Architecture Concept for

1 HANA Integration

HANA (High Performance Analytical Appliance) is a product based on New DB that allows the implementation of analytical application that processes a huge amount of data in real time.

The Gateway HANA integration exposes HANA content as OData services. For this a generic Minimal Gateway application has been developed on the Gateway Hub, i.e. a local MGW application. The application is a prototype only.Additionally references between other Gateway content and HANA content are possible. Therefore the prototype allows federation between HANA content and Minimal Gateway Content. Gateway retrieves the data from HANA via ABAP Database Connectivity (ADBC). ADBC is an object-based ABAP API for programming relational database accesses, which in its class and model structure follows the JDBC (Java Database Connectivity) diction.

For some of the following discussion the different table types in HANA should be known Replicated tables like for example the MM material table MARA Analytic Views are like cube model where Transaction Data is connected to attribute view

They can have multiple dimensions

Data can be sliced and diced (e.g. Grouped by attributes)

Calculation View are based on analytic views enriched with custom functions and calculations

They can be used to define a two dimensional list from a Analytic View1.1 PrototypeA prototype has been developed in system U3F.

1.1.1 Overview

Figure 1 - Gateway HANA Integration

The HANA integration is based on the SAP Data Channel (Minimal Gateway) for local applications. It is developed on the Gateway hub against interfaces not exposed to stakeholders. The main building blocks are "HANA Model Provider" (Class ZHANA_CL_HANA_MODEL_ADP)

"HANA Business Data Provider" (Class ZHANA_CL_HANA_MGW_RUNTIME)

HANA Database Connector (Class ZHANA_CL_HANA_DATABASE_READER)

1.1.2 HANA Model ProviderThe HANA Model Provider extracts metadata out the HANA repository via the HANA Database Connector and adapts it to the SAP Data Channel representation. It implements BADI /IWFND/BD_MED_MDL_MODEL_LOAD and is triggered via the BADI filter EXTERNAL_MODEL_TYPE.

1.1.3 HANA Business Data ProviderThe HANA Business Data Provider delegates requests to HANA via the HANA Database Connector. Only read scenarios are supported. The Business Data Provider supports the common set of SAP Data query functionality (e.g. filter, sorting).It implements BADI /IWFND/BD_MGW_RUNTIME and is triggered via the BADI filter

SERVICE_DOCUMENT_NAME.

1.1.4 HANA Database Connector

The HANA Database Connector executes queries against the HANA database and provides the corresponding metadata.

1.1.4.1 Connection to HANA

To execute queries against HANA class CL_SQL_STATEMENT of package SDB_ADBC (part of BASIS) is used. The corresponding connection has been defined in table DBCON.

HANA supports user based authority checks. These authority checks are filters that are merged to an executed query. However this requires user based connectivity between Gateway and HANA. This is currently not available.1.1.4.2 Additional query information

To execute the queries additional information is needed during runtime. This is stored in table ZHANA_DBTAB_NAME. This table has the following fields

MODEL_IDENTIFIERMGW Model Identifier (key)

SCHEMA_NAMEHANA Database Schema

TABLE_NAME

HANA Database (View) name

CON_NAME

Logical name for a database connection

IS_ACTIVE

Indicates that the GSDO Group is Active

COLUMNS_USEDNames of the columns used from the HANA database

KEY_FIELDS

Names of the columns that are key fields1.1.4.3 MetadataThe metadata (entity description) is derived from the corresponding HANA metadata.

More precisely it is read from a query result. A query requesting only one entry from the database is executed and the metadata of the result set is read. This information is merged with the data stored in table ZHANA_DBTAB_NAME and then adapted to the corresponding MGW format.

1.1.4.4 FeedsTo retrieve a feed an ADBC query statement matching the OData request is composed and executed.1.1.4.5 Entities

To retrieve an entity an ADBC query statement is composed and executed requesting only one entry.

