Appengine Nljug
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Google AppEngine is an application platform that allows developers to build and host web applications in the cloud. It provides automatic scaling of web and worker instances, high availability, load balancing, and simple deployment. The platform handles low-level tasks like hardware provisioning and maintenance. However, applications are limited by the sandbox environment and certain features like file system access and sockets are not supported. Pricing is based on usage of resources like bandwidth, CPU time, and data storage. While deployment is easy, applications need to be designed specifically for the AppEngine platform to work within its constraints.
![Sharded architecture
Row name Values
A [...]
B [...]
C [...]
Row name Values
D [...]
E [...]
F [...]
Row name Values
G [...]
H [...]
I [...]](https://image.slidesharecdn.com/appengine-nljug-100402045112-phpapp02/85/Appengine-Nljug-24-320.jpg)
![GQL
SELECT [* | __key__] FROM <kind>
[WHERE <condition> [AND <condition> ...]]
[ORDER BY <property> [ASC | DESC] [, <property> [ASC | DESC] ...]]
[LIMIT [<offset>,]<count>]
[OFFSET <offset>]
<condition> := <property> {< | <= | > | >= | = | != } <value>
<condition> := <property> IN <list>
<condition> := ANCESTOR IS <entity or key>](https://image.slidesharecdn.com/appengine-nljug-100402045112-phpapp02/85/Appengine-Nljug-46-320.jpg)
![Cron syntax
every N (hours|mins|minutes)
("every"|ordinal) (days) ["of" (monthspec)] (time)
Examples
every 5 minutes
every 12 hours
2nd,third mon,wed,thu of march 17:00
every monday 09:00
1st monday of sep,oct,nov 17:00
every day 00:00](https://image.slidesharecdn.com/appengine-nljug-100402045112-phpapp02/85/Appengine-Nljug-72-320.jpg)
Appengine Nljug
- 1. Google AppEngine Paul Bakker
- 2. About me Paul Bakker • Trainer Info Support Hibernat EJB 3 e • NLJUG speaker JSF Flex • Java Magazine author Seam Groovy JavaFX Grails Spring
- 3. About Info Support • Financieel gezond sinds oprichting 1986 • Focus op IT vakmanschap • Brede en integrale dienstverlening • Partnerships met o.a. Microsoft, IBM, NLJUG • Vestigingen in Nederland en België - 250+ medewerkers in Nederland - 25 medewerkers in België
- 4. Presentation Goal Introduction to Developing applications for AppEngine
- 5. Outline AppEngine Cloud Services offerings Using Introducing frameworks AppEngine Pricing Developing and deploying Storing data
- 7. Infrastructure as a Service Platform as a Service Software as a Service
- 8. Infrastructure as a Service A virtual hardware platform Full control of the operating system Custom configuration of application servers
- 9. Infrastructure as a Service Pros It’s just works like your old hardware No development limitations No lock-in Cons You still have to manage servers No automatic scaling
- 10. Platform as a Service A virtual application server No control of the operating system Running in a sandbox
- 11. Platform as a Service Pros No more server management Easy deployment Automatic scaling Cons Limited by the sandbox Can’t run existing apps
- 12. Software as a Service Run an application from the cloud Might extend the application using a proprietary API
- 13. AppEngine Intro
- 15. Handling requests Each application gets a free domain name http://yourappname.appspot.com You can add your own domain name Each request has a 30 second timeout Streaming responses are not supported
- 16. Scaling JVMs are started on demand on app startup after inactivity when upscaling Starting a JVM causes a “loading request” the app is loaded during that request
- 17. Loading request optimization Application startup time is now important the app might be started after a request Reduce the use of libraries Prevent heavy initialization code share data with multiple JVMs using MemCache
- 18. The sandbox You can’t Write to the file system Open sockets Start threads Invoke most System calls Reflect on classes not belonging to the app Use JRE classes not on the white list
- 19. Supported Java Data Objects (JDO) Java Persistence API (JPA) Java Server Faces (JSF) Java Server Pages (JSP) and JSTL Java Servlet API 2.4 JavaBeans Activation Framework (JAF) Java Architecture for XML Binding (JAXB) JavaMail XML processing APIs including DOM, SAX and XSLT
- 20. Not Supported Enterprise Java Beans (EJB) JAX-WS and JAX-RPC JDBC Java EE Connector Architecture (JCA) Java Management Extensions (JMX) Java Message Service (JMS) Java Naming and Directory Interface (JNDI) Remote Method Invocation (RMI)
- 21. Creating and uploading an application
- 22. Storing Data
- 23. DataStore Distributed architecture Highly scalable Not relational Schemaless Properties have one or more values
- 24. Sharded architecture Row name Values A [...] B [...] C [...] Row name Values D [...] E [...] F [...] Row name Values G [...] H [...] I [...]
