sustainable service design using xtext -...

1 | commerce (NMA) | arvato Systems GmbH | May 19th, 2015

Sustainable Service Design using Xtext

Michael Bischoff – arvato Systems GmbH


Use case: Cross Channel Commerce

?


aroma® - the arvato Order Management System



Databases: Postgres, Oracle, HANA, SQL Server




Application Server: Wildfly, WebLogic

(CDI, JPA, JTA, JMS, JCA)




Application framework: fortytwo









Product core: aroma®







Product core: aroma®

Customizations (project specific)


What‘s my API?


What‘s my API?

KEY QUESTION:

WHAT‘S A VALID REQUEST?


I want a currency code!

It‘s a String! "Euro" ?

"€" ?

" EUR " ?

"EUR" !

Solution: Validate against Java or ICU „Currency“ class. This is an easy example, sometimes validation requires database lookups. What can we do in the outer API layers (before the request hits the datase...)? ISO 4217 (A3): A currency code is exactly 3 characters long, each of which is an upper case ASCII letter.



Java: not nullable string of length 3 (JSR 303 annotations)

XSD definition:



Java: not nullable string of length 3 (JSR 303 annotations)

XSD definition:

DIFFERENT DESCRIPTIONS PER API

(AND NOT REALLY CONCISE)


The Bonaparte DSL

Xtext based description language for Java data transfer objects Data type support:

all Java primitives all wrapped types objects, enums, immutable binary UUID, BigInteger, BigDecimal, some Joda time types (Java 8 date/time WIP) arrays, Lists, Sets, Maps (map keys limited to Integer, Long, String) enum sets (similar to C bitfields): great for the IoT!

Typedefs Type adapters (similar to XmlAdapter) for types which are not supported natively


The Bonaparte DSL – Example



Generate JAXB annotations for all classes in this package




Generate JSR303 annotations





enum type with possible single character serialized form („C“, „D“)





Specification of response object







Parser directives







Parser directives


This is an XML root element


Generated Output

POJOs (Java 6 compliant) Metadata (enhanced java.lang.Class) fields, getters, setters validation code code to freeze an instance (turn immutable) serialization / deserialization methods (reflection free)

invoke methods of MessageParser and MessageComposer different serializers / deserializers implement these interfaces

equals, hashCode defensive cloning methods

optional: XSDs


Example: Writing some nonstandard CSV



Create the configuration




Create the serializer




Create the serializer

Serialize and write the data


Example: Defining a type adapter



target Java type



Converter class specification target Java type




desired external representation in serialized form


Android does not like XML a lot Generated JAXB annotations already cause issues

Delete with JARJAR or ProGuard? Compile run with suppressed JAXB annotations possible in Bonaparte

Bonaparte provides a resource friendly serialization format Generalization of CSV Immune to encoding conversions (ISO 8859 / UTF-8) or Win/UN*X end of line Upwards compatible changes: integral => fractional, enum token to string, added optional fields (also in superclasses) etc. Support for cyclic object nesting! Preserves identity of component objects

The Android Bridge


The Bonaparte DSL – Extension Mechanisms



Directives for add on DSL – only stored in meta data



Directives generating Java annotations – with or without parameter. Used by Xtend Active Annotations (DSL generates Java annotation for class or field)




Directives generating Java annotations – with or without parameter. Used by Xtend Active Annotations (DSL generates Java annotation for class or field)


NO MONOLITHIC DSL!

- SEPARATION OF CONCERNS - PROJECT MODULE REQUIREMENTS


Xtext DSLs + Free syntax definition + IDE integration + Solid basis for grammar and validations - Somewhat longer iteration cycle (build / install cycles) One DSL across multiple projects, keep stable

Xtend Active Annotations + Fast turnaround times + Ideal for straightforward code generation + Java / Xtend crossreferences in a single project (maven module) Active Annotations developed as part of the application Examples: Creation of data access objects (DAOs), mappers between DTO and generated JPA entity classes

Xtext and Xtend Active Annotations – A Dream Team!


Principles of Sustainable Service Design according to Pleus, 2015: Technology-agnostic service definition Unified request/response Consequent contract first Technology bindings

Sustainable Service Design


Use DSL to define logical data structure / syntactic validation While the DSL is closely Java related, code generation for other languages would be possible (a proprietary mapper to COBOL has been implemented for a subset of data types)

End points centrally implemented / created by Active Annotation all request objects are of type ServiceRequest, parameters inherited from RequestParameters all response objects inherit from ServiceResponse project specific additional fields via further inheritance

Implement specific formats / protocols via library xls(x), CSV, JSON, http parameters, Bonaparte formats, fixed field width formats, ... Integrate with vert.x 2 / vertx.3 event bus, Apache Camel, netty 4 In some cases, small enhancements of the DSL were required (Java Externalizable,

Hazelcast‘s Portable and Identified Data Serializable formats)

Sustainable Service Design as in Bonaparte / aroma


Part II: Persisting your Data


DSL to generate JPA 2.x entity classes / DDL statements from DTOs DSL based on Bonaparte DSL Databases currently supported: Postgres 9.x ff, Oracle 11 ff, MS SQL Server 2012 ff, SAP HANA Included definition for tablespaces, synonyms, grants Surrogate keys as well as natural / composite primary keys Definition of unique and non unique indexes Support for @{One,Many}To{One,Many}, @Embeddable and @ElementCollection JPA 2.1 @AttributeConverters Serialized object storage (noSQL within SQL) User types for Joda time & serialized objects supported for Hibernate as well as EclipseLink List unrolling into enumerated fields Creation of multitenancy discriminators Timestamp / user ID tracking fields defined per category of entities Additional history tables (and corresponding triggers in Oracle PL/SQL) Mapping of enums to tokens

Addon DSL: JPA Persistence


JPA Persistence DSL Example



Properties shared by multiple entities



Inheritance type (joined or separate tables)






multitenancy discriminator (homegrown, since not yet standardized in JPA 2.1)






Shared columns (timestamp / user IDs) for auditing purposes







JPA entity listener







JPA entity listener

Generated Java class has more than 700 lines of code


Extension concept Use Eclipse‘s extension points to add more plausi checks & code generators as indepent plugin

Be Polyglot! C#, C++ output

Message Version & Migration Support Support for incompatible message changes

(for example deletion of fields)

Swagger 2.0 Addon DSL IDE support for service description

Binaries on Maven Central

Future Plans


Bonaparte DSLs and support Libraries https://github.com/jpaw (Apache 2 licensed)

aroma Order Management system http://aroma.arvato-systems.de/ (commercial)

Resources

https://github.com/jpaw

https://github.com/jpaw

http://aroma.arvato-systems.de/





Questions


Contact

arvato Systems GmbH

Dr. Michael Bischoff

An der Autobahn 200

33333 Gütersloh

Germany

[email protected]

Phone: + 49 52 41/ 80-74413

Mobile: + 49 160 880 6 880

www.arvato-systems.com

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