1.1.5 Gateway ObjectsSeveral Gateway objects need to be created during design time: One Service Group

One Object Model per HANA database table. The following tables need to be maintained /IWFND/I_MED_OHD

Defines the model identifier and set active

/IWFND/I_MED_EMM

Specifies the external model identifier (used at metadata document)

/IWFND/I_MED_INH

Object inheritance information All models are assigned to the same Service Group. This is done via table

/IWFND/I_MED_SRG Maps models to service groups

While the routing is not done via System Aliases still a GSDO Group is needed to which the Service Group is assigned. 1.1.6 HANA specific meta-data on the Gateway

No additional content specific metadata shall be maintained at Gateway to avoid Lifecycle dependencies between HANA content and Gateway content. As the HANA metadata does currently not support semantic groups of entities that could be translated to SAP Data Service Groups, additions to the current HANA repository are required: SAP Data Service Groups Language Dependent Column Labels 1.2 Conclusions1.2.1 Limitations / Requirements The following limitations and requirements have been identified.

1.2.1.1 ADCB

ADCB is the one big question mark for this integration approach. 1.2.1.1.1 Authorization

HANA supports user based authority checks. These authority checks are filters that are merged to an executed query. However this requires user based connectivity between Gateway and HANA. This is currently not available.1.2.1.1.2 Tools

Connections are created by creating an entry in table DBCON via SE16.

1.2.1.1.3 Scalability

Only a limited fixed numbers (20?) of ADBC connections can be open in parallel from a SAP system. Currently no connection pooling is available.

1.2.1.1.4 SAP Server Operation System

The Gateway retrieves the data from HANA via ADBC. HANA currently only supports Linux (and Windows?), but not for example Solaris for ADBC. Hence the Gateway ABAP server needs to be running on Linux (or Windows?).

1.2.1.1.5 Future

(To the author of this document) The future support and development of ADBC is not clear.1.2.1.1.6 Features needed from BASIS The limitations listed above need to be overcome User based authorization

Tool for connection setup

ADBC scalability Supported operation systems (This is rather a limitation of the new DB database driver than ADBC)1.2.1.2 Renaming of fieldsThe MGW metadata is created generically from HANA metadata. Hence MGW properties are called as the HANA database table columns. But as there are limitations on the MGW property naming (e.g. no / is allowed) certain columns cannot be used.

1.2.1.2.1 Features needed on Gateway

A method to calculate a MGW (OData) compatible name from a String

A possibility for an admin to enhance the generically created transient model1.2.1.3 Hiding (showing) of fieldsThe MGW metadata is created generically from HANA metadata. Hence all HANA database table columns are exposed as Gateway properties.

1.2.1.3.1 Features needed on Gateway

A possibility for an admin to enhance the generically created transient model

Hide certain fields

Define a white-list of fields to be exposed. All other fields are not exposed1.2.1.4 LabelsThe metadata retrieved from HANA does not contain label information.

It might be possible to read a descriptive XML from a HANA database table which contains label information. But even if that is possible no translation would be available. 1.2.1.4.1 Features needed on Gateway

A possibility for an admin to enhance the generically created transient model

1.2.1.5 Key Fields

HANA database tables do not support key fields.

1.2.1.5.1 Workaround

Two workarounds seem reasonable:

The prototype uses database table ZHANA_DBTAB_NAME on the Gateway to store for each model (i.e. each HANA database tables) the fields which shall be exposed as key fields

Flag all characteristics as key.

Attributes (Characteristics) are descriptions of key figures, such as Customer ID, Material Number, Sales Representative ID, Unit of Measure, and Transaction Date.

Measures (Key figures) are numeric values or quantities, such as Per Unit Sales Price, Quantity Sold, and Sales Revenue.

1.2.1.6 READ EntityHANA database tables do not support key fields. Hence it is not possible to uniquely identify a table entry for a select single.

1.2.1.6.1 Workaround

To retrieve an entity an ADBC query statement is composed and executed requesting only one entry. If the correct characteristics are supplied this is sufficient. 1.2.1.7 HANA MetadataThere are currently 3 options how to retrieve metadata for a HANA database table

There is one specific table which contains column information for tables.

This is only filled for replicated tables. No information can be read for analytic and calculation views.

No field labels are available

There is one specific table which contains a metadata XML tables and views.

No library is available retrieve this metadata. A Gateway application would have to parse this XML itself.

