.. _Using_WSDL: ********** Using WSDL ********** .. index:: WSDL .. index:: Web Service Definition Language `WSDL` (Web Service Definition Language) is an `XML` based document which described a set of Web Services either based on `SOAP` or `XML/RPC`. By using a `WSDL` document it is possible to describe, in a formal way, the interface to any Web Services. The `WSDL` document contains the end-point (URL to the server offering the service), the `SOAPAction` (needed to call the right routine), the procedure names and a description of the input and output parameters. `AWS` provides two tools to work with `WSDL` documents: *ada2wsdl* .. index:: ada2wsdl which creates a `WSDL` document from an Ada package spec. *wsdl2aws* .. index:: wsdl2aws which create the interfaces to use a Web Service or to implement Web Services. With this tool the `SOAP` interface is completely abstracted out, users will deal only with `Ada` API. All the `SOAP` marshaling will be created automatically. .. _Creating_WSDL_documents: Creating WSDL documents ======================= .. index:: ada2wsdl Note that this tool is based on `LibAdaLang`. .. _Using_ada2wsdl: Using ada2wsdl -------------- `ada2wsdl` can be used on any Ada spec file to generated a `WSDL` document. The Ada spec is parsed using `LibAdaLang`. .. highlight:: sh The simplest way to use it is:: $ ada2wsdl simple.ads .. highlight:: ada Given the following Ada spec file:: package Simple is function Plus (Value : in Natural) return Natural; end Simple; .. highlight:: xml It will generate the following `WSDL` document:: The value of the `name` attribute in the `description` node is the name of the `WSDL` document (the name of the Ada spec package). On the `portType` section we have the description of the Ada **Plus** function. Something important to note is that in Ada a function does not have a named return parameter, :file:`ada2wsdl` use **Result** for the response. Both the input and output parameter are mapped to `SOAP` `xsd:int` type. Note that the `SOAP` address generated by default (http://.../) must be edited manually or specified using :file:`ada2wsdl`'s -a option. This is of course a very simple example. `ada2wsdl` does support more complex specifications and will map Ada records, arrays, enumerations, derived types to a corresponding `XML` schema definition. See section below for a description of the mapping. .. _Ada_mapping_to_WSDL: Ada mapping to WSDL ------------------- `ada2wsdl` parses Ada records, arrays, derived types, enumerations, procedures and functions and generates the corresponding `WSDL` document. In this section we describe the mapping between Ada and `WSDL`. *Integer* Mapped to **xsd:int**. *Float* Mapped to **xsd:float**. *Long_Float* Mapped to **xsd:double** *Long_Long_Float* Mapped to **xsd:double**, not supported by SOAP, mapped for convenience but precision cannot be guaranteed. *Boolean* Mapped to **xsd:boolean** *String* Mapped to **xsd:string** *Unbounded_String* Mapped to **xsd:string**, note that Unbounded_String should be used only inside a record for full interoperability. This is a current limitation. .. highlight:: xml *Character* Mapped to a Character schema definition:: *Ada.Calendar.Time* Mapped to **xsd:dateTime** *Duration* Mapped to **xsd:duration** *SOAP.Utils.SOAP_Base64* Mapped to **xsd:base64Binary**. `SOAP.Utils.SOAP_Base64` is a subtype of string which is is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Byte* Mapped to **xsd:byte**. `SOAP.Types.Byte` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Short* Mapped to **xsd:short**. `SOAP.Types.Short` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Long* Mapped to **xsd:long**. `SOAP.Types.Long` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Unsigned_Byte* Mapped to **xsd:unsignedByte**. `SOAP.Types.Unsigned_Byte` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Unsigned_Short* Mapped to **xsd:unsignedShort**. `SOAP.Types.Unsigned_Short` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Unsigned_Int* Mapped to **xsd:unsignedInt**. `SOAP.Types.Unsigned_Int` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. *SOAP.Types.Unsigned_Long* Mapped to **xsd:unsignedLong**. `SOAP.Types.Unsigned_Long` is a type which is recognized by `ada2wsdl` to generate the proper SOAP type. .. highlight:: ada *Derived types* Mapped to a type schema definition:: type Number is new Integer; .. highlight:: xml is defined as:: .. highlight:: ada *Derived types with constraints* Mapped to a type schema definition with minInclusive and maxInclusive attributes:: type Number is new Integer range 1 .. 