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

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

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

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

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

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

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

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

Datapacket compression HTTP/1.1 200 OK Content-Type: text/xml Content-Length: 594 Content: <?xml version="1.0"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body SOAP-ENC:encodingStyle="http://schemas.xmlsoap.org/soap/envelope/"> <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

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

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

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

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

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

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

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

SOAP Encryption standards W3C is working on a standard for encryption Recommendation available at: http://www.w3.org/TR/xmlenc-core/ 2/23/2019 Agni Software

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

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

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

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

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

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

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