1. Deepak Shenoy Agni Software http://www.agnisoft.com
Advanced Web Services
Deepak Shenoy
Agni Software

2. Contents Binary data transfer Attachments Compression Encryption
Interoperability with web services written in other languages
Headers
2/23/2019
Agni Software

3. A brief introduction SOAP – Simple Object Access Protocol
WSDL – Web Service Description Language
“Remote method invocation” using XML datapackets
Industry standard
platform independent
language independent
Object oriented structure
2/23/2019
Agni Software

4. Binary Transfer Transfer of binary data over SOAP What we will see:
A binary array of bytes (TByteDynArray) sent over the wire
Files sent to the server from a client, and downloaded back again.
Delphi code for the webservice and the client
2/23/2019
Agni Software

5. DEMO Binary Transfer demo Server Client
Simple server interface passing TByteDynArrays
Reason for GetSOAPWebModule
Critical section required for global array access
Client
Convert from file to TByteDynArray and back
2/23/2019
Agni Software

6. Real world enhancements
Files as TByteDynArray: store in database or as server files instead
Convert Web App Debugger to ISAPI DLL
Synchronize access to the Global FileList
Compression: save data transfer time by compression of datapackets
2/23/2019
Agni Software

7. Compression SOAP Data is sent in XML (character format)
Binary data is encoded into text to be sent
Size can be reduced by compressing the binary document
Simple compression:
Compress before send
Decompress on receive
2/23/2019
Agni Software

8. DEMO: Simple Compression
Generic functions using ZLib in Delphi
Individual parameters are compressed/decompressed
2/23/2019
Agni Software

9. Datapacket compression
HTTP/ OK Content-Type: text/xml Content-Length: 594 Content:
<?xml version="1.0"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV=" xmlns:xsd=" xmlns:xsi=" xmlns:SOAP-ENC=" <SOAP-ENV:Body SOAP-ENC:encodingStyle=" <NS1:GetFileListResponse xmlns:NS1="urn:BinIntf-ISoapBinary"> <return xsi:type="SOAP-ENC:Array" SOAP-ENC:arrayType="xsd:string[2]"> <item>file.doc.rtf</item> <item>file.rtf</item> </return> </NS1:GetFileListResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
Datapacket compression
You may not want to compress every single parameter (int, string, etc.)
The datapacket itself is large:
2/23/2019
Agni Software

10. DEMO: Datapacket compression
Server
Use SoapPascalInvoker.AfterDispatchEvent
Client
Change HTTPRio.AfterExecute
Savings are in datapacket size
2/23/2019
Agni Software

11. Datapacket compression gotchas
Server to client communication is fine – but extra processing is required for each call
Client to server communication
Use “Before” events – HTTPRio.BeforeExecute on the client, SoapPascalInvoker.BeforeDispatchEvent on the server
Compress on the client
Decompress on the server
2/23/2019
Agni Software

12. Using HTTP Headers
Handle both compressed and uncompressed requests on the server (or responses on the client)
Add an HTTP Header indicating that a datapacket is compressed
Server: Use “Response.AddCustomHeaders” to add your own headers.
Client: Use HTTPAddRequestHeaders.
HTTP Handle is not exposed in code
Change the Delphi Source Code to expose it
2/23/2019
Agni Software

13. Attachments
Binary data may not need to be part of the SOAP packet itself
SOAP Attachments: Standard available in SOAP 1.1
Attachment data arrives in a separate part of the transport packet
In HTTP: “Multipart” messages are used
Delphi uses MIME encoding in attachments
2/23/2019
Agni Software

14. DEMO: Attachments Only need to use the TSOAPAttachment class
Persist the attachment file after retrieval using the CacheFilePersist property
Attachments are saved to Windows Temp folder by default
Change THTTPSoapDispatcher.Dispatcher.Converter.TempDir to override
2/23/2019
Agni Software

15. Attachments: Advantages
SOAP Standard, so most SDKs will support it
Separate DATA from SOAP payload
Web server level control for saving/encrypting/compressing attachments
2/23/2019
Agni Software

16. SOAP Encryption
Encrypt data to avoid parameter exposure through wire taps
You can use HTTPS (Secure) to encrypt data
No code changes required
Encrypt SOAP payloads using code
Parameter level
Datapacket level
(Code similar to compression code)
2/23/2019
Agni Software

17. SOAP Encryption standards
W3C is working on a standard for encryption
Recommendation available at:
2/23/2019
Agni Software

18. SOAP Headers
SOAP data goes under the <SOAP:Body> tag in the datapacket
<SOAP:Header> is now available for you to add custom headers
Better than HTTP Headers
Usable on any transport
Standardized: part of SOAP 1.1
Delphi 7 supports SOAP Headers
2/23/2019
Agni Software

19. DEMO: SOAP Headers
ISOAPHeaders interface supports adding and retrieving of headers
Server: Create classes inherited from TSOAPHeader for custom headers
Client: Cast HTTPRio to ISOAPHeaders to access header information
2/23/2019
Agni Software

20. Interoperability Many toolkits support SOAP
Microsoft .NET
Borland Delphi
Apache SOAP
Interop problems are common
Parameters formatted incorrectly
Data type differences
Keywords
2/23/2019
Agni Software

21. Interoperability
Interop Lab: catalog of problems between SOAP implementations
Delphi SOAP has entries there
Big issues with Interop
Namespaces, Complex types
Headers, Attachments
RPC|Encoded vs. Document|Literal
2/23/2019
Agni Software

22. RPC|Encoded vs. Document|Literal
Delphi servers only understand RPC|Encoded requests
Delphi Clients can access both types of servers
Literal parameters: soLiteralParams in Converter options
Invoke options:
ioDocument: Document rules apply
ioLiteral: no “unwinding”
WSDL Importer works well by default
2/23/2019
Agni Software

23. New and upcoming areas
UDDI : Universal Description, Discovery and Integration (Webservice “directory”)
WSIL: Web Service Inspection Language
Other transports: SMTP, FTP etc.
SOAP 1.2 will soon be up
2/23/2019
Agni Software

24. Contact me at shenoy@agnisoft.com
Thank you
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