SOA Patterns

Example SOA Patterns

•          Basic principle:

–        n separate processes better than one

•          Communication:

–        asynchronous query

–        command facade

•          Data integration:

–        VETO: Validation, Enrich, Transform, Operate

–        2 step XRef

–        Forward Cache

–        Federated query

1. Asynchronous Query Pattern

•          Problem: long execution times for queries

–        due to Internet

–        due to distributed systems

•          Solution:

–        de-couple request/response

–        use caching of results

2. The VETO Pattern

•          Problem: invoking a service usually involves:

–        Extract data, modify, convert format, validate

•          Solution:  Separate actions into a 4-action pipeline

•          Actions

–        Validate (the XML document)

•          Simplifies data validation for subsequent steps

–        Enrich

•          Adding value to the data

–        Transform

•          To a target format

–        Operate

•          Interacts with the target service

•          Variation:

–        VET(R)O, where R = Route 

3. The 2 Step XRef Pattern

•          Problem: Integration may involve

–        Content transformation

–        Structure transformation

•          Content-level transformation between source and target can be achieved:

–        By single, complex process

–        By two separate processes

•          One to transform to an abstracted form of target

•          Second to transform to the specific target

4.  Federated Query Patterns

•          Federated query

–        Multiple queries on different data sources

•          Cache pushing may not be appropriate:

–        If data changes regularly

–        If out-of-date data is acceptable

•          E.g., newsfeeds cached once an hour

•          Queries may take variable amounts of time

•          Example patterns:

–        Cache pull (federated query) pattern

–        Long duration request (federated query) pattern