9345; .. highlight:: xml is defined as:: Or for a string:: .. highlight:: ada type Code is String (1 .. 10); .. highlight:: xml is defined as:: .. highlight:: ada *Ranges* Mapped to a type schema definition with minInclusive and maxInclusive attributes:: type Small is range 1 .. 10; .. highlight:: xml is defined as:: .. highlight:: ada *Modular types* Mapped to an unsigned type with an optional maxInclusive attribute:: type Count is mod 14; .. highlight:: xml is defined as:: .. highlight:: ada *Enumerations* Mapped to an enumeration schema definition. For example:: type Color is (Red, Green, Blue); .. highlight:: xml is defined as:: .. highlight:: ada *Records* Mapped to a struct schema definition. For example:: type Rec is record A : Integer; B : Float; C : Long_Float; D : Character; E : Unbounded_String; F : Boolean; end record; .. highlight:: xml is defined as:: .. highlight:: ada *Arrays* Mapped to an array schema definition. For example:: type Set_Of_Rec is array (Positive range <>) of Rec; .. highlight:: xml is defined as:: A SOAP encoded format can be generated with the -sea option: .. highlight:: ada *Array inside a record* This part is a bit delicate. A record field must be constrained but a `SOAP` arrays is most of the time not constrained at all. To support this `AWS` use an Ada.Containers.Vectors or a safe access array component (legacy mode). Both support are described below. *Array inside a record (Ada.Containers.Vectors)* Using an Ada.Containers.Vectors is the preferred way of supporting array inside records. For example, let's say that we have an array of integer that we want to put inside a record:: type Set_Of_Int is array (Positive range <>) of Integer; The first step is to create the corresponding Ada.Containers:: package Set_Of_Int_Type is new Ada.Containers.Vectors (Positive, Integer); And then the vectors can be added into the record:: type Complex_Rec is record SI : Set_Of_Int_Type.Vectors; end record; .. highlight:: xml These Ada definitions are fully recognized by :file:`ada2wsdl` and will generate standard array and record `WSDL` definitions as seen above:: .. highlight:: ada *Array inside a record (legacy)* Using a safe pointer array component to support array inside records. Such a type is built using a generic runtime support package named `SOAP.Utils.Safe_Pointers`. This package implements a reference counter for the array access and will automatically release the memory when no more reference exist to a given object. For example, let's say that we have an array of integer that we want to put inside a record:: type Set_Of_Int is array (Positive range <>) of Integer; The first step is to create the safe array access support:: type Set_Of_Int_Access is access Set_Of_Int; package Set_Of_Int_Safe_Pointer is new SOAP.Utils.Safe_Pointers (Set_Of_Int, Set_Of_Int_Access); Note that the name `Set_Of_Int_Safe_Pointer` (*_Safe_Pointer*) is mandatory (and checked by :file:`ada2wsdl`) to achieve interoperability with :file:`wsdl2aws`. :ref:`Working_with_WSDL_documents`. From there the safe array access can be placed into the record:: type Complex_Rec is record SI : Set_Of_Int_Safe_Pointer.Safe_Pointer; end record; To create a Safe_Pointer given a `Set_Of_Int` one must use `Set_Of_Int_Safe_Pointer.To_Safe_Pointer` routine. Accessing individual items is done with `SI.Item (K)`. .. highlight:: xml These Ada definitions are fully recognized by :file:`ada2wsdl` and will generate standard array and record `WSDL` definitions as seen above:: .. highlight:: ada *Array as routine parameter* When an array is passed as parameter to a `SOAP` routine it is also required to create a corresponding Ada.Containers.Vectors or a Safe_Pointer when using a `Document/Literal` binding and using a user's type package (see `-types` and '`-spec` `wsdl2aws` options). *Array as routine parameter (Ada.Containers.Vectors)* This is needed for the `AWS` generated code to handle this routine. Even if required in a very specific case it is