult to understand. But in here I’m not going to discuss too much on query language, and it’s up to you to refer [2] and learn it. You can try-out those queries from admin UI directly.

registry-indexing in Solr admin UI

Writing a Java client to query information

In some cases, you may need to write a client to client which can talk to a Solr server and retrieve results. So here I am giving out an example Java code which you can use to retrieve results from a Solr server [3]. However, I am not going to explain the code in detail, because I believe it’s self-explanatory.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.buddhima.solr</groupId>
<artifactId>solr-testing</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
    <!-- https://mvnrepository.com/artifact/org.apache.solr/solr-solrj -->
    <dependency>
        <groupId>org.apache.solr</groupId>
        <artifactId>solr-solrj</artifactId>
        <version>7.1.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.solr/solr-common -->
    <dependency>
        <groupId>org.apache.solr</groupId>
        <artifactId>solr-common</artifactId>
        <version>1.3.0</version>
    </dependency>
</dependencies>
</project>
package com.solr.testing;

import java.io.IOException;

import org.apache.solr.client.solrj.SolrClient;
import org.apache.solr.client.solrj.SolrQuery;
import org.apache.solr.client.solrj.SolrServerException;
import org.apache.solr.client.solrj.impl.HttpSolrClient;
import org.apache.solr.client.solrj.response.QueryResponse;
import org.apache.solr.common.SolrDocumentList;

/**
 * Created by buddhima.
 */
public class SolrTesting {

    public static void main(String[] args) throws IOException, SolrServerException {
        // Default Solr port: 8983, and APIM using 'registry-indexing'
        SolrClient client = new HttpSolrClient.Builder("http://localhost:8983/solr/registry-indexing").build();

        SolrQuery query = new SolrQuery();
        query.setQuery("*:*");

        // Fields use for filtering as a list of key:value pairs
        query.addFilterQuery("allowedRoles:internal/everyone", "mediaType_s:application/vnd.wso2-api+xml");

        // Fields to show in the result
        query.setFields("overview_name_s", "overview_status_s", "updater_s", "overview_version_s", "overview_context_s");

        // Limit the query search space
        query.setStart(0);
        query.setRows(500);

        // Execute the query and print results
        QueryResponse response = client.query(query);
        SolrDocumentList results = response.getResults();
        for (int i = 0; i < results.size(); ++i) {
            System.out.println(results.get(i));
        }
    }
}

In addition to that you can refer [4] [5] for further learning on Solr syntax.

Conclusion

In this post I have discussed the use of Solr in WSO2 API Manager and how to investigate existing Solr index. In addition to that I have shown how to construct a Java client which can talk to a Solr server. I hope that the above explanation will help you to solve issues with Solr indexing.

Special thank goes to WSO2 support for providing guidance.

References

[1] Apache Solr project : http://lucene.apache.org/solr/

[2] Solr query syntax : http://www.solrtutorial.com/solr-query-syntax.html

[3] Using SolrJ : http://www.solrtutorial.com/solrj-tutorial.html

[4] Solr Query Syntax : http://yonik.com/solr/query-syntax/

[5] Solr df and qf explanation : https://stackoverflow.com/questions/17363677/solr-df-and-qf-explanation

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