- 25. Entity storage Kind => table Key => primary key Entity Group => partition Typed properties => columns Kind Person Entity Group /Person:Paul Key /Person:Paul name string: Paul Bakker colleagues Key:/Speaker(68) Key:/Speaker(15)
- 26. Entity Groups Entities are hierarchical Useful for “owned” relations a chapter can’t exist without a book /Book(24)/Chapter(2)/Paragraph(3)
- 27. Queries Supported filters < less than <= less than or equal to = equal to > greater than >= greater than or equal to != not equal to
- 28. Indexes Each query uses an index One index for each combination of: kind filter property operator sort order
- 29. Index example JPQL queries select s from Speaker s order by s.firstname, s.lastname select s from Speaker s WHERE s.firstname LIKE :firstname order by s.firstname, s.lastname select s from Speaker s WHERE lastname LIKE :lastname order by s.lastname, s.firstname Index configuration
- 30. Transactions The DataStore is transactional All DataStore write operations are atomic Only a single Entity Group can be used within a transaction entities in the same group live physically together
- 31. Transactions
- 33. Transactions Begin transaction Create new Speaker (/Speaker(1))
- 34. Transactions Begin transaction Create new Speaker (/Speaker(1)) Add Talk (/Speaker(1)/Talk(1))
- 35. Transactions Begin transaction Create new Speaker (/Speaker(1)) Add Talk (/Speaker(1)/Talk(1)) Add new Speaker (/Speaker(2))
- 36. Transactions Begin transaction Create new Speaker (/Speaker(1)) Add Talk (/Speaker(1)/Talk(1)) Add new Speaker (/Speaker(2)) Commit transaction
- 37. Transactions Begin transaction Create new Speaker (/Speaker(1)) Add Talk (/Speaker(1)/Talk(1)) Commit transaction Begin transaction Add new Speaker (/Speaker(2)) Commit transaction
- 38. Transaction Isolation Within a transaction: Serializable transactions are completely isolated Outside a transaction: Read Committed get() will only consist of committed data queries are more subtle
- 39. Understand commits A commit() consists of two milestones 1 changes to entities visible 2 changes to indexes visible the entity is updated, but might not be returned by a predicate query
- 40. Understand commits bob.age == 18 Transaction 1 bob.age += 1 select ... where age = 18 Transaction 2
- 41. Understand commits bob.age == 18 Transaction 1 bob.age += 1 select ... where age = 18 Transaction 2 bob is returned
- 42. Understand commits bob.age == 18 Transaction 1 bob.age += 1 select ... where age = 18 Transaction 2 bob is returned bob.age == 19
- 43. The low level API JDBC like API Work directly with untyped entities and properties Query using GQL
- 45. Queries
- 46. GQL SELECT [* | __key__] FROM <kind> [WHERE <condition> [AND <condition> ...]] [ORDER BY <property> [ASC | DESC] [, <property> [ASC | DESC] ...]] [LIMIT [<offset>,]<count>] [OFFSET <offset>] <condition> := <property> {< | <= | > | >= | = | != } <value> <condition> := <property> IN <list> <condition> := ANCESTOR IS <entity or key>
- 47. GQL
- 48. Setting up JPA Add JPA and DataNucleus jars Create persistence.xml Configure post-compilation class enhancement
- 49. Persistence Unit
- 52. JPA limitations No “Joined” inheritance No “Single Table” inheritance would be technically possible No many-to-many relationships No join-queries No aggregation queries No polymorphic queries
- 53. Owned relationships The “owned” entity only has meaning when it’s parent exists Key includes parent key /Department(24)/Employee(2)
- 54. Owned relations
- 55. Owned relations
- 57. Using JPA
- 58. Unowned relations No referential checks!
- 59. Unowned relations Both entities can exist without the other an employee and it’s colleagues Cannot be used within the same transaction
- 61. Many-to-many GAE doesn’t support JPA many-to-many Work around by mapping key collections
- 63. Constraining pages Uses Google Accounts Require users to log-in Require the admin role admin == developer on GAE
- 64. Require to login Require admin role
- 67. Services Mail Users Queus MemCache Blob Store Cron Jobs
- 68. Mail service
- 69. Receiving mail ! Mail can be send to somename@appid.appspotmail.com! POST! AppEngine! MyServlet! /_ah/mail/address!