never an error to declare such a Ada.Containers.Vectors for an array. For example:: type Set_Of_Int is array (Positive range <>) of Integer; procedure Call (Values : Set_Of_Int); Then the following declaration is required:: package Set_Of_Int_Type is new Ada.Containers.Vectors (Positive, Integer); *Array as routine parameter (legacy)* This is needed for the `AWS` generated code to handle this routine. Even if required in a very specific case it is never an error to declare such a Safe_Pointer for an array. For example:: type Set_Of_Int is array (Positive range <>) of Integer; procedure Call (Values : Set_Of_Int); Then the following declarations are required:: type Set_Of_Int_Access is access Set_Of_Int; package Set_Of_Int_Safe_Pointer is new SOAP.Utils.Safe_Pointers (Set_Of_Int, Set_Of_Int_Access); .. _ada2wsdl: .. highlight:: ada ada2wsdl -------- :: Usage: ada2wsdl [options] ada_spec `ada2wsdl` options are: *-a url* Specify the `URL` for the Web Server address. Web Services will be available at this address. A port can be specified on the `URL`, `http://server[:port]`. The default value is `http://.../`. *-f* Force creation of the `WSDL` file. Overwrite exiting file with the same name. *-doc* Generate document's style binding (default is RPC) *-lit* Generate literal's style binding (default is encoded) *-n name* Specify the schema name space root name. The default value is "soapaws". *-noenum* Do not generate `WSDL` representation for Ada enumerations, map them to standard string. :ref:`Ada_mapping_to_WSDL`. *-sea* Generate SOAP encoded format for array definitions. This option is kept for compatibility reason, but the schema based definition for arrays is recommended for better interoperability. *-o file* Generate the `WSDL` document into file. *-P proj* The project file to use for building the spec. *-q* Quiet mode (no output) *-s name* Specify the Web Service name for the `WSDL` document, by default the spec package's name is used. *-t path* Specify the path to the tree file directory to use. This is needed when using a project file the object directory is not the current directory. *-d* Do not generate date/time in WSDL. *-v* Verbose mode, display the parsed spec. .. _:file:`ada2wsdl`_limitations: ada2wsdl limitations --------------------- .. index:: ada2wsdl limitations * Constrained array field in records unsupported. * Unbounded_String are supported with full interoperability only inside a record. * Only unconstrained arrays are supported. * Arrays with multiple dimensions are not supported. .. _Working_with_WSDL_documents: Working with WSDL documents =========================== .. _Client_side_(stub): Client side (stub) ------------------ .. index:: WSDL, Client This section describe how to use a Web Service. Let's say that we want to use the Barnes & Noble Price Quote service. The WSDL document for this service can be found at `http://www.xmethods.net/sd/2001/BNQuoteService.wsdl `_. In summary this document says that there is a service named `getPrice` taking as input a string representing the ISBN number and returning the price as floating point. The first step is to generate the client interface (stub):: $ wsdl2aws -noskel http://www.xmethods.net/sd/2001/BNQuoteService.wsdl This will create many files, the interesting one at this point is :file:`bnquoteservice-client.ads`, inside we have:: function getPrice (isbn : in String) return Float; -- Raises SOAP.SOAP_Error if the procedure fails Let's call this service to find out the price for *The Sword of Shannara Trilogy* book:: with Ada.Text_IO; with BNQuoteService.Client; procedure Price is use Ada; ISBN : constant String := "0345453751"; -- The Sword of Shannara Trilogy ISBN package LFIO is new Text_IO.Float_IO (Float); begin Text_IO.Put_Line ("B&N Price for The Sword of Shannara Trilogy"); LFIO.Put (BNQuoteService.Client.getPrice (ISBN), Aft => 2, Exp => 0); end Price; That's all that is needed to use this Web Service. This program is fully functional: it is possible to build it and to run it to get the answer. .. _Server_side_(skeleton): Server side (skeleton) ---------------------- .. index:: WSDL, Server Building a Web Service can also be done from a `WSDL` document. Let's say that you are Barnes & Noble and that you want to build Web Service `getPrice` as