Specifications for using the MUX

Introduction

Communication to the MUX happens over the World Wide Web (WWW). The MUX is attached to a standard WWW server, and can thus be given input through the standard CGI method, using either POST protocols. Its output is delivered over the same means, as a response to the input. When presented an HL7 batch conforming to specifications, it will return an HL7 batch as a response. The specifications are as follows:

Expected

BHS
{ MSH (one or more HL7 messages)
...
...
...
}
BTS

Broadcast

If the goal is to send the message to all affiliated site servers, there should be only one message in the whole batch, and its MSH segment should contain the following values:

segment	field number	name	expected value
BHS	5	receiving application	MUX
BHS	6	receiving facility	MUX

Directed delivery

If the goal is to deliver each message in the batch to a specific site, the following values are expected to be present in each MSH segment in the batch:

segment	field number	name	expected value
MSH	5	receiving application	the name of the site to send this message to
MSH	6	receiving facility	the name of the site to send this message to

Output

The following is an example of a JAVA program that can speak to the MUX:

import java.lang.*;
import java.net.*;
import java.io.*;

import util.*;

/**
 * This class can be used as a standalong program to test the MUX at the
 * level of HL7
 */
public class MuxTest {
  /* WebPost is able to accept a HL7 batch string, add some necessary
   * headers for Web, and send it to the server. Then it wait until the
   * result comes back.  After deleting the Web headers at the beginning
   * of the result, WebPost returns a pure HL7 batch as result
   */
  WebPost wp;

  static public void main(String[] args){
    //demograph query
    String queryStr=
"BHS|^~\\&|disag|1111-1111-11|MUX|MUX|19960609173050||||19960609173050-disag-1111-1111-11||\u000D"+
"MSH|^~\\&|agglutinator|1111-1111-11|MUX||19960116184604||RQI^A04|19960116184604-agglutinator-1111-1111-11|P|2.2|||NE|NE|\u000D"+
"QRD|19960116184604|I||19960116184604-RQI-agglutinator-1111-1111-11|||10000^LI|888887|OTH|ALL\u000D"+
  "QRF|ALL|18000101|19960216|||ANY|ANY|ALL\u000D"+
  "PID|||||ALLEN^FRIEDA||19260803|F|||||||||||||||||||\u000D"+
  "BTS|2||\u000D";

    WebPost wp=new WebPost("chip.tch.harvard.edu", 4949,
"/server-java/MainURL", "MUX");
    String result=wp.getAnswer(queryStr);
    System.out.println(result);
  }
}

*******Implementation of WebPost

import java.lang.*;
import java.net.*;
import java.io.*;
import java.util.*;

/**
 * A class that post queries to a given server
 */
public class WebPost {
  String server;
  String cgi;
  int port;
  String appID;

  /**
   *Store the information for the construction of a WEB connection
   */
  public WebPost(String server, int port, String cgi, String appID)
  {
    this.server=server;
    this.cgi=cgi;
    this.port=port;
    this.appID=appID;
  }

  public String getAnswer(String query)
  {
    String out = "";
    try{
      Socket s = new Socket(server, port);
      OutputStream os = s.getOutputStream();

      //add header and send the query
      String httpStr=
        "POST "+cgi+" HTTP/1.0\n"+
        "Content-type: application/x-www-form-urlencoded\n"+
        "Referer: "+appID+"\n"+
        "Accept: */*\n"+
        "Content-length: "+query.length()+"\n\n"+
        query;

      byte httpBytes[]=new byte[httpStr.length()];

      httpStr.getBytes(0,httpStr.length(),httpBytes,0);
      os.write(httpBytes);
      os.flush();

      //get the answer and delete the header
      InputStream is = s.getInputStream();
      DataInputStream di = new DataInputStream(is);
      String line;

      boolean httpHeader=true;
      String hl7Header;

      //the following code only works if MSH or BHS appears in the first
      //10000 bytes
      int bytesRead;
      byte buf[]=new byte[10000];
      int offset=0;
      while ( (bytesRead=is.read(buf, offset, buf.length-offset))!=-1){
        line=new String(buf,0,0,offset+bytesRead);

        if (httpHeader)
          try {
            int mshIdx=line.indexOf("MSH");
            int bhsIdx=line.indexOf("BHS");
            int idx=0;

            if (mshIdx==-1 && bhsIdx==-1)
              idx=-1;
            if (mshIdx==-1 && bhsIdx!=-1)
              idx=bhsIdx;
            if (mshIdx!=-1 && bhsIdx==-1)
              idx=mshIdx;

            if (idx==-1){
              offset=offset+bytesRead;
              continue;
            }

            out=out+line.substring(idx, line.length());
            offset=0;
            httpHeader=false;
          } catch (Exception e) {}
        else {
          offset=0;
          out=out+line;
        }
      }

      s.close();
    } catch (IOException e) {out="Error: "+e.getMessage();}

    return out;
  }
}