It needs to be checked if field labels are available

The ADBC libraries return for every Query result also the corresponding metadata. No field labels are available

It needs to be checked if this returns metadata if the query did not find any record

This can be fairly slow way when only the metadata is needed

1.2.1.8 Field length in ADBC libraries

The ADBC libraries can only handle field (column) names with a length up to 30 characters. HANA allows longer field names. Corresponding problems are very likely. 1.2.1.9 Dynamic Object Model assignment It is not possible on the Gateway to assign Object Models to Service Groups during runtime. Models are assigned to Service Groups during design time via SE80 (or SE16 as in the prototype).

1.2.1.9.1 Features needed on Gateway

It should be possible to assign Object Models to Service Groups during runtime via APIs.

A related requirement for many generic Integration scenarios would be some kind of White-List. HANA as well as Enterprise Search or Analytics (BW) will most likely host hundreds of potential data sources. Once these can be loaded into Gateway dynamically some selection / registration mechanism is needed allowing an administrator to expose any of these data sources individually.

1.2.1.10 CompositionThe following iPhone application has been built for a Sapphire demo based on the prototype Search for customers (Entity Customer) Based on a specific customer MGW application

Display for a selected customer a list of the 5 products with the highest revenue (Entity Revenue) Based on a model of the generic HANA application

Display some detail information for a selected product (Entity Product) Based on a specific product MGW application

To link the HANA model to the Product Details the generically generated Object Model description needs to be enriched with the association information (define the link). To achieve this a new Model Provider class was needed. This class inherits from the original HANA Model Provider class to access the coding describing the Revenue Entity. Specific coding describes the two other entities.

A similar concept was needed for the Business Data Provider. 1.2.1.10.1 Features needed on Gateway

It should be possible to assign different models from different sources to one Service Group.

It should be possible to define associations (links) between models on a Service Group level, i.e. within one Service Group (and for that Service Group only).

It should be checked, if it is needed to allow the definition of associations (links) between models on a model level.1.2.1.11 External Model TypeNot surprisingly the Gateway has no External Model Type for HANA. For the prototype the value B was used as it was available. For a productive coding a specific model type is needed. 1.2.1.11.1 Features needed on Gateway

External Model Type should not be based on a domain but rather be customizing with a customer namespace. 1.2.1.12 Analytic Views

An analytic view describes data in multiple dimensions. An OData response and realistically also a mobile device can only handle 2 dimensional lists. To retrieve such a list from an analytic view grouping information needs to be added to the SQL (ADBC) statement. This could be provided from the client.

It needs to be checked if this is supported by OData or can be added

This could be added by the Gateway.

This would need some additional configuration on the Gateway

This can be overcome by defining corresponding simplified Calculation Views on HANA.

This has been done for the prototype. 1.2.2 Other ideas

Following is a list of some ideas collected before the prototype was designed

Use HANA as accelerator for QUERY operation on GW objects (for that matter the HANA object would need to have similar or identical structure compared to the GW object)

This could be done in case the models are identical.

In case models are not identical this needs a rather extensive application logic or a even more complex mapping

The HANA Business Data Provider would be made available for specific MGW applications. The idea of the prototype is to only provide a generic framework allowing a customer to easily expose HANA database tables which have

Been shipped with a different life cycle

Have been created by the customer

But this merging of HANA and none HANA data is not trivial and hence rather a task for SAP development. It would need to be checked if and how this could be developed and shipped

Use HANA as provider to particular GW object's properties (HANA can deliver KPI information based on analytical information to a Gateway object)

The idea of the prototype is to only provide a generic framework allowing a customer to easily expose HANA database tables which have

Been shipped with a different life cycle

Have been created by the customer

But this merging of HANA and none HANA data is not trivial and hence rather a task for SAP development. It would need to be checked if and how this could be developed and shipped

Use HANA (or more precisely the underlying newDB) may serve as offlining capability for GW caching

Simple two dimensional data (which is all what is needed for any reasonable Gateway caching) can be read from normal SAP database tables with at least similar speed as from a HANA database. HANA has been designed for multi dimensional mass data analysis, which of course is not needed for Gateway caching.

Use HANA ideally also exposes itself via SAPDATA to allow homogenous access to all data sources of SAP and allow a consistent way for GW to access the information accordingly were needed/reasonable

The Prototype and this document are about the question how to expose HANA data via the Gateway. The question what could be done on HANA has not been addressed.