described in the previous section. You have created the `WSDL` document to specify the service spec. From there you can create the skeleton:: $ wsdl2aws -nostub http://www.xmethods.net/sd/2001/BNQuoteService.wsdl This will create many files, the interesting one here is :file:`bnquoteservice-server.ads`, inside we have:: Port : constant := 80; generic with function getPrice (isbn : in String) return Float; function getPrice_CB (SOAPAction : in String; Payload : in SOAP.Message.Payload.Object; Request : in AWS.Status.Data) return AWS.Response.Data; This is a `SOAP AWS`'s callback routine that can be instantiated with the right routine to retrieve the price of a book given its ISBN number. A possible implementation of such routine could be:: function getPrice (isbn : in String) return Float is begin if isbn = "0987654321" then return 45.0; elsif ... end getPrice; function SOAP_getPrice is new BNQuoteService.Server.getPrice_CB (getPrice); `SOAP_getPrice` is a `SOAP AWS`'s callback routine (i.e. it is not a standard callback). To use it there is different solutions: *Using SOAP.Utils.SOAP_Wrapper* This generic function can be used to translate a standard callback based on `AWS.Status.Data` into a `SOAP` callback routine:: function getPrice_Wrapper is new SOAP.Utils.SOAP_Wrapper (SOAP_getPrice); The routine `getPrice_Wrapper` can be used as any other AWS's callback routines. Note that inside this wrapper the `XML` payload is parsed to check the routine name and to retrieve the `SOAP` parameters. To call this routine the payload needs to be parsed (we need to know which routine has be invoked). In this case we have parsed the `XML` payload twice, this is not efficient. *Building the wrapper yourself* This solution is more efficient if there is many `SOAP` procedures as the payload is parsed only once:: function CB (Request : in Status.Data) return Response.Data is SOAPAction : constant String := Status.SOAPAction (Request); Payload : constant SOAP.Message.Payload.Object := SOAP.Message.XML.Load_Payload (AWS.Status.Payload (Request), Schema => BNQuoteService.Schema); Proc : constant String := SOAP.Message.Payload.Procedure_Name (Payload); begin if SOAPAction = "..." then if Proc = "getPrice" then return SOAP_getPrice (SOAPAction, Payload, Request); elsif ... ... end if; else ... end if; Note that the port to be used by the AWS server is described in the server specification. .. _wsdl2aws: wsdl2aws -------- .. index:: wsdl2aws :: Usage: wsdl2aws [options] It is possible to pass a `WSDL` file or direct :file:`wsdl2aws` to a `WSDL` document on the Web by passing it's `URL`. `wsdl2aws` options are: *-q* Quiet mode (no output) *-d* Do not generate date/time in Ada comment. *-debug* Generate debug code. Will output some information about the payload to help debug a Web Service. *-a* Generate using Ada style names. For example `getPrice` will be converted to `Get_Price`. This formatting is done for packages, routines and formal parameters. *-f* Force creation of the file. Overwrite any exiting files with the same name. *-e URL* Specify the default endpoint to use instead of the one found in the WSDL document. *-s* Skip non supported `SOAP` routines. If `-s` is not used, `wsdl2aws` will exit with an error when a problem is found while parsing the `WSDL` document. This option is useful to skip routines using non supported types and still be able to compile the generated files. *-o name* Specify the name of the local `WSDL` document. This option can be used only when using a Web `WSDL` document (i.e. passing an URL to `wsdl2aws`). *-p name* Specify a name prefix for all SOAPActions defined in the `WDSL`. This option can be used when multiple WSDL generated callback are to be used together and some of the `WSDL` may have the same name. *-doc* Handle document style binding as RPC ones. This is sometimes needed because some `WSDL` document specify a document style binding even though the service behave like an RPC one. *-v* Verbose mode, display the parsed spec. *-v -v* Verbose mode, display the parsed spec and lot of information while parsing the `WSDL` document tree. *-wsdl* Add `WSDL` document as comment into the generated root unit. *-cvs* Add CVS Id tag in every generated file. *-nostub* Do not generated stubs, only skeletons are generated. *-noskel* Do