Webinar Introduction to MongoDB's Java Driver

Bryan Reinero, Software Engineer, 10gen

A look into the internals of the Java driver for MongoDB. Learn how the driver supports replication, database connection pooling, and building queries. Also includes an introduction to the BSON (binary JSON) format for serialization of JSON objects, how the drivers handles write behavior with the use of write concerns and how the driver communicates to the database via the Mongo wire protocol. New features, fixes and improvements in the latest release will also be covered.

Transcript

1. 1  
   MongoDB’s  Java  Driver  
   

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2. Topics we’ll cover
   •  Main  responsibilities  of  the  driver  
   •  New  features  for  version  2.9.0  
   

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3. Driver’s Main Responsibilities
   •  Manage  connections  
   •  BSON  serialization  /  deserialization  
   •  Manage  cursors  
   •  Maintain  replica  set  awareness  
   

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4. Connection Management
   /**  The  mechanism  managing  the  pool  */  
   public  class  DBPortPool  extends  SimplePool  
   /**  database  connection  with  internal  pooling  */  
   public  class  Mongo  
   /**  Various  settings  for  the  driver  */  
   public  class  MongoOptions  
   

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5. Wire Protocol
   •  TCP/IP  socket  based  request/response  
   •  Exchanges  BSON  objects  between  client  &  
   server  
   •  BSON  –  a  traversable,  binary  encoded  
   serialization  of  JSON  documents    
   •  BSON  is  the  primary  data  representation  in  
   MongoDB  
   http://bsonspec.org/  
   

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6. Encoding / Decoding BSON
    interface  DBEncoder  
    interface  DBDecoder  
   DBObject  decode(  InputStream  in,    
            DBCollection  collection  );  
   int  writeObject(  OutputBuffer  buf,    
                                  BSONObject  o  );  
   

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7. On to the good stuff…
   Reading, Writing & Arithmetic
   

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8. A  simple  example…  
   

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9. Basics of Replication
   Node 1
   
   Secondary
   
   Node 2
   
   Secondary
   
   Node 3
   
   Primary
   
   Replication  
   Replication  
   Heartbeat  
   

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10. Strong Consistency
    Primary
    
    Secondary
    
    Secondary
    
    Read  
    Write  
    Client  
    

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11. Eventual Consistency
    Primary
    
    Read  
    Write  
    Driver  
    Read  
    Secondary
    
    Secondary
    
    Client  Application  
    

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12. Read Preferences
    •  PRIMARY    
    •  PRIMARY  PREFERRED    
    •  SECONDARY    
    •  SECONDARY  PREFERRED    
    •  NEAREST    
    

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13. Using  Read  
    Preferences…  
    

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14. Writes & Durability
    •  Fire  and  forget    
    •  Wait  for  error  
    •  Wait  for  journal  commit  
    •  Wait  for  fsync  
    •  Wait  for  replication  to  secondary  
    

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15. Using  write  concerns…  
    

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16. Tagging
    •  Each  node  within  a  replica  set  can  be  
    marked  with  descriptors  called  tags    
    •  Tags  can  indicate  a  node’s  location,  
    membership  in  a  set,  or  other  
    characteristics    
    •  Use  tags  to  target  specific  nodes  for  read  
    or  write  operations    
    

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17. Using Tags
    Node 1
    Node 2
    
    Node 3
    
    tags"  :  {  
    "datacenter"  :  "Los  Angeles”,  
    "region"  :  "US_West”  
    }  
    tags"  :  {  
    "datacenter"  :”San  Jose”,  
    "region"  :  ”US_West”  
    }  
    tags"  :  {  
    "datacenter"  :”Richmond”,  
    "region"  :  "US_East”  
    }  
    

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18. Using  tags…  
    

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19. Aggregation Framework
    •  Calculate  aggregate  values  without  
    having  to  use  map-­‐reduce  
    •  Written  in  C++,  high  performance  
    •  Declarative,  no  javascript  
    •  Extensible,  new  operations  easily  added  
    

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20. Aggregation Operators
    •  $match
    •  $project
    •  $unwind
    •  $group
    •  $sort
    •  $skip
    •  $limit
    

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21. Aggregation Example
    sample document:
    {  
     "_id"  :  
    ObjectId("5029e745a0988a275aefd0c0"),  
     "name"  :  "quiz",  
     "score"  :  99,  
     "student"  :  7,  
     "year"  :  "junior"  
    }  
    

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22. Pipelining Operations
    $match
    $project
    $group
    $match  :  {  year  :  'junior'  }    
    $project  :  {  name  :  1,  score  :  1  }    
    $group:  {    
           _id:  '$name',    
         average:  {  $avg:  '$score'  }  
    }  
    

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23. What the command looks like…
    {    
           "aggregate"  :  "scores"  ,    
           "pipeline"  :  [    
                   {  "$match"  :  {  "year"  :  "junior"}}  ,  
                   {  "$project"  :  {  "name"  :  1  ,  "score"  :  1  ,  "_id"  :  0}}  ,    
                   {  "$group"  :  {    
                           "_id"  :  "$name"  ,    
                           "average"  :  {  "$avg"  :  "$score"}  
                           }  
                   }  
           ]  
    }  
    

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24. The  aggregation  helper…  
    

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25. There’s plenty more!...
    •  Tutorials  
    http://www.mongodb.org/display/DOCS/Java
    +Tutorial  
    •  Javadocs  http://api.mongodb.org/java/current/  
    •  Jira  
    https://jira.mongodb.org/secure/Dashboard.jspa  
    

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26. Join  us!  
    We’re  Hiring!  
    Bryan.reinero@10gen.com    
    

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