1.2.3 Design aspects One service group for all exposed HANA database tables has been created on the Gateway. This is needed for example for the authority check.

For every exposed HANA database table one model has been defined. An alternative would be to have one model containing all exposed tables as entities. 1.2.3.1 Gateway Software Component Layer Assignment

The current analytics functionality is a part of IW_CBS. Consequently the integration of High Performance Analytical Appliance should be assigned to the same layer. This allows us to deliver the integration with a later Gateway content pack as well. (Decision pending)1.3 Summary

From a design perspective the generic integration of HANA as described in the document is a very good fit for the MGW (OData Channel).

The current questions around ADBC are the one major obstacles to develop a Gateway quality product based on the ideas of the prototype Developing a generic tool to retrieve a SQL statement for an OData request would be a major part but can be accomplished fairly easy.

The major lesson learned from the prototype for the Gateway is that following aspects should become more flexible or should be double checked:

The use of Service Groups (e.g. should this be a repository object?)

The definition of Object Models (E.g. it should be possible to create and assign them to Service Groups during runtime)

Composition and configuration

1.4 Alternative

There is at least one reasonable alternative architectural approach to integrate HANA.

Instead of accessing HANA directly via ADBC rather integrate the Gateway with HANA implicitly by integrating with Analytics. HANA 1.5 will support Analytics.

Advantages ADBC will not be used Tool support like for example the Query Designer Analytics shall be integrated into Gateway anyway. So with this one stone 2 birds would be killed.1.5 Appendix

1.5.1 Links

Hana Input

1.5.1.1 Links to Prototype1.5.1.1.1 Metadata

http://ldai1u3f.wdf.sap.corp:50050/sap/opu/sdata/sap/ZHANA/$metadata?sap-client=100&$format=xml

1.5.1.1.2 MARA

Feed http://ldai1u3f.wdf.sap.corp:50050/sap/opu/sdata/sap/ZHANA/MARACollection?sap-client=100&$format=xml&$filter=substringof(matnr,'AND') Entry http://ldai1u3f.wdf.sap.corp:50050/sap/opu/sdata/sap/ZHANA/MARACollection(mandt='800',matnr='APO-FG')?sap-client=100&$format=xml1.5.1.1.3 Products per customer Feedhttp://ldai1u3f.wdf.sap.corp:50050/sap/opu/sdata/sap/ZHANA/COPA__ACT_PLCollection?sap-client=100&$format=xml&$filter=gjahr%20eq%202010%20and%20kunnr%20eq%20'0000002140'%20&%20&$orderby=revenue%20desc Costing Sheet http://ldai1u3f.wdf.sap.corp:50050/sap/opu/sdata/sap/ZHANAEXT/COPA__ACT_PLCollection(gjahr='1996',kunnr='0000001360',matnr='M-08',matkl='002',werks='1000')/CopaCostingSheet?sap-client=100&$format=xml1.5.1.2 Classes in U3F(100)

ZHANA_CL_HANA_MODEL_ADP

Class for BAdI Impl.: ZHANA_BI_HANA_MODEL_ADP

MWG Adapter providing the metadata (Model descriptions)

ZHANA_CL_HANA_MGW_RUNTIME

Class for BAdI Impl.: ZHANA_BI_HANA_MGW_RUNTIME

MGW Adapter providing the runtime data(O-Data requests)

ZHANA_CL_HANA_DATABASE_READER

Retrieves data and meta-data from HANA database

1.5.2 Gateway Objects

Service Group ZHANA_SG_ALL_MODELS_0001

Generic HanaService Group -GW / Hana Integration Prototyping

Object Models

ZHANA_OM_MARA_0001_BE

Creation / Assigment for new models

/IWFND/I_MED_OHD

Define the model indentifier and set active

/IWFND/I_MED_EMM

Specify the external model identifier (used at metadata document)

/IWFND/I_MED_INH

Object inheritance table not require -> dummy record

BASE_MDL_IDENT = space

/IWFND/I_MED_SRG

Maps service to models

SRV_IDENTIFIER = ZHANA_SG_ALL_MODELS_0001

ZHANA_DBTAB_NAME

map model id to hana schema and table name

GSDO Group

ZHANA_ALL_OBJECT

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