not generated skeletons, only stubs are generated. *-cb* Generate a `SOAP` dispatcher callback routine for the server. This dispatcher routine contains the code to handle all the operations as described in the `WSDL` document. You need also to specify the `-spec` and/or `-types` options, see below. *-x operation* Add `operation` to the list of `SOAP` operations to skip during the code generation. It is possible to specify multiple `-x` options on the command line. *-spec spec* Specify the name of the spec containing the Ada implementation of the `SOAP` routines. This is used for example by the `-cb` option above to instantiate all the server side `SOAP` callbacks used by the main `SOAP` dispatcher routine. If `-types` is not specified, the type definitions are also used from this spec. *-types spec* Specify the name of the spec containing the Ada types (record, array) used by `SOAP` routines specified with option `-spec`. If `-spec` is not specified, the spec definitions are also used from this spec. *-main filename* Specify the name of the server's procedure main to generate. See below for the description about the way it is generated. *-n name* Specify the schema name space root name. The default value is "soapaws". *-proxy name|IP* Use this proxy to access the `WSDL` document and generate code to access to these Web Services via this proxy. The proxy can be specified by its DNS name or IP address. *-pu name* User name for the proxy if proxy authentication required. *-pp password* User password for the proxy if proxy authentication required. *-sp* Generate legacy Safe Pointers code for the support of array inside records. *-timeouts [timeouts | connect_timeout,send_timeout,receive_timeout ]* Set the timeouts for the SOAP connection. The timeouts is either a single value used for the connect, send and receive timeouts or three values separated by a colon to set each timeout independently. .. _wsdl2aws_code_generator: wsdl2aws code generator ----------------------- .. index:: Code generator .. highlight:: shell The `wsdl2aws` tool reads a `WSDL` document and generates - based on different templates files - a set of packages. The templates are rendered with the Templates_Parser engine. .. index:: Template files All the templates can be found in AWS installation under `share/examples/aws/wsdl2aws-templates`. They can be copied into the directory where `wsdl2aws` is started or pointed to by the environment variable `AWS_TEMPLATE_FILES`. One can then change the generated code by editing those templates. The generated packages and the corresponding templates are described below: ** Template:: s-root.tads This is the main package, it eventually contains the full `WSDL` in comments and the description of the services as read from the `WSDL` document. *._type_pkg* Templates:: s-name-space-pkg.tads s-type-record.tads s-type-record.tadb s-type-enum.tads s-type-enum.tadb s-type-derived.tads s-type-array.tads Contains all the type definitions for non standard Ada types. In these packages we find for example the definition of the records and the operations to convert them to/from SOAP objects. The types defined here have possible constraints like range attributes and/or Dynamic_Predicate aspects for Pattern and/or Length WSDL attributes. The root package is the name-space of the actual type. This ensure that no type name clash will happen. These packages are generally not directly withed. *.Types* Templates:: s-types.tads s-types.tadb s-type-record-types.tads s-type-enum-types.tads s-type-derived-types.tads s-type-array-types.tads s-stub-types.tads This package contains the definitions of the types which are not `SOAP` base types. We find here the definitions of the `SOAP` structs and arrays with routines to convert them between the Ada and `SOAP` type model. A subtype definition is also created for every routine's returned type. In fact, all definitions here are only aliases or renamings of types and/or routines generated in other packages rooted with a name-space as described above. This package is the one that user's should import to gain visibility to the type definitions. This package also contains the schema object which must be used when calling a Web service or parsing a payload. *.Client* Templates:: s-stub.tads s-stub.tadb All specifications to call Web Services. *.Server* Templates:: s-skel.tads s-skel.tadb All specifications to build Web Services. These specifications are all generic and must be instantiated with the correct routine to create the web services. *.CB* Templates:: s-skel-cb.tads s-skel-cb.tadb The `SOAP` dispatcher callback routine. *