- 70. Cron Jobs Tasks that run automatically on specific times or intervals sending a week report nightly cleanup Executing a job is invoking a URL
- 71. Configuring jobs Configure job in WEB-INF/cron.xml
- 72. Cron syntax every N (hours|mins|minutes) ("every"|ordinal) (days) ["of" (monthspec)] (time) Examples every 5 minutes every 12 hours 2nd,third mon,wed,thu of march 17:00 every monday 09:00 1st monday of sep,oct,nov 17:00 every day 00:00
- 73. Cron jobs
- 74. Task Queues Process asynchronous, parallel background tasks Modeled as web hooks a request to a web hook is scheduled the request handler is just like any other user request a web hook has data and code
- 75. Task queue use cases Send multiple confirmation emails each email is sent by a request to the same task with different data Place order send confirmation email (task 1) send notification to admin (task 2)
- 77. Configuring queues WEB-INF/queue.xml rate: throttling task execution bucket-size: “token-bucket” algorithm
- 78. Task Queues
- 79. Saving files Store files up to 50 mb in the BlobStore Upload by form POST file is uploaded to the BlogStore get a blob key in code Serve file using blob key
- 80. Upload file
- 81. Serving files
- 82. Listing blobs
- 83. BlobStore
- 84. MemCache Distributed in-memory cache e.g. cache frequent queries JCache API (JSR 107) Low level API
- 85. Using a cache Cache expires after 3600 miliseconds
- 86. Memcache
- 88. Frameworks A lot of frameworks work “mostly” but you never know if/when it breaks... JSF 1.2 e.g. RichFaces is not! JSF 2 disable threads Grails using a plugin Weld multiple issues JAX-WS EJB Spring some modules are not JMS
- 89. Testing
- 90. Unit Testing Easy out of container unit testing In-memory DataService, MailService, MemcacheService, TaskQueue, AuthenticationService etc.
- 94. Use datastore API directly
- 95. Using JPA
- 97. TaskQueue testing (setup)
- 98. TaskQueue testing (test)
- 99. Unit Testing
- 100. Costs
- 101. Quotas Free Default Quota Billing Enabled Default Quota Resource Daily Limit Maximum Rate Daily Limit Maximum Rate 7,400 requests/ 43,000,000 30,000 requests/ Requests 1,300,000 requests minute requests minute Outgoing 56 megabytes/ 1 gigabyte free; 10 gigabytes/ Bandwidth (billable, 1 gigabyte 1,046 gigabytes minute minute includes HTTPS) maximum Incoming 56 megabytes/ 1 gigabyte free; 10 gigabytes/ Bandwidth (billable, 1 gigabyte 1,046 gigabytes minute minute includes HTTPS) maximum 15 CPU-minutes/ 6.5 CPU-hours free; 72 CPU-minutes/ CPU Time (billable) 6.5 CPU-hours 1,729 CPU-hours minute minute maximum
- 102. Pricing Resource Unit Unit cost Outgoing gigabytes $0.12 Bandwidth Incoming gigabytes $0.10 Bandwidth CPU Time CPU hours $0.10 gigabytes per Stored Data $0.15 month Recipients recipients $0.0001 Emailed
- 103. Setting a budget
- 104. The verdict Deployment can’t get any easier Sandbox can be a show stopper Apps should be developed specifically for AppEngine
- 105. Google AppEngine Paul Bakker
Editor's Notes
- #22: -Maak een nieuwe appengine applicatie -Run de applicatie lokaal -Pas het application id aan in de settings -Upload de applicatie -Bekijk in de browser -Doe een aanpassing -Bekijk opnieuw in de browser
- #46: Demo 1: DataStoreServlet /datastoredemo Een speaker heeft talks /Speaker(1)/Talk(1) Een speaker en talk kan in dezelfde transactie worden opgeslagen Twee verschillende speakers kunnen niet in dezelfde transactie worden opgeslagen.
- #56: Demo 1: DataStoreServlet /datastoredemo Een speaker heeft talks /Speaker(1)/Talk(1) Een speaker en talk kan in dezelfde transactie worden opgeslagen Twee verschillende speakers kunnen niet in dezelfde transactie worden opgeslagen.
- #61: Demo 1: DataStoreServlet /datastoredemo Een speaker heeft talks /Speaker(1)/Talk(1) Een speaker en talk kan in dezelfde transactie worden opgeslagen Twee verschillende speakers kunnen niet in dezelfde transactie worden opgeslagen. Een speaker heeft ook collega&#x2019;s. Collega&#x2019;s zijn niet &#x201C;owned&#x201D; en daarom kan alleen de key worden opgeslagen ipv de entity zelf. Kijk naar speaker.addColleague en speaker.getCollegues
- #65: web.xml /secure
- #72: cron.xml demo.cron.ReportServlet
- #87: http://groups.google.com/group/google-appengine-java/web/will-it-play-in-app-engine
- #108: Creating and uploading an application