* Template:: s-main.tadb The template used to generate the main procedure (see option -main). The template can reference the following variable tags: .. highlight:: ada *SOAP_SERVICE* The name of the service as described into the `WSDL` document. This tag can be used to include the right units:: with @_SOAP_SERVICE_@.Client; with @_SOAP_SERVICE_@.CB; *SOAP_VERSION* The AWS's SOAP version. *AWS_VERSION* The AWS's version. *UNIT_NAME* The name of the generated unit. This is the name of the procedure that will be created:: procedure @_UNIT_NAME_@ is begin ... .. _wsdl2aws_limitations: wsdl2aws limitations -------------------- .. index:: wsdl2aws limitations It is hard to know all the current limitations due to the complexity of the `WSDL` and `SOAP` world is quite complex. We list there all known limitations: * Some `SOAP` base types are not currently supported: *date, time, xsd:hexBinary, decimal*, but all (with the exception of decimal) should be simple to add in the future. * Multi-dimensional arrays are not supported. * Abstract types are not supported. * SOAP MIME attachments are not supported. * WSDL type inheritance is not supported. * The Document/Encoded SOAP messages' style is not supported. * complexType with xs:choice are only supported with a single occurence of each choice. .. _awsascb: awsascb ------- .. index:: awsascb The awsascb (AWS Aggregate Server Callback) tool can be used to aggregate multiple SOAP callback together. That is, after generating multiple SOAP callbacks with wsdl2aws it may be necessary to create a single server handling all the services. This tools is designed for this. :: Usage: awsascb There are no option for this tool. The `root` parameters are the `wsdl2aws` generated root service name units. This tool generates a unit named `agg_server_cb` which contains a SOAP callback and a dispatcher to be used by the server's main subprogram. Here is the specification:: -- DO NOT EDIT : generated by awsasc with AWS.Response; with AWS.Status; with SOAP.Dispatchers.Callback; with SOAP.Message.Payload; with SOAP.WSDL.Schema; package Agg_Server_CB is use AWS; use SOAP; pragma Style_Checks (Off); type Handler is new SOAP.Dispatchers.Callback.Handler with null record; overriding function Schema (Dispatcher : Handler; SOAPAction : String) return WSDL.Schema.Definition; function Create (HTTP_Callback : AWS.Response.Callback) return Handler; -- Returns an handler whose SOAP_Callback is the one below function SOAP_CB (SOAPAction : String; Payload : Message.Payload.Object; Request : AWS.Status.Data) return Response.Data; end Agg_Server_CB; And following is an example on using such generated aggregate server callback from a server's main:: WS : Server.HTTP; Conf : Config.Object; Disp : Agg_Server_CB.Handler; begin Config.Set.Server_Port (Conf, 0); Disp := Agg_Server_CB.Create (HTTP_CB'Access); AWS.Server.Start (WS, Disp, Conf); .. _Using_ada2wsdl_and_wsdl2aws_together: Using ada2wsdl and wsdl2aws together ==================================== Using both tools together is an effective way to rapidly build a `SOAP` server. It can be said that doing so is quite trivial in fact. Let's take the following spec:: package Graphics is type Point is record X, Y : Float; end record; function Distance (P1, P2 : in Point) return Float; -- Returns the distance between points P1 and P2 end Graphics; We do not show the body here but we suppose it is implemented. To build a server for this service it is as easy as:: $ ada2wsdl -a http://localhost:8787 -o graphics.wsdl graphics.ads The server will be available on localhost at port 8787:: $ wsdl2aws -cb -main server -types graphics graphics.wsdl $ gnatmake server -largs ... Options *-cb* is to create the `SOAP` dispatcher callback routine, *-main server* to generate the main server procedure in :file:`server.adb`, *-types graphics* to use :file:`graphics.ads` to get references for user's specification (reference to `Graphics.Point` for example).